Numerical fracture and physical fracture in SPH method

Numerical fracture often appears in the SPH simulation under large deformation. In order to find the influence of the numerical fracture, a sample of wave propagation with 3-dimensional case of numerical fracture is designed. The results show that the numerical fracture may lead to very large error. A newly proposed and convenient technique of adding-particle is introduced to prevent the numerical fracture in the SPH simulation, which can be easily applied to 3-dimensional case under large deformation. During the adding-particle process, it is certified that the mass conservation and momentum conservation are kept constant except the energy has a little change. The experiment of penetration on the skin of aircraft is simulated by the improved method with the technique of adding-particle. It is clear that the numerical fracture can be cured effectively. With the help of physical fracture criterion, the deformation diameter and deformation depth of the sample of the skin plate and the residual velocity of the steel projectile agree well with the experiment.