Progressive Damage Analysis Of Tri-angle-ply Punctured Composites

C/C punctured composites are given much concern for its superior mechanical properties and great prospect in aeronautics and astronautics. However, their mechanical properties are hard to predict by theoretical methods, for their complex meso-structure, which constrains their further development. Compared with theoretical methods, Finite Element Method (FEM) shows its superior. With Representative Volume Cell (RVC), the mechanical properties of punctured composites can be accurately predicted by FEM.Firstly, Umat subroutine was written for fiber reinforced composites, by which damage model and damage evolvement model were introduced into the material's constitutive equation, in order to predict the failure mode and tensile strength of this punctured composites. The effectiveness of this subroutine was verified by conducting progressive damage analysis of a unidirectional reinforced composite.Then, the stiffness properties of punctured composites are studied using FEM. The RVC was found based on periodic properties of punctured composites, and its calculation model was found to obtain the mechanical properties. Through stiffness analysis with the RVC under periodic boundary conditions, the elastic modulus, Poisson's ratios and shear modulus of this punctured composite were obtained.At last, the tensile strength and failure modes of punctured composites under tensile loads were predicted. Three RVC models were set up: the one without interface; the one containing strong interface between bundles and matrix; and the one containing weak interface. The tensile load in X, Y, Z directions were applied on the RVC respectively and the strength and failure modes of punctured composites were obtained. It was found that the strength of the punctured composite is uniformly distributed in each direction. There are fiber bundles reinforcing the structure in X, Y, Z direction respectively, without directions very weak in strength. And also, the strength of the interface between bundles and matrix does not have much influence on the strength and failure modes of the punctured composite.