长杆弹侵彻的2D模型研究

For its prominent background in military application, the long-rod penetration is a hot research topic in the field of penetration. Experiments and numerical simulations indicate that, the rods made of different materials may have different nose shapes during the penetration process. Such phenomenon, especially known as “self-sharpening”, will further affect the long-rod penetration performance. However, all the present theoretical models are almost one dimensional and it is impossible to analyze the effect of the nose shape on the penetration. In order to investigate this effect on the long-rod penetration, a systematic study will be performed by means of theoretical analysis, numerical simulation and experimental test in this project. Firstly, establishing the nose shape function including quasi-steady mass erosion rate and considering the effect of material properties on target resistance, 2D theoretical model is developed to simultaneously forecast the crater diameter and penetration depth. Then, the effect of nose shape during the penetration process and initial nose shape is analyzed. The reasons for the differences in penetration performances are discussed in the perspective of energy transformation. Finally, the mechanics and the critical conditions of the nose shape deformation are known through this study. This project can not only develop the 2D theoretical model of long-rod penetration, which is helpful for analyzing and forecast the penetration performance, but also provide scientific guidance for the engineering practice.

长杆弹高速侵彻具有显著军事应用背景，是穿甲侵彻领域的研究热点。实验和模拟发现，不同材料长杆弹在高速侵彻过程中可能出现不同头部形状，进而影响其侵彻性能，如“自锐”现象。然而目前的理论模型一般为1D模型，无法考虑和分析头形因素。本项目拟采用理论分析、数值模拟和实验验证相结合的方法，研究头部形状对长杆高速侵彻能力的影响。首先，构造包含准定常质量侵蚀率的头部形状函数，考虑材料性质对靶体阻力的影响，建立2D理论分析模型，同时预测弹坑直径与侵彻深度；其次，分析侵彻过程中头形和初始头形的影响，从能量变化的角度揭示产生侵彻能力差异的原因；最后，认知侵彻过程中头形演变规律，提出头形演化的临界条件。本项目在理论上能建立长杆高速侵彻的2D模型,有助于更准确地分析和预测长杆弹的侵彻能力，同时具有实际应用指导意义。

长杆弹在1.5-3.0 km/s的高速下具有很强的侵彻和贯穿能力。不同于刚性弹，长杆弹与靶体相互作用发生严重质量侵蚀。由于侵彻机理的独特性和军事应用需求，长杆高速侵彻是穿甲侵彻的热点领域。本项目按计划完成预定研究内容，实现了预期目标，取得以下成果：针对Alekseevskii-Tate模型，我们对剩余弹体相对长度的对数表达式进行线性简化近似，获得两组显式的理论解析解，运用该近似解获得平均侵彻速度与初始速度的显式表达式；运用A-T模型近似解定义了无量纲速度衰减系数，并重新定义了Johnson破坏数和特征时间系数，可实现对准定常阶段的弹尾速度的完全表征；在弹头质量准定常侵蚀条件下，构造头形函数，建立了长杆高速侵彻准定常阶段的2D模型，指出头杆径比和头形因子是弹体头形影响侵彻的两个主要无量纲参量；针对初始瞬态、准定常侵彻和次级侵彻三阶段的头形因子、头杆径比和质量侵蚀率的变化规律，建立了长杆弹三阶段侵彻2D理论模型，指出相关参数在不同阶段表现出非定常和定常变化，同时建立了弹体质量损失与弹体头形变化之间的联系；建立了长杆弹撞击陶瓷装甲的数值模拟方法，分析了界面击溃、驻留转侵彻和直接侵彻不同模式中弹靶相互作用和陶瓷损伤变化，澄清了陶瓷脆性靶区别于金属靶的侵彻机制；针对长杆弹超高速侵彻，根据可压缩流体理论和准定常侵彻特征，建立了忽略冲击波影响的可压缩流体侵彻理论模型，适用速度范围为1.5-12km/s。相关理论模型有助于更准确地分析和预测长杆弹的侵彻能力，同时具有实际应用指导意义。