大长细比结构弹体侵彻2024-O铝靶的弹塑性动力响应

Elastic-plastic dynamic response of slender projectiles penetrating into 2024-O aluminum targets

为研究大长细比结构弹体在撞击典型硬目标早期的结构动力学响应,利用57轻气炮进行了直径1.4 cm、量纲一壁厚0.1和0.15、长细比8和12、头部系数3和4.5的卵形空心弹体对2024-O铝靶的侵彻实验研究,利用高速摄影系统记录了弹体撞靶过程,观察到大长细比弹体垂直撞击硬目标过程中的局部墩粗、塑性屈曲2种结构破坏模式,以及斜侵彻过程中的整体塑性弯曲、弯曲与墩粗耦合、弯曲与屈曲耦合3种结构破坏模式和实时动力学响应过程。基于对指数硬化材料的空腔膨胀理论建立了弹体垂直侵彻模型,给出了在轴向及横向载荷交互作用下计算刚塑性自由梁危险截面屈服函数的控制方程,计算值与实验结果吻合较好。

A series of normal and oblique penetration experiments were performed to explore the dynamic response of slender projectiles penetrating into typically hard targets. In the experiments, the parameters of the ogive-nose steel projectiles are as follows： the diameter is 14 mm; the lengths are 168, 112 mm; the dimensionless wall thicknesses of the cartridges are 0.1, 0. 15; the head factors are 3.0, 4. 5. The projectiles were made from 30CrMnSiNi2A and were launched by a light gas gun with 57 mm diameter impact velocities of 100-250 m/s. The processes of impact and projectile deformation were photographed at up to 2 × 10^4 s^-1 using a photron fastcam. The recorded information indicates the following five different structural failure modes for a slender hollow projectile penetrating a typically hard target： （1） local bulges near the dangerous sections on normal impact; （2） plastic buckling on the especial sections without local bulges on normal impact; （3） plastic bending along the deformed region on oblique impact; （4） local plastic bulges couplecl and local plastic buckling coupled with generally plastic bending on oblique impact. The penetration modes were established based on the cavity expansion theory. And the control equations were given, which can be used to calculate the yield function in a rigid-perfect plastic free-free beam section subjected to dynamic lateral loading and axial loading. The calculated results are in good agreement with the experiment.