Failure Mechanisms of Sandwich Specimens With Epoxy Foam Cores Under Bending Conditions

Sandwich specimens with DP590 steel face sheets and structural epoxy foam cores are investigated under three-point bending conditions. Experimental results indicate that the maximum loads correspond to extensive cracking in the foam cores. Finite element simulations of the bending tests are also performed to understand the failure mechanisms of the epoxy foams. In these simulations, the plastic behavior of the steel face sheets is modeled by the Mises yield criterion with consideration of plastic strain hardening. A pressure sensitive yield criterion is used to model the plastic behavior of the epoxy foam cores. The epoxy foams are idealized to follow an elastic perfectly plastic behavior. The simulation results indicate that the load-displacement responses of some sandwich specimens agree with the experimental results. Based on the results of finite element simulations, for the given geometry and the combination of materials, cracking within the foam cores is due to large shear deformation which comes from the large difference in the load carrying capacities of the steel face sheets and the epoxy foam cores.