Verification and Validation of Progressive Damage Analysis Methods for Explicit Analysis of Progressive Delamination

The NASA Advanced Composite Consortium (ACC), which includes as its members Lockheed Martin Aeronautics, Boeing, GE, UTC, Aurora, Orbital ATK, NASA, and FAA has embarked on an ambitious mission to reduce aircraft structural certification timeline by 30% using a combination of technologies, one of which is high fidelity progressive damage computational methods. A highly structured process is adopted to accomplish this mission where the progressive damage methods are first verified and validated before it is applied to structures of increasing complexity akin to a typical building-block approach currently adopted for structural certification of aircrafts. This study focuses on the verification of two methods for studying progressive interlaminar damage; the cohesive zone method embedded in Abaqus native cohesive element and a beta version of the Discrete Cohesive Zone (DCZM) model, acquired through the University of Michigan, implemented as a user defined element within Abaqus. The methods are verified by predicting delamination initiation and growth in the Double Cantilever Beam (DCB), the End Notched Flexure (ENF), and the Mixed Mode Bending (MMB) and comparing the predictions to high fidelity numerical solution obtained using Virtual Crack Closure Technique (VCCT). The lessons learned in the verification exercise are then applied to a validation exercise of a three-point bend doubler problem. For the doubler, in addition to modeling the interlaminar progressive damage, the intralaminar progressive damage is modeled using two continuum damage models; NASA’s CompDam and a beta version of the Enhanced Schapery Theory (EST), acquired through the University of Michigan. Analysis predictions for the doubler using the different progressive damage techniques are compared.