The Static Dynamic Characteristics Analysis And Optimization Design Of A Heavy Truck Frame

Heavy truck frame as the main bearing part of the truck,its function is to connect the truck assembly and bear the complex load and torque which is transmitted to it.Therefore,the design of the truck frame is an important part of the vehicle performance.With the improvement of computer hardware development and modern optimization theory,analysis of the static and dynamic characteristics of truck frame is carried out by using the finite element method and find the defects existing in the truck frame design process,on the truck frame of optimization design with respect to the traditional experience design method has a great advantage.In this paper,it takes a section of heavy truck frame as the model.Combining with FEM theory and optimal design theory,to conduct static and dynamic characteristics analysis of the frame,after finding the potential defect of frame,topology optimization design,size and optimization design,verification analysis are carried out.Specific work content as follows:Firstly,based on the actual size of a heavy truck frame,the finite element model of the frame is established by using HyperWorks software,and the four typical conditions of the truck frame are selected to analyze the static and dynamic characteristics of the frame.The analysis results show that the stiffness and strength of the frame can meet the design requirements,but the stiffness of the frame is small.The low frequency of the frame is not in the range of the frame mode design requirements,and it is easy to produce resonance.Secondly,aiming at the defect of the truck frame,the design method of topology optimization is used to improve the structure of the frame.At the same time,considering the importance of the frame stiffness in the design process,the multi-objective topology optimization of the frame is carried out by taking the maximum of the Stiffness and the three order natural frequency as the goal.Meanwhile,in order to coMPare different multi-objective optimization methods in topology optimization difference,this paper establishes three kinds of multi-objective optimization mathematical models which are linear weighted method,the square and weighted method and the compromise programming method.These methods are applied in the frame topology optimization.At the same time the theory of satisfaction is introduced to multi-objective optimization mathematical model,satisfaction dynamic weight is established,eliminate the conditions of each stiffness and natural frequencies of the first three order between the influence of weight,the realization of the three methods of multi-objective topology optimization results of coMParative analysis.The optimization results show that: the three methods can achieve the multi-objective topology optimization of the frame,and the operating conditions and the first three order frequencies of the frame can be greatly improved.Under the dynamic weight of satisfaction,there are differences between the three optimization methods.the optimization results of compromise programming approach for the frequency and the stiffness of the vehicle frame are more obvious than the other two methods.Then,Based on the topological configuration of the truck frame,the geometric model of the new truck frame is established,the number and the optimal position of the beam are determined.In order to further determine the thickness of the horizontal rails,frame beams and longitudinal thickness are taken as the design variables,the frame size optimization design is carried out.At the same time,to meet the design requirements of the premise,through the size optimization to achieve the purpose of lightweight,reduce the quality of 19.5%,the effect is obvious.checking the static and dynamic characteristics of the new truck frame,the strength,stiffness and low order natural frequency of the new frame are found to meet the design requirements,which shows the correctness of the optimization design process.At last,checking the fatigue life of the frame after the static and dynamic characteristics checking,verified that the optimized truck frame the most dangerous fatigue life for 1.037×105 times,meet the fatigue safe life standard(105 times).The validity and rationality of the optimization design results of the truck frame are enhanced by the fatigue life check.This paper studied the multi-objective topology optimization results of three kinds different evaluation functions under the dynamic weight of truck frame satisfaction,In addition,the paper established a set of complete commercial truck frame optimization design process and ideas have a certain guiding significance and reference value on optimization design research for the commercial truck.