Research On Fatigue Life Of Casting Crane Bridge Base On Thermo-elastic Dynamic Analysis

Casting crane is widely used as hoisting and conveying equipment in the metallurgical industry. The bad andfailure working environment caused remarkable accident harm, so mechanical properties and fatigue analysis accurately on thisequipment seem very important. As the rapid development of steel smelting industry, the casting cranes are developed tend to high speed and large-scale. The reliability and safety of a crane was largely affected by the dynamic property of the bridge.Taking casting crane actual condition as the research background, and then conducting thermo-elastic dynamic analysis by using the finite element analysis software. After that, acquiring structure dynamic stress and vibration propery of bridge in the iron melt ladle lifting, transportation and unloading process. This research results can be provided reliable data support for the fatigue life prediction and structure optimization.The simplified 3D bridge model of 200/63t casting crane is established in this paper. The iron melt is taken as the heat source and taking heat radiation and conduction as heat transfer mode to analysis the temperature field of the bridge in the iron melt ladle lifting and transportation process. The temperature field analysis is finished in the finite element analysis software. And then, research on the effect of casting crane bridge under different iron melt lifting and transporting conditions. The iron melt ladle lifting and transportation process dynamic model are established to analysis steel rope tension and the influence relationship under different conditions. After that, loading the node temperature of the bridge model and applying structural load which is the sum of the steel wire rope tension and the weight of the main trolley, and the corresponding transient dynamic analysis is implemented by using thermo-elastic coupling method. Besides, the dynamic stress and property of the bridge in the lifting process was investigated in this step.On the basis of thermo-elastic dynamic analysis of 200/63t casting crane bridge, the impact fatigue damage evolution model can be established by combine damage mechanics by extracting stress amplitude (greater than the threshold σd). The impact fatigue damage evolution model is utilized to study the fatigue crack initiation life of the bridge under impacting load conditions. Combining with the theory of linear elastic fracture mechanics theory to consduct the fatigue crack propagation life of beans under dynamic load. And then, analysising the relationship of stress cycles (Nf),initial crack (αo) and critical crack (ac).Collecting the dynamic stress of bridge structure in the load-lifting, tasporting and unloading process by taking the large overhead crane as the test object, and analysing of dynamic stress signals. Researching on the influence of different lifting speed of crane trolley on the each testing point’s dynamic stress in the load-lifting process. To verify the accuracy of thermo-elastic dynamic analysis method by contrasting between the results of theory calculation test experiment.