结构钢开孔管断裂试验及有限元分析

The Fracture Experimental and Finite Element Analysis of the Steel Pipe with Hole

借助经典力学和断裂力学对断裂解释的力学原理和试验分析，总结出裂纹的扩展伴随着金属的屈服，断裂面沿着第一主应力的法平面发生破坏，开孔管在有限的塑性变形的情况下，发生脆性破坏。通过对六个结构钢开孔管进行拉伸试验和数值模拟分析；模拟的力-位移曲线与试验吻合较好，模拟的应力场可以作为断裂机理分析。断裂分析结果显示：试件的承载力、塑性变形随着管孔径比的增加而减小，管孔径比相同时，双孔管的承载力高于单孔管，塑性变形能力强于单孔管；管孔径比太小和太大时，断裂延性系数均很小，只有当管孔径比η位于某定值时，钢管的断裂延性系数μ才取得峰值。初始裂纹出现在应力集中区域，裂纹区域存在复杂的应力状态，第一主应力和VonMisses等效应力集中在开孔管两侧，其它部位的等效应力值较小，三轴应力比沿试件厚度近似成线性。

By virtue of mechanics principle and experimental analysis of fracture explained in classical mechanics and fracture mechanics, it is concluded that the extension of cracks accompanies the yield of metals, fracture surface breaks along the normal plane of the first main stress, and the brittle failure of the pipe with hole occurs in the case of finite plastic deformation. By the tensile tests of six structural steel pipes with hole and the numerical simulation analysis, the stimulant force-displacement curve is in agreements well with the experimental one, so the stimulant stress field can be used for the analysis of fracture mechanism. The result of the fracture analysis shows： the bearing capacity and the plastic deformation decrease with the increase of the ratio between the pipe diameter and the pore diameter; the bearing capacity of the pipe with diplopore and the plastic deformation capacity are larger than those of the pipe with single hole when the ratios are the same; If the ratio is too large or small, the fracture ductility coefficient is always small. Only if the ratio η is a certified value, the fracture ductility coefficient μ of the steel pipe can get the peak. The initial crack appears in the stress concentration region. There are complex stress states in the crack regions. The first main stress and the equivalent stress concentrate on the both sides of the pipe with hole, and the equivalent stress in other positions is small. Triaxial stress ratio takes on linear distribution along specimens thickness.