Reliability-based Design Optimization For Truck Frame

As the main load-carrying component for the truck,the frame plays a very important role in the structure of the truck,so the safety and reliability of the frame are very important for the finished automobile.Therefore,this paper based on genetic algorithm,under the premise of satisfying the reliability,carried out the reliability-based design optimization for a truck frame.The work of this paper was as follows:1.The model for frame topology optimization was established.Taking the element density as density variables,the minimum structural flexibility as objective function,the structural volume fraction as constraint condition,respectively for bending,twisting,braking and turning four kinds of typical condition to the topology optimization for the frame,then referring to the same type of frame beam and girder structure,finally the frame geometry model was obtained.2.The static strength for the frame was analyzed.The finite element model for the frame was established,and the static strength for the frame under four typical working conditions of bending,twisting,braking and turning were analyzed.The dangerous positions for the frame were pointed out,and the stress and displacement cloud images for the frame were obtained.It was verified that the static strength for the frame under four typical working conditions all meet the requirements.3.Based on the dimension reduction method,the reliability-based analytic model for the frame was established.The performance function for the frame was transformed into a univariate function by the dimension reduction method,and then the moment method of the performance function were obtained by the Taylor method,finally,the failure probability for the frame was obtained by the moment method.The results showed that the reliability for the frame under bending,brake and turn conditions all meet the design requirements,but the reliability under torsion condition did not meet the design requirements.In addition,by comparing the proposed method with the Monte Carlo Simulation,First-order Reliability Method and Second-order Reliability Method,it could be concluded that the proposed method has the advantages of smaller relative error and shorter analysis time.4.The reliability-based design optimized model for the frame was established.Selected the nine key components of thickness as the design variables,with yield limit stress as the random variables,with frame bending,twisting,braking and turning the performance functions under the condition of reliability were all greater than the specified reliability as the constraint conditions,with the minimum total weight for the frame as the objective function,the reliability-based optimization for the frame was carried out.