锥台嵌挤预应力约束混凝土的抗侵彻性能

在侧限约束条件下，混凝土材料的抗侵彻性能可得到较大提高，在此基础上施加预应力围压，其抗侵彻性能可进一步提高，但现有预应力方法对约束混凝土施加预应力较为困难。基于此，提出了一种相对简便的锥台嵌挤预应力约束方法，采用楔形块楔紧的原理，将锥面倾角为3°和直径微大于约束环的锥台形混凝土靶体挤入与之匹配的约束钢环内，通过锥面配合契紧的方式对混凝土靶体沿径向施加预应力，以锥台靶体的下压深度、盈差以及压入力的大小等指标控制预应力大小。采用LS-DYNA软件验证了该方法施加预应力的可行性，并通过重启动算法开展了预应力约束混凝土靶的抗侵彻性能研究。数值计算结果表明，靶体预应力随着其下压深度或盈差的增大近似线性增加，且混凝土靶体的抗侵彻性能随预应力增大而提高，但预应力过大时靶体内部发生损伤，导致其抗侵彻性能反而快速下降。对钢环强度、混凝土强度、含钢率和弹体速度等参数进行敏感性分析，结果表明，合理匹配钢环强度和混凝土强度，并选择合适的靶体含钢率，可有效提高靶体的预应力、抗侵彻性能以及钢材利用率；且弹体初速度越高，预应力对提高靶体抗侵彻性能的作用越明显。提出的锥台嵌挤预应力约束方法可为提高混凝土等脆性材料的抗侵彻性能提供一种新思路和方法。

Anti-penetration capability of pre-stressed confined concrete with truncated cone

The penetration resistance of concrete can be greatly improved by lateral confinement, and it would be continued to increase when pre-stress is further applied. However, the existing methods are difficult to realize the pre-stress on the confined concrete. In this paper, a relatively simple method for pre-stress confinement is proposed. Based on the principle of wedging the wedge-shaped block, a truncated cone-shaped concrete target with a cone inclination of 3° and a diameter slightly larger than the ferrule was squeezed into the matching steel ferrule, so the concrete target was pre-stressed along the radial direction by means of cone-shaped fitting and tightening, while the pre-stress was controlled by the indicators such as the pressing depth of the concrete target, the margin, and the pressing force. The feasibility of this method is then verified by simulation using LS-DYNA, and the penetration resistance of pre-stressed confined concrete is studied by the so-called restart algorithm. Numerical results demonstrate that the proposed method can provide enough radial pre-stress to the confined concrete target, and the pre-stress of the target increases approximately linearly with the increase of the pressing depth or the margin. Furthermore, within a certain range, the penetration resistance of the concrete target increases with the increase of pre-stress, while it decreases rapidly when the pre-stress is too high, which causes the damage of the concrete target. Parametric study on the parameters such as steel ferrule strength, concrete strength, steel ratio and projectile velocity, shows that reasonable matching of the steel ferrule strength with the concrete strength and selection of appropriate steel ratio of the target can effectively improve the pre-stress, penetration resistance of the target and the efficiency of steel; the higher the projectile velocity, the more obvious the effect of pre-stress on the improvement of the anti-penetration performance of the target. The proposed method for applying pre-stress provides a new approach to improve the anti-penetration capability of brittle materials such as concrete.