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对不同速度弹丸撞击花岗岩靶产生的弹坑深度和裂纹长度进行实验和数值分析。利用轻气炮进行五发实验,得到3种撞击速度下的弹坑直径、弹坑深度、靶板表面裂纹分布等破坏效应,并对撞击速度为654 m/s的正侵彻实验靶进行切割,得到靶板内部的裂纹分布情况。采用非线性动力学软件Autodyn对正侵彻花岗岩实验进行数值模拟。将Johnson-Homquist损伤本构模型(JH–2模型)与拉伸断裂软化模型相耦合,来模拟靶板内高应力区材料的压缩和剪切破坏效应,以及低应力区靶板在主拉伸应力作用下产生的损伤和裂纹扩展。相对于传统有限元计算中删除单元形成裂纹的处理方法,本文采用SPH算法,通过定义损伤来描述材料的压缩破坏以及由剪切和拉伸断裂形成的裂纹。模拟得到的弹坑尺寸以及裂纹长度与实验结果符合较好。根据模拟结果进行数值试验,拟合出不同撞击速度下的弹坑深度和裂纹长度的经验关系式。相关方法及材料模型参数可为后继实验和相关数值模拟提供参考。
Experimental and numerical analyzes of the crater depth and crack length produced by projectile impacting granite targets at different velocities are carried out. Five experiments were carried out with light gas guns, and the destructive effects of crater diameter, crater depth and surface crack distribution on the target were obtained under three kinds of impact velocities, and the positive penetration experiment target with the impact velocity of 654 m / s was cut to obtain Crack distribution inside the target. Nonlinear dynamics software Autodyn was used to simulate the experiment of penetrating granite. The Johnson-Homquist damage constitutive model (JH-2 model) is coupled with the tensile fracture softening model to simulate the compression and shear failure of the high-stress zone material in the target plate, Damage and crack propagation under stress. Compared with the traditional finite element method for calculating the formation of cracks in a unit, SPH algorithm was used to describe the compression failure and the cracks caused by shear and tensile fracture by defining the damage. The simulated crater size and crack length are in good agreement with the experimental results. According to the simulation results, numerical experiments are carried out to fit the empirical relationship between crater depth and crack length under different impact velocities. The related method and material model parameters can provide reference for subsequent experiments and related numerical simulation.