Fatigue Optimization And Vehicle Dynamics Of Rigid-flexible Coupling Heavy Truck Frame

Heavy trucks are the main type of vehicle in transportation industry.With the rapid development of logistics industry in recent years,heavy trucks have been widely used.As the assembly carrier of the various components in the whole vehicle,the frame is also the most complex component under force.During the driving process,especially under some severe working conditions,fatigue damage is easy to occur,which has a great impact on the stability,ride comfort and safety of the whole vehicle.In this paper,the parameterized three-dimensional CAD model of the frame is firstly established according to the design parameters.The static analysis of the frame under full load bending,full load torsion and full load bending and torsion is carried out by introducing the finite element software ANSYS.The strength of the frame is checked,and the natural frequencies and vibration modes of the frame are determined by dynamic analysis.Then,the flexible frame is imported into ADAMS/car,and the rigid-flexible coupling vehicle model with flexible frame is established.The rigid-flexible coupling model was verified by the double-shift test data.The dynamics simulation of the rigid-flexible vehicle model and the multi-rigid model was carried out on the random road surface to obtain the load-time history of the push-pull rods of the shock absorber and the middle and rear axles.The influence of rigid frame and flexible frame on the dynamics of the vehicle is analyzed by using the effective value as a comparative measure.aking the boundary dynamic load of the frame as the input condition of load spectrum,the fatigue life of the frame is predicted,and the fatigue danger points of the frame are obtained.Next,for the purpose of lightweight,the frame is optimized by taking the thickness of two longitudinal beams,main cross beams and beam connectors as input variables.The optimization results are verified by static analysis,modal analysis and fatigue life comparison before and after optimization.Finally,the optimized frame is flexible processed,and the whole vehicle model is reassembled.According to the evaluation criteria of handling stability and ride comfort,the optimized rigid-flexible coupling vehicle model is simulated and compared with the prototype vehicle modelThe research shows that(1)compared with the rigid-flexible coupling model,the calculated load of each component is too small,and there are certain safety hazards.The flexible frame can better reflect the connection and force relationship of the various components of the vehicle.(2)The fatigue strength of the frame satisfies the driving requirements.Although there are a few dangerous nodes,it has little effect on the fatigue strength of the overall frame.(3)After frame optimization,its mass is reduced by 7.3%,strength and natural frequency are increased,fatigue life is reduced by 3.9%,but it can still meet the normal use requirements of the frame.The rigid-flexible coupled vehicle model after frame optimization can better simulate the dynamic performance of the whole vehicle.The research results of this paper can provide new ideas and references for frame fatigue optimization analysis,rigid-flexible coupling heavy vehicle modeling and dynamics analysis.