Analysis Of Structure And Acoustic Characteristic For Heavy Commercial Vehicle Cab

Demands of heavy commercial vehicles especially large load, long distance, high-powered heavy-duty commercial vehicle have increased rapidly as a result of social and economic development. Cab noise and vibration not only impacted on the strength and fatigue life of the vehicles'body, but also affect driver's attention easily which could arose a wrong judgment. CAE methods was used in this paper to analyze the cab's structure characteristic and interior acoustic environment, in order to reduce the vibration level and improve the acoustic environment of the cab.The finite element model of the cab was set up by Hypermesh based on three-dimensional geometric model of the cab. This finite element model was imported into MSC.NASTRAN to complete the freedom modal analysis. The cab structure modal parameters (natural frequencies, damping ratio, mode shape, etc.) were obtained. It proved that the finite element model can be considered correct and accurate when compared with other cab's modal parameters.The strength and rigidity calculation of the cab based on two conditions is bending and torsion. It proved that the rigidity basically meet the requirements of static by comparing it with another cab's. By strength analysis we can find that the max stress is less than permit stress of the materials, so the cab wouldn't be destroyed. Fatigue life distribution under torsion condition gained and it proved that the fatigue life meets the requirement and modification proposals based on fatigue life of dangerous point was proposed to improve the fatigue life.The transient response of the simplified finite element model was analyzed; we can find peak frequencies that lead the vibration. The displacement of the outcome document was used as the boundary condition of the acoustic field analysis.Based on the platform of Sysnoise, the acoustic field modes of the acoustic model and the coupled modes of the acoustic-structure coupling model were analyzed. Compared with these two modes and its acoustic distribution, it showed that the structure couple has a great influence to the acoustic field. By calculating the acoustic pressure from the place of the driver'ears; we can understand the sound field distribution of the cab.BEM was used to calculate panel acoustic contribution of the cab. From the results of acoustic panel contribution, we can conclude that the main positive panel is floor panel. Finally, improvement on the thickness of floor has been made according to the former analysis and the result showed that the interior noise of the cab has been reduced.