Fuzzy fatigue reliability analysis and optimization of A-type frame of electric wheel dump truck based on response surface method
Due to many bends on the mine road surface, the electric wheel dump trucks turn frequently. The A-type frame is regarded as the key bearing component in the steering system for the electric wheel dump truck , while its fatigue reliability is one of the important factors to ensure truck’s running safety. In order to accurately evaluate fatigue reliability performances of A-type frame, a fuzzy fatigue reliability calculation method based on response surface method is proposed, considering the uncertainties of A-type frame in the actual manufacture and use stage. The material parameters of welding seam of A-type frame were obtained through experimental work. The load information of pivotal connection sites of A-type frame was obtained by the rigid and flexible coupling multi-body dynamics analysis for the whole vehicle. The finite element model of A-type frame with welding details was constructed, and its accuracy was verified by stress test on the mine road surface. Then, the material parameters and load information of A-type frame were taken as random variables and fatigue limit was regarded as a fuzzy variable. The random variables were sampled by Latin hypercube method, and the corresponding response values were obtained by the elastic and plastic finite element simulation under cyclic loadings. The fatigue reliability performance function of A-type frame was constructed based on response surface method. Finally, based on fuzzy theory, the fatigue reliability performance of A-type frame under the condition of downhill and turning braking with full load was evaluated, and its fatigue reliability was found to be less than 90%. Then, the fuzzy fatigue reliability performance was optimized by genetic algorithm. According to the optimized results, a new flexible front lateral stabilizer for this steering system was presented，which could improve the bearing capacity and force status of A-type frame and guarantee the fatigue reliability performance of A-type frame. The final fatigue reliability of the optimized A-type frame reached up to 98%.