流固耦合对油底壳振-声特性的影响研究

对于复合钢板油底壳进行了自由模态、约束模态以及流固耦合下湿模态的计算与试验，较高的一致性表明耦合模型是合理的.模态对比结果说明当油底壳盛油后，模态振型出现了变化，且整体模态频率降低.使用最小二乘法拟合了盛油前后油底壳的瑞利阻尼比例系数.结果表明润滑油对于复合钢板油底壳的阻尼影响不大.采用多体动力学计算了耦合与非耦合油底壳的振动响应，在整体幅值和变化趋势上与试验值较接近.耦合模型的振动响应在整体上略低于非耦合模型，但500 Hz前的振动峰值更突出，尤其在330 Hz附近.耦合模型在峰值频率和趋势上与试验值吻合得更好.进一步通过边界元法计算了两种油底壳模型的辐射噪声，结果显示考虑耦合后油底壳辐射声功率在3 000 Hz内显著下降，仅在333 Hz处有较高的峰值. 

The Fluid-Structure Interaction Influence on the Vibro-Acoustic Characteristics of the Oil Pan

Calculations and experiments of free modes, constraint modes and wet modes were proceeded for a sandwich steel plate oil pan. Their well matching results show that, a coupled model is feasible. The comparison between coupled and uncoupled modes demonstrates that the modal shapes change and the entire modal frequencies decrease when taking the oil into account. The ordinary least square method was applied to fit the Rayleigh damping scale factors of the oil pan with and without oil, which indicated that the oil could hardly affect the damping of the sandwich steel plate oil pan. The vibration responses of coupled and uncoupled models calculated by multi-body dynamic method indicate that the entire acceleration amplitude is close to the experimental one as well as the variation trend. It is shown that the entire vibration of the coupled model is weaker, and is prominent below 500 Hz, especially in the vicinity of 330 Hz. Besides, the peak frequencies and the trend of the coupled model coincide with the experimental result much better. Furthermore, the comparison of the radiation noise calculated by the boundary element method demonstrates that an evident entire decline occurs after considering the oil in the range of 0~3 000 Hz except 333 Hz.