Two kinds of fractures can be observed in the SPH(smoothed particle hydrodynamics) simulations,which are the physical fracture and the numerical fracture.The physical one exists in reality,while the numerical one is fictitious.This paper presents the effects of both fractures and proposes a simple adding particle technique to avoid the numerical fracture.The real physical fracture is then figured out by using an applicable fracture criterion.Firstly,the effect of the numerical fracture on the computational accuracy is investigated by introducing the artificial fracture in a model of wave propagation.Secondly,a simple adding particle technique is proposed and validated by a three dimensional bending test.Finally,the experiments of penetration on the skin of aircrafts are simulated by both the initial SPH method and the improved method with the adding particle technique.The results show that the improved SPH method can describe the physical fracture very well with better accuracy.
