Interaction of a metallic liner with lumped elements and transfer of perturbations over these elements

Abstract

Results of an experimental and numerical study of interaction of a metallic liner accelerated by an explosion to a velocity of several kilometers per second with lumped elements in the form of plates are presented. Parameters of perturbations transferred over these elements are quantified.Metallic liners of plane, cylindrical, or spherical symmetry accelerated by explosive energy to velocities of several kilometers per second is often used in explosive generators to obtain high dynamic pressures [1]. In some cases important for practice, the moving liners can interact with various lumped elements in the form of metallic plates (stiffness ribs and supports) [2, 3] or rods (electrodes and segments of cable lines) [4,5]. The qualitative pattern of such interaction has been well studied. It was shown [3,4] that the process of interaction of a plate or a rod with a moving plate or cylindrical shell are little different and occur with formation of jets from their materials, the displaced material is distributed between them, and a cavity is formed. The quantitative aspect of these processes, however, which is associated with determining the amplitude of perturbations transferred over the lumped elements, has not been studied in much detail.Detailed quantitative information can be obtained from well-tested two-dimensional numerical calculations. Normally they are tested against experimental results in a simplified formulation. In the present work, we used a rather complicated arrangement of experi-; root@gdd.vniief.ru. ments, which was fairly close to real processes, to test two-dimensional calculations.Under shock-wave loading of lumped elements (plates and rods), the shock waves (SWs) generated therein degenerate with time into acoustic perturbations. As these perturbations propagate with a velocity of sound in the plate or the rod, which can be greater than the velocity of the liner accelerated in the explosive generator, the perturbations can arrive in the examined target earlier than the SW generated in the target by the liner impact. Thus, the perturbations can be responsible for distortions affecting the interpretation of test results. Clearly, determining the amplitude of these perturbations is of particular importance. A preliminary analysis shows that the amplitude of the perturbations considered may change from 0.01 to 0.1 GPa, depending on particular operation conditions of explosive generators, and the duration of the perturbations can reach 10 μsec. In the present work, the quantitative characteristics of the perturbations (amplitude and time) were determined by the capacitance gauge technique [6], and the process was visualized by the method of flash radiography and by the method of an ejected indicator, as in [3].The arrangement of experiments aimed at studying perturbations transferred over lumped elements is illustrated in Fig. 1. We used a 50/50 TNT/RDX high explosive (HE) charge 120 mm in diameter and 60 mm high. The charge was initiated over its entire