Ram Load Simulation of Wing Skin-Spar Joints: New Rate-dependent Cohesive Model.

摘要

A new rate-dependent cohesive zone model for use in impact and/or hydrodynamic ram delamination problems is presented. The traction based model includes a damage-dependent term and two cohesive zone viscosity parameters. The first viscosity parameter adjusts the yield traction of the material, while the second parameter adjusts the peak or maximum traction. This new rate- dependent cohesive model is implemented in Ls-DYNA (971 beta revision 5397), an explicit time integration FEA code, by defining a user cohesive material model. It may be used with shell or brick elements. Previously published Double cantilever beam (DCB) experiments of epoxy and PEEK/carbon-fiber composites are modeled in order to validate the rate-dependent cohesive model. Also, in order to provide a methodology to obtain data to determine material constants for this rate-dependent cohesive zone model, a simple inexpensive experimental apparatus for high rate DCB (Double Cantilever Beam) sample testing was developed.