Numerical methods for the characterization of transverse low velocity impact in stochastic tow based discontinuous fiber composites

Abstract

Stochastic tow-based discontinuous composite (STBDC) laminates are made from compression-molded tows of carbon fiber reinforced polymer (CFRP). STBDCs are a material system that can be manufactured in complex three-dimensional geometries which provides an alternative to metallic components for primary and secondary structures. The discontinuous mesostructure gives the material system increased moldability versus continuous fiber composites allowing complex three-dimensional parts to be manufactured. However, the discontinuous mesostructure creates challenges for engineers designing parts as the effective properties are variable. Low velocity impact induced damage is a primary sizing constraint to ensure a structure is damage tolerant. Significant work has been done to experimentally and numerically characterize the LVI induced damage of continuous fiber composites, however little has been performed for STBDCs. The objective of this work is to develop a framework that enables the prediction of LVI induced damage through simulation of the mesostructural fine element models. Full mesostructures are generated, enabling simulations capturing the unique failure modes, which are primarily tensile matrix cracking and delamination. The results correlate well with experimental data collected and prove useful in predicting the initiation and evolution of damage in STDBCs. From the simulations, an impact damage threshold is established, demonstrating the value of the framework in predicting the damage of STBDCs.