转向架焊接构架强度模型及其对寿命预测的影响

THE STRENGTH MODELING OF BOGIE WELDED FRAME AND ITS INFLUENCE ON LIFE PREDICTION

为了对转向架焊接构架疲劳分析模型的合理性进行了探讨,以构架箱体梁为研究对象,针对主焊缝的不同处理方法建立了名义应力模型、结构应力模型和缺口应力模型。通过三种应力模型下应力特点、疲劳评估、累积损伤和参数影响的比较,结果表明:名义应力模型和结构应力模型下的应力大小和方向相似度较高,名义应力模型忽略焊缝的做法具有一定合理性,但前提是以焊趾前端应变片测试位置为应力取值点。缺口应力模型的特点在于能够较真实的描述焊缝局部的应力状态和循环特性;其优势也体现在能够同时对焊趾和焊根进行疲劳评估,因为计算结果显示箱体梁疲劳破坏也可能源于焊根处。由于结构应力模型对焊缝参数的变化并不敏感,进行焊缝参数优化时只能选择缺口应力模型。

In order to discuss the rationality of fatigue analysis models of bogie welded frame,this paper regards box girder as the research object and establishes nominal stress model,structure stress model and notch stress model by aiming at different processing methods of main weld. Through stress characteristics,fatigue assessment,cumulative damage,and weld parameter influence of three models are compared. The results show that stress size and orientation under nominal stress model and structure stress model have higher similarity,it is reasonable to ignore the weld for nominal stress model on condition that stress value must locate in the weld toe front,where sets the strain gauges. Characteristics of notch stress model lie in describing local stress state and cycling performance of weld really,and its advantages are also reflected in conducting fatigue assessment on both weld toe and weld root simultaneously,for the reason that fatigue failure of box girder may occur in weld root,as shown in the computed results. Because structure stress model is not sensitive to changes of weld parameters,optimization of weld parameters only chooses notch stress model.