Predicting the matrix cracking formation in symmetric composite laminates subjected to bending loads

The present study investigates analytically the effects of matrix crack formation on the properties of composite laminates subjected to bending loads, using a crack density-based model. For this purpose, by assuming that the plies prone for matrix cracking are sufficiently thin, the relationships of the stiffness reduction due to matrix cracking formation is applied. Then, by considering the equivalent damaged lamina and using the relationships of classical laminates theory (CLT), the variation of mechanical properties of symmetric laminates in the presence of matrix crack is calculated. In addition, a method is proposed to estimate the fracture toughness caused by the matrix crack in composite laminates by using the concept of finite fracture mechanics and calculating the energy release rate due to a matrix crack in a laminate under bending loading. Finally, the progressive growth of matrix crack in the cross-ply symmetric composite laminates is studied by applying the developed relationships into the nonlinear finite element code. The credibility of the proposed method is verified by comparing the obtained results with those achieved numerically and experimentally.