Modeling of functionally graded materials in dynamic analyses

In this investigation, functionally graded material is modeled in several different ways. Five models are presented, two of which simulate fiber phases and three simulate particle phases. For fibers, there is a model in which the detailed micro-structure is simulated and one in which the material is represented by layers such that the volume fraction of the fibers in each layer changes. For the particles, a model with layers is employed and two models with continuously changing material parameters are presented. Four different dynamic input loads are applied to the detailed micro-structure to examine its effect. The finite element method is employed to determine the effective stress. Then one of the dynamic loads which simulates a step function is applied to all models. It is observed that there are no significant differences in the effective stresses at particular points 1 within the time domain. The amplitude of the wave for each model is quite similar. The phase of the wave shifts as time increases. Thus, in the space domain, differences are observed in the effective stress at a particular time. As may be expected, the stresses are rather high within the fibers in the detailed micro-structural model. It is concluded that a continuously changing material model is a good candidate for carrying out dynamic analyses of functionally graded material. (C) 2002 Elsevier Science Ltd. All rights reserved.