Global Engineering and Materials, Inc. — Department of Defense STTR Phase I: A combined discrete cohesive interface fracture and continuum damage mechanics initiation

Description

A combined discrete cohesive interface fracture and continuum damage mechanics initiation and propagation toolkit for Abaqus will be developed for the residual strength prediction of adhesively bonded composite structures subjected to multi-axial loading. This tool will allow us, for the first time, to be able to simulate concurrently both the continuum and discrete damage progression at the bonded interface and in the adhesive, respectively, under multiaxial loading. To capture the highly nonlinear material constitutive response and the environmentally-driven mechanical properties along the bondline, the adhesive layer will be characterized explicitly without introducing a smearing procedure. An advanced cohesive fracture model will be developed to account for the combined energy dissipation from decohesion, frictional sliding, and yielding. A hydrostatic stress dependent plasticity model coupled with a continuum shell description will be implemented to capture the damage accumulation in a thin adhesive layer subjected to a combined tension/compression/shear loading. Testing will be performed to identify model parameters and to validate the toolkit at coupon and component levels. GEM has secured commitments for technical support from Virginia Tech, Lockheed Martin, Sikorsky, and Air Force Research Lab.