Multi-objective shape optimization for axially functionally graded microbeams

摘要

Nonuniform microbeams made of functionally graded materials (FGMs) have been studied extensively in literature to predict their mechanical and thermal behavior, those demonstrated that each of material variation, non-uniformity and micro-scale effects have significant influences on the static stability sand dynamic behavior. Therefore, this research exploited the multi-objective shape optimization method to optimize the beam shape and its volume fraction distribution in order to maximize the critical buckling loads and fundamental frequencies while minimizing the mass and cost of the FG microbeam, for the first time. Modified continuum model based on both Euler-Bernoulli beam theory as kinematic assumptions and constitutive equation of modified couple stress theory, is developed to derive equilibrium equations (in static analysis) and equations of motion (in dynamic analysis) of axially FGMs nonuniform microbeam. To control the variation of height and width along the beam length, three different shape functions are proposed in the analysis. The multiobjective particle swarm optimization (MOPSO) is adopted to get the Pareto optimal solutions. In addition to the FGM power index, the shape functions types and parameters are considered as the design variables. Several optimization problems are studied to demonstrate the multi-objective optimal shape design of axially functionally graded microbeams.