超声频分量双周疲劳载荷作用下焊接接头疲劳行为

Fatigue behavior of welded joints under combined cycle fatigue with ultrasonic component

使用带超声频载荷分量的双周疲劳试验装置对Q345钢焊接接头分别进行纯低周、纯高周以及双周循环加载条件下的疲劳试验.应力比R为0.5,高周载荷频率约19 kHz.结果表明,叠加于大幅低周循环载荷上的小幅高周循环载荷及叠加于大幅高周循环载荷上的小幅低周循环载荷都能够对焊接接头造成严重的疲劳损伤.通过按外包络线表征双周疲劳强度,如果疲劳寿命使用低周载荷循环周次表征,低估了高周载荷分量对焊接接头造成的损伤;如果疲劳寿命使用高周载荷循环周次表征,又高估了低周载荷分量对焊接接头造成的损伤.

Q345 steel welded joints were tested to failure under low cycle fatigue(LCF),high cycle fatigue(HCF) and combined cycle fatigue(CCF) using an apparatus that is capable of providing interactive LCF/HCF loading.The stress ratio R is 0.5 and the frequency of HCF is about 19 kHz.The results indicate that not only high frequency minor cycles superimposed on low frequency major cycles,but also low frequency minor cycles superimposed on high frequency major cycles can do remarkable damage to fatigue performance of welded joints.The CCF strength is characterized by amplitude envelope.While CCF fatigue life is characterized by LCF life,adverse effect of HCF component is underestimated.If CCF fatigue life is characterized by HCF life,adverse effect of LCF component is overrated.