薄壁管壳高速正撞击穿孔特性的数值研究

受径向曲率的影响,薄壁管壳遭受高速弹丸撞击产生的局部穿孔毁伤与薄板结构并不相同。本文利用LS-DYNA3D动力学程序,采用光滑粒子流体动力学和有限元法相耦合的方法(SPH-FEM),对球形弹丸高速正撞击不同直径薄壁钢管的穿孔毁伤特性进行数值研究。根据小弹丸高速撞击薄板的物理力学性质,可把穿孔过程简化为初始流动扩孔和随后的惯性扩孔两个阶段,提出一种圆柱管壳高速正撞击穿孔的简化物理模型,并分析圆管直径对轴向孔径和径向孔径尺寸差值比的影响。数值模拟结果表明,撞击速度为2~3 km/s时,薄壁钢管的正撞击穿孔略呈椭圆状,其轴向孔径尺寸稍大于径向孔径尺寸;随着薄壁钢管直径的增加,两个方向的孔径尺寸差值比减小。另外,薄壁钢管遭受小弹丸撞击穿孔后产生碎片云的分布形态受径向直径影响明显,相同撞击条件时,钢管直径越大,则产生碎片云的膨胀角和残余速度也较大。

Numerical investigation on characteristics of perforation for thin cylinder pipes by normal impact at high velocity

The characteristics of perforation damage for thin cylinders suffered by high velocity impact is different from that of thin plates because of the curvature. In this paper, numerical investigation on the perforation damage behavior for thin steel cylinder pipes with different radial diameters is performed with the use of LS-DYNA3D program and smoothed partide hydrodynamics finite element method (SPH-FEM) algorithm. Based on the physics mechanics characteristics of thin plate impacted by fragment projectile at high velocity, perforation can be simplified as two stages, initial fluid dynamical piercing and the following inertia piercing, and a new simplified physics model has been proposed to illustrate the perforation process. The effect of the diameter of the pipes has been discussed on the difference ratio between axial diameter size and the radial size of the perforation hole. The result shows that the perforation displays oval in shape and the axial size of the hole is a little longer than the radial size. For the range of 2-3 km/s, the difference ratio decreases with the diameter of the thin cylinder pipe increasing. What's more, the distribution of debris cloud after perforation shows sensitive to the diameter of cylinder pipes. Under the similar impact condition, it reveals that cylinder pipes with larger diameter tend to produce relatively larger expansion angle and larger residual velocity of the debris.