Research on Acoustic-structure Coupled Modal Test Based on PolyMAX

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Journal of Vibration and Shock ›› 2013, Vol. 32 ›› Issue (2) : 158-163.

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Research on Acoustic-structure Coupled Modal Test Based on PolyMAX

Yunkai Gao1， Haixing Feng1， Fangwu Ma2

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Abstract

Modal frequencies and modal shapes of the BIW (body-in-white) reflect the inherent characteristics of the automotive body. It has an important influence on the interior noise. The car cavity also has modal frequencies and modal shapes. Acoustic modal experiment of the car cavity on a domestic SUV is carried out by LMS data acquisition system. Firstly, response points’ signals are gained by microphone array, and then acoustic modal frequencies and modal shapes are extracted by PolyMAX method. The compare between the acoustic modal frequencies and the experimental modal frequencies of the BIW implies that the first and the second acoustic modal of the car cavity strongly coupled with the fourth and the tenth structure modal of the BIW. Finally, acoustic resonance is verified through the test during the vehicle running. There are several ways to change the local modal of the automotive structure, such as increasing the thickness of the key components, adding damping layer in the roof and floor, and strengthening the roof with ribs and so on. That these actions can destroy the strong coupling between the modal of the BIW and the acoustic modal of the car cavity, decrease the low frequency boom in the automotive.

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PolyMAX / Acoustic-structure coupled modal / Modal Experiment / NVH

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Yunkai Gao;Haixing Feng;Fangwu Ma. Research on Acoustic-structure Coupled Modal Test Based on PolyMAX[J]. Journal of Vibration and Shock, 2013, 32(2): 158-163