Medium-duty Truck Frame Based On The Finite Element Analysis To Improve The Design And Its Pilot Study

With the development of a medium-duty truck frame, finite element analysis of the frame had been completed based on the theory of FEM. According to the analysis results, frame's structure was improved and lightweighted. In order to verify the reliability of finite element analysis and evaluate the fatigue life of the frame, frame bench tests were processed by using non electrical parameters measurement technology.According to the geometric shape of the frame structure, proper element types were chosen, the bolt connections and welding joints were simulated, a complete finite element model of the truck was built up by Hyper Works software, including with cabin, box, brackets, front and rear suspensions. The methods were researched to set up the model of leaf springs, and add the constraints and loads. Then, under different conditions, the stress distributions on the frame and its torsion stiffness were calculated with NX.Nastran. The weakness and unreasonable structure of the original frame design had been found.According to the analysis results, the fifth and sixth crossbeam connectors were strengthened. Then, lightweight design on the frame parts were carried out, which made the weight of frame reduce 4.93%. Meanwhile, new frame could meet the stiffness and strength requirement.In order to study the dynamic response, free modal analysis of the optimized frame was completed. The result showed that, its low frequency is higher than the excitation frequency from wheels, and below the frequency of idle speed engine. The whole frequency avoided the frequency range of engine normal work. That means, resonance between frame, wheels and engine is impossible. The dynamic response of the optimized frame was reasonable.Finally, under bending and torsion conditions, the frame static stress-strain tests and fatigue life tests had been processed, and the stress-strain distribution on the frame were obtained. Test data and finite element theoretical calculations were in good agreement, that proved the finite element analysis have a highly accuracy. Frame fatigue life tests proved its fatigue life meets the requirement, further illustrated its structure and property are reasonable.