Failure Induced by Instability in Structural Composites under Longitudinal Compression

Abstract

The objective of this work is to develop a damage propagation model applicable to the study of failure mechanism in composites induced by longitudinal compression. The damage propagation model shall be based on an energy principle, quantified by the critical energy release rate associated to matrix cracking, and on the study of the kinematics of the equilibrium of a representative volume of a ply material within the damaged region of the laminate. It is expected that the model proposed will be implemented within the context of the finite element technology in order to expand its usefulness to realistic situations where multiple ply laminates are used. The model to be proposed shall capture the onset of formation of kink-bands and subsequently its propagation. It is formulated within the context of an energy based approach that considers the critical energy release rate of the matrix in the failed elements of the mesh. A damage parameter that ranges from 0 (intact) to 1 (fully damaged) is used that relates relative shear strains in the matrix induced by loss of stability of a representative volume. The damage models developed will be useful to realistically predict failure due to kink-band formation and propagation mechanism. The results obtained will serve as the starting point for larger collaborative projects involving strain rate effects and damage tolerant composites.