弹体斜侵彻双层钢板的结构响应和失效研究

Structural response and failure of projectiles obliquely penetrating into double-layered steel plate targets

为探究弹体斜侵彻多层钢板的结构响应及失效规律,开展了圆形、椭圆和非对称椭圆三种截面弹体对双层钢板的斜侵彻试验,获得了不同弹体的弹道特性和结构失效情况。在此基础上,采用有限元软件对弹体斜侵彻过程的弹道特性、动态载荷以及结构响应进行了数值分析。基于空间自由梁理论和弹体动态载荷,给出了侵彻过程中弹体轴力和弯矩的分布规律,建立了弹体结构强度与失效分析方法。结果表明,弹体以正着角水平侵彻多层钢板时,存在一个临界攻角;当攻角小于临界值时,侵彻过程中会出现弹体低头、弹道向下偏转的现象;当攻角大于临界值时,则出现弹体抬头、弹道向上偏转的现象;该临界攻角随着靶板厚度的减小而增大。对于强度高、韧性低的弹体,失效模式为脆性断裂,断裂位置距头部0.72~0.81倍弹长,弹身后部所受横向冲击载荷是造成弹体断裂的主要原因。建立的弹体结构响应模型可准确预测弹体断裂失效及发生位置。此外,在三种截面弹体中,非对称椭圆弹体的断裂位置更接近头部。

In order to investigate the structural response and failure of projectiles obliquely penetrating into a multi-layered steel plate target,oblique penetration tests were conducted,in which three kinds of projectiles with circular,elliptical,and asymmetric elliptical cross-sections were employed while the ballistic trajectory and structural failure of projectiles were recorded.With the photographs captured by high-speed camera,a pixel measuring method was used to obtain the velocity and attitude deflection angle of projectiles.Based on the test results,the ballistic characteristics,dynamic loads and structural response of projectiles are analyzed by using FEM code ABAQUS/explicit,focusing on the oblique penetration at initial speed of 480 m/s and attack angle within 2°.Then,based on the free-free beam theory and the dynamic loads obtained by numerical simulation,the distributions of axial force,shear force and bending moment within projectiles are calculated,and an analytical method for structural strength and dynamic failure of projectiles is developed.The results show that when the projectile horizontally penetrates a multi-layered steel plate target with positive inclined angle,there exists a critical attack angle.If the attack angle is smaller than this critical value,the projectile will head drop and its trajectory turns downwards;when the attack angle is larger than the critical value,the projectile will be raised and its trajectory turns upwards.In addition,the critical attack angle increases as the thickness of the target plate decreases.For the projectiles with high strength and low ductility,the failure mode is brittle fracture and the distances between the fracture position and the projectile nose is 0.72−0.81 times of its length,which is mainly due to the lateral impact load at the rear part of projectile.Moreover,by means of the dynamic model of the projectile based on the free-free beam theory,the fracture position of projectile during oblique penetration process could be well predicted.Also,among the three types of projectiles with the same length and cross-sectional area,the projectile with asymmetric elliptical cross-section is easier to fracture and the position is even closer to the projectile nose.