Implementation of New Adaptive Cohesive Elements for the Simulation of Delamination in Composite Materials in LS-DYNA

Summary: A new 8-node adaptive cohesive element is developed and implemented in LS-DYNA to stabilize the finite element simulations of delamination propagation in composite laminates under transverse loads. In this model, a pre-softening zone is proposed ahead of the existing softening zone. In this presoftening zone, the initial stiffness and the interface strength are gradually decreased. The onset displacement and the critical energy release rate of the materials are kept constant. The validity of this new model is proved by an excellent agreement between the numerical findings and the experimental results of DCB specimen in Mode-I. The numerical results show that the proposed model brings stable simulations and overcome the numerical instability.