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Dynamic Stability of Cylindrical Shells Made of Functionally-Graded Materials under Axial Follower Forces

Torki Harchegani, Mohammad Ebrahim | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42162 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Kazemi, Mohammad Taghi
  7. Abstract:
  8. Due to major problems induced by delamination in laminated composites, functionally-graded materials (FGM) have been put to growing use in recent years. In the present research, dynamic stability of FGM cylindrical shells under axial follower loads is addressed. Loading was considered in three forms: concentrated (Beck’s problem), uniformly-distributed (Leipholz’s problem), and linearly-distributed (Hauger’s problem). In order to derive the governing equations, Love’s hypotheses and First-order Shear Theory (FST) were used. To solve the equations, polynomial mode shapes were used to approximate the displacements, and the extended Galerkin method was applied. The problem was solved for mild steel, nickel- stainless steel FGM, and stainless steel- alumina FGM. Metal and ceramic phases were considered to be placed so that the FG material could be either hardening or softening when the power parameter (N) is increased. Parametric studies included the effects of thickness, length, shear deformations, power parameter, loading distribution degree (changing to Leipholz’s and Hauger’s problem), and axial vibration of the shell particles on the flutter load and the critical circumferential wave number. Among the most important results were discovering the optimum and critical thicknesses, optimum and critical power parameters, and the beam-like ranges (in which the shell can be analyzed using an equivalent beam)
  9. Keywords:
  10. Functionally Graded Materials (FGM) ; First-Order Shear Deformation Theory ; Flutter ; Follower Force ; Beck Problem ; Leipholz Problem ; Hauger Problem

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