两点侧面对称起爆下不同金属的激波斜碰行为

Investigating the Shockwave Collision of Different Metals Driven by Two-point Lateral Symmetric Initiation

研究对称起爆加载下金属样品内激波斜碰的早期动态力学行为,对分析其后续的动态演化与失效机制有着重要的意义。结合激波极曲线理论和数值模拟方法,开展两点侧面对称起爆加载下金属铅(Lead,Pb)、无氧铜(Oxygen-free high conductive copper,Cu-OFHC)和钨合金(W-Ni-Fe alloy,W4Ni2Fe)的动态行为研究。利用激波极曲线方法和Hugoniot状态方程,得到3种金属激波反射形式发生转变时入射角和入射压力临界值之间的关系,并基于此结果分析仿真中3种金属内激波的对称斜碰特征。模拟结果显示3种金属都发生了马赫反射,吻合理论预测。通过对比3种金属内部横向同一区域的压力剖面发现:Pb的马赫杆宽度远大于Cu-OFHC和W4Ni2Fe;Pb中由入射激波、马赫杆和反射激波形成的三波加载区域也大于后两者,分析认为主要原因是Pb中的声速远小于后两者,造成碰撞区内激波相互作用的差异。基于自由面的速度历史剖面和判定准则估算这3种金属中最终形成的马赫杆宽度并讨论碰撞区的动态演化特征。结合对金属内部压力及自由面速度剖面的分析建立斜激波对称碰撞动态演化模型,为深入认识碰撞区的动态力学行为提供了理论支持。

The initial interactions of oblique shockwaves in metal samples under symmetric detonation loading is studied for the analysis of its subsequent dynamic evolution and failure mechanisms.Prior experimental and numerical investigations primarily centered on the dynamic process at later stage and initial interactions of shockwaves within the metal are very scarce to be examined.The dynamic characteristics of metal lead(Pb),oxygen-free high-conductive copper(Cu-OFHC)and W-Ni-Fe alloy(W4Ni2Fe)impacted by two oblique shockwaves are investigated using the shockwave polar theory and numerical simulations.Based on the shockwave polar theory and the Hugoniot equation of state,the critical conditions of the transition from regular reflection to Mach reflection for the shockwave reflections of three metals above are obtained to predict their reflection characteristics in the numerical simulations.The numerical results show that Mach reflection occurs in all three metals,which is consistent with the theoretical predictions.Through the comparative analysis of transverse pressure profiles in the same region of the three metals,it is found that the Mach stem for Pb is much wider than those of Cu-OFHC and W4Ni2Fe,and the three-wave loading region formed by the incident shockwave,Mach stem and reflected shockwave in Pb is also larger than those in the latter two.The fundamental origin stems from the lower sound velocity for metal Pb.For the three metals,the ultimate width of Mach stem is estimated and the dynamic behavior in the collision zone is discussed based on the free-surface velocity profile and decison criteria.Finally,based on the pressure and free-surface velocity profile,a symmetric oblique shockwave collision dynamics model is established,laying the fundamental theory on elucidating the dynamic behavior of metal.