Study On Low-velocity Impact Performance Of Plain Weave Composites With Holes

Plain weave composites are widely used in aerospace and military structures because of superior out of plane performance compared with traditional composites.Due to the fact that materials are often opened with holes of different sizes and shapes and impacted in some low energy levels in the process of service,these impacts can easily cause some invisible damage.In this paper,so the effect of hole opening on the low-velocity impact performance of plain weave composites is studied by means of multi-scale analysis.Firstly,by using the maximum stress failure criterion and the maximum principal stress failure criterion to characterize the damage initiation of fiber and matrix separately,and by using the direct stiffness degradation method and the progressive stiffness degradation method to characterize the damage evolution of fiber and matrix separately,micro-scale unit cell under the periodical boundary condition was established to predict the elastic and strength properties of the fiber bundle by means of theoretical and numerical analysis,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° and 90° subcell 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.Finally,the effects of different hole shapes and hole distance on the impact performance of materials at low speed were studied based on the model established above.The results show that the failure of the circular hole presents a kind of hole tear pattern,while the others present the cruciform failure pattern.The holes of different shapes can hinder the expansion of fiber compression damage and interlaminar damage.The closer the distance between the hole and the impact point is,the smaller the area of fiber compression damage and interlaminar damage get,and the larger the area of fiber tension damage gets.