无网格法研究进展及其应用

  目的  针对有限元法处理弹体侵彻船用钢板时因网格畸变而无法准确模拟破口破坏形态及其形成的动态过程的问题，  方法  采用基于物质点法（Material Point Method，MPM）构建弹体侵彻舰船板壳结构的数值仿真模型，模拟弹体在侵彻过程中的破甲特性。将在不同初速度下侵彻5和10 mm厚靶板后的破口及塑性变形模拟结果与实验结果进行对比，以验证所提方法的有效性。  结果  结果表明：物质点法的模拟结果与实验结果吻合较好；弹体侵彻靶板的破口以及塑性变形区基本保持不变，且破口略大于弹体直径；弹体对靶板的破坏属于冲塞形式的穿甲破坏；半球形弹体以低、中、高的速度侵彻舰船外壳的靶板破坏形式属于冲塞破坏模式，速度大小对靶板的破口影响不大，而对靶板破口处隆起的高度影响较大。  结论  所提数值方法可为研究导弹侵彻舰船板壳提供新的有效途径，计算结果可为舰船结构的防护设计提供参考依据。

A numerical approach to the testing of the fission hypothesis

  Objectives  The FE method cannot accurately simulate crevasse patterns and the crevasse forming process when dealing with a projectile penetrating into a ship's plate because of mesh distortion.  Methods  To this end, this paper establishes a numerical simulation model of a projectile's penetrating shell structure based on the Material Point Method (MPM) and successfully simulates the failure process of crevasses. A comparison is made between the simulation results and the experimental results, showing that the MPM simulation results match the experimental results more closely, thus verifying the effectiveness of researching the crevasse failure process in the context of a projectile penetrating a ship's plate and providing a new approach to researching missiles penetrating a ship's shell plate. On the basis of the simulation model, simulations are made of a projectile penetrating 5 mm and 10 mm target plates with various velocities.  Results  The findings indicate that the crevasse size and plastic deformation area of the target plates are basically unchanged, and the crevasse size is slightly larger than the diameter of the projectile, with a 'washing crevasse' fracture mode. The target plate exhibits a plugging failure mode when hemispherical head projectiles penetrate such as the hull of shup at low, medium and high speed, and the speed has little influence on the size of the crevasses in the target plates while having a great influence on the height of the bump at the crevasse.  Conclusions  The results of this study can provide useful references for the protection design of ship structures.