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Simulation and Experimental Research on Low-frequency Acoustics and Vibration Characteristics of Heavy Duty Commercial Vehicle Cab

Author: ZhangYunTao
Tutor: MaTianFei
School: Jilin University
Course: Vehicle Engineering
Keywords: All equipment cab Acoustics and vibration characteristics Fluid-Structure interaction Finite element Modal analysis
CLC: U467
Type: Master's thesis
Year: 2009
Downloads: 124
Quote: 1
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Abstract

Noise easily causes people to reduce the work efficiency, and seriously causes hearing loss. Noise problem in cab has always been difficult to the domestic and foreign scholars in the study, Reducing the noise level in cab as much as possible has become one of the objectives that must be completed in the conceptual design stage. Internal noise is usually caused by the vibration of the wall, so this paper takes a heavy commercial vehicle cab for the researching object and analyzes the characteristics of its sound and vibration, so that the noise level in cab can be reduced.The level of credibility of the results calculated by finite element analysis are directly related to the accuracy of the model. Therefore, to modify the finite element model through the sample tests to make it more in line with the actual structure of the model is an ideal method to get a high-precision model.This paper, basing on the body-in-white FEM、doors and the windshields of the heavy-duty commercial vehicle, applying software MSC.Nastran/Patran and Hyepermesh, established an all equipment cab FEM(body-in-white doors、glasses、trims、exterior parts、instrument panel、Vice dashboard、seats、pad)—Str_C_All.First of all, on the base of the interior cab Str_C_All, in the corresponding position of the suspension added the vertical stiffness and dampness of the real vehicle suspension system, the cab FEM with all trims and suspensions was established.Based on the all equipment cab FEM Str_C_All, with the exception of the establishment of the cavity in cab Cav_A, but also the cavity Cav_B between the larger parts of the trims and the body panel were also established . The cavity associated the last two cavities is Cav_Both.In addition, according to the principle of similar mode, by adjusting the thickness of the panel, the simplified interior trim panels of model were established.The trim panels、the seats、sleeper、the dashboard of the simplified model structure were established. On the basic of the simplified model Str_S,the simplified cab model Str_S with all trims was established.Based on the simplified cab model Str_S_All, the simplified cavity model Cav_S of the cab was established.According to compare the analysed results of the all equipment model with the suspensions with the experimental results, the modes and the the corresponding vibration picture are both similar. The accuracy of the all equipment cab FEM Str_C_All is verified.The modes of the all equipment cab without suspensions and the model with suspensions were computed. by comparing the two results, the elastomer formation modes and the corresponding vibration picture between the two models are similar, so the suspensions has little effect on the elastomer formation modes, but has a greater impact on the riding comfort.The models of the two cavity FEM—Cav_Both and Cav_A were analysed and results were compared. Due to the existence of the interlayer cavity, the models of Cav_Both increased, but the former 4-order modes are reduced less than 4Hz, it is limited.The models of the simplified all equipment cab FEM were computed,The results and the models of the detailed structure of the all equipment cab calculated were compared . By comparing the results, the accuracy of the simplified model of the entire interior cab is feasible.The modals of the simplify cavity FEM were analysed,and the results were compared with the experimental results, the error is less than 10 percent, so the accuracy of the cavity FEM is right.Finally, The simplified structure FEM Str_S_All and the simplify cavity FEM Cav_S were established, the structure’s vibration on low-frequency and the effective on high frequency between the cavity and the structure were also discussed.Since then, The establishment of the accurate all equipment cab FEM and the cavity FEM were based for the establishment of the Fluid-Structure interaction FEM and the acoustic response analysis.

Simulation and Experimental Research on Low-frequency Acoustics and Vibration Characteristics of Heavy Duty Commercial Vehicle Cab

Abstract

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