Effect of void content on stiffness and strength of composites by a peridynamic analysis and static indentation test

Composite structures are susceptible to defects in the form of voids arising from the entrapment of gases or water during impregnation of the fiber reinforcement with resin or during the lay-up process. These manufacturing-induced defects, such as voids and delaminations, influence several mechanical properties. Therefore, it is important to understand the effects of voids on the mechanical properties of composites so that the requirements on void content can be relaxed to reduce manufacturing costs. Although classical continuum mechanics has been applied to explain the behavior of deformable bodies under external loads, the local nature of continuum theory makes it difficult to predict how and when a delamination would occur from porosity. The available special techniques for modeling residual strength prediction by using the finite element method are generally not fully satisfactory because they usually require a failure criterion in advance. This study employs a new approach, known as the peridynamic theory, to capture the effect of void content on the stiffness and residual strength of composite materials. The predictions by the peridynamic theory are compared against the in-house static indentation measurements.