一种新的焊接构架疲劳分析方法

A Novel Fatigue Analysis Method of Welded Frames

为了在多工况下进行焊接构架多轴应力的疲劳强度评估,在直接法和投影法的基础上,将二阶张量坐标变换的性质应用于构架的多轴应力疲劳评估,提出了张量法.该方法将多轴应力转换到同一坐标系和同一截面下,根据获得的最大应力和最小应力进行疲劳评估.以某型转向架焊接构架为例,建立了该构架的有限元模型,计算结构在多工况下的应力,并用直接法、投影法和张量法计算了焊接构架的疲劳强度.通过临界面法和Ncode软件的计算,验证3种方法的合理性.结果表明:考虑多轴应力方向的张量法明显优于另外两种方法,与Ncode计算结果误差最小,为4.42%.

In order to evaluate the fatigue strength of welded bogie frames under multi-axial stress in load cases, a tensor method based on the direct method and projection method was proposed by applying coordinate transformation property of the second-order tensor. This method, by transforming multi-axial stress to the same coordinate system and the same section, uses the obtained maximum stress and minimum stress for the fatigue evaluation. The finite element model was then built based on a certain welded bogie frame. The stresses in several static conditions were calculated. For comparison purpose, the direct method, projection method, and tensor method were used to evaluate the fatigue strength of this bogie frame, respectively. The rationality of the three methods was verified by critical plane approach and Ncode. The results show that the tensor method, which took the direction of multi- axial stress into consideration, is obviously better than the other two methods, with the smallest error of 4.42% compared with the Ncode result.