Damage Initiation and Propagation Modeling in Laminated Composites under Fatigue Loading

Abstract

Discrete Damage Modeling methodology and results of stress and fracture analysis in laminated composite materials are reported. This work is a direct continuation of efforts which begun in the early 90’s at the Materials Directorate Wright Patterson Air Force Base, WPAFB OH and since the mid 90’s were championed by Captain Jeffrey Schaff until the conclusion of his tenure with the Air Force. The essence of DDM is the insertion of true displacement discontinuities independent of mesh orientation to simulate matrix cracking and interaction with delaminations between plies. The fiber failure mode is modeled by property degradation methodology for progressive damage analysis in compression and statistical fiber macro failure criterion in tension. Static as well as fatigue analysis is enabled. Accurate tensile strength prediction was demonstrated in static analysis of pristine as well as fatigue cycled laminates. Compression strength was overpredicted in both cases and requires additional effort.