Abstract: A new free surface scheme for 1-D and 2-D numerical calculation of elastic-plastic flow is proposed to study e-beam or X-ray radiation,high velocity impact and blast.Some numerical examples given here show that the pressent free surface scheme is more suitable than Richtmyer's for solving thermal-mechanical effects of material subjected to e-beam or X-ray pulse radiation.It is proved that this scheme should give a third-order accuracy.

Key words: elastic-plastic flow, irradiation, thermal-mechanical effects, free-surface scheme