You searched for subject:(Isogeometric analysis).
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University of New South Wales
1.
Wang, Junchao.
Integrating CAD Geometry and Scaled Boundary Finite Element Analysis.
Degree: Civil & Environmental Engineering, 2018, University of New South Wales
URL: http://handle.unsw.edu.au/1959.4/60921 
;
https://unsworks.unsw.edu.au/fapi/datastream/unsworks:54292/SOURCE02?view=true
► The Finite element method (FEM) constitutes a general tool for the numerical solution of partial differential equations in engineering and applied science. Great amount of…
(more)
▼ The Finite element method (FEM) constitutes a general tool for the numerical solution of partial differential equations in engineering and applied science. Great amount of research has been conducted on FEM in terms of mathematics and applications, contributing to its dominance over numerical method in solid mechanics and structural
analysis. Although it is a principle method for solving complex problems in the engineering field, deficiency in geometric representation has been detected. Besides, it could be expensive in terms of time and human resource to create the mesh required by the FEM.The research towards integrating geometry and
analysis has led to the ‘
Isogeometric Analysis’ (IGA) (Hughes et al., 2005).However, as the CAD model provides information only of the boundary, a 2D/3D stress
analysis is still one major step away.This thesis presents a simple and efficient technique based on the combination of the scales boundary finite element method (SBFEM), automatic mesh generation and adaptive refinement algorithms to reduce the human efforts in the structural
analysis. In the SBFEM, only the boundary information is required and hence a seamless integration can be provided with the CAD modelling. The NURBS basis functions are adopted to discretize the unknown fields in the circumferential direction within the proposed framework, whilst analytical solution is sought in the radial direction. This framework will also be further extended to problems with singularities and to dynamic
analysis.To mode problems with complex geometries, the problems domains are divided into a mesh of scaled boundary finite elements. A quad-tree based mesh generation algorithm is developed. High quality mesh will be generated with the help of the algorithm and the computational cost will also be improved due to the utilization of the patterns in the quad-tree. Furthermore, no human efforts are required for the pre-processing as the output of the CAD software (i.e. IGES file) will be used to determine the geometric information automatically. Any mismatch between the geometric representation in design and in numerical
analysis may be prevented as the design is used directly.To ensure a controllable accuracy and minimal computational cost, an adaptive and robust mesh refinement algorithm is also developed to prevent unnecessary refinement in the region which contributes little to the improvement to the accuracy. The expressions related to the eigenvalues of the SBFEM formulation representing the quantity of the error in the interpolation are adopted as one of the error indicators, together with the area and other geometric properties of the Scaled Boundary Finite Element. A machine learning model using the Multilayer Perceptron (MLP) is trained to determine whether a Scaled Boundary Finite Element needs refinement or not based on all these information.The proposed method is further extended to 3D with an initial mesh generated based on the STL file and octree algorithm. The octree mesh provides a high quality mesh in 3D for SBFEM and the…
Advisors/Committee Members: Chongmin, Song, Civil & Environmental Engineering, Faculty of Engineering, UNSW.
Subjects/Keywords: Computational mechanics; Isogeometric analysis
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APA (6th Edition):
Wang, J. (2018). Integrating CAD Geometry and Scaled Boundary Finite Element Analysis. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/60921 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:54292/SOURCE02?view=true
Chicago Manual of Style (16th Edition):
Wang, Junchao. “Integrating CAD Geometry and Scaled Boundary Finite Element Analysis.” 2018. Doctoral Dissertation, University of New South Wales. Accessed April 12, 2021.
http://handle.unsw.edu.au/1959.4/60921 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:54292/SOURCE02?view=true.
MLA Handbook (7th Edition):
Wang, Junchao. “Integrating CAD Geometry and Scaled Boundary Finite Element Analysis.” 2018. Web. 12 Apr 2021.
Vancouver:
Wang J. Integrating CAD Geometry and Scaled Boundary Finite Element Analysis. [Internet] [Doctoral dissertation]. University of New South Wales; 2018. [cited 2021 Apr 12].
Available from: http://handle.unsw.edu.au/1959.4/60921 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:54292/SOURCE02?view=true.
Council of Science Editors:
Wang J. Integrating CAD Geometry and Scaled Boundary Finite Element Analysis. [Doctoral Dissertation]. University of New South Wales; 2018. Available from: http://handle.unsw.edu.au/1959.4/60921 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:54292/SOURCE02?view=true
University of Texas – Austin
2.
Lynd, Eric Alexander.
An exploration of the IGA method for efficient reservoir simulation.
Degree: MSin Engineering, Petroleum Engineering, 2017, University of Texas – Austin
URL: http://hdl.handle.net/2152/64254
► Novel numerical methods present exciting opportunities to improve the efficiency of reservoir simulators. Because potentially significant gains to computational speed and accuracy may be obtained,…
(more)
▼ Novel numerical methods present exciting opportunities to improve the efficiency of reservoir simulators. Because potentially significant gains to computational speed and
accuracy may be obtained, it is worthwhile explore alternative computational algorithms
for both general and case-by-case application to the discretization of the equations of porous media flow, fluid-structure interaction, and/or production. In the present
work, the fairly new concept of
isogeometric analysis (IGA) is evaluated for its suitability
to reservoir simulation via direct comparison with the industry standard finite difference (FD) method and 1st order standard finite element method (SFEM). To this end, two main studies are carried out to observe IGA’s performance with regards to geometrical modeling and ability to capture steep saturation fronts. The first study explores IGA’s ability to model complex reservoir geometries, observing L2 error convergence rates under a variety of refinement schemes. The numerical experimental setup includes an 'S' shaped line sink of varying curvature from which water is produced in a 2D homogenous domain. The accompanying study simplifies the domain to 1D, but adds in multiphase physics that traditionally introduce difficulties associated with modeling of a moving saturation front. Results overall demonstrate promise for the IGA method to be a particularly effective tool in handling geometrically difficult features while also managing typically challenging numerical phenomena.
Advisors/Committee Members: Foster, John T., Ph. D. (advisor), Nguyen, Quoc P. (advisor).
Subjects/Keywords: Isogeometric analysis; Reservoir simulation
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APA (6th Edition):
Lynd, E. A. (2017). An exploration of the IGA method for efficient reservoir simulation. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/64254
Chicago Manual of Style (16th Edition):
Lynd, Eric Alexander. “An exploration of the IGA method for efficient reservoir simulation.” 2017. Masters Thesis, University of Texas – Austin. Accessed April 12, 2021.
http://hdl.handle.net/2152/64254.
MLA Handbook (7th Edition):
Lynd, Eric Alexander. “An exploration of the IGA method for efficient reservoir simulation.” 2017. Web. 12 Apr 2021.
Vancouver:
Lynd EA. An exploration of the IGA method for efficient reservoir simulation. [Internet] [Masters thesis]. University of Texas – Austin; 2017. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2152/64254.
Council of Science Editors:
Lynd EA. An exploration of the IGA method for efficient reservoir simulation. [Masters Thesis]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/64254
University of Texas – Austin
3.
Kamensky, David Michael.
Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.
Degree: PhD, Computational science, engineering, and mathematics, 2016, University of Texas – Austin
URL: http://hdl.handle.net/2152/46874
► The purpose of this dissertation is to develop numerical methods for fluid–structure interaction (FSI) analysis that are suitable for modeling and simulating bioprosthetic heart valves…
(more)
▼ The purpose of this dissertation is to develop numerical methods for fluid–structure interaction (FSI)
analysis that are suitable for modeling and simulating bioprosthetic heart valves (BHVs). BHVs are prosthetic replacements for the valves that regulate blood flow through the heart. BHVs reproduce natural hemodynamic conditions by mimicking the structure of native heart valves: they consist of thin flexible leaflets, passively driven by interaction with surrounding fluid. Current designs frequently require replacement 10–15 years after implantation. Computer simulation may help identify causes of and solutions to durability issues. Despite much previous research into computer simulation of heart valve FSI, inconvenience or inaccuracy of readily available numerical methods have prevented widespread incorporation of FSI into models of heart valve mechanics. Challenges associated with heart valve FSI simulation include large deformations of the region occupied by fluid, with changes of topology as the valve opens and closes, and low mass of the structure relative to the fluid, which necessitates careful treatment of fluid–structure coupling. The presence of large pressure gradients also requires special attention to the treatment of fluid mass conservation. Further, a useful numerical method for studying and improving designs of BHVs should be able to capture variations of valve geometry without requiring major effort to construct geometry-specific discretizations. To meet these challenges, I develop a new numerical approach, combining the immersed boundary concept of capturing fluid–structure interfaces on unfitted discretizations with recent developments in
isogeometric analysis (IGA), which directly uses geometrical designs of engineered systems as discrete
analysis meshes. In this work, I immerse an
isogeometric structure discretization into an unfitted
analysis mesh of the fluid subproblem. I refer to the immersion of design geometries into unfitted
analysis meshes as immersogeometric
analysis. To reliably couple unfitted discretizations of the fluid and structure subproblems, I introduce a new semi-implicit time integration procedure and analyze its stability and convergence in the context of linear model problems. I verify that this
analysis extrapolates to the nonlinear setting through numerical experiments and explore the validity of my modeling assumptions by comparing computer simulations with observations from an in vitro experiment.
Advisors/Committee Members: Sacks, Michael S. (advisor), Hughes, Thomas J. R. (advisor), Ghattas, Omar (committee member), Moser, Robert D (committee member), Hsu, Ming-Chen (committee member).
Subjects/Keywords: Fluid–structure interaction; Isogeometric analysis; Immersogeometric analysis
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APA (6th Edition):
Kamensky, D. M. (2016). Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46874
Chicago Manual of Style (16th Edition):
Kamensky, David Michael. “Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021.
http://hdl.handle.net/2152/46874.
MLA Handbook (7th Edition):
Kamensky, David Michael. “Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.” 2016. Web. 12 Apr 2021.
Vancouver:
Kamensky DM. Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2152/46874.
Council of Science Editors:
Kamensky DM. Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/46874
Delft University of Technology
4.
Salden, P.H.W. (author).
Consistent formulation in isogeometric topology optimization for structural applications.
Degree: 2016, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd
► Topology optimization is an automated design approach for structural applications that is gaining popularity in industry, including the aerospace sector. Resulting designs can be made…
(more)
▼ Topology optimization is an automated design approach for structural applications that is gaining popularity in industry, including the aerospace sector. Resulting designs can be made suitable for traditional manufacturing techniques, although it is a technique that is particularly useful for non-conventional approaches such as additive manufacturing. The procedure allows for choosing a design objective, such as minimum compliance or maximum heat conduction. Given one or more constraints, the optimal distribution of material within a domain is computed. A popular topology optimization method is the so-called Solid Isotropic Material with Penalization (SIMP). It is traditionally implemented using piecewise constant density values, specified per element. One technical difficulty with this approach is the formation of “checkerboard-like” patterns where the material is assigned to one element while the adjacent elements contain no material. This issue has been circumvented through the application of filters that explicitly prevent the formation of checkerboards. However, as a result of the filtering process, the designs display structural members with relatively high thicknesses and, at the same time, the structural detail level is relatively low. Several authors in the scientific literature argue that this effect is beneficial from a manufacturing viewpoint. However, recent progress in manufacturing techniques, such as additive manufacturing (also known as 3D-printing), allows to manufacture components with an increased level of detail and complexity. From this point of view, it is relevant to study optimization procedures that preserve the level of detail displayed by unfiltered designs. In this project, SIMP is implemented using Isogeometric Analysis (IGA). In IGA, Non-Uniform Rational B-Splines (NURBS) replace the Lagrange polynomials classically used in Finite Element Analysis (FEA). Through the use of Bézier extraction, implementation changes are confined to the “shape routine”. Rather than working with piecewise constant density values, density is consistently approximated using NURBS. A consistent gradient formulation is derived as well. The effects on checkerboard formation are studied. Instead of filtering, separate meshes are used for density and displacement definition. A displacement mesh is obtained by further refining the density mesh, such that the displacement representation is more accurate. Adequate procedures for Gaussian integration are determined. The treatment is limited to two dimensional minimum compliance problems. It is found that a consistent density representation using NURBS does not prevent checkerboard formation. However, the use of separate meshes for density and displacement diminishes checkerboards. It also generates more detailed designs than those produced by filters. Obtained compliance values are lower as well. Through the use of IGA, arc-like geometries may be studied. At the same time, non-classical checkerboard patterns are observed.
Aerospace Engineering
Aerospace…
Advisors/Committee Members: Turteltaub, S.R. (mentor).
Subjects/Keywords: topology optimization; isogeometric analysis; SIMP; Bézier extraction
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APA (6th Edition):
Salden, P. H. W. (. (2016). Consistent formulation in isogeometric topology optimization for structural applications. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd
Chicago Manual of Style (16th Edition):
Salden, P H W (author). “Consistent formulation in isogeometric topology optimization for structural applications.” 2016. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd.
MLA Handbook (7th Edition):
Salden, P H W (author). “Consistent formulation in isogeometric topology optimization for structural applications.” 2016. Web. 12 Apr 2021.
Vancouver:
Salden PHW(. Consistent formulation in isogeometric topology optimization for structural applications. [Internet] [Masters thesis]. Delft University of Technology; 2016. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd.
Council of Science Editors:
Salden PHW(. Consistent formulation in isogeometric topology optimization for structural applications. [Masters Thesis]. Delft University of Technology; 2016. Available from: http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd
5.
Kadapa, Chennakesava.
Mixed Galerkin and least-squares formulations for isogeometric analysis.
Degree: PhD, 2014, Swansea University
URL: https://cronfa.swan.ac.uk/Record/cronfa42221
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678592
► This work is concerned with the use of isogeometric analysis based on Non- Uniform Rational B-Splines (NURBS) to develop efficient and robust numerical techniques to…
(more)
▼ This work is concerned with the use of isogeometric analysis based on Non- Uniform Rational B-Splines (NURBS) to develop efficient and robust numerical techniques to deal with the problems of incompressibility in the fields of solid and fluid mechanics. Towards this, two types of formulations, mixed Galerkin and least-squares, are studied. During the first phase of this work, mixed Galerkin formulations, in the context of isogeometric analysis, are presented. Two-field and three-field mixed variational formulations - in both small and large strains - are presented to obtain accurate numerical solutions for the problems modelled with nearly incompressible and elasto-plastic materials. The equivalence of the two mixed formulations, for the considered material models, is derived; and the computational advantages of using two-field formulations are illustrated. Performance of these formulations is assessed by studying several benchmark examples. The ability of the mixed methods, to accurately compute limit loads for problems involving elastoplastic material models; and to deal with volumetric locking, shear locking and severe mesh distortions in finite strains, is illustrated. Later, finite element formulations are developed by combining least-squares and isogeometric analysis in order to extract the best of both. Least-squares finite element methods (LSFEMs) based on the use of governing differential equations directly - without the need to reduce them to equivalent lower-order systems - are developed for compressible and nearly incompressible elasticity in both the small and finite strain regimes; and incompressible Navier-Stokes. The merits of using Gauss-Newton scheme instead of Newton-Raphson method to solve the underlying nonlinear equations are presented. The performance of the proposed LSFEMs is demonstrated with several benchmark examples from the literature. Advantages of using higher-order NURBS in obtaining optimal convergence rates for non-norm-equivalent LSFEMs; and the robustness of LSFEMs, for Navier-Stokes, in obtaining accurate numerical solutions without the need to incorporate any artificial stabilisation techniques, are demonstrated.
Subjects/Keywords: 518; Isogeometric analysis; Galerkin methods; Least squares
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APA (6th Edition):
Kadapa, C. (2014). Mixed Galerkin and least-squares formulations for isogeometric analysis. (Doctoral Dissertation). Swansea University. Retrieved from https://cronfa.swan.ac.uk/Record/cronfa42221 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678592
Chicago Manual of Style (16th Edition):
Kadapa, Chennakesava. “Mixed Galerkin and least-squares formulations for isogeometric analysis.” 2014. Doctoral Dissertation, Swansea University. Accessed April 12, 2021.
https://cronfa.swan.ac.uk/Record/cronfa42221 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678592.
MLA Handbook (7th Edition):
Kadapa, Chennakesava. “Mixed Galerkin and least-squares formulations for isogeometric analysis.” 2014. Web. 12 Apr 2021.
Vancouver:
Kadapa C. Mixed Galerkin and least-squares formulations for isogeometric analysis. [Internet] [Doctoral dissertation]. Swansea University; 2014. [cited 2021 Apr 12].
Available from: https://cronfa.swan.ac.uk/Record/cronfa42221 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678592.
Council of Science Editors:
Kadapa C. Mixed Galerkin and least-squares formulations for isogeometric analysis. [Doctoral Dissertation]. Swansea University; 2014. Available from: https://cronfa.swan.ac.uk/Record/cronfa42221 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678592
University of Texas – Austin
6.
-5607-5242.
Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity.
Degree: PhD, Mechanical Engineering, 2016, University of Texas – Austin
URL: http://hdl.handle.net/2152/68545
► In the field of Computer-Aided Geometric Modeling (CAGD) stands one critical problem that plagues not only users of Computer-Aided Design (CAD) applications, but all downstream…
(more)
▼ In the field of Computer-Aided Geometric Modeling (CAGD) stands one critical problem that plagues not only users of Computer-Aided Design (CAD) applications, but all downstream uses of a geometric model, namely, computational
analysis, animation, graphics, rendering, metrology, manufacturing, and 3D printing. When complicated real world models are created using the core Boolean operations of a CAD program, massive numbers of approximations set off a cascade of consequences that requires extensive additional CAD infrastructure, creates models unfit for direct downstream use, and necessitates entire industries to mitigate the crippling side effects. Termed the surface-surface intersection (SSI) issue, or trim problem, intersecting spline surfaces are known to create complex nonlinear exact solutions of a very high degree. CAD applications have addressed this by approximating these intersections and introducing gaps between the discrete surfaces, using an independent topological structure to then manage model integrity through solid modeling processes. This document accepts the intersection approximation as an unavoidable computational circumstance and uses this to update the otherwise independent surfaces to create a single conformal, watertight model. This is accomplished using a novel approach that first analyzes the trim geometry and topology, and then uses this information to form an admissible global parameter space. The attention to parameter space management is often an underappreciated and neglected process that is shown to be critical in any sound solution to the trim problem. Finally, the model space geometry is updated to embed the trim information while maintaining the existing trajectories and continuities of the original objects. This is accomplished through solving a system of isoparametric curve equations, under the right constraints, in reverse, a surface creation strategy without precedent in CAGD literature. The result is a watertight model representing the users' deign intent and ready for downstream processing, e.g. computational
analysis, without the need of the current immense framework of amelioration.
Advisors/Committee Members: Crawford, Richard H. (advisor), Hughes, Thomas J. (committee member), Cohen, Elaine (committee member), Riesenfeld, Richard F. (committee member), Fahrenthold, Eric P. (committee member), Beaman, Joseph J. (committee member).
Subjects/Keywords: CAGD; Trim; Surface-surface intersection; Isogeometric analysis
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APA ·
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APA (6th Edition):
-5607-5242. (2016). Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68545
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-5607-5242. “Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021.
http://hdl.handle.net/2152/68545.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-5607-5242. “Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity.” 2016. Web. 12 Apr 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-5607-5242. Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2152/68545.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-5607-5242. Reconstruction of tensor product spline surfaces to integrate surface-surface intersection geometry and topology while maintaining inter-surface continuity. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/68545
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
7.
Taus, Matthias Franz.
Isogeometric Analysis for boundary integral equations.
Degree: PhD, Computational Science, Engineering, and Mathematics, 2015, University of Texas – Austin
URL: http://hdl.handle.net/2152/32824
► Since its emergence, Isogeometric Analysis (IgA) has initiated a revolution within the field of Finite Element Methods (FEMs) for two reasons: (i) geometry descriptions originating…
(more)
▼ Since its emergence,
Isogeometric Analysis (IgA) has initiated a revolution within the field of Finite Element Methods (FEMs) for two reasons: (i) geometry descriptions originating from Computer Aided Design (CAD) can be used directly for
analysis purposes, and (ii) the availability of smooth exact geometry descriptions and smooth basis functions can be used to develop new, highly accurate and highly efficient numerical methods. Whereas in FEMs the first issue is still open, it has already been shown that
Isogeometric BEMs (IBEMs) provide a complete design-through-
analysis framework. However, in contrast to FEMs, the effect of smoothness provided by IgA has not yet been explored in IBEMs. In this dissertation, we address this aspect of IgA. We show that the smoothness and exactness properties provided by the IgA framework can be used to design highly accurate and highly efficient BEMs which are not accessible with conventional BEMs. We develop Collocation IBEMs on piecewise smooth geometries. This allows us to show that IBEMs converge in the expected rates and result in system matrices with mesh-independent condition numbers. The latter property is particularly beneficial for large-scale problems that require iterative linear solvers. However, using conventional Collocation BEMs, this approach is not accessible because hyper-singular integrals have to be evaluated. In contrast, using Collocation IBEMs, the smoothness properties of the IgA framework can be used to regularize the hyper-singular integrals and reduce them to weakly singular integrals which can be evaluated using well-known techniques. We perform several numerical examples on canonical shapes to show these results. In addition, we use well-known mathematical results to develop a sound theoretical foundation to some of our methods, a result that is very rare for Collocation discretizations. Finally, using the exactness of IgA geometry descriptions, we design Patch Tests that allow one to rigorously test IBEM implementations. We
subject our implementation to these Patch Tests which not only shows the reliability of our method but also shows that IBEMs can be as accurate as machine precision. We apply our IBEMs to Laplace's equation and the equations of linear elasticity. In addition, input files for our implementation can be automatically obtained from commercial CAD packages. These practical aspects allow us to apply IBEMs to analyze a propeller under a wind load.
Advisors/Committee Members: Rodin, G. J. (Gregory J.) (advisor), Hughes, Thomas J. R. (advisor), Demkowicz, Leszek F. (committee member), Biros, George (committee member), Sayas, Francisco Javier (committee member).
Subjects/Keywords: Boundary integral equations; Isogeometric Analysis; Boundary element methods; Isogeometric boundary element methods; Collocation
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APA (6th Edition):
Taus, M. F. (2015). Isogeometric Analysis for boundary integral equations. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32824
Chicago Manual of Style (16th Edition):
Taus, Matthias Franz. “Isogeometric Analysis for boundary integral equations.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021.
http://hdl.handle.net/2152/32824.
MLA Handbook (7th Edition):
Taus, Matthias Franz. “Isogeometric Analysis for boundary integral equations.” 2015. Web. 12 Apr 2021.
Vancouver:
Taus MF. Isogeometric Analysis for boundary integral equations. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2152/32824.
Council of Science Editors:
Taus MF. Isogeometric Analysis for boundary integral equations. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32824
8.
Blidia, Ahmed.
Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields.
Degree: Docteur es, Mathématiques, 2020, Université Côte d'Azur
URL: http://www.theses.fr/2020COAZ4015
► Dans les systèmes de CAO, une fonction polynomiale par morceaux se trouve derrière toute représentation de courbe, de surface ou de champ scalaire. Ainsi, il…
(more)
▼ Dans les systèmes de CAO, une fonction polynomiale par morceaux se trouve derrière toute représentation de courbe, de surface ou de champ scalaire. Ainsi, il est important d'analyser les propriétés des espaces des fonctions polynomiales par morceaux. Dans cette thèse, nous étudions des outils d'algèbre commutative qui peuvent être utilisés pour analyser la dimension d'espaces polynomiaux par morceaux et pour en construire des bases. Nous testons les méthodes que nous produisons pour modéliser des surfaces de forme libre et pour des calculs d'analyse numérique.La principale motivation du concept de continuité géométrique est la construction de surfaces multi-patchs et de champs scalaires. Le principal défi dans ce type de surfaces est de gérer les zones de la surface autour des sommets avec un certain nombre de patchs voisins différents de 4 (que nous appelons sommets extraordinaires). Dans ces régions, les méthodes de collage habituelles provoqueront l'apparition de singularités. La continuité géométrique est un moyen spécial de coller deux patchs de surface 3D le long de leur bord commun dans une surface multi-patchs, et qui produit des surfaces lisses même autour de sommets extraordinaires.La condition de collage de continuité géométrique est exprimée en termes de relations linéaires entre les paramétrisations des surfaces le long des bords de jonction. Les coefficients de ces relations sont appelés les données de collage, et le choix est crucial pour la régularité de la surface résultante. Les données de collage que nous proposons sont des fonctions splines qui respectent la contrainte de lissage telle que la contrainte d'enceinte de sommet. Nous expliquons notre choix en fournissant une formule que les données de collage doivent respecter à chaque sommet extraordinaire.Nous exigeons que la spline géométriquement continue (Nous appelons Gsplines les splines géométriquement continues) que nous produisons pour pouvoir interpoler n'importe quelle position donnée des sommets de son maillage correspondant. C'est ce que nous appelons la condition de séparabilité. Nous décrivons les conditions sur les données de collage qui permettent à l'espace d'être séparable, et donnons une liste d'exemples de telles données de collage. Le manuscrit décrit également un «schéma d'assemblage» qui permet de produire une base pour l'espace des Gsplines.Nous avons abordé la possibilité d'étendre les méthodes d'homologie existantes pour analyser la dimension de l'espace spline avec des conditions de continuité géométrique. Ces extensions fournissent de nombreuses formules qui expriment les dimensions de nos espaces splines au moyen d'autres groupes d'homologie.Notre analyse de cet espace conduit à trois applications : La première est un algorithme qui, étant donné un maillage, produit une surface lisse qui s'en rapproche. Cet algorithme est basé sur la projection de la surface approximative catmull-clark sur l'espace des splines que nous produisons. Les deux autres tests portent sur la reconstruction de surfaces lisses et l'analyse…
Advisors/Committee Members: Mourrain, Bernard (thesis director).
Subjects/Keywords: Continuité géometrique; Splines; Analyse IsoGeometric; Reconstruction de surface; Geometric continuity; Splines; IsoGeometric analysis; Surface reconstruction
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APA (6th Edition):
Blidia, A. (2020). Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields. (Doctoral Dissertation). Université Côte d'Azur. Retrieved from http://www.theses.fr/2020COAZ4015
Chicago Manual of Style (16th Edition):
Blidia, Ahmed. “Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields.” 2020. Doctoral Dissertation, Université Côte d'Azur. Accessed April 12, 2021.
http://www.theses.fr/2020COAZ4015.
MLA Handbook (7th Edition):
Blidia, Ahmed. “Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields.” 2020. Web. 12 Apr 2021.
Vancouver:
Blidia A. Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields. [Internet] [Doctoral dissertation]. Université Côte d'Azur; 2020. [cited 2021 Apr 12].
Available from: http://www.theses.fr/2020COAZ4015.
Council of Science Editors:
Blidia A. Continuité géométrique pour les surfaces et les champs scalaires : Geometric continuity for surfaces and scalar fields. [Doctoral Dissertation]. Université Côte d'Azur; 2020. Available from: http://www.theses.fr/2020COAZ4015
Delft University of Technology
9.
Meijer, Moos (author).
Isogeometric Potential Flow Analysis of Linear Surface Waves.
Degree: 2018, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:0e0fc9c8-6c42-465e-9fb5-41342aa04f84
► In numerical methods, correct geometry description and mesh refinement are a challenge. By using a more geometrically based Finite Element Analysis (FEA) type method called…
(more)
▼ In numerical methods, correct geometry description and mesh refinement are a challenge. By using a more geometrically based Finite Element
Analysis (FEA) type method called ‘
Isogeometric Analysis’ (IGA), exact geometry description can be attained, even on coarse meshes. Furthermore, mesh refinement is relatively easy, since no communication with a geometry description is necessary. From a maritime perspective, this method seems to be very interesting. Therefore, a first step towards an all-inclusive IGA framework for potential flow problems of ships and offshore structures is made by using IGA to solve linear free surface waves in a bounded 2D and 3D domain. The goal of this thesis is twofold. The first goal is finding out which of three weak formulations is best suited for further development. The second goal is testing the advantages of IGA in a potential frame work. A secondary goal is testing MFEM, the C++ finite element library that was used. These goals were reached by testing the three formulations on (1) a sloshing wave, (2) an airy wave and (3) a step wave in a square tank of 1 square m and (4) a sloshing wave in a cubic tank of 1 cubic m3with a cylinder in the middle. The first two have analytical solutions that can be used for verification and validation, the last two are used to compare standard FEA with IGA. The three weak formulations are formed by transforming the strong problem definition into three different weak forms. The main difference between these three being the way the boundary conditions are implemented. The first, reduced formulation is formed by combining the free surface boundary conditions, the second, mixed formulation by implementing all three boundary conditions directly and the third decoupled formulation by decoupling the problem into a free surface and an interior part. The first formulation is the simplest, but is hard to extend towards more complicated problems and is therefore used as a reference solution. The mixed and decoupled formulations are more complicated but can be extended. The first two tests showed that the reduced and mixed formulations have identical results. These results were very accurate: the wave period could be calculated accurately for coarse meshes and, very important, energy was conserved perfectly. The results for the decoupled formulation were significantly worse: more refined meshes were needed to calculate the wave period accurately and the energy showed periodic behaviour. The last two tests demonstrated that IGA offers results comparable to FEA for less degrees of freedom. The more difficult geometry of the fourth problem was much better represented by IGA.
Advisors/Committee Members: Akkerman, Ido (mentor), ten Eikelder, Marco (mentor), Delft University of Technology (degree granting institution).
Subjects/Keywords: Hydromechanics; isogeometric analysis; Finite Element Analysis; Linear; Free Surface; Waves
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APA (6th Edition):
Meijer, M. (. (2018). Isogeometric Potential Flow Analysis of Linear Surface Waves. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:0e0fc9c8-6c42-465e-9fb5-41342aa04f84
Chicago Manual of Style (16th Edition):
Meijer, Moos (author). “Isogeometric Potential Flow Analysis of Linear Surface Waves.” 2018. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:0e0fc9c8-6c42-465e-9fb5-41342aa04f84.
MLA Handbook (7th Edition):
Meijer, Moos (author). “Isogeometric Potential Flow Analysis of Linear Surface Waves.” 2018. Web. 12 Apr 2021.
Vancouver:
Meijer M(. Isogeometric Potential Flow Analysis of Linear Surface Waves. [Internet] [Masters thesis]. Delft University of Technology; 2018. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:0e0fc9c8-6c42-465e-9fb5-41342aa04f84.
Council of Science Editors:
Meijer M(. Isogeometric Potential Flow Analysis of Linear Surface Waves. [Masters Thesis]. Delft University of Technology; 2018. Available from: http://resolver.tudelft.nl/uuid:0e0fc9c8-6c42-465e-9fb5-41342aa04f84
Delft University of Technology
10.
Hinz, J.P. (author).
Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development.
Degree: 2016, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:3081550f-a0ac-4812-9acc-7f574a188fa9
► In my thesis I present a numerical scheme to tackle the Gray-Scott Reaction-Diffusion Model for Human Brain Development. The numerical scheme is based on the…
(more)
▼ In my thesis I present a numerical scheme to tackle the Gray-Scott Reaction-Diffusion Model for Human Brain Development. The numerical scheme is based on the principles of Isogeometric Analysis and a number of simulations are given in the report.
Computational Science and Engineering
Numerical Analysis
Electrical Engineering, Mathematics and Computer Science
Advisors/Committee Members: Vermolen, F.J. (mentor), Möller, M. (mentor).
Subjects/Keywords: Isogeometric Analysis; Applied Mathematics; Numerical Analysis; Mathematical Biology; Brain Development
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APA (6th Edition):
Hinz, J. P. (. (2016). Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:3081550f-a0ac-4812-9acc-7f574a188fa9
Chicago Manual of Style (16th Edition):
Hinz, J P (author). “Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development.” 2016. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:3081550f-a0ac-4812-9acc-7f574a188fa9.
MLA Handbook (7th Edition):
Hinz, J P (author). “Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development.” 2016. Web. 12 Apr 2021.
Vancouver:
Hinz JP(. Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development. [Internet] [Masters thesis]. Delft University of Technology; 2016. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:3081550f-a0ac-4812-9acc-7f574a188fa9.
Council of Science Editors:
Hinz JP(. Isogeometric Analysis of a Reaction-Diffusion Model for Human Brain Development. [Masters Thesis]. Delft University of Technology; 2016. Available from: http://resolver.tudelft.nl/uuid:3081550f-a0ac-4812-9acc-7f574a188fa9
Virginia Tech
11.
Devarajan, Balakrishnan.
Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners.
Degree: PhD, Engineering Mechanics, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/99425
► This dissertation discusses the thermomechanical analyses performed on threaded fasteners and curvilinearly stiffened composite panels with internal cutouts. The former problem was analyzed using a…
(more)
▼ This dissertation discusses the thermomechanical analyses performed on threaded fasteners and curvilinearly stiffened composite panels with internal cutouts. The former problem was analyzed using a global/local approach using the commercial finite element software ANSYS while a fully functional code using
isogeometric analysis was developed from scratch for the latter. For the threaded fasteners, a global simplified 3D model is built to evaluate the deformation of the structure. A second local model reproducing
accurately the threads of the fasteners is used for the accurate assessment of the stresses
in the vicinity of the fasteners. The
isogeometric analysis code, capable of performing static, buckling and vibration
analysis on stiffened composite plates with cutouts using single patch, multiple patches and level set methods is then discussed. A novel way to achieve displacement compatibility
between the panel and stiffeners interfaces is introduced. An easy way of modeling plates with complicated cutouts by using edge curves and generating a ruled NURBS surface between them is described. Influence on the critical thermal buckling load and the fundamental mode of vibration due to the presence of circular, elliptical and complicated cutouts is also investigated. Results of parametric studies are presented which show the influence of ply orientation, size and orientation of the cutout, and the position and profile of the curvilinear stiffener. The numerical examples show high reliability and efficiency when compared with other published solutions and those obtained using ABAQUS, a commercial software.
Advisors/Committee Members: Kapania, Rakesh K. (committeechair), Cramer, Mark S. (committee member), Ragab, Saad A. (committee member), Seidel, Gary D. (committee member), Case, Scott W. (committee member).
Subjects/Keywords: Thermomechanical; stiffener; threaded fasteners; isogeometric analysis; NURBS; dynamic and eigenvalue analysis
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APA (6th Edition):
Devarajan, B. (2019). Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/99425
Chicago Manual of Style (16th Edition):
Devarajan, Balakrishnan. “Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners.” 2019. Doctoral Dissertation, Virginia Tech. Accessed April 12, 2021.
http://hdl.handle.net/10919/99425.
MLA Handbook (7th Edition):
Devarajan, Balakrishnan. “Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners.” 2019. Web. 12 Apr 2021.
Vancouver:
Devarajan B. Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10919/99425.
Council of Science Editors:
Devarajan B. Thermomechanical and Vibration Analysis of Stiffened Unitized Structures and Threaded Fasteners. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/99425
Brigham Young University
12.
Humpherys, Candice Marie.
Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies.
Degree: MS, 2014, Brigham Young University
URL: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=5370&context=etd
► In contrast to the structural modes, which describe the physical motion of vibrating structures, acoustic radiation modes describe the radiated sound power. Radiation modes are…
(more)
▼ In contrast to the structural modes, which describe the physical motion of vibrating structures, acoustic radiation modes describe the radiated sound power. Radiation modes are beneficial in active noise control because reducing an efficiently radiating radiation mode guarantees the reduction of radiated sound power. Much work has been done to calculate the radiation modes for simple geometries, where analytic solutions are available. In this work, isogeometric analysis (IGA) is used to provide a tool capable of analyzing the radiation modes of arbitrarily complex geometries. IGA offers increased accuracy and efficiency by using basis functions generated from Non-Uniform Rational B-Splines (NURBS) or T-Splines, which can represent geometries exactly. Results showing this increased accuracy and efficiency with IGA using T-Splines are shown for a sphere to validate the method, comparing with the exact analytical solution as well as results from a traditional boundary element method. A free cylindrical shell is also analyzed to show the usefulness of this method. Expected similarities, as well as expected differences, are observed between this free shell and a baffled cylindrical shell.
Subjects/Keywords: isogeometric analysis; boundary element method; radiation modes; Astrophysics and Astronomy; Physics
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APA (6th Edition):
Humpherys, C. M. (2014). Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies. (Masters Thesis). Brigham Young University. Retrieved from https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=5370&context=etd
Chicago Manual of Style (16th Edition):
Humpherys, Candice Marie. “Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies.” 2014. Masters Thesis, Brigham Young University. Accessed April 12, 2021.
https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=5370&context=etd.
MLA Handbook (7th Edition):
Humpherys, Candice Marie. “Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies.” 2014. Web. 12 Apr 2021.
Vancouver:
Humpherys CM. Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies. [Internet] [Masters thesis]. Brigham Young University; 2014. [cited 2021 Apr 12].
Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=5370&context=etd.
Council of Science Editors:
Humpherys CM. Application of an Isogeometric Boundary Element Method to the Calculation of Acoustic Radiation Modes and Their Efficiencies. [Masters Thesis]. Brigham Young University; 2014. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=5370&context=etd
Brigham Young University
13.
Zou, Zhihui.
Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking.
Degree: PhD, 2020, Brigham Young University
URL: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9142&context=etd
► The fundamental advantages of applying Isogeometric Analysis (IGA) to shell analysis have been extensively demonstrated across a wide range of problems and formulations. However,…
(more)
▼ The fundamental advantages of applying Isogeometric Analysis (IGA) to shell analysis have been extensively demonstrated across a wide range of problems and formulations. However, a phenomenon called numerical locking is still a major challenge in IGA shell analysis, which can lead to dramatically deteriorated analysis accuracy. Additionally, for complex thin-walled structures, a simple and robust coupling technique is desired to sew together models composed of multiple patches. This dissertation focuses on addressing these challenges of IGA shell analysis. First, an isogeometric dual mortar method is developed for multi-patch coupling. This method is based on Be ?zier extraction and projection and can be employed during the creation and editing of geometry through properly modified extraction operators. It is applicable to any spline space which has a representation in Be ?zier form. The error in the method can be adaptively controlled, in some cases recovering optimal higher-order rates of convergence, by leveraging the exact refineability of the proposed dual spline basis without introducing any additional degrees-of-freedom into the linear system. This method can be used not only for shell elements but also for heat transfer and solid elements, etc. Next, a mixed formulation for IGA shell analysis is proposed that addresses both shear and membrane locking and improves the quality of computed stresses. The starting point of the formulation is the modified Hellinger-Reissner variational principle with independent displacement, membrane, and shear strains as the unknown fields. To overcome locking, the strain variables are interpolated with lower-order spline bases while the variations of the strain variables are interpolated with the proposed dual spline bases. As a result, the strain variables can be condensed out of the system with only a slight increase in the bandwidth of the resulting linear system and the condensed approach preserves the accuracy of the non-condensed mixed approach but with fewer degrees-of-freedom. Finally, as an alternative, new quadrature rules are developed to release membrane and shear locking. These quadrature rules asymptotically only require one point for Reissner-Mindlin (RM) shell elements and two points for Kirchhoff-Love (KL) shell elements in B-spline and NURBS-based isogeometric shell analysis, independent of the polynomial order p of the elements. The quadrature points are Greville abscissae and the quadrature weights are calculated by solving a linear moment fitting problem in each parametric direction. These quadrature rules are free of spurious zero-energy modes and any spurious finite-energy modes in membrane stiffness can be easily stabilized by using a higher-order Greville rule.
Subjects/Keywords: Isogeometric analysis; Mortar methods; Dual basis; Locking; Reduced quadrature; Engineering
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APA ·
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Export
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APA (6th Edition):
Zou, Z. (2020). Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking. (Doctoral Dissertation). Brigham Young University. Retrieved from https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9142&context=etd
Chicago Manual of Style (16th Edition):
Zou, Zhihui. “Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking.” 2020. Doctoral Dissertation, Brigham Young University. Accessed April 12, 2021.
https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9142&context=etd.
MLA Handbook (7th Edition):
Zou, Zhihui. “Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking.” 2020. Web. 12 Apr 2021.
Vancouver:
Zou Z. Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking. [Internet] [Doctoral dissertation]. Brigham Young University; 2020. [cited 2021 Apr 12].
Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9142&context=etd.
Council of Science Editors:
Zou Z. Isogeometric Shell Analysis: Multi-patch Coupling and Overcoming Locking. [Doctoral Dissertation]. Brigham Young University; 2020. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9142&context=etd
Delft University of Technology
14.
Feij, Christiaan (author).
Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA.
Degree: 2019, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:e5bbffcc-346d-4b59-9d7c-8cbf33df7df8
► The case of the flow around a rotating circular cylinder is very complex. This thesis investigates the properties of a fluid flow for Reynolds numbers…
(more)
▼ The case of the flow around a rotating circular cylinder is very complex. This thesis investigates the properties of a fluid flow for Reynolds numbers ranging from 50 to 400. Numerical simulations are performed using a combination of isogeometric analysis and the residual-based variational multiscale method, providing high accuracy. The results show how the lift and the drag generated by the cylinder are related to the spin rate and the Reynolds number. When comparing the lift and drag values to the required amount of torque which is needed to spin the cylinder, it is shown that at medium spin rates, a very high aerodynamic efficiency is obtained at a reasonable amount of torque. 3D simulations are performed and show at high spin rates strong vorticity and a wake that is dominated by vortex shedding. These results differ strongly from the 2D simulations, which leads to the question whether 2D simulations are still representative for real real at high spin rates, despite the low Reynolds number.
Ship Hydromechanics & Structures
Advisors/Committee Members: Akkerman, Ido (mentor), ten Eikelder, Marco (mentor), Westerweel, Jerry (graduation committee), Delft University of Technology (degree granting institution).
Subjects/Keywords: Cylinders; Spin rate; CFD; isogeometric analysis; RBVMS; NURBS; Flettner rotor
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APA ·
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APA (6th Edition):
Feij, C. (. (2019). Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:e5bbffcc-346d-4b59-9d7c-8cbf33df7df8
Chicago Manual of Style (16th Edition):
Feij, Christiaan (author). “Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA.” 2019. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:e5bbffcc-346d-4b59-9d7c-8cbf33df7df8.
MLA Handbook (7th Edition):
Feij, Christiaan (author). “Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA.” 2019. Web. 12 Apr 2021.
Vancouver:
Feij C(. Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:e5bbffcc-346d-4b59-9d7c-8cbf33df7df8.
Council of Science Editors:
Feij C(. Analysis of fluid flow around a rotating circular cylinder using RBVMS and IGA. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:e5bbffcc-346d-4b59-9d7c-8cbf33df7df8
15.
Yan, D. (author).
Structural Shape Optimization: Using Isogeometric Analysis.
Degree: 2014, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:5e06cbe4-c7ed-49f5-aa7b-c9eecb72eb3e
Mechanics, Aerospace Structures & Materials
Aerospace Engineering
Advisors/Committee Members: Turteltaub, S. (mentor).Subjects/Keywords: isogeometric analysis; shape optimization
…vi
C ONTENTS
5 Numerical Implementation of Isogeometric Analysis
47
5.1 Gaussian… …isogeometric analysis
that offers a possibility of integrating FEA into CAD, followed by rapid… …is to study the possibility of carrying out shape optimization with isogeometric analysis… …geometry (foundation of CAD) is an elementary tool for
both isogeometric analysis and… …namely isogeometric analysis. Later on, the corresponding
functions are also brought into shape…
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Yan, D. (. (2014). Structural Shape Optimization: Using Isogeometric Analysis. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:5e06cbe4-c7ed-49f5-aa7b-c9eecb72eb3e
Chicago Manual of Style (16th Edition):
Yan, D (author). “Structural Shape Optimization: Using Isogeometric Analysis.” 2014. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:5e06cbe4-c7ed-49f5-aa7b-c9eecb72eb3e.
MLA Handbook (7th Edition):
Yan, D (author). “Structural Shape Optimization: Using Isogeometric Analysis.” 2014. Web. 12 Apr 2021.
Vancouver:
Yan D(. Structural Shape Optimization: Using Isogeometric Analysis. [Internet] [Masters thesis]. Delft University of Technology; 2014. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:5e06cbe4-c7ed-49f5-aa7b-c9eecb72eb3e.
Council of Science Editors:
Yan D(. Structural Shape Optimization: Using Isogeometric Analysis. [Masters Thesis]. Delft University of Technology; 2014. Available from: http://resolver.tudelft.nl/uuid:5e06cbe4-c7ed-49f5-aa7b-c9eecb72eb3e
Delft University of Technology
16.
Gillebaart, E.
Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings.
Degree: 2018, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
;
urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
;
a88f215a-3185-47ed-b3e4-bd309c4c8b34
;
10.4233/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
;
urn:isbn:978-94-028-1081-3
;
urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
;
http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
Subjects/Keywords: Aeroelasticity; Isogeometric analysis; Aerostructural optimization
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APA (6th Edition):
Gillebaart, E. (2018). Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; 10.4233/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:isbn:978-94-028-1081-3 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
Chicago Manual of Style (16th Edition):
Gillebaart, E. “Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings.” 2018. Doctoral Dissertation, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; 10.4233/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:isbn:978-94-028-1081-3 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34.
MLA Handbook (7th Edition):
Gillebaart, E. “Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings.” 2018. Web. 12 Apr 2021.
Vancouver:
Gillebaart E. Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings. [Internet] [Doctoral dissertation]. Delft University of Technology; 2018. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; 10.4233/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:isbn:978-94-028-1081-3 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34.
Council of Science Editors:
Gillebaart E. Towards Geometrically Consistent Aerostructural Optimisation of Composite Aircraft Wings. [Doctoral Dissertation]. Delft University of Technology; 2018. Available from: http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; 10.4233/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; urn:isbn:978-94-028-1081-3 ; urn:NBN:nl:ui:24-uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34 ; http://resolver.tudelft.nl/uuid:a88f215a-3185-47ed-b3e4-bd309c4c8b34
17.
Hilmersson, Joel.
Isogeometric analysis and form finding
.
Degree: Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap, 2020, Chalmers University of Technology
URL: http://hdl.handle.net/20.500.12380/301616
► Recent developments within the design of shells have seen an increased interest in utilizing active bending as form giving procedure [1]. This enables complex structures…
(more)
▼ Recent developments within the design of shells have seen an increased interest in utilizing active bending
as form giving procedure [1]. This enables complex structures to be built from simple off-the-shelf
materials. However, forming bending-active structures is highly dependent on the material properties,
which makes the design process reliant on either physical testing or digital simulations. An associated
problem with the simulation of this behavior is the lack of integration between modeling and analysis in
conventional simulation techniques, a crucial concern since the final design is always an equilibrium shape
with requirements on both structural and spatial integrity. IsoGeometric Analysis (IGA) is a method
that aims to bridge precisely that gap between analysis and design, making it a suitable method for
bending active structural design.
This thesis explores an approach to the modeling and digital design of actively bent shells using the
implementation of nonlinear IGA. Further on, two different ways of controlling the geometry, either by
following the process forward and predicting the outcome or tracing it backwards during the construction
procedure are proposed. Following the process forwards returns an implicitly controlled shell geometry
through stepwise displacement of the boundaries of a flat sheet. However, as a design approach, one
appealing strategy is to explicitly control the final geometry by a backwards tracing. This allows the
designer to start from a desired outcome and instead tailor the stiffness to approximate this desired
form. The procedure is tested in a case study where a combination of both forward prediction and
backwards tracing is included. Both processes apply the Kirchhoff-Love shell theory [27] and uses the
total Lagrangian formulation for the nonlinear computations
Subjects/Keywords: Isogeometric analysis;
Shell Design;
Bending Active;
Nonlinear;
Form Finding
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Export
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APA (6th Edition):
Hilmersson, J. (2020). Isogeometric analysis and form finding
. (Thesis). Chalmers University of Technology. Retrieved from http://hdl.handle.net/20.500.12380/301616
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hilmersson, Joel. “Isogeometric analysis and form finding
.” 2020. Thesis, Chalmers University of Technology. Accessed April 12, 2021.
http://hdl.handle.net/20.500.12380/301616.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hilmersson, Joel. “Isogeometric analysis and form finding
.” 2020. Web. 12 Apr 2021.
Vancouver:
Hilmersson J. Isogeometric analysis and form finding
. [Internet] [Thesis]. Chalmers University of Technology; 2020. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/20.500.12380/301616.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hilmersson J. Isogeometric analysis and form finding
. [Thesis]. Chalmers University of Technology; 2020. Available from: http://hdl.handle.net/20.500.12380/301616
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Texas – Austin
18.
-8857-3599.
Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design.
Degree: MSin Engineering, Petroleum Engineering, 2019, University of Texas – Austin
URL: http://dx.doi.org/10.26153/tsw/2010
► The drilling industry today relies on torque and drag models to analyze and ensure success during all phases of well construction and operations, including planning,…
(more)
▼ The drilling industry today relies on torque and drag models to analyze and ensure success during all phases of well construction and operations, including planning, drilling, and completion. Analytical models are based on equations that are undergoing constant development and improvement. The finite element method is an alternative to complex analytical calculations that is used often to determine torque and drag forces that are present when a drillstring is lowered, raised, and rotated in a wellbore. Traditional finite element
analysis (FEA), however, is not time efficient or computationally able to simulate the complexities of a real wellbore. Thus, we introduce an alternative to the traditional finite element approach:
isogeometric analysis.
Isogeometric analysis is similar to finite element
analysis except that it uses NURBS (Non-Uniform Rational B-Splines), as opposed to interpolatory polynomials used in traditional FEA, as the basis functions. NURBS functions are the same as those used in CAD programs, and they are able to construct exact conic shapes, such as circles and ellipses. Adopting NURBS basis functions allows finite element
analysis to be performed directly on the exact geometrical surface - not on an approximate geometric surface mesh, as in traditional FEA. IGA yields a significantly faster and more accurate simulation. This thesis presents a real-world application of IGA to a drag force model to determine the resultant surface hook load during run-in-hole (RIH) operations. Real well data is used, and IGA results are compared to a similar FEA
analysis. The outcome shows that IGA is indeed a superior finite element method that has immense potential for further application in the industry
Advisors/Committee Members: Oort, Eric van (advisor), Foster, John T., Ph. D. (advisor).
Subjects/Keywords: Isogeometric analysis; Drillstring design; BHA design; Finite elements; Torque; Drag; Model
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-8857-3599. (2019). Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design. (Masters Thesis). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/2010
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-8857-3599. “Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design.” 2019. Masters Thesis, University of Texas – Austin. Accessed April 12, 2021.
http://dx.doi.org/10.26153/tsw/2010.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-8857-3599. “Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design.” 2019. Web. 12 Apr 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-8857-3599. Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design. [Internet] [Masters thesis]. University of Texas – Austin; 2019. [cited 2021 Apr 12].
Available from: http://dx.doi.org/10.26153/tsw/2010.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-8857-3599. Isogeometric analysis : applications for torque and drag models, drillstring and bottom-hole assembly design. [Masters Thesis]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/2010
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
King Abdullah University of Science and Technology
19.
Moy, Pedro Henrique Rocha.
Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling.
Degree: Physical Science and Engineering (PSE) Division, 2012, King Abdullah University of Science and Technology
URL: http://hdl.handle.net/10754/238360
► The discretization of time-dependent wave propagation is plagued with dispersion in which the wavefield is perceived to travel with an erroneous velocity. To remediate the…
(more)
▼ The discretization of time-dependent wave propagation is plagued with dispersion
in which the wavefield is perceived to travel with an erroneous velocity. To remediate
the problem, simulations are run on dense and computationally expensive grids
yielding plausible approximate solutions. This work introduces an error
analysis tool
which can be used to obtain optimal simulation parameters that account for mesh
size, orders of spatial and temporal discretizations, angles of propagation, temporal
stability conditions (usually referred to as CFL conditions), and time of propagation.
The classical criteria of 10-15 nodes per wavelength for second-order finite differences,
and 4-5 nodes per wavelength for fourth-order spectral elements are shown to be unrealistic
and overly-optimistic simulation parameters for different propagation times.
This work analyzes finite differences, spectral elements, optimally-blended spectral
elements, and
isogeometric analysis.
Advisors/Committee Members: Calo, Victor M. (advisor), Efendiev, Yalchin R. (committee member), Sun, Shuyu (committee member).
Subjects/Keywords: Dispersion; Finite Elements; Wave Propagation; Wave Equation; Spectral Elements; Isogeometric Analysis
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APA ·
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CSE |
Export
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APA (6th Edition):
Moy, P. H. R. (2012). Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling. (Thesis). King Abdullah University of Science and Technology. Retrieved from http://hdl.handle.net/10754/238360
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Moy, Pedro Henrique Rocha. “Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling.” 2012. Thesis, King Abdullah University of Science and Technology. Accessed April 12, 2021.
http://hdl.handle.net/10754/238360.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Moy, Pedro Henrique Rocha. “Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling.” 2012. Web. 12 Apr 2021.
Vancouver:
Moy PHR. Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling. [Internet] [Thesis]. King Abdullah University of Science and Technology; 2012. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10754/238360.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Moy PHR. Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling. [Thesis]. King Abdullah University of Science and Technology; 2012. Available from: http://hdl.handle.net/10754/238360
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Delft University of Technology
20.
Verhelst, Hugo (author).
Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses.
Degree: 2019, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:56c0cc91-643d-4817-9702-93fedce5fd78
► <p class="MsoNormal">With increasing attention to climate change,renewable energy generation has become a major topic for research anddevelopment. Wind and solar energy are generated on land,…
(more)
▼ <p class="MsoNormal">With increasing attention to climate change,renewable energy generation has become a major topic for research anddevelopment. Wind and solar energy are generated on land, whereas wave, windand tidal energy generators are getting attention in the offshore domain. Anovel extension of onshore solar energy is the concept of offshore solar energyusing floating platforms. As little research has been performed on the conceptof offshore solar energy generations, main challenges in the field are relatedto consequences to the marine ecology, economics and production and structuraldesign of the platforms. In this thesis, a numerical model to assess wrinklingbehaviour of thin, floating sheets with application to the structural design ofoffshore solar platforms is developed. Since wrinkling of thin sheets, in general, isinitiated by a structural instability (i.e. buckling), the developed modelconsists of an arc-length method that is capable to deal with bifurcationpoints and to switch to bifurcation branches. In this way, buckling andpost-buckling behaviour of thin sheets are modelled and wrinkled shapes can beassessed without imposing <i>a priori </i>definition of unbalancingimperfections or loads. The computational model is developed using a shelldiscretization with
Isogeometric rotation-free Kirchhoff-Love elements, whichare higher-order elements with a B-spline or NURBS basis with global supportand global higher-order continuity of the solution. For the illustrativepurpose and future use, a similar Euler-Bernoulli beam model was developed andnumerical solvers for static, dynamic, modal and linear buckling
analysis wereimplemented. The model was verified using various benchmarkstudies for static, modal, (post-)buckling and dynamic
analysis. In particular,the post-buckling solver was assessed by modelling the collapse of a sphericalroof and using buckling (post-)bucking of a cantilever strip. Both benchmarkshave shown excellent agreement with previous publications. Additionalverification was done on the approaching accuracy and prediction of bifurcationpoints. It was found that this accuracy showed the accurate prediction of thebifurcation point, although slightly underpredicted for finer meshes and higherorders. Additionally, the model wasapplied to three cases where wrinkling is involved. In these cases, sheets withlow bending stiffness were modelled such that their post-buckling shapes showmultiple half-waves and thus wrinkles. Based on the model of a floating sheetsubject to surface traction (e.g. wind or current), design parameters werevaried. From this case, it follows a decrease in foundation stiffness or anincrease in flexural rigidity (either by varying Young's modulus or thickness)implies the number of wrinkles to decrease and the wrinkling instability tooccur for lower loads. Thirdly, based on the wrinkling geometries of a quarterdisk, design consideration for VLFTSs for offshore solar energy generation weregiven. These are: (i) adding reinforcement to arrest wrinkles and to…
Advisors/Committee Members: den Besten, Henk (mentor), Kaminski, Mirek (mentor), Möller, Matthias (mentor), Negenborn, Rudy (graduation committee), Schuttelaars, Henk (graduation committee), Vermolen, Fred (mentor), Delft University of Technology (degree granting institution).
Subjects/Keywords: isogeometric analysis; Arc-length methods; Post-buckling analysis; Offshore energy; Buckling Analysis; Thin Structures
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Verhelst, H. (. (2019). Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:56c0cc91-643d-4817-9702-93fedce5fd78
Chicago Manual of Style (16th Edition):
Verhelst, Hugo (author). “Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses.” 2019. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:56c0cc91-643d-4817-9702-93fedce5fd78.
MLA Handbook (7th Edition):
Verhelst, Hugo (author). “Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses.” 2019. Web. 12 Apr 2021.
Vancouver:
Verhelst H(. Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:56c0cc91-643d-4817-9702-93fedce5fd78.
Council of Science Editors:
Verhelst H(. Modelling Wrinkling Behaviour of Large Floating Thin Offshore Structures: An application of Isogeometric Structural Analysis for Post-Buckling Analyses. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:56c0cc91-643d-4817-9702-93fedce5fd78
Virginia Tech
21.
Kapoor, Hitesh.
Isogeometric Finite Element Code Development for Analysis of Composite Structures.
Degree: PhD, Aerospace Engineering, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/50567
► This research endeavor develops Isogeometric approach for analysis of composite structures and take advantage of higher order continuity, smoothness and variation diminishing property of Nurbs…
(more)
▼ This research endeavor develops
Isogeometric approach for
analysis of composite structures and take advantage of higher order continuity, smoothness and variation diminishing property of Nurbs basis for stress
analysis of composite and sandwich beams and plates. This research also computes stress concentration factor in a composite plate with a hole.
Isogeometric nonlinear/linear finite element code is developed for static and dynamic
analysis of laminated composite plates. Nurbs linear, quadratic, higher-order and k-refined elements are constructed using various refinement procedures and validated with numerical testing. Nurbs post-processor for in-plane and interlaminar stress calculation in laminated composite and sandwich plates is developed. Nurbs post-processor is found to be superior than regular finite element and in good agreement with the literature. Nurbs Isgoemetric
analysis is used for stress
analysis of laminated composite plate with open-hole. Stress concentration factor is computed along the hole edge and good agreement is obtained with the literature. Nurbs
Isogeometric finite element code for free-vibration and linear dynamics
analysis of laminated composite plates also obtain good agreement with the literature. Main highlights of the research are newly developed 9 control point linear Nurbs element, k-refined and higher-order Nurbs elements in
isogeometric framework. Nurbs elements remove shear-locking and hourglass problems in thin plates in context of first-order shear deformation theory without the additional step and compute better stresses than Lagrange finite element and higher order shear deformation theory for comparatively thick plates i.e. a/h = 4. Also, Nurbs
Isogeometric analysis perform well for vibration and dynamic problems and for straight and curved edge problems.
Advisors/Committee Members: Kapania, Rakesh K. (committeechair), Batra, Romesh C. (committee member), Philen, Michael K. (committee member), Clay, Stephen Brett (committee member).
Subjects/Keywords: Nurbs Isogeometric analysis; k-refinement procedure; shear-deformable plates and beams; nonlinear analysis; interlaminar stress
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APA ·
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MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Kapoor, H. (2013). Isogeometric Finite Element Code Development for Analysis of Composite Structures. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/50567
Chicago Manual of Style (16th Edition):
Kapoor, Hitesh. “Isogeometric Finite Element Code Development for Analysis of Composite Structures.” 2013. Doctoral Dissertation, Virginia Tech. Accessed April 12, 2021.
http://hdl.handle.net/10919/50567.
MLA Handbook (7th Edition):
Kapoor, Hitesh. “Isogeometric Finite Element Code Development for Analysis of Composite Structures.” 2013. Web. 12 Apr 2021.
Vancouver:
Kapoor H. Isogeometric Finite Element Code Development for Analysis of Composite Structures. [Internet] [Doctoral dissertation]. Virginia Tech; 2013. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10919/50567.
Council of Science Editors:
Kapoor H. Isogeometric Finite Element Code Development for Analysis of Composite Structures. [Doctoral Dissertation]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/50567
UCLA
22.
Clyde, David.
Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth.
Degree: Mathematics, 2017, UCLA
URL: http://www.escholarship.org/uc/item/30g0h9r5
► We present the derivation details necessary for simulation of thin shells with finite strains based on the Kirchhoff-Love assumptions. With an eye towards cloth simulation,…
(more)
▼ We present the derivation details necessary for simulation of thin shells with finite strains based on the Kirchhoff-Love assumptions. With an eye towards cloth simulation, we combine this with a nonlinear orthotropic constitutive model framework. We leverage a conforming spatial discretization using Catmull-Clark subdivision surfaces to ensure convergence under refinement, which we confirm by numerical experiments. The dynamics are handled in a fully implicit fashion to allow for large timesteps and solution of quasistatic problems. Accurate constitutive modeling and parameter estimation for woven fabrics is essential in many fields. To achieve this we first design an experimental protocol for characterizing real fabrics based on commercially available tests. Next, we present a new orthotropic hyperelastic constitutive model for woven fabrics. Finally, we create a method for accurately fitting the material parameters to the experimental data. The last step is accomplished by solving inverse problems using our Catmull-Clark subdivision finite element discretization of the Kirchhoff-Love equations. Through this approach we are able to reproduce the fully nonlinear behavior corresponding to the captured data with a small number of parameters while maintaining all fundamental invariants from continuum mechanics. The resulting constitutive model can be used with any discretization and not just subdivision finite elements, which we demonstrate by providing an alternate implementation based on simple triangle meshes. We illustrate the entire process with results for five types of fabric and compare photo reference of the real fabrics to the simulated equivalents.
Subjects/Keywords: Applied mathematics; cloth simulation; constitutive modeling; data fitting; isogeometric analysis; orthotropy; subdivision finite elements
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Clyde, D. (2017). Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth. (Thesis). UCLA. Retrieved from http://www.escholarship.org/uc/item/30g0h9r5
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Clyde, David. “Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth.” 2017. Thesis, UCLA. Accessed April 12, 2021.
http://www.escholarship.org/uc/item/30g0h9r5.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Clyde, David. “Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth.” 2017. Web. 12 Apr 2021.
Vancouver:
Clyde D. Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth. [Internet] [Thesis]. UCLA; 2017. [cited 2021 Apr 12].
Available from: http://www.escholarship.org/uc/item/30g0h9r5.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Clyde D. Numerical Subdivision Surfaces for Simulation and Data Driven Modeling of Woven Cloth. [Thesis]. UCLA; 2017. Available from: http://www.escholarship.org/uc/item/30g0h9r5
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Iowa State University
23.
Balu, Aditya.
Deep learning and GPU-accelerated algorithms for computer-aided engineering.
Degree: 2020, Iowa State University
URL: https://lib.dr.iastate.edu/etd/17882
► Computer-Aided Engineering (CAE) is necessary for fast and efficient product development in design and manufacturing. Historically, CAE played a vital role in the drastic improvement…
(more)
▼ Computer-Aided Engineering (CAE) is necessary for fast and efficient product development in design and manufacturing. Historically, CAE played a vital role in the drastic improvement of production time and production cost over the past two to three decades. While it used to take several months to years to realize a product earlier, the same process takes only a few hours to days now, due to the availability of state-of-the-art CAE techniques. This thesis is a contribution to the CAE ecosystem with the motivation to integrate advanced ideas from machine learning and computational sciences with current CAE tools to improve the product development cycle. These ideas can be broadly classified into (i) data-driven/machine learning-based approaches, (ii) GPU acceleration for massively parallelizable tasks. These ideas have been adopted extensively and have become prevalent over the past five to eight years, with a substantial focus on other cyber-physical systems in the aerospace, automotive, agriculture, healthcare, and transportation sectors. However, applications to the manufacturing sector have not seen as much advancement compared to the other areas. In this work, we focus on our contributions to CAE, which is an integral part of the manufacturing cyber-physical system.
Over the past decade, transition to a new economy driven by automation and revolutionary changes in manufacturing technologies has enabled highly sophisticated, creative, and customizable products to be manufactured on demand by flexible robotic systems. Consequently, the demand for designing and customizing products for each user has grown exponentially. However, end-users who wish to customize their products or designs often do not have sufficient knowledge, experience, or expertise about manufacturing technologies and computational methods to analyze the design. This limitation requires CAE systems to be intelligent in making decisions with fewer interventions from the end-users (often termed as Industry 4.0). While several cyber-physical systems have embedded advanced data-driven tools such as deep learning and reinforcement learning into their workflow, their usage in the manufacturing systems is still very sparse. This dissertation is an attempt to fill this lacuna.
Another critical idea explored for integration to the state-of-the-art CAE tools is the development of algorithms accelerated with graphical processing units (GPUs). Almost a decade ago, GPUs were meant for accelerating the rendering pipeline of an application by computing a the geometric transformations of triangles and rendering them interactively (at a rate of more than 30 frames per second). However, the trend to use GPUs for general-purpose computations (GPGPUs) has been catching on. Many CAE applications have started to embrace the use of GPUs for general computations since they can perform certain typical computations in less than a minute, while the traditional computational methods take minutes/hours to do the same. Such low latency provides users with the opportunity to…
Subjects/Keywords: Deep Learning; Design Optimization; GPU Computing; Isogeometric Analysis; Solid Modeling; Topology Optimization
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APA (6th Edition):
Balu, A. (2020). Deep learning and GPU-accelerated algorithms for computer-aided engineering. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/17882
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Balu, Aditya. “Deep learning and GPU-accelerated algorithms for computer-aided engineering.” 2020. Thesis, Iowa State University. Accessed April 12, 2021.
https://lib.dr.iastate.edu/etd/17882.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Balu, Aditya. “Deep learning and GPU-accelerated algorithms for computer-aided engineering.” 2020. Web. 12 Apr 2021.
Vancouver:
Balu A. Deep learning and GPU-accelerated algorithms for computer-aided engineering. [Internet] [Thesis]. Iowa State University; 2020. [cited 2021 Apr 12].
Available from: https://lib.dr.iastate.edu/etd/17882.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Balu A. Deep learning and GPU-accelerated algorithms for computer-aided engineering. [Thesis]. Iowa State University; 2020. Available from: https://lib.dr.iastate.edu/etd/17882
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
24.
F. Marini.
PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS.
Degree: 2015, Università degli Studi di Milano
URL: http://hdl.handle.net/2434/336923
► We present a multi-level massively parallel additive Schwarz preconditioner for Isogeometric Analysis, a FEM-like numerical analysis for PDEs that permits exact geometry representation and high…
(more)
▼ We present a multi-level massively parallel additive Schwarz preconditioner for
Isogeometric Analysis, a FEM-like numerical
analysis for PDEs that permits exact geometry representation and high regularity basis functions. Two model problems are considered: the scalar elliptic equation and the advection-diffusion equation. Theoretical
analysis proves that the adoption of a coarse correction grid is crucial in order to have the condition number of the preconditioned stiffness matrix independent from the number of subdomains, whenever the ratio between the coarse mesh size and the fine mesh size is kept fixed. Numerical tests for the scalar elliptic equation (in 2D and 3D on trivial and non-trivial domains) confirm the theory. The preconditioner is then applied to the advection-diffusion equation in 2D and 3D. Again, the numerical results shows that the condition number of the preconditioned linear system scales with the number of subdomains up to 8100 processors, eventually with SUPG stabilization. The tests are implemented in C programming language on the top of PETSc library.
Advisors/Committee Members: tutor: L. F. Pavarino, coordinatore: G. Naldi, PAVARINO, LUCA FRANCO, NALDI, GIOVANNI.
Subjects/Keywords: isogeometric analysis; domain decomposition; parallel programming; advection-diffusion; Settore MAT/08 - Analisi Numerica
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APA ·
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APA (6th Edition):
Marini, F. (2015). PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS. (Thesis). Università degli Studi di Milano. Retrieved from http://hdl.handle.net/2434/336923
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Marini, F.. “PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS.” 2015. Thesis, Università degli Studi di Milano. Accessed April 12, 2021.
http://hdl.handle.net/2434/336923.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Marini, F.. “PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS.” 2015. Web. 12 Apr 2021.
Vancouver:
Marini F. PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS. [Internet] [Thesis]. Università degli Studi di Milano; 2015. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2434/336923.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Marini F. PARALLEL ADDITIVE SCHWARZ PRECONDITIONING FOR ISOGEOMETRIC ANALYSIS. [Thesis]. Università degli Studi di Milano; 2015. Available from: http://hdl.handle.net/2434/336923
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Univerzitet u Beogradu
25.
Milošević, Jelena Ž.
Изогеометријска анализа у морфогенези површинских
конструктивних система.
Degree: Arhitektonski fakultet, 2016, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:11987/bdef:Content/get
► Архитектура и урбанизам - Конструктивни системи / Architecture and Urbanism - Structural Systems
Тезом је предложен неконвенционални поступак за пројектовање површинских конструктивних система којим се…
(more)
▼ Архитектура и урбанизам - Конструктивни системи /
Architecture and Urbanism - Structural Systems
Тезом је предложен неконвенционални поступак за
пројектовање површинских конструктивних система којим се интегришу
геометријске методе за моделовање форме и рачунарске процедуре за
симулацију понашања структура. Предложени поступак је у форми
морфогенетске процедуре у којој се потенцијали структуралне анализе
користе у фази конципирања решења, а који се одликује
интерактивношћу и флексибилношћу неопходним за специфичан процес
пројектовања површинских структура. Дефинисање алгоритма, који
омогућава једноставније и ефикасније пројектовање површинских
конструктивних система, реализовано је имлементацијом
изогеометријске анализе, нумеричким поступком у ком се геометрија и
кинематика описују истим функцијама. За разлику од уобичајено
коришћене класичне анализе методом коначних елемената, у којој се
врши интерполација геометрије, изогеометријски концепт подразумева
анализу на основу егзактно дефинисане почетне геометрије, описане
NURBS технологијом, чиме је омогућено пројектовање, анализа и
подешавање модела употребом јединственог типа података. Полазећи од
теоријског и концептуалног оквира развијен је оригинални
алгоритамско-програмски код који је имплементиран у оквир CAD
система заснованог на NURBS геометријској репрезентацији, а који
омогућава аутоматско генерисање форми оптималних у погледу
структуралних перформанси. Имплементација процедуре демонстрира
ефикасност предложеног приступа и потврђује да унапређење
креативних алата омогућава иновацију и оптимизацију процеса
пројектовања.
Advisors/Committee Members: Nestorović, Miodrag..
Subjects/Keywords: Surface structural systems; generating of structures;
optimization of structures; digital morphogenesis; Isogeometric
analysis; NURBS
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Milošević, J. . (2016). Изогеометријска анализа у морфогенези површинских
конструктивних система. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:11987/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Milošević, Jelena Ž. “Изогеометријска анализа у морфогенези површинских
конструктивних система.” 2016. Thesis, Univerzitet u Beogradu. Accessed April 12, 2021.
https://fedorabg.bg.ac.rs/fedora/get/o:11987/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Milošević, Jelena Ž. “Изогеометријска анализа у морфогенези површинских
конструктивних система.” 2016. Web. 12 Apr 2021.
Vancouver:
Milošević J. Изогеометријска анализа у морфогенези површинских
конструктивних система. [Internet] [Thesis]. Univerzitet u Beogradu; 2016. [cited 2021 Apr 12].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:11987/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Milošević J. Изогеометријска анализа у морфогенези површинских
конструктивних система. [Thesis]. Univerzitet u Beogradu; 2016. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:11987/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Colorado
26.
Engvall, Luke H.
Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.
Degree: PhD, 2018, University of Colorado
URL: https://scholar.colorado.edu/mcen_gradetds/170
► This dissertation presents two novel contributions to the fields of isogeometric analysis and <i>p</i>-version finite elements. First, we present a framework for geometrically exact…
(more)
▼ This dissertation presents two novel contributions to the fields of
isogeometric analysis and <i>p</i>-version finite elements. First, we present a framework for geometrically exact volumetric mesh generation. By leveraging ideas from both traditional mesh generation as well as
isogeometric analysis, we develop a framework for volumetric mesh generation using rational Bernstein – Bézier discretizations. Within this framework, we provide a set of easily verifiable sufficient conditions for guaranteeing that a mesh will be geometrically exact. Second, we develop a complete theory of mesh quality for these rational Bernstein – Bézier elements. From this, we derive a set of easily computable mesh quality metrics for verifying that a rational Bernstein – Bézier discretization will be
analysis suitable.
Advisors/Committee Members: John A. Evans, Peter Hamlington, Kenneth Jansen, Daven Henze, Franck Vernerey.
Subjects/Keywords: curvilinear mesh generation; higher-order finite elements; isogeometric analysis; mesh generation; discretization; Engineering; Mechanical Engineering
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APA ·
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Export
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APA (6th Edition):
Engvall, L. H. (2018). Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/mcen_gradetds/170
Chicago Manual of Style (16th Edition):
Engvall, Luke H. “Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 12, 2021.
https://scholar.colorado.edu/mcen_gradetds/170.
MLA Handbook (7th Edition):
Engvall, Luke H. “Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.” 2018. Web. 12 Apr 2021.
Vancouver:
Engvall LH. Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 12].
Available from: https://scholar.colorado.edu/mcen_gradetds/170.
Council of Science Editors:
Engvall LH. Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/mcen_gradetds/170
University of Cambridge
27.
Zhang, Qiaoling.
Subdivision and manifold techniques for isogeometric design and analysis of surfaces.
Degree: PhD, 2019, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/293575
► Design of surfaces and analysis of partial differential equations defined on them are of great importance in engineering applications, e.g., structural engineering, automotive and aerospace.…
(more)
▼ Design of surfaces and analysis of partial differential equations defined on them are of great importance in engineering applications, e.g., structural engineering, automotive and aerospace. This thesis focuses on isogeometric design and analysis of surfaces, which aims to integrate engineering design and analysis by using the same representation for both. The unresolved challenge is to develop a desirable surface representation that simultaneously satisfies certain favourable properties on meshes of arbitrary topology around the extraordinary vertices (EVs), i.e., vertices not shared by four quadrilaterals or three triangles. These properties include high continuity (geometric or parametric), optimal convergence in finite element analysis as well as simplicity in terms of implementation. To overcome the challenge, we further develop subdivision and manifold surface modelling techniques, and explore a possible scheme to combine the distinct appealing properties of the two. The unique advantages of the developed techniques have been confirmed with numerical experiments.
Subdivision surfaces generate smooth surfaces from coarse control meshes of arbitrary topology by recursive refinement. Around EVs the optimal refinement weights are application-dependent. We first review subdivision-based finite elements. We then proceed to derive the optimal subdivision weights that minimise finite element errors and can be easily incorporated into existing implementations of subdivision schemes to achieve the same accuracy with much coarser meshes in engineering computations. To this end, the eigenstructure of the subdivision matrix is extensively used and a novel local shape decomposition approach is proposed to choose the optimal weights for each EV independently.
Manifold-based basis functions are derived by combining differential-geometric manifold techniques with conformal parametrisations and the partition of unity method. This thesis derives novel manifold-based basis functions with arbitrary prescribed smoothness using quasi-conformal maps, enabling us to model and analyse surfaces with sharp features, such as creases and corners. Their practical utility in finite element simulation of hinged or rigidly joined structures is demonstrated with Kirchhoff-Love thin shell examples.
We also propose a particular manifold basis reproducing subdivision surfaces away from EVs, i.e., B-splines, providing a way to combine the appealing properties of subdivision (available in industrial software) for design and manifold basis (relatively new) for analysis.
Subjects/Keywords: isogeometric analysis; finite elements; subdivision surfaces; manifold-based surfaces; unstructured meshes; thin shell
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APA ·
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MLA ·
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APA (6th Edition):
Zhang, Q. (2019). Subdivision and manifold techniques for isogeometric design and analysis of surfaces. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/293575
Chicago Manual of Style (16th Edition):
Zhang, Qiaoling. “Subdivision and manifold techniques for isogeometric design and analysis of surfaces.” 2019. Doctoral Dissertation, University of Cambridge. Accessed April 12, 2021.
https://www.repository.cam.ac.uk/handle/1810/293575.
MLA Handbook (7th Edition):
Zhang, Qiaoling. “Subdivision and manifold techniques for isogeometric design and analysis of surfaces.” 2019. Web. 12 Apr 2021.
Vancouver:
Zhang Q. Subdivision and manifold techniques for isogeometric design and analysis of surfaces. [Internet] [Doctoral dissertation]. University of Cambridge; 2019. [cited 2021 Apr 12].
Available from: https://www.repository.cam.ac.uk/handle/1810/293575.
Council of Science Editors:
Zhang Q. Subdivision and manifold techniques for isogeometric design and analysis of surfaces. [Doctoral Dissertation]. University of Cambridge; 2019. Available from: https://www.repository.cam.ac.uk/handle/1810/293575
University of Colorado
28.
Rothstein-Dowden, Ansel.
Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization.
Degree: MS, 2018, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/201
► The preliminary design phase of any engineering project is characterized by computationally efficient low-fidelity predictive modeling to inform early-stage design choices. It is essential…
(more)
▼ The preliminary design phase of any engineering project is characterized by computationally efficient low-fidelity predictive modeling to inform early-stage design choices. It is essential to have fast, efficient tools for preliminary
analysis in order to maximize the amount of time that can be allocated to the detailed design phase, where high-fidelity models must be used to determine design parameters as accurately as possible. Much of the relevant
analysis applicable to engineering systems is described by partial differential equations, to which the analytical solution is known for a very small class of problems. Instead we resort to compuational methods. One of the most common ways of approximating the solution to a partial differential equation in engineering applications is the finite element method. However, this method and other like it introduce a substantial computational bottleneck in the design process because of their indirect link with the geometric representation of engineering designs. The recently developed field of
isogeometric analysis shows great promise due to its ability to circumvent the design-to-
analysis bottleneck inherent in conventional finite element methods. More recently still,
isogeometric analysis has been utilized to perform shape optimization, providing the potential to eliminate the design-
analysis loop altogether. Low-fidelity automatic optimization routines offer to preliminary design the distinct advantage of replacing heuristic human-guided design iteration with mathematically informed iteration toward the optimal design for a system. In this thesis we propose a novel method for the
analysis of an airfoil in high Reynolds number sub-sonic flow as a tool for early stage aircraft design. The geometry of the airfoil is left arbitrary and the airfoil may consist of multiple distinct bodies. We investigate the validity of the method and apply the method to a surrogate optimization problem.
Advisors/Committee Members: John A. Evans, Brian Argrow, John Farnsworth.
Subjects/Keywords: aerodynamics; isogeometric; optimization; fidelity; design-analysis; Aerodynamics and Fluid Mechanics; Aerospace Engineering
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APA ·
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MLA ·
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Rothstein-Dowden, A. (2018). Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/201
Chicago Manual of Style (16th Edition):
Rothstein-Dowden, Ansel. “Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization.” 2018. Masters Thesis, University of Colorado. Accessed April 12, 2021.
https://scholar.colorado.edu/asen_gradetds/201.
MLA Handbook (7th Edition):
Rothstein-Dowden, Ansel. “Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization.” 2018. Web. 12 Apr 2021.
Vancouver:
Rothstein-Dowden A. Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization. [Internet] [Masters thesis]. University of Colorado; 2018. [cited 2021 Apr 12].
Available from: https://scholar.colorado.edu/asen_gradetds/201.
Council of Science Editors:
Rothstein-Dowden A. Isogeometric Analysis of Subsonic Aerodynamic Flows with Application to Shape Optimization. [Masters Thesis]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/201
Iowa State University
29.
Nallagonda, Sahiti.
Deep learning for design and optimization of bioprosthetic heart valves.
Degree: 2018, Iowa State University
URL: https://lib.dr.iastate.edu/etd/17272
► In the traditional industry model, even the slightest design change has to go through the entire optimization process. Once the parametric geometry is created, an…
(more)
▼ In the traditional industry model, even the slightest design change has to go through the entire optimization process. Once the parametric geometry is created, an analysis is run, depending on the various inputs, boundary conditions and the desired output values. These outputs are studied and optimized against the input values using either traditional data analytics or by analysis of testing results. Based on the results of this analysis, the design parameters and inputs are changed as desired and the optimization cycle is repeated. Such industries need methods to reduce this time by a significant amount. The motivation of this study is to create an algorithm that learns the structural analysis of a bioprosthetic heart valve using a convolutional neural network, which on being trained can predict the results of the analysis given any new geometry without going through the process of simulation, which is time consuming and may not be feasible without appropriate resources at all times. This is achieved by exploiting the parametric non-uniform roational B-splines (NURBS) formulation of the heart valve geometry through isogeometric analysis. The initial and final deformations of about 18000 simulations are provided as training data to a deep convolutional neural network. Key parameters of interest such as coaptation area are predicted and all results are validated against the results obtained from traditional structural analysis.
Subjects/Keywords: Biomedical devices; Deep learning; Isogeometric analysis; Machine learning; Neural networks; Simulation; Mechanical Engineering
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Nallagonda, S. (2018). Deep learning for design and optimization of bioprosthetic heart valves. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/17272
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Nallagonda, Sahiti. “Deep learning for design and optimization of bioprosthetic heart valves.” 2018. Thesis, Iowa State University. Accessed April 12, 2021.
https://lib.dr.iastate.edu/etd/17272.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Nallagonda, Sahiti. “Deep learning for design and optimization of bioprosthetic heart valves.” 2018. Web. 12 Apr 2021.
Vancouver:
Nallagonda S. Deep learning for design and optimization of bioprosthetic heart valves. [Internet] [Thesis]. Iowa State University; 2018. [cited 2021 Apr 12].
Available from: https://lib.dr.iastate.edu/etd/17272.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Nallagonda S. Deep learning for design and optimization of bioprosthetic heart valves. [Thesis]. Iowa State University; 2018. Available from: https://lib.dr.iastate.edu/etd/17272
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Delft University of Technology
30.
Jaeschke, A.M. (author).
Isogeometric Analysis for Compressible Flows with Application in Turbomachinery.
Degree: 2015, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:0570c58a-4366-4fee-8ceb-73808529fd2d
► Computer-aided design (CAD) and finite element analysis (FEA) tools are extensively used in industrial design processes. The idea of isogeometric analysis (IGA) is to bring…
(more)
▼ Computer-aided design (CAD) and finite element analysis (FEA) tools are extensively used in industrial design processes. The idea of isogeometric analysis (IGA) is to bring those worlds closer together. Combining them significantly increases the efficiency of the design and development processes. The general idea of the IGA approach is to use non-uniform rational B-splines (NURBS) that are used to represent the geometry in the CAD tool also as a basis for numerical analysis of the partial differential equations (PDE) via FEA. The simplest setting is to use the space spanned by NURBS as a search/test space in the standard Galerkin method. Nowadays, increasing the efficiency of turbo-engines and therefore decreasing the emissions of mainly CO_2 and NO_x is a field of very active research. Therefore, design optimization of turbomachines, largely based on numerical simulations, is extensively performed in industry. An additional motivation for solving the underlying flow problems by IGA is its ability to exactly represent the complex shapes of domains, which is an important feature for flow solvers that need to accurately resolve boundary layers. The topic of this thesis project: application of isogeometric analysis to compressible flow problems is very broad and it is beyond the scope of this thesis to answer all questions arising during the pilot implementation of an IGA solver for compressible flows. Therefore, it was decided to set the implementation of a B-spline-based IGA solver for the compressible Euler equations as the main goal. To achieve this goal several intermediate milestones were set. The first was the implementation of a simple B-spline basis generator and evaluator. The next step was to solve the Poisson problem with IGA. The next step consisted in implementing the solver for the convection-diffusion equation in stationary and time-dependent variants. Those steps led to the final milestone - the implementation of the compressible inviscid flow solver based on the IGA approach. It is well known that the standard Galerkin finite element method as well as its isogeometric counterpart suffer from infamous oscillatory behaviour for convection-dominated problems and problems including discontinuities or steep gradients in the domain. Therefore, the algebraic flux correction (AFC) stabilization was implemented to avoid oscillations and non-physical values in the solution. The main novelty of this thesis is to combine AFC with IGA for the compressible Euler equations. All solvers implemented during the thesis work were successfully validated using common benchmark problems. This work sets a base for further research and development that will hopefully lead to a productive implementation of IGA-based optimisation in industrial turbomachinery design.
COSSE
Applied mathematics
Electrical Engineering, Mathematics and Computer Science
Advisors/Committee Members: Möller, M. (mentor), Vuik, K. (mentor), Schuttelaars, H. (mentor).
Subjects/Keywords: IGA; isogeometric analysis; AFC; algebraic flux correction; B-splines; compressible Euler equations
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APA (6th Edition):
Jaeschke, A. M. (. (2015). Isogeometric Analysis for Compressible Flows with Application in Turbomachinery. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:0570c58a-4366-4fee-8ceb-73808529fd2d
Chicago Manual of Style (16th Edition):
Jaeschke, A M (author). “Isogeometric Analysis for Compressible Flows with Application in Turbomachinery.” 2015. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:0570c58a-4366-4fee-8ceb-73808529fd2d.
MLA Handbook (7th Edition):
Jaeschke, A M (author). “Isogeometric Analysis for Compressible Flows with Application in Turbomachinery.” 2015. Web. 12 Apr 2021.
Vancouver:
Jaeschke AM(. Isogeometric Analysis for Compressible Flows with Application in Turbomachinery. [Internet] [Masters thesis]. Delft University of Technology; 2015. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:0570c58a-4366-4fee-8ceb-73808529fd2d.
Council of Science Editors:
Jaeschke AM(. Isogeometric Analysis for Compressible Flows with Application in Turbomachinery. [Masters Thesis]. Delft University of Technology; 2015. Available from: http://resolver.tudelft.nl/uuid:0570c58a-4366-4fee-8ceb-73808529fd2d
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