摘要:
弹体侵彻阻力是遮弹层抗侵彻性能研究及弹体结构优化设计最关注的问题。本文分析了现有钢筋有限长度固支梁理论模型局限。根据钢筋屈服准则研究和耗能分析,提出了弹体直接命中钢筋剪切-塑性铰链模型,以及弹体与钢筋侧面接触时的塑性弦模型,通过耗能分析得到了弹体直接阻力函数。以空腔膨胀理论模型为基础,根据弹体侵彻深度经验公式计算结果,得到了钢筋间接影响下混凝土阻力方程。通过与已有试验数据对比,验证了理论模型的合理性。通过分析钢筋屈服强度、直径、网眼尺寸等配筋方式,以及弹体命中部位对遮弹层抗侵彻性能的影响,给出了遮弹层配筋设计建议:相邻两层钢筋网错孔设置;钢筋网眼与弹体直径比值宜设为0.5-0.8;应结合钢筋极限塑性应变进行高强钢筋选择。
Abstract:
Penetration resistance is a crucial issue in the study of armor's anti-penetration performance and the optimization design of projectile structures. Through the analysis of the mechanical response of reinforcing bars under the dynamic constraint of both the projectile and concrete, the limitation of existing finite-length rigid beam models have been obtained. Based on this foundation, a shear-plastic hinge model was used to analyze the case of a projectile directly hitting the reinforcing bars, and a plastic string model was used to analyze the case of a projectile colliding with the side of the reinforcing bars, resulting in a more accurate equation for penetration resistance. In the shear plastic hinge model, stress analysis was performed based on the shear sliding of the reinforcing bar before fracture, and energy dissipation was calculated based on the deformation of the plastic hinge after the reinforcing bar fractures. In the plastic string model, the yield criterion of reinforcing bars under the combined action of bending moment and axial force was analyzed, and the plastic energy dissipation equations for reinforcing bar tension and bending were established. At the same time, the influence of changes in reinforcing bar kinetic energy was considered. Based on the theoretical model of cavity expansion and the empirical formula for the depth of projectile penetration, the concrete resistance equation under the indirect influence of steel reinforcement was obtained. By comparing with existing experimental data, the rationality of the theoretical models was verified. By analyzing the yield strength, diameter, mesh size of reinforcing bars, as well as the impact location of projectile, suggestions for the reinforcement design of the bulletproof layer were given. The adjacent two layers of reinforcing bars mesh should be staggered. The ratio of steel mesh to projectile diameter should be set between 0.5 and 0.8. It is not advisable to simply pursue high-strength reinforcing bars, and the ultimate plastic strain of reinforcing bars should also be considered as an important factor.