金属/聚氨酯波形发生器复合弹体冲击载荷特性及调控机制

Impact Load Characteristic and Regulation Mechanism of Metal/polyurethane Waveform Generator Composite Projectile

采用撞击方式模拟爆炸/冲击加载是一种有效的实验室规模的加载手段。为探究金属/聚氨酯波形发生器(Polyurethane Waveform Gnerator,PWG)复合弹体的冲击载荷特性及PWG对载荷的调控作用,进行不同尺寸PWG的准静态压缩加载-卸载实验,分析PWG的基本力学特性及PWG的刚度、能量耗散比与PWG尺寸的定性关系。开展不同配置的金属/PWG复合弹体的直接撞击实验,对复合弹体撞击过程进行系统分析,探究冲击速度及PWG尺寸等因素对冲击载荷的影响,并分别建立冲击载荷特征参数与冲击速度、PWG尺寸因子的定量关系。通过金属/PWG复合弹体直接撞击实验的单自由度系统运动方程及PWG动力学模型,探究PWG刚度对冲击载荷的调控作用。研究结果表明:PWG的静刚度系数随直径的增加而增大,随厚度的增加而减小;与PWG直径相比,厚度对能量耗散比的影响更加显著;冲击载荷特征参数与PWG直径D、厚度H的乘积D×H具有显著相关性,且随D×H的增加,峰值压力呈指数下降,持续时间及峰值比冲量分别呈2阶、3阶非线性增长;随着冲击速度的增加,峰值压力和峰值比冲量分别呈现3阶非线性快速增长和线性增长趋势,载荷持续时间则呈现2阶非线性下降趋势;PWG直径对冲击载荷的影响主要通过调控线性静刚度系数α实现,直径越大,α越大,冲击载荷峰值越小,冲量越大,载荷越趋近于半正弦曲线;PWG厚度的影响主要通过调控非线性静刚度系数γ实现,厚度越小,γ越大,冲击载荷峰值越大,冲量越小,载荷的尖峰细腰形状越明显。

Using projectile impact to simulate blast/shock loading is an effective laboratory-scale loading method which has attracted great attention.The quasi-static compressive loading-unloading experiments of PWGs with different geometric sizesaremade to investigate the impact load characteristics of metal/polyurethane waveform generator(PWG)composite projectile and the regulation effect of PWG on the load.The basic mechanical properties of PWG,including the qualitative relationship among the stiffness,energy dissipation ratio and the geometric size of PWG,are analyzed.Direct impact tests of metal/PWG composite projectiles with different PWG configurations are performed.Based on direct impact test results,the impact process of metal/PWG composite projectile is systematically analyzed,and the quantitative relationships among the characteristic parameters of impact load,the impact velocity and the PWG geometric size are established,respectively.The regulation effect of PWG stiffness on impact load is explored by the motion equation of single degree of freedom system for projectile direct impact test and the dynamic model of PWG.The results show that the static stiffness coefficient and energy dissipation ratio increase with the increase in diameter,but decrease with the thickness.The results show that the static stiffness coefficient of PWG increases with the diameter,but decreases with the increase in thickness.Compared with PWG diameter,the thickness shows more significant influence on the energy dissipation.The impact load characteristic parameters are significantly correlated with the product of diameter and thickness(D×H)of PWG.With the increase in D×H,the peak pressure decreases exponentially,and the duration and peak specific impulse increase nonlinearly in 2-order and 3-order,respectively.With the increase in the impact velocity,the peak pressure increases nonlinearly in 3-order,the peak specific impulse increases linearly,and the pulse duration decreases nonlinearly in 2-order.In addition,the influence of PWG diameter on impact load is mainly realized by regulating the linear static stiffness coefficientα.The larger the PWG diameter is,the larger theαis,the smaller the peak load is,the greater the impulse is,and the more similar the load shape to half-sinusoid.The influence of PWG thickness on impact load is mainly realized by regulating the nonlinear static stiffness coefficientγ.The smaller the PWG thickness is,the larger the peak load is,the smaller the impulseis,and the more obvious the shape of‘peak and thin waist’is.