M Asgari - Assistant Professor, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
A. Khanmohammadi - Graduate Student, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
M Parsa - Graduate Student, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran

The composition of several different materials is often used in structural components in order to optimize the responses of structures subjected to severe thermal and mechanical loads. Functionally graded materials (FGMs) aresuitable to achieve this purpose in the case of pressure vessels. On the other hand these structures usually sustain cyclic loadings resulting in ratcheting and shakedown behavior. In this study the nonlinear kinematic hardening theories areused to evaluate the cyclic loading behavior of a thick walled FGM Cylinder under internal pressure. The power law volume fraction distribution of materials, geometry and mechanical load are assumed to be axisymmetric. The finiteelement method combined with a multi-layered approach is used to model the structure. The response of structure under cyclic loadings is considered. Nonlinear kinematic hardening theories based on different type of back stressnumbers are used to predict the ratcheting and shakedown behavior of the structure. The effects of variation of materials distribution on cyclic behavior are also studied. The achieved results show that using functionally gradedmaterial leads to a more flexible design so that cyclic rupture can be improved by selecting a suitable material distribution profiles.

Cyclic Plasticity, FEM, FGM Thick Cylinder, Ratcheting