颗粒阻尼对封闭空腔内场点声压影响的试验研究

首次研究了颗粒阻尼对封闭空腔内场点声压的影响。通过推导声压的计算公式,揭示了声压与模态振型之间的联系。通过某轿车车身简化缩小模型的模态试验,研究了其模态振型的构成。并通过在此封闭空腔的低阶振型内相对位移较大的面上布置颗粒阻尼,降低了此封闭空腔内参考点的声压。结果显示,相比无颗粒阻尼,当颗粒阻尼安装于此封闭空腔的第一阶模态振型内相对位移较大的面上时,封闭空腔内参考点的A计权声压级降低程度最大,由104.56 d B降至101.03 d B,下降了约3.4%。

Experimental Study on Acoustic Pressure in the Enclosed CavityAffected by Particle Damping

Acoustic pressure in the enclosed cavity affected by particle damping was firstly studied. By inducing the formula of acoustic pressure, the contact between modal shapes and acoustic pressure was studied. The modal shapes of the enclosure cavity which is simplified and reduced proportionally from a vehicle body were analyzed by modal test. By equipping the board of which relative displacement is the maximum in lower-order modal shapes of the enclosure cavity with particle damping, the vibration of the lower-order modal is reduced. Then the acoustic pressure of the enclosure cavity is reduced. The results show that compared with none particle damping, the decrease of the A-weighted RMS acoustic pressure at the reference point in the enclosure cavity is the most, from 104.56dB to 101.03dB, decreased by 3.4% when particle damping was equipped on the board of which relative displacement is the maximum in first modal shape of the enclosure cavity.