Characterization of Damage Evolution as a Function of Material Architecture: A Computational Model Comparison

Abstract

The ever-increasing use of composite materials in aerospace structure is well documented due to their high strength-to-weight ratios. However, an important design limitation associated with utilizing composite materials is the uncertainty of how damage will evolve in components under in-service conditions. Compound this problem with the various material forms (unidirectional vs. fabric) and the difficulty of predicting damage evolution increases exponentially. This necessitates the development of a predictive framework that is capable of simulating composite damage evolution in a wide variety of load conditions and form factors. This need can potentially be met by BSAM, a progressive damage analysis (PDA) framework developed by AFRL/UDRI/UTA with an extensive history in modeling damage evolution in composite materials. In this work the damage evolution and mechanical properties of Hexcel’s HexPly® M-21 carbon/epoxy were investigated. A variety of ASTM standard tests were conducted to produce mechanical properties for the computational models. In addition, notched over-height compact tension (OCT) and compact compression (CC) specimens were fabricated and tested to evaluate damage evolution for comparison with the computational predictions. Various ply sequences were explored using both unidirectional and woven materials. For the sake of comparison, ply sequences were chosen such that a woven layer in the woven composite corresponded to two orthogonal unidirectional plies in the unidirectional composite. Surface damage evolution was monitored with digital image correlation (DIC), and interior damage