发动机油底壳的低噪声结构设计

对某铸铝油底壳进行有限元建模，计算其自由模态，并采用有限元法和边界元法相结合的方法对其进行振动和表面辐射噪声的预测计算，得到其表面振动速度和总声功率级。对原油底壳侧面大面积平板部位进行加筋，在底部进行形状上的修改，并预测改进后结构的振动和辐射噪声水平。通过改进前后的对比表明：结构改进后自由模态频率有很大的提高，振型也有显著变化，振动幅值有所降低，总噪声水平降低3.1 dB。

Low-noise Design for Engine Oil Pan

The FE model for a cast aluminum?oil pan was built. The modals of free vibration, the surface vibration and radiation noise if the pan were calculated using the combination of FEM and BEM method. The surface vibration velocity and the total sound power level were obtained. Then, the side face of the oil pan was reinforced and the shape of its bottom was improved, and the levels of structure vibration and radiation noise of the oil pan were predicted. The results were compared with those of the original pan. It is found that after the improvement, the frequency of free vibration is greatly increased, the vibration mode also changes obviously, the vibration amplitude is decreased, and the total sound power level is reduced by 3.1 dB.