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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Von Misses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。
Based on the mechanics principle and experimental analysis of fracture interpretation by classical mechanics and fracture mechanics, it is concluded that the crack propagation is accompanied by the yield of metal, and the fracture surface ruptures along the normal plane of the first principal stress. In the case of brittle failure. Tensile test and numerical simulation of the six structural steel tubes were carried out. The simulated stress-displacement curve is in good agreement with the experimental data. The simulated stress field can be used as the fracture mechanism analysis. Fracture analysis results show that the bearing capacity and plastic deformation of specimens decrease with the increase of pore-diameter ratio. When the pore-diameter ratio is the same, the bearing capacity of the double-perforated tube is higher than that of the single- ; When the pore diameter ratio is too small and too large, the fracture ductility coefficient is very small. Only when the pore diameter ratio η is at a certain value, the fracture ductility coefficient μ of the steel pipe reaches the peak value. The initial crack appears in the stress concentration area, and the crack area has complex stress state. The first principal stress and Von Misses equivalent stress are concentrated on both sides of the open pipe. The equivalent stress of other parts is smaller. The triaxial stress ratio along the test The thickness of the piece is approximately linear.