A modified PUFF equation of state is proposed with considenation of both non-linear volume change and anisotropic strength of material under compression and dilation.Taking 2-D impact of orthotropic material and thermal shock wave under X-ray radiation as examples,a finite element program is developed.The mean stresses obtained by traditional and modified PUFF equation of state are compared.They are obviously different at low compression and tension states.With increase of stress,they tends to be consistent gradually.

High-speed impact problems are simulated with smoothed particle hydrodynamics method.Initial smoothing length and nonconforming space between particles in simulation are analyzed.A modified smoothing length approach is put forward.With increase of initial smoothing length, projectile rigidity decreases gradually.A rational range of initial smoothing length is d₀< h₀≤ 1.5d₀.With decrease of space between particles,rigidity of material decreases.With XSPH correction on velocity of a particle,results by nonconforming space between particles agree well with those from identical particle distribution.