Development In Commercial Vehicle Frame System Of Vibration Reduction Model

With the living standard rising, people have put forward higher requ irement for the riding comfort. At the same time, the goods transport quality(mainly for commercial trucks) has become an important reference index for consumers to purchase automobiles. Therefore, the vibration problem is unavoidable in the vehicle development process. As the important base of the full vehicle, frame is the installation base of powertrain, body, container and suspension parts,and undertake the various static and dynamic loads. Thus, the vibration characteristics of the frame system would have a significant impact on the vibration of the full vehicle system.However, There are several issues in the research of model vibration:(1)Th e frame is assumed to be rigid,and the flexibility of frame is neglected.(2)The research on frame model characteristics is just from the angle of the sepa rated subsystems, and the coupling relationship among subsystems is rarely considered.(3)The frame model is commonly analyzed by commercial finite element software. Although the flexibility is considered, a huge number of degrees of freedom of the frame m odel could cause lower computational efficiency and higher computer memory requirements.Because of �the frame should be regarded as flexible body�, �frame model and other sub components constitute frame system�, �less freedom model�, �high computational efficiency� and other strict demands for computational model, it is necessary to use model reduction method and other key technologies, not only to make the model has fewer degrees of freedom but also retain structures more flexible characteristics. In this case, the precise reduced frame model which has the same modal characteristics of the original model would be established.With a large enterprise horizontal topic research support, called "Research on the method of establishing a vehicle vibration model based on the model reduction", considering the frame system of the truck model as the research object, modal analysis and dynamic response analysis based on the theory and methods of model reduction would be conducted. According to the modal validation cri teria, the reduced model precision could be verified, optimized and improved, and then a set of high efficiency and high precision theory and method of model reduction would be put forward. The main research contents are as follows:1. To complete model reduction method selection,the stiffness matrix and mass matrix extraction, the master nodes selection, modal frequencies reservation, solving large-scale matrix and numerical example verification. Compare the accuracy of Guyan, IRS and other model reduction methods, using model validation criteria to ensure that the reduced model has a high degree of approximation;2. To establish the finite element model of the frame, including the choice of element type, the grid division and model processing etc;3. To perform the reduced frame systems modal analysis, and compare modal parameters before and after model reduction, and use modality validation guidelines to verify the accuracy of model reduction, and study the influence of the number of master degrees of freedom selection on the reduced model precision;4. To perform the reduced frame system dynamic response analysis, and get the response of goods support node and the body rear suspension node,and use average gray correlation coefficient to verify the accuracy of reduced model.