+publisher:"University of Colorado" +contributor:("Jeong-Hoon Song")

University of Colorado

1. Culp, David B. Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics.

Degree: MS, 2018, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/362

► The application of fracture mechanics is an increasingly important topic in fields including geophysics, geomechanics, materials engineering, structural mechanics and engineering design. The initiation and… (more)

Subjects/Keywords: coupled; phase-field; pressure; mechanics; fluid; Aerodynamics and Fluid Mechanics; Computational Engineering; Physics

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APA (6^th Edition):

Culp, D. B. (2018). Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/362

Chicago Manual of Style (16^th Edition):

Culp, David B. “Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics.” 2018. Masters Thesis, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/362.

MLA Handbook (7^th Edition):

Culp, David B. “Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics.” 2018. Web. 11 Apr 2021.

Vancouver:

Culp DB. Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics. [Internet] [Masters thesis]. University of Colorado; 2018. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/362.

Council of Science Editors:

Culp DB. Numerical Coupling of Fracture and Fluid Pressure Using a Phase-Field Model with Applications in Geomechanics. [Masters Thesis]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/cven_gradetds/362

University of Colorado

2. Heichelheim, Eric William. Investigation of Aerosol Particles Produced from Rapid Failure of Concrete.

Degree: MS, 2016, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/430

► This work addresses the hypothesis that modern concrete admixtures and inclusions have changed the microstructure mechanical properties sufficiently to result in undocumented concrete response to… (more)

Subjects/Keywords: aerosols; fracture energy; fragmentation; particle size; concrete; Civil Engineering; Environmental Health; Materials Science and Engineering

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APA (6^th Edition):

Heichelheim, E. W. (2016). Investigation of Aerosol Particles Produced from Rapid Failure of Concrete. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/430

Chicago Manual of Style (16^th Edition):

Heichelheim, Eric William. “Investigation of Aerosol Particles Produced from Rapid Failure of Concrete.” 2016. Masters Thesis, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/430.

MLA Handbook (7^th Edition):

Heichelheim, Eric William. “Investigation of Aerosol Particles Produced from Rapid Failure of Concrete.” 2016. Web. 11 Apr 2021.

Vancouver:

Heichelheim EW. Investigation of Aerosol Particles Produced from Rapid Failure of Concrete. [Internet] [Masters thesis]. University of Colorado; 2016. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/430.

Council of Science Editors:

Heichelheim EW. Investigation of Aerosol Particles Produced from Rapid Failure of Concrete. [Masters Thesis]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/cven_gradetds/430

University of Colorado

3. Beel, Andrew Christian. Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications.

Degree: MS, 2019, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/471

► The strong form meshfree collocation method based on Taylor approximation and moving least squares is an alternative to finite element methods for solving partial differential… (more)

Subjects/Keywords: collocation; higher-order partial differential equations; meshfree; nonlinear; ocean circulation; thermomechanical contact; Civil Engineering; Partial Differential Equations

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APA (6^th Edition):

Beel, A. C. (2019). Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/471

Chicago Manual of Style (16^th Edition):

Beel, Andrew Christian. “Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications.” 2019. Masters Thesis, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/471.

MLA Handbook (7^th Edition):

Beel, Andrew Christian. “Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications.” 2019. Web. 11 Apr 2021.

Vancouver:

Beel AC. Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications. [Internet] [Masters thesis]. University of Colorado; 2019. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/471.

Council of Science Editors:

Beel AC. Strong Form Meshfree Collocation Method for Higher Order and Nonlinear Pdes in Engineering Applications. [Masters Thesis]. University of Colorado; 2019. Available from: https://scholar.colorado.edu/cven_gradetds/471

University of Colorado

4. Zhang, Boning. Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils.

Degree: PhD, 2016, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/28

► The discrete properties and different constituents, i.e. sand grains, clay matrix, pore-air, and pore-water in natural soil make it very complicated to investigate its… (more)

▼ The discrete properties and different constituents, i.e. sand grains, clay matrix, pore-air, and pore-water in natural soil make it very complicated to investigate its mechanical behavior. As granular material, the macro-behavior of natural soil depends very much on the particle-level interactions. Thus it is necessary to develop a computational modeling for natural soils at grain-scale considering sand grains, clay matrix, pore-air, and pore-water. The Discrete Element Method (DEM) is used very often to study the behaviors of sand grains. A three-dimensional DEM code ellip3d is extended to polyEllip3d to simulate sand grains using poly-ellipsoids, which are non-symmetric and have more resistance to rolling than ellipsoids. In order to bridge DEM simulation to experiments, Colorado Mason sand grains in SMT images are approximated by poly-ellipsoids and these equivalent polyellipsoids can be used directly to conduct DEM simulations. In addition, a simple particle fracture model is proposed to study the fracture behavior of sand grains. This particle fracture model will be calibrated and compared with the experimental results. A coupling model for DEM and Peri-Dynamics (PD) is established to study the sand-clay matrix interaction, in which cohesive soil clay matrix is modeled using PD with ability to fracture and fragment clay constituent. Both DEM-PD coupled model and Finite Element Analysis (FEA) are used to solve a rigid inclusion problem and their results are compared to semi-verify our DEM-PD model. In the case that the soil is purely cohesionless (e.g.,only sand grains) and modeled using DEM, then the pore-water is modeled using another particle method, Smoothed Particle Hydrodynamics (SPH). DEM-SPH coupled model is also developed to study the interaction between fluid and particles, which can be used in the future to conduct more simulations in sand-pore-water-system, such as drainage problem. Several test examples are conducted to verify the DEM-SPH coupling model in this research. The various C++ codes developed, such as polyEllip3d, DEM-SPH, and DEM-PD are parallelized using hybrid MPI/OpenMP. Finally, stress and strain measures for granular material at large deformation are developed and implemented to study the macroscopic mechanical behavior of natural soils. Thus these stress and strain measures can be used in upscaling to bridge microscale (e.g., grain-scale in this research) to the macroscale (e.g., continuum scale of natural soil). Advisors/Committee Members: Richard Regueiro, Ronald Pak, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song, Franck Vernerey.

Subjects/Keywords: computational modeling; discrete element method; grain-scale; natural soils; peri-dynamics; smoothed particle hydrodynamics; Civil Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, B. (2016). Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/28

Chicago Manual of Style (16^th Edition):

Zhang, Boning. “Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils.” 2016. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/28.

MLA Handbook (7^th Edition):

Zhang, Boning. “Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils.” 2016. Web. 11 Apr 2021.

Vancouver:

Zhang B. Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/28.

Council of Science Editors:

Zhang B. Grain-Scale Computational Modeling of Quasi-Static and Dynamic Loading on Natural Soils. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/cven_gradetds/28

University of Colorado

5. Jensen, Erik Wallace. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/386

► The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite… (more)

▼ The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite this fact, many soil models assume the material is a continuum essentially averaging the inter-particle interactions to predict the behavior of the bulk material. In recent years, multiscale modeling techniques have been developed to reintroduce the effect of the grain-scale interactions to help model situations where the continuum assumption fails, such as shear band development in triaxial tests or soil disaggregation under blast loading. One of such multiscale models called hierarchical upscaling, or global-local analysis, model the problem domain using typical continuum-based approaches, but replace the continuum constitutive model with grain-scale models that represent the microstructure at the given point. The deformation of the material is solved via the continuum-scale boundary value problem, which is then passed to the grain-scale as boundary conditions on these representative volume elements (RVEs). The RVEs are then allowed to deform, and the resulting stress is passed back to the continuum scale. Three hierarchical multiscale models were developed to model a series of experimental results on dry Colorado Mason Sand. In all three models, the grain-scale was modeled using the discrete element method through a code called ellip3D. Ellip3D models of dry Colorado Mason Sand were integrated with three continuum models: a one dimensional, finite strain finite element model with full dynamics (1D FEM-DEM model), a one dimensional material point method implementation (1D MPM-DEM model), and a two dimensional, small strain, axisymmetric finite element model (2Daxi FEM-DEM model). The one dimensional models were used to model a split Hopkinson pressure bar test and the two dimensional model was used to model two triaxial tests. With the inclusion of a particle fracture model, the results of the split Hopkinson pressure bar experiment were reasonably well replicated; however, the 2Daxi FEM-DEM model over-predicts the stress response of the triaxial tests. Regardless, to the author's knowledge, the results herein presented are the first attempt to directly compare FEM-DEM global-local analysis models to experimental data. Also, the MPM-DEM implementation is a novel extension of other FEM-DEM models to a meshfree numerical methods. Advisors/Committee Members: Richard Regueiro, Ronald Pak, Rebecca Brannon, Hongbing Lu, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song.

Subjects/Keywords: continuum modeling; fem-dem modeling; hierarchical modeling; multiscale modeling; soils; Applied Mechanics; Civil Engineering; Geological Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Jensen, E. W. (2017). Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/386

Chicago Manual of Style (16^th Edition):

Jensen, Erik Wallace. “Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/386.

MLA Handbook (7^th Edition):

Jensen, Erik Wallace. “Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.” 2017. Web. 11 Apr 2021.

Vancouver:

Jensen EW. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/386.

Council of Science Editors:

Jensen EW. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/cven_gradetds/386

University of Colorado

6. Jensen, Erik Wallace. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/99

► The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite… (more)

▼ The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite this fact, many soil models assume the material is a continuum essentially averaging the inter-particle interactions to predict the behavior of the bulk material. In recent years, multiscale modeling techniques have been developed to reintroduce the effect of the grain-scale interactions to help model situations where the continuum assumption fails, such as shear band development in triaxial tests or soil disaggregation under blast loading. One of such multiscale models called hierarchical upscaling, or global-local analysis, model the problem domain using typical continuum-based approaches, but replace the continuum constitutive model with grain-scale models that represent the microstructure at the given point. The deformation of the material is solved via the continuum-scale boundary value problem, which is then passed to the grain-scale as boundary conditions on these representative volume elements (RVEs). The RVEs are then allowed to deform, and the resulting stress is passed back to the continuum scale. Three hierarchical multiscale models were developed to model a series of experimental results on dry Colorado Mason Sand. In all three models, the grain-scale was modeled using the discrete element method through a code called ellip3D. Ellip3D models of dry Colorado Mason Sand were integrated with three continuum models: a one dimensional, finite strain finite element model with full dynamics (1D FEM-DEM model), a one dimensional material point method implementation (1D MPM-DEM model), and a two dimensional, small strain, axisymmetric finite element model (2Daxi FEM-DEM model). The one dimensional models were used to model a split Hopkinson pressure bar test and the two dimensional model was used to model two triaxial tests. With the inclusion of a particle fracture model, the results of the split Hopkinson pressure bar experiment were reasonably well replicated; however, the 2Daxi FEM-DEM model over-predicts the stress response of the triaxial tests. Regardless, to the author's knowledge, the results herein presented are the first attempt to directly compare FEM-DEM global-local analysis models to experimental data. Also, the MPM-DEM implementation is a novel extension of other FEM-DEM models to a meshfree numerical methods. Advisors/Committee Members: Richard Regueiro, Ronald Pak, Rebecca Brannon, Hongbing Lu, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song.

Subjects/Keywords: continuum modeling; FEM-DEM modeling; hierarchical modeling; multiscale modeling; soils; Civil Engineering; Engineering Mechanics; Geotechnical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Jensen, E. W. (2017). Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/99

Chicago Manual of Style (16^th Edition):

Jensen, Erik Wallace. “Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/99.

MLA Handbook (7^th Edition):

Jensen, Erik Wallace. “Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils.” 2017. Web. 11 Apr 2021.

Vancouver:

Jensen EW. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/99.

Council of Science Editors:

Jensen EW. Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/cven_gradetds/99

University of Colorado

7. Lawry, Matthew W. A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena.

Degree: PhD, 2016, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/186

► This thesis introduces a comprehensive computational methodology for the topology optimization of contact problems, which is relevant to a broad range of engineering applications. The… (more)

▼ This thesis introduces a comprehensive computational methodology for the topology optimization of contact problems, which is relevant to a broad range of engineering applications. The proposed methodology is capable of handling geometric and material nonlinearities, unilateral and bilateral contact behavior, small and large contact surface sliding, various contact constitutive relations, and the analysis of both two and three dimensional problems. The Level Set Method (LSM) in combination with the eXtended Finite Element Method (XFEM) is used to provide geometry control while maintaining precise definition of the interface. Contact constitutive relations are enforced weakly at the interface using a surface-to-surface integration method. A nonlinear programming scheme is used to solve the optimization problem, and sensitivities are determined using the adjoint method. To demonstrate mechanical model accuracy and explore the defining characteristics of the proposed method, verification and optimization studies were performed on small strain frictionless contact problems in two dimensions, small strain cohesive problems in two and three dimensions, and large strain frictionless contact problems in two dimensions. The proposed method has shown great promise to achieve optimized geometry for a wide variety of contact behavior. Numerical examples demonstrate that in general, optimal geometry for contact problems depends heavily on the interface constitutive behavior. Three dimensional studies reveal design traits that cannot be characterized in two dimensions. Finally, numerical examples with large sliding contact behavior demonstrate that non-intuitive design solutions can be achieved for surfaces which experience contact over a broad range of motion. Mechanical model accuracy and optimization reliability concerns are discussed for a variety of contact behavioral assumptions and stabilization techniques. Advisors/Committee Members: Kurt Maute, Alireza Doostan, Carlos Felippa, John Evans, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song.

Subjects/Keywords: computational contact mechanics; level set methods; structural optimization; topology optimization; XFEM; Aerospace Engineering; Mechanical Engineering

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APA (6^th Edition):

Lawry, M. W. (2016). A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/186

Chicago Manual of Style (16^th Edition):

Lawry, Matthew W. “A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena.” 2016. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/asen_gradetds/186.

MLA Handbook (7^th Edition):

Lawry, Matthew W. “A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena.” 2016. Web. 11 Apr 2021.

Vancouver:

Lawry MW. A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/asen_gradetds/186.

Council of Science Editors:

Lawry MW. A Topology Optimization Method for Structural Designs Reliant on Contact Phenomena. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/asen_gradetds/186

University of Colorado

8. Jing, Yuxiang. Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/360

► To ensure safe operation of nuclear power plants (NPPs) during their service life and enhance the performance of spent nuclear fuel (SNF) storage systems, comprehensive… (more)

▼ To ensure safe operation of nuclear power plants (NPPs) during their service life and enhance the performance of spent nuclear fuel (SNF) storage systems, comprehensive investigation on the behavior of concrete and their components under the long-term nuclear radiation is needed. A theoretical model was developed first to predict the deterioration of concrete under neutron radiation, taking into account both of the effects of neutron radiation and the radiation-induced heating on the mechanical property and volume change of concrete. It was shown that the volume change of concrete is dominated by the expanding characteristic of aggregates. Since neutron radiation can deteriorate mechanical properties of the concrete materials, it’s critical to obtain the accurate neutron radiation levels in concrete structures during their service live. Neutron diffusion equations and heat conduction equation were used for prediction of neutron radiation and thermal field in concrete, respectively. The effects of potential variations of transport properties due to neutron radiation and elevated temperature on neutron diffusion in concrete were estimated. A simplified example of a typical concrete biological shielding wall was analyzed up to 80 years, and the results were discussed. The results show that neutron radiation and elevated temperature can result in considerable increases of neutron flux and fluence in the concrete. In order to understand the current state of knowledge about nuclear irradiated concrete, a collection of articles on neutron and gamma-ray radiation damage to concrete and/or its components was acquired. Information on testing conditions and concrete performance was extracted from the collected literature, and a database was developed. Data analysis of the effect of neutrons levels, water-cement ratio, aggregate fraction, and temperature on various properties of cementitious materials subjected to neutrons irradiation was conducted, and the results were presented. In order to monitor the long-term deterioration process of concrete used in NPPs, the self-sensing capability of carbon fiber reinforced cementitious composites under mechanical loading and elevated temperature was experimentally studied, and the results were described. It has potential to become a sensor and can be used to monitor the long-term variation of strain in concrete of NPPs structures or SNF storage systems. Advisors/Committee Members: Yunping Xi, Franck Vernerey, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song, Mija H. Hubler, Ross B. Corotis.

Subjects/Keywords: spent nuclear fuel; neutron radiation; concrete; nuclear power plants; deterioration; Civil Engineering; Nuclear

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Jing, Y. (2018). Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/360

Chicago Manual of Style (16^th Edition):

Jing, Yuxiang. “Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/360.

MLA Handbook (7^th Edition):

Jing, Yuxiang. “Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants.” 2018. Web. 11 Apr 2021.

Vancouver:

Jing Y. Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/360.

Council of Science Editors:

Jing Y. Deterioration of Multi-Functional Cementitious Materials in Nuclear Power Plants. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/cven_gradetds/360

University of Colorado

9. Shahabi, Farhad. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/404

► This study stands as an attempt to consider the micro-structure of materials in a continuum framework by the aid of micromorphic continuum theory in… (more)

▼ This study stands as an attempt to consider the micro-structure of materials in a continuum framework by the aid of micromorphic continuum theory in the sense of Eringen. Since classical continuum mechanics do not account for the micro-structural characteristics of materials, they cannot be used to address the macroscopic mechanical response of all micro-structured materials. In the "representative volume element (RVE)" based methods, classical continuum mechanics may be applied to analyze mechanical deformation and stresses of materials at the relevant micro-structural length-scale (such as grains of a polycrystalline metal, or sand, or metal matrix composite, etc), but when applying standard homogenization methods, such lower length scale effects get smeared out at the continuum scale. The micromorphic continuum theory provides the ability to incorporate the micro-structural effects into the macroscopic mechanical behavior. Therefore, the micromorphic continuum is a tool for a higher resolution multi-scale material modeling through capturing the material's micro-structural physics via bridging to the direct numerical simulations (DNS) at the lower length scale. In the micromorphic continuum theory of Eringen, the fundamental assumption is that the material is made of "micro-elements" in such a way that the classical continuum mechanics balance equations and thermodynamics are valid within a micro-element. Note that micro-elements represent the material's micro-structure in a micromorphic continuum. The micro-element deformation with respect to the centroid of a macroscopic continuum point is governed by an independent micro-deformation tensor χ which adds 9 additional degrees of freedom to the continuum model. The micromorphic additional degrees of freedom represent micro-stretch, micro-shear, and micro-rotation of the micro-elements. The macroscopic deformation (macro-element deformation) in the micromorphic continuum is handled through the deformation gradient tensor F. If the hypothesis of micromorphic continuum works, in a multi-scale modeling framework, assuming proper constitutive models can be formulated, and material parameters calibrated, micromorphic continuum theory may fill the gap between the RVE-micro-structural-length-scale models and the macroscopic continuum scale. The advantage of using micromorphic continuum is that it provides a chance of linking the macroscopic model to the lower length scale simulations (DNS) and reducing the computational cost by switching from DNS to the macro-scale finite element analysis or other numerical methods at the continuum scale. The linking is done through defining the overlap coupling region between the lower length scale analysis and micromorphic continuum to calibrate the material parameters and the micromorphic continuum model degrees of freedom. Therefore, in the framework of multi-scale modeling, micromorphic continuum can be used as a filter on top of the DNS simulations to capture underlying length scale and better inform the… Advisors/Committee Members: Richard A. Regueiro, Ronald Y. S. Pak, John A. Evans, Franck Vernerey, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song.

Subjects/Keywords: dynamics; elastoplasticity; finite element analysis; large deformation; micromorphic continuum; micropolar continuum; Applied Mechanics; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Shahabi, F. (2017). Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/404

Chicago Manual of Style (16^th Edition):

Shahabi, Farhad. “Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/404.

MLA Handbook (7^th Edition):

Shahabi, Farhad. “Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.” 2017. Web. 11 Apr 2021.

Vancouver:

Shahabi F. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/404.

Council of Science Editors:

Shahabi F. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/cven_gradetds/404

University of Colorado

10. WANG, YAO. Mechanical and Durability Properties of Concrete Under Low Temperatures.

Degree: PhD, 2019, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/482

► Frost attack can heavily damage concrete materials and concrete structures. Therefore, it is important to predict the service life of concrete structures considering the effect… (more)

▼ Frost attack can heavily damage concrete materials and concrete structures. Therefore, it is important to predict the service life of concrete structures considering the effect of the deterioration process. A theoretical model based on Mori-Tanaka micromechanics method was developed to estimate the deterioration of elastic properties of concrete under low temperatures. The model took into account a continuous pore size distribution for cement paste, freezing temperatures with different pore sizes, and damage development in cement paste. The model was able to characterize the stiffening effect due to the formation of solid ice and the weakening effect of the damage development due to excessive ice formation. The accuracy of model predictions was validated with published experimental data. Moreover, the effective diffusivities of concrete under low temperatures were predicted based on a multiple-scale generalized self-consistent (GSC) model. The results show that the diffusivities of concrete under low temperatures vary based on the amount of ice formation and the extent of damage production. An experimental study was conducted to determine the coupling parameter for the effect of thermal gradient on moisture transfer. The theoretical models for the elastic and transport properties and the coupling parameter were implemented in a finite element code. The estimations of temperature distributions by the finite element code were compared with the experimental data, and a good agreement was obtained. In order to mitigate the frost damage, nano-silica was incorporated in concrete mix design to optimize the pore structure of cement paste and thus to improve the mechanical properties of concrete. A comprehensive experimental study was conducted to evaluate the effect of nano-silica on mechanical and durability properties of the concrete, particularly on its low temperature resistance. The results indicated that nano-silica can be used as an effective additive to improve the resistance of concrete to the frost attack. Advisors/Committee Members: Yunping Xi, Edward Garboczi, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song, Mija Helena. Hubler, Yida Zhang.

Subjects/Keywords: concrete; durability; low temperatures; mechanical; Civil Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

WANG, Y. (2019). Mechanical and Durability Properties of Concrete Under Low Temperatures. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/482

Chicago Manual of Style (16^th Edition):

WANG, YAO. “Mechanical and Durability Properties of Concrete Under Low Temperatures.” 2019. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/482.

MLA Handbook (7^th Edition):

WANG, YAO. “Mechanical and Durability Properties of Concrete Under Low Temperatures.” 2019. Web. 11 Apr 2021.

Vancouver:

WANG Y. Mechanical and Durability Properties of Concrete Under Low Temperatures. [Internet] [Doctoral dissertation]. University of Colorado; 2019. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/482.

Council of Science Editors:

WANG Y. Mechanical and Durability Properties of Concrete Under Low Temperatures. [Doctoral Dissertation]. University of Colorado; 2019. Available from: https://scholar.colorado.edu/cven_gradetds/482

University of Colorado

11. Shahabi, Farhad. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/96

► This study stands as an attempt to consider the micro-structure of materials in a continuum framework by the aid of micromorphic continuum theory in the… (more)

▼ This study stands as an attempt to consider the micro-structure of materials in a continuum framework by the aid of micromorphic continuum theory in the sense of Eringen. Since classical continuum mechanics do not account for the micro-structural characteristics of materials, they cannot be used to address the macroscopic mechanical response of all micro-structured materials. In the “representative volume element (RVE)” based methods, classical continuum mechanics may be applied to analyze mechanical deformation and stresses of materials at the relevant micro-structural length-scale (such as grains of a polycrystalline metal, or sand, or metal matrix composite, etc), but when applying standard homogenization methods, such lower length scale effects get smeared out at the continuum scale. The micromorphic continuum theory provides the ability to incorporate the micro-structural effects into the macroscopic mechanical behavior. Therefore, the micromorphic continuum is a tool for a higher resolution multi-scale material modeling through capturing the material's micro-structural physics via bridging to the direct numerical simulations (DNS) at the lower length scale. In the micromorphic continuum theory of Eringen, the fundamental assumption is that the material is made of “micro-elements” in such a way that the classical continuum mechanics balance equations and thermodynamics are valid within a micro-element. Note that micro-elements represent the material's micro-structure in a micromorphic continuum. The micro-element deformation with respect to the centroid of a macroscopic continuum point is governed by an independent micro-deformation tensor χ which adds 9 additional degrees of freedom to the continuum model. The micromorphic additional degrees of freedom represent micro-stretch, micro-shear, and micro-rotation of the micro-elements. The macroscopic deformation (macro-element deformation) in the micromorphic continuum is handled through the deformation gradient tensor F. If the hypothesis of micromorphic continuum works, in a multi-scale modeling framework, assuming proper constitutive models can be formulated, and material parameters calibrated, micromorphic continuum theory may fill the gap between the RVE-micro-structural-length-scale models and the macroscopic continuum scale. The advantage of using micromorphic continuum is that it provides a chance of linking the macroscopic model to the lower length scale simulations (DNS) and reducing the computational cost by switching from DNS to the macro-scale finite element analysis or other numerical methods at the continuum scale. The linking is done through defining the overlap coupling region between the lower length scale analysis and micromorphic continuum to calibrate the material parameters and the micromorphic continuum model degrees of freedom. Therefore, in the framework of multi-scale modeling, micromorphic continuum can be used as a filter on top of the DNS simulations to capture underlying length scale and better inform the macroscopic model. This is… Advisors/Committee Members: Richard A. Regueiro, Ronald Y. S. Pak, John A. Evans, Franck Vernerey, Hoon%20Song%22%29&pagesize-30">Jeong-Hoon Song.

Subjects/Keywords: Dynamics; Elastoplasticity; Finite Element Analysis; Large Deformation; Micromorphic Continuum; Micropolar Continuum; Engineering Mechanics; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Shahabi, F. (2017). Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/96

Chicago Manual of Style (16^th Edition):

Shahabi, Farhad. “Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 11, 2021. https://scholar.colorado.edu/cven_gradetds/96.

MLA Handbook (7^th Edition):

Shahabi, Farhad. “Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis.” 2017. Web. 11 Apr 2021.

Vancouver:

Shahabi F. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 11]. Available from: https://scholar.colorado.edu/cven_gradetds/96.

Council of Science Editors:

Shahabi F. Finite Strain Micromorphic Elasticity, Elastoplasticity, and Dynamics for Multiscale Finite Element Analysis. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/cven_gradetds/96

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