A Coupled Damage-plasticity Model for Energy Absorption in Composite

Predicting the energy absorption of composite structures requires a constitutive model that is capable of representing post-peak softening and irreversible strains, i.e., a coupled damage-plasticity model. The development of such models requires a general damage-plasticity framework. This article examines the merits and limitations of the continuum damage mechanics (CDM) framework and the plasticity framework. Based on the physical evidence of damage accumulation process in composites and the fundamentals of the two theories, a simple coupling method was proposed. This method employs a perfect plastic flow rule within a CDM framework. The capability of this method was examined by incorporating plasticity into the Matzenmiller-Lubliner-Taylor (MLT) model, a classic CDM model for composites. The coupled MLT-plasticity model was implemented as a user defined material law in explicit finite element code LS-DYNA ^® , and subsequently numerical tests were conducted. It was demonstrated that the proposed method can extend an existing composite CDM model into a coupled damage-plasticity model seamlessly with only a few extra parameters, while retaining its computational efficiency. The capability of the coupled CDM-plasticity model in energy absorption prediction was validated in axial impact simulations of a composite tube reinforced with 1-ply carbon fiber tri-axial braid.