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HFMI处理的钢制焊接接头疲劳评估模型探讨

Discussion on fatigue evaluation models of steel welded joints treated by HFMI

  • 摘要: 为评估不同应力比R和材料屈服强度fy下的高频机械冲击(high frequency mechanical impact,HFMI)处理钢制焊接接头疲劳寿命,引入SWT(smith-watson-topper)模型与Walker模型,利用缺口应力法对广泛的疲劳试验数据进行了重新分析. 结果表明,名义应力系统下,接头疲劳等级FAT,Rfy三者关系可通过FAT = 0.1fy + M(R)来表达;缺口应力系统下,对于同种材料不同应力比下的接头,两种模型均能用来评估其疲劳寿命,但Walker模型精度更高;对于不同种材料在不同应力比下的接头,SWT模型形式固定,且能综合考虑Rfy的影响,基于该模型分析得到的存活率PS = 97.7%的S-N曲线,其FAT = 325 MPa,斜度m = 6.5.研究成果将直接支撑工程结构疲劳评估和抗疲劳设计.

     

    Abstract: High frequency mechanical impact (HFMI) is widely used in the field as a reliable and efficient repost-weld treatment. In order to evaluate the fatigue life of steel welded joints treated by HFMI under different stress ratio R and material yield strength fy, extensive fatigue test data were re-analyzed using the notch stress approach combined with SWT (smith-watson-topper) and Walker models. The results reveal that the relationship between the fatigue grades FAT, R and fy of the joints under nominal stress system can be expressed by FAT = 0.1 fy + M(R). Under the notched stress system, for joints made of the same material loaded under different R values, both models can be used to predict fatigue life, but the Walker model has higher accuracy. For joints of various materials with different R values, SWT model has a fixed form and can comprehensively consider the influence of R and fy. Based on this, the survival rate PS = 97.7% of the S-N curve with FAT = 325 MPa and slope m = 6.5 is obtained. The research will directly support the fatigue assessment and anti-fatigue design of engineering structures.

     

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