Characterization and modeling of progressive damage in angle-ply composite laminates under varying strain rate loading

The strain-rate-dependent damage progression of toughened-matrix carbon/epoxy composite (IM7/8552) angle-ply laminates was characterized over the range of quasi-static (10-4 s-1) to dynamic (103 s-1) strain rates. A progressive damage model was proposed to describe the matrix-dominated transition from linear elastic to non-linear material behavior. The Northwestern Failure Theory was adapted to provide a set of physical-based yield criteria for predicting the matrix-dominated damage initiation using the lamina transverse tension, transverse compression, and shear yield strengths. The characteristic damage state of the angle-ply laminates was determined for the tested strain rates to provide a length scale-relevant benchmark for characterizing progressive damage in the angle-ply laminates. The framework evaluated the angle-ply laminate yield, characteristic damage state, and ultimate failure based on matrix-dominated response and the Northwestern Criteria were found to provide superior prediction of the matrix-dominated behavior for all evaluated cases compared to the classical approaches. The results indicate the potential to use the Northwestern Criteria to provide the predictive baseline for damage propagation in composite laminates based on experimentally identified damage response on a length-scale-relevant basis.