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Static Analysis of Plates and Spherical Shells with Composite/Elastomer Stack-Up in Presence of Free Edge Effects

Velayati, Hamed Reza | 2024

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 57019 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hosseini Kordkheili, Ali
  7. Abstract:
  8. As a result of technology advancement in composite materials and the growth of analytical tools, applications of these materials is increasing in various industries, especially in aerospace industry. One of the structures developed using these materials is hybrid structure with composite/elastomer layering. Stress analysis and study of free-edge effect in this type of structures is possible by using three-dimensional elasticity in composite layers as well as nonlinear hyperelasticity in elastomeric layers, and this is the topic that this thesis deals with. The proposed approach to solving the problem is that the composite/elastomer hybrid structure is first analyzed by the finite element method with simplifying assumptions in the properties of the composite laminate and composite layers are analyzed as an exact sub-model with three-dimensional elasticity. In general, for the three-dimensional simulation of the stress field in composite laminates, firstly, using the energy principle and the generalized Kantrovich method, the system of differential equations of equilibrium is extracted and by solving this system in the state space and applying the boundary conditions, finally displacement , strains and stresses are calculated. In this report, the accuracy of the code developed to solve the elasticity of a flat composite layer is validated by experiment. In the continuation of the report and in the second step, with the development of an improved version of the code called FLagSHyp, the analysis of the flat hybrid structure has been done with nonlinear analysis using the finite element method. Then, the results of the above code are used and the displacements and changes of the stress components, especially the interlaminar components, are drawn in the thickness direction and in the transverse direction. In the third step, with the aim of extending the proposed method to spherical shell geometry, three-dimensional elasticity analysis relations in spherical composite multilayers were also extracted by the generalized Kantrovich method, and stress and displacement changes along the shell thickness and meridian direction were studied. In this section, in addition to comparing the results with the simulation results in the finite element software, a study on the dependence of the method on variables such as the order of approximation of the Kantrovich method, the ratio of thickness to radius, and the ratio of arc length to the thickness of the spherical shell is also presented
  9. Keywords:
  10. Hybrid Structure ; Free Edge Effect ; Elastomer Materials ; Composite Materials ; Composite Laminated Spherical Shells ; Hyperelasticity ; Kantorovich Potential ; Three-Dimensional Elasticity

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