钻地弹侵彻混凝土结构的尺寸效应及终点弹道研究

Since the researches on the projectile penetrations into concrete structures could not reveal the size effect which has been indicated by some penetration experiments and most of them were only validated by the small reduced scale penetration tests, they should not be directly used in the design of protective engineering. Thus, there is an urgent need to carry out the studies on the size effect of the earth penetration weapon (EPW) into concrete structure and the terminal ballistics of the projectile. This project intends to first carry out penetration experiments with different sizes to explore the size effect of penetration, and then explore the law of penetration size effect through the three-dimensional microscopic finite element method. By combining the results from simulation and the penetration theory, a formula for resistance acting on the projectile which is applicable to projectiles with different sizes penetrating into concrete structures will be proposed. On the basis of the resistance with the size effect considered, a decay function and a model will be further constructed to account for the free-surface effect and wake separation and reattachment effect, respectively. Then, the ballistic trajectory model of the projectile is intended to be developed based on the rigid dynamics equation. The law of ballistic trajectory will be studied based on the above model. Finally, for the structure of the projectile, the deformation or failure of the projectile is considered from the aspects of compression/pull, buckling and bending, and the criterion of the rigidity and failure of the projectile will be given.

由于已有关于混凝土结构抗侵彻的理论研究没有反应已被侵彻实验证实的尺寸效应，且多基于缩比侵彻实验验证，不宜直接用于防护工程抗钻地弹侵彻设计，因此迫切需要开展钻地弹侵彻混凝土结构的尺寸效应及终点弹道研究。本项目拟首先开展不同尺寸的相似垂直侵彻实验以探讨侵彻尺寸效应，得到尺寸效应实验数据，然后通过混凝土三维细观有限元模拟，探讨侵彻尺寸效应的规律，并结合侵彻理论提出适用于不同尺寸弹体侵彻混凝土结构的阻应力表达式。在此基础上，进一步构造与混凝土特性相符的自由面效应衰减函数、分离-再接触函数，再通过刚体动力学建立钻地弹运动方程，给出弹体侵彻弹道轨迹计算方法并开展偏航规律研究。最后针对弹体结构，从抗压/拉、屈曲及抗弯三方面考虑弹体的变形或失效，给出弹体近似刚性及失效的判据。

我国防护工程和重要民用建筑面临钻地武器打击的严峻威胁，已有侵彻理论没有反应已被侵彻实验证实的尺寸效应，直接采用这些侵彻理论设计的防护工程将偏于危险。聚焦重要工程抗钻地武器打击的防护建设需求，本项目开展了弹体侵彻混凝土结构的尺寸效应研究、考虑尺寸效应的终点弹道轨迹研究以及针对侵爆弹的毁伤效能评估研究，取得了预期的研究成果，可为重要工程抗钻地武器的设计提供理论和技术支撑。项目主要研究内容和创新点如下：.（1）基于量纲理论以及侵彻实验数据，揭示了粗骨料是引起侵彻尺寸效应的主要原因之一，进而基于三维细观数值模拟探讨了粗骨料对侵彻尺寸效应幅值的影响。开展了5mm、20mm、30mm直径弹体的侵彻实验研究，为侵彻尺寸效应提供了实验支撑。建立了考虑尺寸效应的侵彻阻应力模型，使其可以计算原型尺寸弹体的侵彻问题，计算结果与实验数据吻合较好。.（2）针对斜侵彻问题，基于弹、靶分离思想，通过将基于侵彻理论并考虑侵彻尺寸效应的阻应力施加于弹体表面网格之上，并考虑自由面效应、分离-接触效应，再结合刚体动力学原理建立了弹体侵彻混凝土结构的弹道快速计算模型，编制了计算工具软件。开展了弹体贯穿多层间隔混凝土靶板的弹道轨迹实验研究，获得了斜侵彻条件下的弹道轨迹规律。弹道计算软件预测结果与侵彻实验数据误差在15%以内。进一步开展了异形弹体侵彻弹道轨迹研究，为异形弹弹道性能优化提供了模型和工具。.（3）基于侵爆弹毁伤特征，提出了针对侵爆弹的毁伤效能评估通用方法，建立了评估模型和计算流程，并以侵爆弹打击机库为例，进行了典型案例分析。案例分析中，研究对比了侵彻速度、入射角度、目标尺寸、投射精度等因素的影响，清晰表明了弹体威力参数以及目标参数与毁伤结果间的关系。提出的方法较为明确地给出了毁伤效能评估的内涵定义、评估内容、评估技术要点，对于侵爆弹打击坚固目标的毁伤效能评估具有较强的指导意义和参考价值。