考虑轮压载荷的铸造起重机多轴疲劳特性分析

Multiaxial Fatigue Analysis of Casting Crane Considering Wheel Pressure Loads

铸造起重机金属结构是一种典型的复杂焊接结构,在移动轮压载荷和复杂焊缝几何的共同作用下,一些非常规部位时常出现疲劳裂纹。针对某在役铸造起重机主梁轨道下方T型钢与小筋板连接焊缝区域发生的密集疲劳裂损问题,采用Soild-Shell混合单元和子模型技术,建立了裂损局部区域的精细有限元模型,模拟了移动轮压载荷作用下整体金属结构的完整应力时间历程,分析了裂损部位的多轴特性。采用基于临界平面法的多轴疲劳模型,计算并讨论了裂损区域的疲劳性能。结果表明:多轴应力是导致裂损部位萌生裂纹的主要原因,F-S多轴疲劳模型可以有效评估裂损部位的疲劳性能。

The metal structure of casting crane is a typical complex welding structure.Under the combined action of moving wheel pressure load and complex weld geometry,fatigue cracks often appear in several unconventional locations.In view of the intensive fatigue damage problem in the connection area of T-shaped steel and small rib plate under the main beam track of an in-service casting crane,the Soild-Shell mixed element and sub-model technology were used to establish the fine finite element model for crack area.The complete stress change process of the whole metal structure under the action of moving wheel pressure load was simulated,and the obvious multiaxial characteristics of the crack area were analyzed.The multiaxial fatigue model based on the critical plane method were used to calculate and discuss the fatigue performance of the crack area.The results show that the multiaxial stress is the main reason for the initiation of cracks at the crack area,and the F-S multiaxial fatigue model can effectively evaluate the fatigue performance of the crack area.