Forming Mechanism Of Linear Explosively Formed Penetrator

LEFPs are linear explosively formed penetrators with definite length in thesymmetrical direction formed from the liner invert caused by the detonation productionsact of linear EFP shaped charges. As a new conceptual destroying unit, LEFP overcomesthe shortcomings of linear shaped charge jet swords which can only be used under smallstand off distance, and that of axial symmetrical EFPs which have low shooting efficiency.This LEFP have many merits such as wide action range on targets, broad effective standoff distance and remarkable aftereffects. Hence, the study on LEFPs has academic andguiding significances to the new destroying units and warheads.Forming mechanisms of LEFPs under different initiation conditions are studiedsystemically through theoretical analysis, experimental and numerical simulation methods.The followings are the main contents of this dissertation:(1) Forming mechanism of LEFPs when the shaped charges were initiatedsynchronously from the ridge of the charges was studied. On the assumption that thecharge is infinitely long, the model of LEFP forming due to liner reversing was established.Using various theoretical analyzing formats of explosive driving plate and round pipe,two-dimensional formulation for the liner reversing velocity calculating was educedthrough introducing distributed function. Factors which affect the LEFP forming includingcurvature radius and wall thickness of the liner, height of the charge, having shell or notand shell thickness were analyzed and studied, and the regularities were gained. Theanalyses above were proved through experiments and numerical modeling and accordantresults were obtained. This lays a theoretical foundation for excellent LEFPs designing.(2) Shapes and velocities changing regularities of the detonation waves propagatingin the LEFP charges were studied. It was found that the action manners of detonation wavegenerated by the end point initiated and central point initiated charges to the liners aresame when boundary and comer effects were not considered. But the propagating distanceof spherical detonation wave generated by the central point initiated charges is twice asthat of the wave generated by the end initiated charges.(3) LEFPs forming mechanism under the conditions of central point initiating andend point initiating were studied. The actions of detonation wave to the liners were dividedinto three parts and were analyzed theoretically. Three- dimensional model of LEFPsforming caused by liner reserving was built and expressions for the maximum velocity ofthe liner reserving and each velocity components were induced. In the mean time, experiment and numerical simulation were conducted and the results were accordant.Velocity components changing process and their distribution of the infinitesimal elementon the liner were obtained through numerical modeling. The study is theoretical significantto people to understand the effect of the initiation manner on the forming of LEFP.(4) Furcate split is a main problem that affects the performance of LEFP. The reasonof furcate split was analyzed. With dynamic elongation percentage of the liner material ascriterion, measures to prevent furcated split were put forward. Furcate split wasnumerically simulated and the results were in agreement with that of experiments. Thiswill offer theoretical support for enhancing the action range of LEFPs.