Modeling of deformation and fracture of porous media taking into account their morphological composition

This paper investigates the mechanical behavior and fracture of porous materials with an aluminum matrix. The purpose of the work was to create numerical models of failure of representative volume elements of such materials and to reveal the dependences of the nature of the failure processes on their structural morphology. Representative volume elements of these materials are random non-uniform structures of closed-cell and open-cell types. To create three-dimensional geometric models of the closed-cell structures, methods of sequential synthesis the possibility of their mutual intersection were used. For creation of models of interpenetrating structures of the open-cell type, methods based on the analytical determination of surfaces separating the two phases are used. In this paper, three approaches to fracture mechanics of representative volume elements of porous materials were studied and implemented. The first approach is an implementation of the elastic model and damage accumulation based on elastic properties degradation in accordance with the criterion of maximum stresses with reduction of the stiffness matrix coefficients in individual elements. The second approach is an implementation of the same model, but with removal of the failed elements. The third approach is based on the Johnson-Cook elastic plastic behavior and fracture model. Numerical modeling of the representative volumes was carried out with finite element analysis using each of the above approaches. The influence of the internal structure of the representative volumes of the porous materials on the processes of deformation and failure was studied on the example of several structures of open-cell and closed-cell types. The influence of stress concentrators on the distribution of stresses in representative volumes and character of their subsequent failure has been studied.