基于结构应力法的起重机焊缝多轴疲劳寿命研究

RESEARCH ON MULTI-AXIAL FATIGUE LIFE OF CRANE WELD BASED ON STRUCTURAL STRESS METHOD

以580 t级龙门起重机主梁与刚腿连接处焊缝为例,基于结构应力法分析起重机作业的应力历程,确定多轴非比例的应力特征。建立危险位置处具有焊缝细节的壳-实体混合模型,借助Ansys和Fe-Safe软件的Verity模块,结合载荷谱获取多轴结构应力。通过基于路径依赖的循环计数法(PDMR)确定损伤累积路径,引入载荷路径力矩(MLP)概念,将非比例加载路径向比例加载路径转化。根据主S-N曲线估算焊缝处疲劳寿命,并与多轴比例加载寿命分析方法、单轴等效结构应力寿命分析方法的计算结果对比,表明多轴非比例变幅应力的疲劳分析方法的必要性,这为起重机复杂的多轴疲劳分析提供参考与借鉴。

As an example of life evaluation of the weld between main girder and rigid leg of 580 t gantry crane based on structural stress method,the non-proportional stress characteristics of multi-axis are obtained by analyzing the working stress history of crane.The shell-solid mixed model with weld details in the dangerous position is built,and the multi-axial structural stress is obtained by combining the load spectrum with the ANSYS and Verity module of FE-SAFE software.The damage accumulation path is obtained by Path Dependent Maximum Range(PDMR).Moment of Load Path(MLP)is introduced to realize the transformation from non-proportional loading path to proportional loading path.The fatigue life of the weld is estimated according to the master S-N curve and compared with the multi-axis proportional and uni-axial life estimation methods.It shows the necessity of multi-axial non-proportional fatigue analysis method,which provides reference for the complex multi-axial fatigue analysis of cranes.