Dynamic fracture analysis of multi-layer composites using an improved RHT model

The present study investigates the dynamic fracture behaviour of concrete in multi-layer composite targets subjected to projectile impact loading. The Riedel, Hiermaier, and Thoma (RHT) model is widely used for simulating concrete damage under impact and extreme loading conditions. While the original RHT model provides reasonable penetration depth and residual velocity predictions, it has notable limitations in capturing tensile failure mechanisms, particularly spalling damage and tensile cracking. An improved RHT (M-RHT) model has been proposed to address these shortcomings, incorporating an exponential hydrostatic expansion damage model and an exponential tensile crack-softening damage model within a user-defined material subroutine. These modifications enable more accurate predictions of spalling damage and dynamic crack paths. The effectiveness of the proposed M-RHT model is demonstrated through single-element simulations, showing a significant improvement in the representation of tensile damage evolution. The model is further validated using projectile penetration simulations, where it accurately predicts damage sizes, crack propagation, and residual velocities, aligning well with experimental observations. The improved RHT model has been applied to simulate the projectile impact on the multi-layer composite target. Compared to the original RHT model, the M-RHT model exhibits improved damage predictions in multi-layer composite targets by accurately capturing spalling and tensile cracking.