A coupling algorithm of finite element(FE) and smoothed particle hydrodynamics(SPH) is introduced.It couples FE calculation with SPH calculation by attaching particles to element segments.In the algorithm,a particle can be fixed to an arbitrary position of an element segment and an element segment can be attached to many particles simultaneously.This makes arrangements of particles and elements at the coupling interface free.The algorithm is applied to simulate stress-wave propagation and high-velocity impact problems.It shows that the algorithm has good accuracy in simulation of stress-wave propagation.In high-velocity impact problems it achieves nearly same accuracy with higher efficiency compared with pure SPH algorithms.

Some natures have been studied for the propagation process of very intense and very short laser pulse in underdense plasma.The wave equation is derived and solved using the method of 2-D Fast Fourier Transformation.The basic equations for relativistic self-focusing include the nonlinear source term and the effect of diffraction.As a result of ponderomotive forces and relativism,the plasma frequency is reduced and so the refractive index is changed.It affects the propagation of laser in plasma.When the incident laser power (p) exceeds the critical power (p_c),self-focusing appears during the propagation of laser.On the contrary,laser damps gradually and self-focusing doesn't appear.

The stress produced by a series of chemical explosions were numerically simulated with one dimension spherical symmetric elastic-plastic flow model. The acceleration, velocity, stress and displacement of particle in rock were calculated and the approximate agreement was observed between calculated value and experimental data.