Research On The Improvement Of Vibration Characteristics For The Non-Integral Type SUV Cab

Non-integral structure is an important bearing form in the commercial vehicles and passenger cars, such as the non-integral SUV. In terms of vehicle performance, the non-integral SUV has strong torsional and shock resistance. However, due to the existence of chassis frame and cab mounting, the transmission path from engine to cab becomes more complex, which increases the difficulty to study the vibration characteristics of cab. Although there is lots of research in this area on commercial vehicles, there is few on non-integral SUV. Therefore a systematic methodology should be established.Based on the “engine-powertrain mounting system-car frame-cab mounting system-car body-seat track”, aiming at a more systematic analysis and comprehensive improvement of non-integral SUV’s cab vibration characteristics, the paper presents a method named BTP(B: optimization design of car-body, car-frame structure modal&cab mounting; T:specific transmission path; P: optimization design of powertrain mounting system) considering various aspects of the transfer path. For each component module system of the proposed method, the paper discusses the physical meaning of the transfer function, the method to calculate modal frequencies and mode shapes and the principle of decoupling.The proposed method is applied to an instance of a non-integral SUV to verify its feasibility. In the car-body and car-frame transfer link, the technology roadmap of modal analysis and structural optimization is formulated, finite element models are established. The suspension points and incentive points are arranged according to the simulation results. The simulation and experimental results are compared to verify the model’s correctness. The dynamic characteristics are obtained.The thickness of BIW is optimized according to the frequency of coupling relationship between BIW, car frame and the engine idling vibration.The BTP method is applied to analyze the powertrain mounting system transfer link.The technology roadmap of mount bracket analysis and the analysis decoupling of mounting system are formulated After the establishment of the mount bracket’s finite element model, the stiffness and natural frequency are analyzed. After the establishment of the powertrain mounting system’s dynamic model and mathematical model, it is found that the decoupling of other directions do not meet the requirements in addition to the X and RYY direction’ modal kinetic. According to energy decoupling theory, the optimization model which aims to the maximum kinetic energy is established. Finally, based on the optimization results, a new powertrain mounting system is manufactured. The test of the cab vibration levels optimized before and after are conducted to carry out. By comparison of the data, the total vibration value of seat track has declined on different conditions. The isolation rate of each mount has been improved. The vibration value was reduced by 42.2% and 32.9% respectively when the engine speed is 1000 rpm and 2500 rpm. From what has been discussed above, it verifies the significant advantage of the systematic and practical of the proposed method.