液滴─固面高速撞击问题中固体变形性的影响

将液滴—固面高速撞击的非线性流体动力学模型应用于固体动力学行为的研究之中,导出了固体可变形系数及其内部应力张量的计算方法,从而使作者提出的非线性理论模型能够计及固体变形性对撞击效应的影响。对刚性和可变形固面的撞击过程进行了比较计算和分析,表明在高速撞击条件下两者有较大的差别,并且固体的可变形性对撞击有着强化—缓解双重作用,这在工程选材时必须加以考虑。同时,本文还给出了工程材料的刚性判据。

EFFECTS OF SOLID DEFORMABILITY ON HIGH-SPEED IMPACT OF A LIQUID DROP AGAINST A SOLID SURFACE

When a liquid drop strikes against a solid plane at high speed,huge transient pressure is generated and the contact periphery progresses more quickly than the shock wave fronts in either liquid or solid.If the impact velocity is high enough,the linear theory is totally inadequate in predicting the collision pressure,which is critical in explaining the damage mechanisms and erosion processes.Therefore a non-linear shock model is applied to studying the dynamic behavior of solid under high-speed liquid-solid collision.The model takes the deformability of the target into account by the aid of the deformable coefficient Y and provides the formula of the stress tensor in the solid.The impacts of a liquid drop against a deformable target have been compared.A considerable difference between them appears if the impact velocity is high.It is shown that the solid deformability has two-edged effects on impact phenomenon,enhancement and relaxation,whcih must deserve extra attention in material selection.A "rigid criterion" concept is suggested to determine when the material deformability must be considered,and two criterions are proposed for stainless steel and glass.