Tests of Mode-I delamination in Double Cantilever Beam (DCB) specimens were modeled with the finite element solver, LS-DYNA, to simulate the behavior of composite materials at high speed loading rates (between 2 in/s and 100 in/s). Cohesive elements were used to model the crack growth behavior. The investigation examines the dynamic effects of the loading block or loading hinge on the simulations. Recommendations are made for which material models, boundary conditions, and other modeling techniques to use for best results. A factor for strain energy release rate is also introduced to account for reductions in GIc at high loading rates. The adjustment factor would apply to a test-derived value of GIc and would result in a reduction ranging from 1.6% at 2 in/s to 87% at 100 in/s. The implications of the finding are that testing would need to indicate a power-law increase in the apparent GIc value in order to maintain a constant actual GIc.

Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering.