Effect of architecture on mechanical properties of carbon/carbon composites

Three-directional orthogonal, 3-directional plain-woven and 4-directional in-plane composites are three architectures commonly used in components made of carbon/carbon composites. Homogenization and finite element analysis of a three-dimensional periodic unit cell characterizing the structure of the composite and periodic boundary conditions are used to compute the elastic moduli of carbon/carbon composites for different architectures. First, the mechanical properties of a fiber bundle are predicted assuming the fiber bundle to be a perfectly bonded uni-directional composite. Second, these properties are used to predict the mechanical properties of the multidirectional composite. Cohesive zone models are used to simulate the interfacial debonding at the fiber bundle/matrix interfaces. The application of cohesive zone model when there are debonds at the interface between the fiber bundle and the matrix results in a remarkable change in the values of shear modulus when compared to that obtained for perfectly bonded composites. The analysis predicts a significant effect of architecture on the properties of composite.