加筋板穿透数值仿真中网格尺寸对失效应变的影响分析研究

Analysis and research on influence of mesh size on failure strain in stiffened plates penetration numerical simulation

运用数值仿真分析碰撞过程时,基于最大等效塑性应变失效准则确定的材料失效应变取值与网格尺寸具有明显的依赖关系,因此,研究碰撞载荷下加筋板网格尺寸对失效应变取值的影响对于评估加筋板架的耐撞性及开展耐撞性结构设计具有重要意义。文中基于LS-DYNA非线性有限元分析软件对光板及加筋板穿透过程分别进行仿真分析,以国外学者相应准静态穿透试验的结果为参照,探讨了加筋板与光板的有限元网格尺寸和失效应变之间的关系,同时对是否有必要考虑骨材与板壳之间的焊缝进行了探究。研究表明:加筋板与光板的失效应变取值存在明显的差异,确定加筋板材料失效应变取值时,应优先参考适用于加筋板网格尺寸与失效应变取值的关系曲线;在决定是否考虑加筋板结构中的焊缝时需要结合网格尺寸与焊缝等效单元的相对大小进行判断。

Using the numerical simulation analysis of the collision process,the material strain failure value based on the maximum equivalent plastic strain failure criterion has a significant dependency on the mesh size.Therefore,it is significant to study the influence of the mesh size of stiffened-plate under the impact load on the failure strain values to evaluate the crashworthiness of stiffened plate structure and carry out the structure design for improving crashworthiness.In this paper,based on the LS-DYNA none linear finite element analysis software,the unstiffened-plate and stiffened-plate penetration process is simulated and analyzed by the result of corresponding quasi-statically indentation test carried out by Hagbart S.Alsos for reference.The relationship between the mesh size and the failure strain of stiffened-plate and unstiffened-plate is analyzed,at the meantime,whether it is necessary to consider the weld between the stiffener and the plate are explored.The research shows that there are obvious differences in the failure strain values between the stiffened-plate and the unstiffened-plate,when determining the failure strain value of stiffened-plate,the relationship curve of the mesh size and the strain value of the stiffened-plate should be referred p rio rity;it is necessary to combine the mesh size with the relative size of the weld equivalent element when determ ining whether or not to consider the w eld in the stiffened plate.