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在试验分析的基础上,本研究提出了一种程序,以建立C-Mn结构钢在韧性断裂过程中的空穴增长与塑性应变及三轴应力状态之间的关系,并确定了空穴增长系数。由光滑拉伸试样和预制裂纹侧槽三点弯曲试样试验所确定的空穴增长系数,可能适宜较宽的试样拘束变化范围。空穴增长的实验关系式表明,当三轴应力状态(σm/(?))约大于1.2时,在该结构钢中的实际空穴增长速率低于由Rice-Tracey理论所确定的空穴增长速率,然而当三轴应力状态(σm/(?))约小于1.2时,由Rice-Tracey理论所确定的空穴增长表现为对实际材料中的空穴增长估计略为不足。另外,根据实验空穴增长研究,对预制裂纹侧槽三点弯曲试样在韧性起裂时钝化裂纹前端的塑性应变、相对空穴体积和应力状态三轴性的变化进行了测量和估计。
Based on the experimental analysis, this study presents a procedure to establish the relationship between the hole growth and the plastic strain and the triaxial stress state of the C-Mn structural steel during ductile fracture and to determine the hole growth coefficient. The coefficient of hole growth, as determined by the test of a three-point bend specimen with a smooth tensile specimen and a pre-cracked side groove, may be suitable for a wide range of specimen confinement variations. The experimental relationship for hole growth shows that the true hole growth rate in the structural steel is below the hole growth determined by the Rice-Tracey theory when the triaxial stress state (σm / (?)) Is greater than about 1.2 However, when the triaxial stress state (σm / (?)) Is less than about 1.2, the hole growth determined by the Rice-Tracey theory appears to be a slight underestimation of hole growth in real materials. In addition, according to the study of experimental hole growth, the change of plastic strain, relative cavity volume and stress state triaxiality at the crack tip of the prefabricated cracked side slot three-point bending specimen during ductile fracture was measured and estimated.