【摘要】：奧氏體不銹鋼301L系列板材是用于制造輕量化客車的主要材料,其具有良好的力學性能和耐腐蝕性。當列車時速在250km以上時,由點焊制造的車體由于其密閉性差的特點不再滿足需要,而非熔透激光焊接在滿足強度和安全性的前提下,同時具有良好的氣密性和表面光潔度。本論文通過疲勞試驗,斷裂模式分析,應力強度因子計算和應力分析對0.8mm+1.5mm、0.8mm+2.0mm、1.5mm+1.5mm和2.0mm+2.0mm四種不同板材組合的疲勞性能及疲勞斷裂機理進行研究,并在此基礎上提出優(yōu)化板材組合疲勞性能的方案。研究結(jié)果表明,疲勞斷裂模式相同時,外墻板厚度相同的不同板材組合有相近的疲勞性能,當外墻板厚度不同,而試樣疲勞斷裂模式相同時,不同板材組合的S-N曲線變化趨勢相近或相同。試樣應力強度因子進行計算分析表明,應力強度因子是影響疲勞斷裂模式的原因。并且等效應力強度因子對數(shù)與試樣疲勞壽命對數(shù)存在良好的線性關系,可根據(jù)等效應力強度因子對的試樣疲勞壽命進行預測。通過局部應力強度因子計算分析認為疲勞裂紋萌生階段為試樣疲勞壽命的主要部分。試樣缺口應力分析表明,疲勞斷裂發(fā)生在應力集中處,應力集中是造成試樣疲勞破壞的主要原因。對同一板材組合,最大應力集中值越大,其疲勞壽命越小。試樣內(nèi)板厚度的變化是引起應力分布及大小變化的主要原因。
[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.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG456.7

【引證文獻】

相關碩士學位論文 前1條

1 呂盎然;301L/Q235B異種鋼電阻點焊數(shù)值仿真及試驗研究[D];北京交通大學;2018年

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本文編號：2377312