基于能量耗散的Q460焊接接头疲劳强度评估

Fatigue strength evaluation of Q460 weld joints based on energy dissipation

传统基于温度数据的疲劳强度预测方法,无法揭示疲劳过程背后的不可逆能量耗散机理.针对Q460焊接接头疲劳强度,提出一种新的基于不同载荷等级下能量耗散斜率转折的疲劳强度预测方法,即最大斜率法.采用红外热像仪测得的试件表面实时热像数据,建立高周疲劳过程能量耗散模型,并计算不同载荷等级下的Q460焊接接头能量耗散值.借助不同载荷等级下的能量耗散随载荷等级增加时其值存在转折点这一理论,将能量耗散作为疲劳强度的预测参量,实现其疲劳强度的快速预测.为验证模型的准确性,将由最大斜率法得出的疲劳强度估计值分别与传统双线法和升降法的计算值进行对比.结果表明,由最大斜率法得到的疲劳强度预测值与通过双线法和升降法得到的预测值较为接近,误差分别为0.04%和7.40%,能够为焊接接头疲劳强度预测提供一定的参考.

Traditional temperature-based fatigue strength prediction method,fail to reveal the irreversible energy dissipation behind the fatigue evolution.For the fatigue strength evaluation of Q460 welded joints,a new fatigue strength prediction method,which is based on the energy dissipation of different load levels that exists the turning point,was proposed,i.e.maximum slope method.The energy dissipation was firstly established based on the obtained realtime thermographic data of the specimen surface,and then the energy dissipation value of Q460 welded joints were calculated.Based on the theory of the energy dissipation turning point exists when the load level increases,the energy dissipation was set as an index for rapid fatigue strength estimation.To verify the accuracy of the developed model,the fatigue strength value estimated by the maximum slope method was compared with the predicted value by the traditional bilinear and staircase methods.The results show that a good agreement is reached between the predicted fatigue strength by the maximum slope method and the traditional bi-linear and staircase methods,and the errors are 0.04% and 4.76%,respectively,which may provide a certain reference for fatigue strength prediction of welded joints.