混凝土靶体计及压实效应的球腔动态膨胀模型和侵彻计算

Penetration computation and spherical cavity-expansion model of concrete targets with crushing effects

建立了一混凝土靶体的球腔动态膨胀的侵彻模型。靶体的静水压力-体积应变关系考虑了不同的密实混凝土模型。也研究了混凝土作为多孔材料在高压下的压实效应。混凝土有拉伸强度极限值,其剪切强度与压力相关为Mohr-Coulomb定律。球腔动态膨胀模型考虑球对称空腔在无限介质里从零半径开始以常速度膨胀,产生一塑性区和一弹性区。当膨胀速度足够小时,由于介质的低拉伸强度,塑性区和弹性区之间可存在一径向裂纹区。可由解析方法获得空腔表面压力和弹塑性区界面传播速度随空腔表面扩张速度变化的曲线,再由球腔动态膨胀模型所得的空腔表面压力分布用于计算混凝土靶体的刚性杆弹侵彻深度。本文模型的计算结果与经验公式,不可压缩和线性可压缩混凝土模型的进行了比较。

This paper developed a spherical cavity-expansion penetration model for concrete targets. The hydrostatic pressure-volumetric strain relation of concrete targets expressed by different solid concrete models and porous model. Concrete has a tension cutoff value and its shear strength relevant to pressure is described by Mohr-Coulomb's law. In the spherical cavity-expansion model, a spherically symmetric cavity is expanded from zero initial radius at constant velocity in an infinite medium, which consists of elastic, plastic regions and an additional radially cracked region if the cavity expansion velocity is low. The curves of pressure distribution on the cavity surface and the propagation velocity of interface between the plastic and the elastic region versus the cavity expansion velocity were obtained by an analytic method. The cavity surface pressure obtained from the spherical cavity-expansion models was used to calculate the penetration depth of concrete targets stricken by an olive-nosed rod projectile. Numerical results of different concrete target models were compared with the data of empirical equations.