【摘要】 为了对车外噪声进行预测,提出一种基于统计能量分析(Statistical energy analysis,SEA)原理分析预测车外噪声的新方法,建立包含47个车身结构和车外声腔子系统的车外噪声分析预测SEA模型,采用理论计算方法确定各形状规则子系统的模态密度与内损耗因子,对车门等复杂车身结构子系统的模态密度与内损耗因子进行试验测试,计算线连接、面连接子系统间的耦合损耗因子。确定所研究车型55km/h的车速作为车外噪声预测的计算工况,通过试验测量动力总成悬置振动和路面随机输入对车身的激励,并在半消声室内对发动机舱辐射的声激励进行测试,建立被试轿车的计算流体动力学(Computational fluid dynamics,CFD)模型,对车外噪声预测工况下车身外表面的风压激励进行仿真计算。利用参数化及施加激励后的车外噪声SEA预测模型进行车外噪声的分析预测,并与试验结果进行对比,结果表明预测结果与试验结果间的差值小于2dB(A),相对误差小于2.7%,从而验证了所提出的车外噪声预测方法的有效性,该方法能够满足工程上在汽车产品开发设计阶段对车外噪声分析预测的要求。进一步分析不同截面形状的预测声腔及声腔厚度变化对车外噪声预测结果的影响。结果表明,随着预测声腔厚度的增大,声压级逐渐减小,不同截面形状的预测声腔对车外噪声预测结果影响较小。更多还原

【Abstract】 In order to predict the exterior noise of the car,a new method for exterior noise prediction based on statistical energy analysis(SEA) is proposed.A SEA model is built,including 47 body substructures and exterior acoustic cavities.The modal density and damping loss factor of the regular shaped subsystems are determined by using theoretical method,and the modal density and damping loss factor of the complex structure subsystems are measured.Meanwhile,the coupling loss factors between line junction and area junction subsystems are calculated.A uniform speed of 55 km/h is determined as the computational condition,and the excitations to car body caused by vibration of powertrain mounts and random input of the road.Meanwhile,the acoustic radiation excitation of engine cabin is measured in semi-anechoic chamber.The computational fluid dynamics(CFD) model of the car is built,and the wind excitation of the exterior surface of the car is computed.Then,the exterior noise is predicted by the SEA model with all of parameters and excitations,and the prediction result is compared with the experimentation result,which shows that the error of the prediction result is less than 2 dB(A),the relative error is less than 2.7%.The proposed method for exterior noise prediction is fully validated.And the prediction method also meets the requirements of exterior noise analysis and prediction in the development and design stage of car products.Furthermore,the effects of the prediction cavity with different section and changes of the thickness of the cavity on the exterior noise prediction are analyzed.The analysis result shows that the sound pressure level of the exterior noise gradually decreases along with the increase of thickness of prediction cavity,and the prediction cavity with different section has little effect on the exterior noise prediction of the car.更多还原