Effects of micromechanical factors in the strain invariant failure theory for composites

Abstract

In this thesis, strain amplification factors of Strain Invariant Failure Theory (SIFT) for composites are obtained by three-dimensional finite element method. Strain amplification factors are obtained for a particular composite system, i.e. carbon/epoxy, and for a certain fiber volume fraction Vf (in this case, as reference, Vf = 60%). Parametric studies have also been performed to obtain strain amplification factors for Vf = 50% and Vf = 70%. Other composite systems such as glass/epoxy and boron/epoxy are also discussed in terms of strain amplification factors. Open-hole tension specimen is chosen to perform the growth of damage in composite plate. Finite element analysis incorporating Element-Failure Method (EFM) and SIFT within an in-house finite element code was performed to track the damage propagation in the open-hole tension specimen. The effect of fiber volume fraction can be captured by observing the damage progression.