Abstract The mechanisms governing penetration of pyramidal projectile into concrete medium were studied. The relationship of normal stress and normal velocity on the surface of the projectile nose was modified based on the assumption that the shape of the tunnel section is the same as that of the projectile. Then, in the low velocity range, a formula for predicting the final penetration depth of the pyramidal projectile is proposed, and the penetration ability of pyramidal projectiles with and without a shank is discussed. The results showed that the penetration depth decreases with the increasing side numbers of the projectile section shape, and the maximum depth of penetration corresponds to the triangular cross-section. In addition, the penetration processes of triangular and circular projectiles into concrete targets were simulated by employing the finite element software LS-DYNA. The Mises stress, tunnel shape, depth of penetration and velocity were investigated. It suggested the triangular projectile has a slight penetration advantage over the circular projectile when the penetration velocity is less than threshold velocity, and this advantage gradually disappears with the increase of impacting velocity. Finally, the shear weakening effect is used to explain the resistance characteristics of the triangular projectile in various velocity ranges, and a method to estimate the upper limit of threshold velocity is given by using the dynamic cavity expansion theory.

中文翻译：

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锥体弹丸对混凝土目标的穿透特性

摘要 研究了锥体弹丸对混凝土介质的穿透机理。基于隧道截面形状与弹头形状相同的假设，修正了弹头表面法向应力与法向速度的关系。然后，在低速范围内，提出了锥体弹丸最终穿透深度的预测公式，并讨论了锥体弹丸有无柄的穿透能力。结果表明，随着弹丸截面形状边数的增加，穿透深度减小，最大穿透深度对应于三角形截面。此外，采用有限元软件LS-DYNA模拟了三角形和圆形弹丸对混凝土目标的穿透过程。研究了米塞斯应力、隧道形状、穿透深度和速度。这表明当穿透速度小于阈值速度时，三角形弹丸比圆形弹丸具有轻微的穿透优势，这种优势随着撞击速度的增加而逐渐消失。最后，利用剪切弱化效应解释了三角形弹丸在不同速度范围内的阻力特性，并利用动态空腔膨胀理论给出了估计阈值速度上限的方法。研究了穿透深度和速度。这表明当穿透速度小于阈值速度时，三角形弹丸比圆形弹丸具有轻微的穿透优势，这种优势随着撞击速度的增加而逐渐消失。最后，利用剪切弱化效应解释了三角形弹丸在不同速度范围内的阻力特性，并利用动态空腔膨胀理论给出了估计阈值速度上限的方法。研究了穿透深度和速度。这表明当穿透速度小于阈值速度时，三角形弹丸比圆形弹丸具有轻微的穿透优势，这种优势随着撞击速度的增加而逐渐消失。最后，利用剪切弱化效应解释了三角形弹丸在不同速度范围内的阻力特性，并利用动态空腔膨胀理论给出了估计阈值速度上限的方法。