MULTI-SCALE METHOD OF PLAIN WOVEN COMPOSITES SUBJECTED TO LOW VELOCITY IMPACT BASED ON ASYMPTOTIC HOMOGENIZATION

A multi-scale approach was presented to analyze low velocity impact response and damage of plain woven composites. Firstly, by using the maximum principal stress failure criterion and direct stiffness degradation model to characterize the damage initiation and damage evolution of fiber and matrix, micro-scale unit cell under the periodical boundary condition was established to predict the elastic and strength properties of fiber bundles, which were substituted into the meso-scale unit cell. After that, the progressive damage simulation of meso-scale unit cell under six boundary conditions was carried out based on the mixed failure criteria of Hashin and Hou, and continuum damage model. Then the effective properties of 0^\circand 90^\circsubcell were predicted based on the asymptotic homogenization method by using meso-scale unit cell as the media, and the subcell model of plain woven composites was established. The subcell model was then extended into a macro-scale low velocity impact model. Based on the above methods, the mechanical response and damage characteristics of plain woven composites under low velocity impact were studied. The results show that macro-scale impact simulation results agree well with experimental results, which verifies the correctness of multi-scale approach. The maximum contact force, absorbed energy and delamination area increase with the increasing impact energy, and the delamination damage morphology gradually transforms from ellipse to circle.The long axis direction of matrix tensile damage and matrix compressive damage are orthogonal and consistent with the material principal direction of subcell respectively, and the damage area of the former is much larger than that of the latter.