PLASTIC LIMIT ANALYSIS OF DUCTILE COMPOSITES BASED ON HOMOGENIZATION THEORY
基于均匀化理论韧性复合材料塑性极限分析

This paper is to determine the bearing capacities of ductile composites by means of the homogenization theory of micromechanics and the plastic limit analysis. To reflect the microstructures of a composite, a representative volume element (RVE) is first selected. According to the homogenization theory, the overall fields are decomposed into macroscopic average and microscopic fluctuation terms, which can reflect the relation between macroscopic and microscopic scales. Then, by introducing the homogenization theory into the plastic limit analysis, a strategy for the direct computation of the limit load of a microstructure RVE is put forward. For such ductile composites as metal matrix composites (MMC), the constitutions is assumed as rigid-perfectly plastic solids and obey the von Mises yield criterion. By means of the kinematic limit approach and finite element method, the numerical modeling of the plastic limit analysis of a composite is formulated as a nonlinear mathematical programming with equality-constraint conditions, which can be solved by a direct iterative algorithm developed. Numerical examples show the validity of the method and the high effectivity of the algorithm. It can be concluded from numerical results that the macroscopic strength of a composite is mainly determined by weak constitutions in the plane model and that the reinforced effects of fibers are most intensive in the off-axis direction. The method presents an effective tool for the strength analysis of ductile composites.