冲击载荷作用下Q345钢失效应变与单元尺寸关系研究

Influence of element size on failure strain of Q345B steel under intensive loading

冲击载荷作用下结构的损伤破坏仿真计算中,材料的失效应变取值与单元尺寸具有很大的关系。为建立冲击载荷作用下结构失效应变与单元尺寸之间的关系,本文以开展的Q345B钢各类力学性能试件(压缩、扭转、拉伸等)获取的材料失效应变为依据,借助数值仿真手段,研究各类试件网格尺寸对失效应变影响关系,并进一步依托开展的弹体穿甲试验、简单方板冲击试验、近场爆炸下舰船毁伤破坏试验,建立三类典型冲击问题中单元失效应变取值与尺寸之间的对应关系。计算结果表明:网格尺寸对单元失效应变的影响主要在于单元尺寸可改变结构变形过程中局部塑性变形分布区域的分布度;不同冲击载荷作用下,由于所使用的单元类型及受力状态存在一定的差异,需针对各类冲击问题分别建立单元失效应变与网格尺寸之间的关系。研究成果可为后续数值仿真计算中单元失效应变的选取提供指导。

Element size used in the numerical simulation of structure damage calculation under intensive loadings has a strong influence on the value of material failure strain. Firstly, experiments of material mechanical properties including compress tests, torsion tests, tensile tests were performed to acquire the material failure strain. Then, the influence of different element sizes on the failure strain value was studied by numerical simulation method. The relationship between element size and failure strain was discussed for three typical shocking engineering problems containing projectile penetrating test, plates shocking test and warship damage test under close-in underwater explosion. The results indicate that the key factor of element size influencing the failure strain is that the element size can change the distribution of the local plastic deformation distribution area during the structural deformation, and that it is necessary to establish an independent relationship between the element failure strain and the mesh size for various impact problems for different stress conditions, capable of providing assistance for selecting accurate failure strain in numerical simulation.