Study On NVH Characteristics And Dynamic Response Of Heavy Truck Cab

Taking the cab of a heavy truck in an enterprise as the research object,to achieve the goal of controlling the cab's NVH performances,it is of practical engineering value to analyze and study NVH characteristics and dynamic responses.First,the structural characteristics of heavy truck cab is analyzed and the vibration characteristics of cab system is studied,to put forward specific NVH performance requirements in this article.The finite element model of heavy truck cab is built,and the modal,static stiffness,dynamic stiffness and vibration transfer function of the key response points of cab are analyzed,soas to obtain the static and dynamic characteristics of cab.Compared with the NVH target values,the values of modal and static stiffness are slightly greater than that of the benchmarking car.The value of the dynamic stiffness at the rear suspension is equivalent to that of the benchmarking car.The value of attachment points' X – direction dynamic stiffness at the both sides of front suspension is only half of the benchmarking car.The values of vibration responses at the steering wheel,the floor under the driver's feet and the seat frame all meet the target requirements,providing a reference for subsequent analysis and improvement.Then,vibration and dynamic response tests were carried out on the real sample vehicle.In order to verify the validity and feasibility of CAE analysis on finite element model,a test platform was set up,and vibration response tests were carried out respectively on the real sample vehicle at idle of 600r/min and at a constant speed of 60km/h to obtain the actual accelerations of the engine mount,front axle,middle axle,rear axle,steering wheel in the cab at 3 o'clock on times and at the seat frame.The transfer function from the center of the engine mount,front wheel,middle wheel and rear wheel to the corresponding accelerate sensor position was obtained by finite element method,and the force at the center of the engine mount,front wheel,middle wheel and rear wheel was obtained based on the inverse matrix principle.Finally,the dynamic response of the model under test conditions was calculated and analyzed,and compared with the test results.The dynamic responses of the steering wheel and seat frame were calculated by finite element method with the center force of the powertrain mount under the condition of 600r/min idle and the center forces of the front wheel,middle wheel and rear wheel under the constant driving speed of 60km/h as the excitation inputs for the CAE model of the whole vehicle,and the results were compared with the test results.The results showed that the response was in good accordance with the test results in frequency.But the response amplitude varies greatly because the stiffness and damping of various bushings in the cab are not accurate in the CAE model.Through the CAE calculation of NVH characteristics and dynamic responses based on finite element method,and the comparative analysis with the test results,the NVH problem in the developmentof the heavy truck cab of the enterprise is well solved.The results show that the research method and process have practical guiding significance for correcting CAE model and solving engineering problems.