非熔透激光焊接疲劳断裂机理研究
发布时间：2018-12-13 21:55
【摘要】：奥氏体不锈钢301L系列板材是用于制造轻量化客车的主要材料,其具有良好的力学性能和耐腐蚀性。当列车时速在250km以上时,由点焊制造的车体由于其密闭性差的特点不再满足需要,而非熔透激光焊接在满足强度和安全性的前提下,同时具有良好的气密性和表面光洁度。本论文通过疲劳试验,断裂模式分析,应力强度因子计算和应力分析对0.8mm+1.5mm、0.8mm+2.0mm、1.5mm+1.5mm和2.0mm+2.0mm四种不同板材组合的疲劳性能及疲劳断裂机理进行研究,并在此基础上提出优化板材组合疲劳性能的方案。研究结果表明,疲劳断裂模式相同时,外墙板厚度相同的不同板材组合有相近的疲劳性能,当外墙板厚度不同,而试样疲劳断裂模式相同时,不同板材组合的S-N曲线变化趋势相近或相同。试样应力强度因子进行计算分析表明,应力强度因子是影响疲劳断裂模式的原因。并且等效应力强度因子对数与试样疲劳寿命对数存在良好的线性关系,可根据等效应力强度因子对的试样疲劳寿命进行预测。通过局部应力强度因子计算分析认为疲劳裂纹萌生阶段为试样疲劳寿命的主要部分。试样缺口应力分析表明,疲劳断裂发生在应力集中处,应力集中是造成试样疲劳破坏的主要原因。对同一板材组合,最大应力集中值越大,其疲劳寿命越小。试样内板厚度的变化是引起应力分布及大小变化的主要原因。
[Abstract]:Austenitic stainless steel 301L series sheet is the main material used in the manufacture of lightweight passenger cars. It has good mechanical properties and corrosion resistance. When the train speed is above 250km, the car body made by spot welding is no longer satisfied with the need because of its poor sealing property, while the non-penetration laser welding can satisfy the requirement of strength and safety, at the same time, it has good air tightness and surface finish. In this paper, the fatigue test, fracture mode analysis, stress intensity factor calculation and stress analysis were performed on 0.8mm 1.5mm to 0.8mm. The fatigue properties and fatigue fracture mechanism of four different kinds of plate combinations of 1.5mm 1.5mm and 2.0mm 2.0mm were studied, and a scheme to optimize the combined fatigue properties of plates was put forward. The results show that when the fatigue fracture mode is the same, the combination of different plates with the same thickness of outer wall plate has similar fatigue performance, and when the thickness of outer wall plate is different, the fatigue fracture mode of specimen is the same. The change trend of S-N curve of different plate combinations is similar or the same. The calculation and analysis of the stress intensity factor of the specimen show that the stress intensity factor is the reason of influencing the fatigue fracture mode. There is a good linear relationship between the logarithm of the equivalent stress intensity factor and the logarithm of the fatigue life of the specimen. The fatigue life of the specimen can be predicted according to the equivalent stress intensity factor. Through the calculation and analysis of local stress intensity factor, it is considered that the fatigue crack initiation stage is the main part of the fatigue life of the specimen. The notch stress analysis shows that the fatigue fracture occurs at the stress concentration, and the stress concentration is the main cause of fatigue failure. For the same plate combination, the greater the maximum stress concentration value, the smaller the fatigue life. The change of plate thickness is the main cause of stress distribution and size change.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG456.7
本文编号：2377312
[Abstract]:Austenitic stainless steel 301L series sheet is the main material used in the manufacture of lightweight passenger cars. It has good mechanical properties and corrosion resistance. When the train speed is above 250km, the car body made by spot welding is no longer satisfied with the need because of its poor sealing property, while the non-penetration laser welding can satisfy the requirement of strength and safety, at the same time, it has good air tightness and surface finish. In this paper, the fatigue test, fracture mode analysis, stress intensity factor calculation and stress analysis were performed on 0.8mm 1.5mm to 0.8mm. The fatigue properties and fatigue fracture mechanism of four different kinds of plate combinations of 1.5mm 1.5mm and 2.0mm 2.0mm were studied, and a scheme to optimize the combined fatigue properties of plates was put forward. The results show that when the fatigue fracture mode is the same, the combination of different plates with the same thickness of outer wall plate has similar fatigue performance, and when the thickness of outer wall plate is different, the fatigue fracture mode of specimen is the same. The change trend of S-N curve of different plate combinations is similar or the same. The calculation and analysis of the stress intensity factor of the specimen show that the stress intensity factor is the reason of influencing the fatigue fracture mode. There is a good linear relationship between the logarithm of the equivalent stress intensity factor and the logarithm of the fatigue life of the specimen. The fatigue life of the specimen can be predicted according to the equivalent stress intensity factor. Through the calculation and analysis of local stress intensity factor, it is considered that the fatigue crack initiation stage is the main part of the fatigue life of the specimen. The notch stress analysis shows that the fatigue fracture occurs at the stress concentration, and the stress concentration is the main cause of fatigue failure. For the same plate combination, the greater the maximum stress concentration value, the smaller the fatigue life. The change of plate thickness is the main cause of stress distribution and size change.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG456.7
【引证文献】
相关硕士学位论文 前1条
1 吕盎然;301L/Q235B异种钢电阻点焊数值仿真及试验研究[D];北京交通大学;2018年
，本文编号：2377312
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