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Numerical Study of the Behavior of Two-Dimensional Materials with Microstructure Bistability

Talebpour Parizi, Mohammad | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52378 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Arghavani Hadi, Jamal
  7. Abstract:
  8. In the present study, the energy absorption mechanism is presented that used in two-dimensional microstructures. By studying the angular geometric parameters and the narrow ratio of the tilted members, we can use the property of the geometry of the structure to be bistable. In this way, there can be two stable geometries with different energies, which enters energy into the structure, such as the phase transformation to the second geometry that has more energy. By changing the geometric parameters, the deformed state can be stable or unstable. Because of the complex geometries that exist in this mechanism, additive production methods are more effective than geometric ratios or sharp points compared to other production methods. By modeling this mechanism in a one-dimensional model with a truss and spring, it is possible to use structural behavior against loads of the previous knowledge. For this purpose, for the analysis of its post buckle trusses, the analysis of the buckling patterns, which occur when they are most likely to be utilized Has been. By obtaining the geometric constraints and conditions, one can obtain the nonlinear equation of forces in the tilted members. Since this equation is nonlinear, we use a numerical solution to obtain a displacement curve for different stiffness of the spring. In order to investigate two-dimensional models, in general, structures based on Foursquare, hexagonal, and octagonal are used. By studying the displacement curves, one can construct each structure with different geometric parameters and for a variety of applications Made in order to use the mechanism under consideration in various conditions, the analysis of loading conditions at different rates is used to determine the degree of dependence of the structural behavior to the rate of loading, and it is clear from the results that this property is somewhat independent The viscoelastic behavior of the material is desired. In selecting the material, we have to have different conditions, such as the ability to tolerate the strain in your elastic region. In addition to the amount of strain in the elastic region, the ability of this material to be built in 3D printers is another parameter that can play a role in the selection of the type of material, in which the PDMS (Polydimethylsiloxane) material has been used. The purpose of this research is to provide a class of two-dimensional geometries that can withstand strength in different two-dimensional directions, as well as features that can highlight this mechanism over other mechanisms, the lack of dependence on the rate The application of force and the ability to reuse the mechanism, which is one of the challenges posed by the energy absorption mechanisms. Of course, there are financial constraints in the construction phase as well as structural testing, which makes it impossible to construct this mechanism with the material under study
  9. Keywords:
  10. Architected Materials ; Lattice Materials ; Energy Absorption ; Buckling ; Post-Buckling Behavior ; Tiled Beams

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