不同壁厚下40CrMnSiB钢柱壳内爆炸膨胀裂纹生成机制分析

The Formation Mechanism Analysis of Explosion Expansion Crack of 40CrMnSiBSteel Cylindrical Shell with Different Wall Thicknesses

针对内爆加载下弹体钢壳膨胀断裂机制,采用光滑粒子流体动力学方法(smoothed particle hydrodynamics,SPH)对几种壁厚下40CrMnSiB钢柱壳在内爆载荷下的膨胀断裂过程与裂纹分布规律进行了数值模拟;利用爆炸水井回收技术开展了对比实验研究;结合柱壳断裂破片的宏观形貌与微观组织分析了其裂纹的生成机制。结果表明,40CrMnSiB钢柱壳的断裂模式随着壁厚的增加由纯剪切逐渐过渡到拉剪混合;当柱壳壁厚由4 mm增至17 mm时,拉伸裂纹所占比例由0逐渐增至4/5,柱壳裂纹周向密度和形成破片总数则分别减小了54.54%和67.06%,并且随着金属柱壳壁厚的增加,最终破片的质量分布逐渐分散;分析回收破片微观组织发现,柱壳的断裂实际是由壳体内表面产生的剪切裂纹与外表面产生的拉伸裂纹共同作用及相互竞争的结果,裂纹之间存在相互屏蔽的现象。

Aiming at the expansion fracture mechanism of projectile steel shell under implosion loading,the smooth particle fluid dynamics method(smoothed particle hydrodynamics,SPH)was used to simulate the expansion fracture process and crack distribution law of 40CrMnSiB steel cylindrical shell with several wall thicknesses under implosion loading.The comparative experimental study was carried out by using the explosive water well recovery technology,and the crack formation mechanism was analyzed by combining the macroscopic morphology and microstructure of the cylindrical shell fracture fragments.The results show that the fracture mode of 40CrMnSiB steel cylindrical shell gradually changes from pure shear to tension-shear mixing with the increase of wall thickness.When the wall thickness of the cylindrical shell increases from 4 mm to 17 mm,the proportion of tension cracks gradually increases from 0 to 4/5,and the circumferential density of the cylindrical shell cracks and the total number of fragments formed decrease by 54.54%and 67.06%,respectively.With the increase of the wall thickness of the metal cylindrical shell,the mass distribution of the final fragments gradually disperses.By analyzing the microstructure of the recovered fragments,it is found that the fracture of the cylindrical shell is actually the result of the interaction and competition between the shear cracks generated on the inner surface of the shell and the tension cracks generated on the outer surface,and there is a phenomenon of mutual shielding between the cracks.