Study On Technology Of Car Body Modeling About Dynamic Analysis

With the development of the automobile industry, the demand for automobile's comfortableness by the consumers is increasing. The automobile body dynamic response characteristic research become the important field of FEM (finite element method), and the important content of analysis and design of new car. The influence of the technology about building finite element model for the automobile dynamic analysis are studied in this article, and build the car body adapt to dynamic analysis. On the basis of car body, conduct harmonic response analysis on the car body and sound field. The main research content is as follows:(1) The finite element method is applied to the typical connecting way–welded spots which have important influence on the automobile body dynamic character. Build five kinds of finite element model, through the contrast of analytic modal and experimental modal, considering the accurate rate of the analysis and the time expended on building model, it is suggested that mpc184 element is adopted to simulate welded-spots. In order to reduce the work of manual building welded-spots, introduce the APDL (ANSYS Parameter Design Language) to realize the automation in the ANSYS software.(2) On the basis of the building finite body researches on ban and the door, put more attentions on the building finite car body model, including choice of element type, control of element size, simplification method of typical characteristic and so on. The analytic result of BIW (body in white) accord with the experimental result well, which shows the car finite element model can satisfy the precision in dynamic analysis.(3) On the basis of BIW, put on engine inspirit at the eight join point of engine and BIW, analyze the syntonic computation, compute the vibration displacement on all frequency under constraint, get the frequency at vibration peak and the maximal swing of eight measure point, which provide the ground for reducing vibration design.(4) Build the structure-acoustic coupling finite element model, and analyze the car compartment acoustic frequency response of coupling model by the stimulation of the engine and suspension. The result show that under 120Hz, the noise level of the four measure point are below, above 120Hz, noise level increase obviously. The coupling model is stimulated by the engine and suspension respectively, compared with the result stimulated by both engine and suspension, which show the engine's contribution to noise level is higher, and above 120 Hz, noise level change little by suspension stimulation, but noise level increase obviously by engine stimulation.Through this article research, gain a series of method and guide line about building the finite element car body model, including the simulative method of welded spots, automatic building and simplification of BIW structure and so on. Through the application on the typical vehicle and test validation, show that these methods can improve veracity the model, which provide the ground for positive design of the automobile body structure and the optimization design.