【作者】 李如江；

【导师】 沈兆武； 刘天生；

【作者基本信息】 中国科学技术大学 ， 工程力学， 2008， 博士

【摘要】 聚能效应能够显著提高能量密度,高效传递炸药爆炸能量,已被广泛应用于军事和民用领域。药型罩作为战斗部的核心部件,其性能直接影响着聚能效应的发挥。本文通过理论分析、试验研究和数值模拟、宏观理论分析和细观机理相结合的研究方法,对多孔药型罩聚能射流及其侵彻机理进行了系统的分析和研究。正确选取状态方程是多孔材料冲击温升计算问题的关键。本文首先对现有的多孔材料的状态方程进行了综述和分析,讨论了现有多孔材料状态方程的优缺点和使用范围。由于Hosson和Herrmann状态方程的参数比较少,精度有保证,可用于工程实际,为冲击温升计算奠定了基础。对多孔材料的冲击特性进行了分析和研究,给出了多孔材料药型罩聚能射流速度的近似计算方法,并与实际测试进行了对比。理论分析和计算表明,多孔药型罩聚能射流的速度降低主要是由于冲击温升引起的能量耗散和作用于罩壁的二次冲击压缩压力降低造成。考虑了多孔材料的物理特性,给出了多孔材料药型罩形成射流的高低速条件,即药型罩的压垮速度必须小于c(T),同时冲击温升使低速条件降低。给出了含有低熔点金属多孔射流的形成凝聚条件,在满足声速的同时,还要保证药型罩在压垮之后不发生液气相的转变,为多孔药型罩聚能装药的工程设计提供了依据。对多孔药型罩聚能射流的稳定性进行了理论分析,结合脉冲X光和侵彻实验对两种不同孔隙度的多孔药型罩聚能射流稳定性进行了研究,得出合适的孔隙度可以降低低速段射流的动态屈服强度,提高射流的稳定性。同时初始冲击温升可以使射流的高速段的粘性降低,与紫铜射流进行了侵彻对比试验,揭示了多孔药型罩低炸高大穿深的机理。提出了聚能粒子流概念。在密度自锁模型的假设基础上,结合粒子流的多孔特性,提出了粒子流的侵彻模型,弥补了经典理论不能计算粒子流侵彻深度的不足。该模型在一定条件下可以转化为现有的侵彻模型。对回收的紫铜射流和多孔铜射流的杵体进行了细观观测,探讨了多孔药型罩聚能射流在高应变和高应变率下的主要变形机制,冲击温升为动态再结晶创造了有利条件。同时观察到射流和杵体分离处经受了较大的剪切变形。采用数值模拟方法,系统的研究了细直径射流引爆包覆炸药物理影响因素,模拟结果显示射流头部形状对侵彻引爆的影响取决于盖板厚度,对于一定厚度的盖板,当射流直径小到一定程度可以不考虑头部形状的影响。对于不同密度的射流引爆同样条件的包覆炸药,随着射流密度的降低需要较高的速度。盖板越厚,需要的射流速度越高;随着射流速度的提高,盖板密度的影响减弱。在分析飞板与射流作用的机理上,建立了飞板断续干扰射流频率计算的物理模型,并分析了NAT0角、飞板速度及盖板硬度对干扰频率的影响。提出了断续干扰和连续干扰的转变条件。本文的研究工作为多孔材料药型罩聚能装药的设计及其应用提供了新的指导思想。更多还原

【Abstract】 Shaped charge effect is broadly used in military arena and civil construction, because the focusing of the detonation products creates an intense localized force and decays slowly. As a critical part of the warhead, property of the shaped charge liner has great effect on the application of the shaped charge effect. The jet property and penetration mechanism of shaped charge with porous liner were studied systematically with experimental, analytical and numerical methods.Equation of state (EOS) of the porous material is key to the shock temperature rising calculation. All of the EOS of porous materials in the open literatures were analyzed and compared, the merits of which and application conditions were discussed. Because of the few parameters and accuracy, the EOS of Griineisen revised by Herrmann was selected.Porous material property shocked was studied and analyzed. Approximated jet speed calculation method was presented and compared with the measurement results. It is shown that the lower speed with porosity increase may be caused by the energy dissipation and degradation of the shocked pressure.Porous nature considered, the criteria for the jet coherence were presented, that is, the collapse flow speed must be less than the sound speed, which is after the shock wave compressed and released. The condition for the jet coherence produced by the shaped charge liner made up of low melting point was put forward, that is, sound speed satisfied, and the shock temperature rising after collapse must be less than the material evaporating point to avoid the phase transformation from liquid to vapor, which is helpful for the shaped charge design.The jet stability produced from shaped charge with porous liner was studied theoretically, compared with X-Ray measurement and penetration test, it is shown that proper porosity can decrease the jet dynamic strength and enhance the breakup time. Penetration Compared with the homogeneous liners, the deeper penetration mechanism at low standoff distance was presented ,that is, the shock temperature rising can decrease the viscosity of the high-speed part.Concept of shaped charge granular jet was presented. Based on the assumption of density locking model, the penetration model of granular jet was put forward, which covers shortage of the classical theory, and can become any of all the forms under certain condition.The slug microstructures was examined by optical microscopy and electronic scanning microscopy and compared with the spanned homogeneous one, it reveals that the dynamic recrystallization is the main plastic deformation mechanism at great high-strain-rate, and initial temperature rise is helpful for the dynamic recrystallization. The great shear deformation at the separated location of jet and slug was also observed.A nonlinear finite element software LS-DYNA was used to simulate the initiation of confined explosive penetrated vertically by shaped charge jet, the physical property is analyzed systematically. Calculations show that, jet head shape effect on the initiation depends on the covered plate thickness and it has no effect on the initiation when the plate thickness is ascertained and jet diameter is less than some value. For the jet initiation with different density, the less the density and the thicker plate, the higher is the speed. The plate density becomes less important with the higher jet speed.Based on the analysis of the interaction between jet and flying plate, a physical model for calculating the intermittent disturbance frequency was presented. The parameters such as NATO-angle, plate velocity and hardness were analyzed; the transition condition from intermittent to continuous disturbance was put forward.This work is of significance and guidance for the design and application of shaped charge with porous liner in the future.更多还原