EMAS Core Material Modeling with LS-DYNA

With Lagrangian meshes and the LS-DYNA FEA explicit solver, Mat #63 – Crushable Foam is used to simulate the Phenolic foam – a candidate material for an EMAS core [7]. The simulated conditions include three scenarios: unconfined uniaxial compression, confined uniaxial compression and plate penetration into a large block. The three scenarios are purposely chosen for utilizing test data and validating simulation results. The simulations reveal that when an hourglass control is needed, the parameters for the control can significantly affect the results. The simulations with element formulations ELFORM=2 and 3 deliver better results than ELFORM=1. However, ELFORM=1 is the least expensive due to savings in computation time. ELFORM=3 is much more expensive than ELFORM=2 even with similar accuracy. When there is a symmetrical modeling condition, a reduced model size not only can save computational cost, but also sometimes can achieve greater accuracy. The simulation results are very sensitive to the value of TSC. For the very weak crushable material, a proper small value of TSC is preferred, instead of absolute zero. At extreme large deformation, the Lagrangian meshes may not work well because of extreme element distortion, which is observed in the scenario of plate penetration into a large block.