Abstract: This paper describes a methodology based on “Bidirectional Evolutionary Structural Optimization” (BESO) for topological design of microstructures of materials with more than two constituent phases. The composite material is made by repeating microstructures known as periodic base cells. The aim is to achieve appropriate topology of microstructure phases that enhances the material’s bulk or thermal conductivity performance in macro-scale. Constituent phases are divided into some groups and by performing finite element analyses on microstructure, sensitivity numbers are calculated with the application of Homogenization theory. Properties of elements are gradually changed in the finite element model based on their sensitivity numbers and controlling volume of each constituent phase in the model. Some sample microstructures are generated and presented to show the capability of the approach. The results indicate that the proposed approach is very cost efficient. Moreover, there are distinctive boundaries between the constituent phases in the generated microstructures; which is an inherent advantage of application of BESO approach.
Abstract: Microcapsules are used in a wide range of applications, especially in self-healing composite materials and phase change materials. There is a growing body of literature that recognizes the importance of reinforcement on the mechanical properties of composites, however the effect of microcapsules during service needs to be further investigated. In this study, numerical investigations were conducted to examine the effects of the various geometric parameters on the mechanical behavior of microcapsules-based composites. The effective Young’s modulus and Poisson’s ratio of core-shell microcapsules distributed in a continuous matrix were predicted. A detailed three-dimensional finite element modeling (FEM) was presented. The numerical results were compared with a hierarchical proposed analytical model for three-constituent composites. Good agreements were achieved.