液固高速撞击时材料表面损伤的数值模拟

Numerical Simulation of Material Surface Damage by High Speed Liquid-Solid Impact

为了研究液固撞击的机理,采用光滑粒子流体动力学方法(SPH)与有限单元法(FEM)建立了考虑流固耦合效应的高速液固撞击数值模型,详细分析了直径为2 mm、撞击速度为1 000 m/s的液滴和射流对有机玻璃(PMMA)的三维撞击和破坏状况.分析表明:射流与液滴在撞击初始时刻的前缘变形和内部压力分布几乎是完全相同的;液滴撞击固体的最大压力值出现在0.20μs时,但此时材料内部最大等效应力只有104 MPa,材料还不足以发生破坏;产生于液固撞击瞬时后0.32μs、速度高达2 925 m/s的侧向射流是使固体表面产生破坏的主要原因,因此撞击最初的破坏位于以撞击中心为圆心的一个圆环区域处.所得材料表面损伤情况与Brunton的实验数据吻合良好,证明了数值模型的可行性和精确性.

The numerical model for high speed liquid-solid impact considering fluid-structure interaction coupling effect was developed based on smoothed particle hydrodynamics （SPH） and finite element method （FEM）. The damage of polymethylmethacrylate （PMMA）, caused by a single droplet and a jet impact with a radius of 2 mm and a speed of 1 000 m/s, was analyzed. The numerical results show that the distortion and interior pressure of the droplet and the jet are almost the same at the beginning of impact. The maximum pressure inside the droplet occurs at 0.20 μs after impact, and the maximum equivalent stress inside solid is only 104 MPa which can not lead to material damage. It is mainly the inclined jet which has a speed of 2 925 m/s and occurs at 0. 32μs that causes the material surface damage. The initial damage by impact is located in a circular region whose center is the impact position. The material surface damage predicted by the numerical simulation shows good agreement with the experimental data of Brunton.