强激光诱导的应力波在靶板中衰减特性数值模拟

利用ABAQUS 数值模拟软件对脉宽为ns量级的强激光诱导的应力波在铜靶中传播特性进行了模拟研究。建立了适合于高压高应变率下一维平面应力波在铜靶中传播的有限元分析模型，模拟了两种不同激光冲击波峰值压力诱导的应力波在铜靶中衰减的特性。结果显示，峰值压力为0.35 GPa和3.5 GPa 下驱动的应力波在铜靶中的传播速度分别为4 600 m/s，4 000 m/s。峰值压力为3.5 GPa 冲击波在靶体内诱导的应力波出现了弹性波和塑性波的双波结构。应力波峰值的衰减规律呈指数形式衰减。模拟计算的结果与理论和实验结果较为一致。

Numerical simulation on attenuation of stress wave in copper target irradiated by intense laser

The code Abaqus/Explicit was employed to simulate on propagation of stress wave in a copper foil target, which was induced by intense laser with ns level width. A model was developed to simulate one dimensional planar stress wave propagation and attenuation, and its simulated model consisted of two kinds of elements: finite elements and infinite elements. Fine finite elements were used in laser shocked zone, and coarse infinite elements were used in surrounding zone as no reflecting boundaries. The strain rate effects and ultrahigh pressure effects on material yield stress were also considered. Series of simulations were performed using two different peak values, 0.35 GPa and 3.5 GPa, which were exerted on the target surface by shock wave. The two-step stress wave profile was obtained in copper target under the pressure of 3.5 GPa. The numerical results suggest that shock velocity is 4 600 m/s under the pressure of 0.35 GPa, and 4 000 m/s under the pressure of 3.5 GPa. The value of peak stress attenuates with the propagated distance in form of an exponential function. Some numerical results are in good agreement with the experimental results.