subject:(elastic arch)

University of Colorado

1. Sonavane, Trupti. Analysis of Arches.

Degree: MS, 2014, University of Colorado

URL: https://scholar.colorado.edu/cven_gradetds/119

► The purpose of this thesis is to develop a preliminary guide for the analysis and design of symmetrical circular arches. In the context of… (more)

Subjects/Keywords: elastic arches; arch behavior; Engineering

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APA (6^th Edition):

Sonavane, T. (2014). Analysis of Arches. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/cven_gradetds/119

Chicago Manual of Style (16^th Edition):

Sonavane, Trupti. “Analysis of Arches.” 2014. Masters Thesis, University of Colorado. Accessed April 22, 2021. https://scholar.colorado.edu/cven_gradetds/119.

MLA Handbook (7^th Edition):

Sonavane, Trupti. “Analysis of Arches.” 2014. Web. 22 Apr 2021.

Vancouver:

Sonavane T. Analysis of Arches. [Internet] [Masters thesis]. University of Colorado; 2014. [cited 2021 Apr 22]. Available from: https://scholar.colorado.edu/cven_gradetds/119.

Council of Science Editors:

Sonavane T. Analysis of Arches. [Masters Thesis]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/cven_gradetds/119

Penn State University

2. Pontecorvo, Michael Eugene. CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE .

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/12616

► In classical cellular structures the unit cells have typically not had any inclusions. In the current research, unit cells with various types of inclusions or… (more)

▼ In classical cellular structures the unit cells have typically not had any inclusions. In the current research, unit cells with various types of inclusions or internal features are envisaged. Different types of internal features such as linear springs or dashpots, and a wide variety of nonlinear elements (buckling beams which display softening behavior, mechanical stops or contact elements which display stiffening behavior, and bistable elements which display negative stiffness or snap-through behavior) can be introduced into the unit cell. These internal features will strongly impact the behavior of the unit cell. Unit cells with different types of inclusions can then be thought of as ``Lego blocks'. A structure can be assembled using specific types of ``blocks' in specific arrangements, to provide desired system level behavior. The current study is based on the concept of a two-dimensional cellular structure with hexagonal cells made of pinned-pinned rigid links. Since such a cell has no stiffness of its own, the behavior of the internal feature dominates. The study presents the necessity to include three constraints within the hexagonal cell for its stability. Of the different elements/inclusions that can be used, this thesis focuses on two: a linear spring, and a bistable elastic arch. The selection of the linear spring is based on its being the simplest possible inclusion. For different spring arrangements, closed-form analytical expressions are derived for the in-plane modulus and Poisson's ratio of the hexagonal cell (and by extension, of a cellular structure with that unit cell repeated). The analytical expressions are validated using NASTRAN finite element simulations, as well as against tensile/compressive tests of unit cells with internal springs in an Instron machine. When the spring stiffness exceeds certain values, the rigid cell wall assumption is no longer valid, and these bounds are established. The validated analysis is used to conduct design studies on how the cell modulus (nondimensionalized by the spring stiffness) would vary with cell geometric parameters such as cell angle and cell wall length ratio. An in-plane cell modulus as high as 1.15 GPa was calculated using springs that were stiff but yet compliant enough so as not to violate the rigid cell wall assumption. The second part of the study focused on a bistable elastic arch. This is of interest because of the negative stiffness or snap-through behavior it can display. The large stroke and velocity of the arch, when transitioning from one stable equilibrium condition to the other, can be exploited for enhanced energy dissipation when coupled to a damping element. In the present study a finite element model of the arch is developed and its bistable behavior examined. Experiments on Nitinol and Delrin arches are used to validate the finite element analysis. The analysis is further used to conduct a parametric study on how variation in arch height, thickness or restraining spring stiffness influences the critical snap-through… Advisors/Committee Members: Farhan Gandhi, Thesis Advisor/Co-Advisor, Farhan S Gandhi, Thesis Advisor/Co-Advisor.

Subjects/Keywords: cellular structure; elastic arch; bistable; hexagonal cell; internal features; cell modulus

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

APA (6^th Edition):

Pontecorvo, M. E. (2011). CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/12616

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Pontecorvo, Michael Eugene. “CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE .” 2011. Thesis, Penn State University. Accessed April 22, 2021. https://submit-etda.libraries.psu.edu/catalog/12616.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Pontecorvo, Michael Eugene. “CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE .” 2011. Web. 22 Apr 2021.

Vancouver:

Pontecorvo ME. CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE . [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Apr 22]. Available from: https://submit-etda.libraries.psu.edu/catalog/12616.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Pontecorvo ME. CELLULAR STRUCTURES WITH INTERNAL FEATURES FOR ENHANCED STRUCTURAL PERFORMANCE . [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/12616

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

3. Wager, Justin Charles. Assessment of elastic energy in the plantar aponeurosis and its contributions to human running.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/26210

► One of the primary roles of tendons during human locomotion is the storage and release of elastic energy. As the limbs move in cyclic patterns,… (more)

▼ One of the primary roles of tendons during human locomotion is the storage and release of elastic energy. As the limbs move in cyclic patterns, some of the lower limb tendons stretch and recoil, functioning like springs that reuse a portion of the energy during each step. This function assists in improving the efficiency of human locomotion by reducing the work that is required of the muscles. Testing of cadaveric specimens in situ has demonstrated that the arch of the foot operates in this capacity during simple loading. However, it remains unclear whether the arch functions in this manner during the more complex task of human locomotion. Therefore, the aim of this study was to investigate one of the main elastic tissues in the arch (the plantar aponeurosis; PA), to examine its ability to store and release elastic energy that potentially contributes to the mechanical energetics of the foot during running. A second aim was to investigate the influence of the initial foot contact pattern on the function of the PA during the stance phase of running. A kinematically driven rigid-body model of the human foot was used to estimate the strain, tensile force, and elastic energy stored within the PA. Calculation of the foot joint moments, powers, and work created by the PA allowed an assessment of the contribution of the PA to the mechanical energetics of running gait. Elastic energy stored within the PA was found to be approximately 3 J, which is comparable to values found during in situ loading. The release of this elastic energy generated a small amount of joint power at the talonavicular joint. This joint power amounted to approximately 5-10% of the combined lower limb joint powers during late stance and contributed to push-off slightly after peak power generation at the ankle. In addition, this analysis revealed that differences existed in the early stance phase behavior of the PA between a non-rearfoot strike and a rearfoot strike, but that these differences did not exist during push-off. Future work will use these findings as a foundation to investigate how the mechanical power generated by the PA influences the energetics of other joints within the lower limb as well as the metabolic cost of locomotion. Advisors/Committee Members: John Henry Challis, Thesis Advisor/Co-Advisor.

Subjects/Keywords: biomechanics; multisegment foot model; locomotion; plantar fascia; elastic energy; strain; longitudinal arch; foot strike

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

APA (6^th Edition):

Wager, J. C. (2015). Assessment of elastic energy in the plantar aponeurosis and its contributions to human running. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/26210

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Wager, Justin Charles. “Assessment of elastic energy in the plantar aponeurosis and its contributions to human running.” 2015. Thesis, Penn State University. Accessed April 22, 2021. https://submit-etda.libraries.psu.edu/catalog/26210.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Wager, Justin Charles. “Assessment of elastic energy in the plantar aponeurosis and its contributions to human running.” 2015. Web. 22 Apr 2021.

Vancouver:

Wager JC. Assessment of elastic energy in the plantar aponeurosis and its contributions to human running. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Apr 22]. Available from: https://submit-etda.libraries.psu.edu/catalog/26210.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Wager JC. Assessment of elastic energy in the plantar aponeurosis and its contributions to human running. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/26210

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Oxford

4. Gomez, Michael. Ghosts and bottlenecks in elastic snap-through.

Degree: PhD, 2018, University of Oxford

URL: http://ora.ox.ac.uk/objects/uuid:11ab7b19-ee4b-4cd6-ac9a-116363a4e4d7 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757801

► Snap-through is a striking instability in which an elastic object rapidly jumps from one state to another. It is seen in the leaves of the… (more)

▼ Snap-through is a striking instability in which an elastic object rapidly jumps from one state to another. It is seen in the leaves of the Venus flytrap plant and umbrellas flipping on a windy day among many other examples. Similar structures that snap-through are used to generate fast motions in soft robotics, switches in micro-scale electronics and artificial heart valves. Despite the ubiquity of snap-through in nature and engineering, its dynamics is usually only understood qualitatively. In this thesis we develop analytical understanding of this dynamics, focussing on how the mathematical structure underlying the snap-through transition controls the timescale of instability. We begin by considering the dynamics of 'pull-in' instabilities in microelectromechanical systems (MEMS) - a type of snap-through caused by electrostatic forces in which the motions are dominated by fluid damping. Using a lumped-parameter model, we show that the observed time delay near the pull-in transition is a type of critical slowing down - a so-called 'bottleneck' due to the 'ghost' of a saddle-node bifurcation. We obtain a scaling law describing this slowing down, and, in the process, unify a large range of experiments and simulations that exhibit delay phenomena during pull-in. We also investigate the pull-in dynamics of MEMS microbeams, extending the lumped-parameter approach to incorporate the details of the beam geometry. This provides a model system in which to understand snap-through of a continuous elastic structure due to external loading. We develop a perturbation method that systematically exploits the proximity to pull-in to reduce the governing equations to a simpler evolution equation, with a structure that highlights the saddle-node bifurcation. This allows us to analyse the bottleneck dynamics in detail, which we compare with previous experimental and numerical data. The remainder of the thesis is concerned with the dynamics of snap-through in macroscopic systems. In particular, we explore the extent to which dissipation is required to explain anomalously slow snap-through. Considering an elastic arch as an archetype of a snapping system, we use the perturbation method developed earlier to show that two bottleneck regimes are possible, depending delicately on the relative importance of external damping. In particular, we show that critical slowing down occurs even in the absence of damping, leading to a new scaling law for the snap-through time that is confirmed by elastica simulations and experiments. In many real systems material viscoelasticity is present to some degree. Finally, we examine how this influences the snap-through dynamics of a simple truss-like structure. We present a regime diagram that characterises when the timescale of snap-through is controlled by viscous, elastic or viscoelastic effects.

Subjects/Keywords: 510; Applied Mathematics; MEMS; Elasticity; Viscoelasticity; Bistability; Snap-through; Microbeam; Creep; Saddle-node ghost; Dynamics; Instability; Buckling; Electrostatic pull-in; Critical slowing down; Elastic arch

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

APA (6^th Edition):

Gomez, M. (2018). Ghosts and bottlenecks in elastic snap-through. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:11ab7b19-ee4b-4cd6-ac9a-116363a4e4d7 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757801

Chicago Manual of Style (16^th Edition):

Gomez, Michael. “Ghosts and bottlenecks in elastic snap-through.” 2018. Doctoral Dissertation, University of Oxford. Accessed April 22, 2021. http://ora.ox.ac.uk/objects/uuid:11ab7b19-ee4b-4cd6-ac9a-116363a4e4d7 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757801.

MLA Handbook (7^th Edition):

Gomez, Michael. “Ghosts and bottlenecks in elastic snap-through.” 2018. Web. 22 Apr 2021.

Vancouver:

Gomez M. Ghosts and bottlenecks in elastic snap-through. [Internet] [Doctoral dissertation]. University of Oxford; 2018. [cited 2021 Apr 22]. Available from: http://ora.ox.ac.uk/objects/uuid:11ab7b19-ee4b-4cd6-ac9a-116363a4e4d7 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757801.

Council of Science Editors:

Gomez M. Ghosts and bottlenecks in elastic snap-through. [Doctoral Dissertation]. University of Oxford; 2018. Available from: http://ora.ox.ac.uk/objects/uuid:11ab7b19-ee4b-4cd6-ac9a-116363a4e4d7 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757801

5. Kwabi, Essi. Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study.

Degree: MSin Engineering, Petroleum Engineering, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/22369

► Organic shales have become one of the greatest sources of hydrocarbon thanks to novel production techniques such as hydraulic fracturing. A successful hydraulic fracturing job,… (more)

▼ Organic shales have become one of the greatest sources of hydrocarbon thanks to novel production techniques such as hydraulic fracturing. A successful hydraulic fracturing job, however, is dependent on several rock properties such as mineralogy and elasticity. A reliable estimation of such properties is therefore necessary to determine ideal rocks for horizontal well placement. In this study, rock types within the Eagle Ford shale that would be suitable for hydraulic fracturing are identified through interpretations of available well logs and core data. A comparative study of petrophysical properties such as mineral content, kerogen type and maturity, porosity, and saturation in six wells is performed to characterize the Eagle Ford shale. Two of the wells studied are within the wet gas window of the shale while the remaining four are in the oil window. Based on the calculated petrophysical properties, rock typing was performed using k-means clustering. Two rock types (RT1 and RT2) were identified and their compositions compared in each well. Elastic properties for the various rock types identified were then estimated using the differential effective medium (DEM) theory and were validated through simulation of slowness logs. The final rock type assessment was then performed to identify ideal rocks for hydrofracturing. Results indicate that the Eagle Ford mineralogy varies greatly with depth and with geographic location relative to the San Marcos Arch, a geological arching prominence across the shale. Northeast of the arch, the Eagle Ford shale is clay-rich. Preferred rocks for hydrocarbon production, RT1, are characterized by volumetric concentrations of ~0.44 carbonate, ~0.09 kerogen, ~0.07 porosity, and ~0.42 clay; RT1 also exhibits high sonic velocities (> 3400 m/s and > 1500 m/s compressional and shear, respectively) and high apparent electrical resistivity (> 2 ohm-m). In the Southwest region, on the other hand, the Eagle Ford shale is mostly calcareous. Ideal rocks in the region, RT1, are rich in kerogen (~0.1) with carbonate content of ~0.56, ~0.1 porosity, ~0.19 clay content, and resistivity > 20 ohm-m. In both regions, porosity and pore aspect ratio displayed substantial effects on elastic properties. For example, over 80% decrease in Young’s modulus was quantified when pore aspect ratio approached zero; high pore aspect ratio is preferred for stiff rocks. Poisson’s ratio estimates were not always reliable therefore fracturability was assessed based on Young’s modulus estimates. The study shows that depth intervals exhibiting Young’s moduli above 18GPa and 21GPa in the Northeast and Southwest region, respectively, are suitable for hydrofracturing. Advisors/Committee Members: Torres-Verdín, Carlos (advisor).

Subjects/Keywords: Eagle Ford shale; Mineral composition; Elastic properties; Kerogen; San Marcos Arch

…depth and with geographic location relative to the San Marcos Arch, a geological arching… …prominence across the shale. Northeast of the arch, the Eagle Ford shale is clay-rich. Preferred… …effects on elastic properties. For example, over 80% decrease in Young’s modulus was quantified… …of Elastic Properties and Final Rock Typing ........................22 3.3.1 Rock Physics… …Model ...................................................................22 3.3.2 Elastic and…

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

APA (6^th Edition):

Kwabi, E. (2013). Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/22369

Chicago Manual of Style (16^th Edition):

Kwabi, Essi. “Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study.” 2013. Masters Thesis, University of Texas – Austin. Accessed April 22, 2021. http://hdl.handle.net/2152/22369.

MLA Handbook (7^th Edition):

Kwabi, Essi. “Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study.” 2013. Web. 22 Apr 2021.

Vancouver:

Kwabi E. Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study. [Internet] [Masters thesis]. University of Texas – Austin; 2013. [cited 2021 Apr 22]. Available from: http://hdl.handle.net/2152/22369.

Council of Science Editors:

Kwabi E. Mineral, fluid, and elastic property quantification from well logs and core data in the Eagle Ford shale play : a comparative study. [Masters Thesis]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/22369

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