Bus Interior Structure-Borne Noise Identification And Control Based On Transfer Path Analysis

Combining with the engine excitation under idling condition,the interior structure-borne noise of vehicle was calculated based on the FEM(finite element model)of the vehicle.The traditional TPA(transfer path analysis)was applied to diagnose the structure-borne noise problems,so as to deeply understand the transfer path of vibration and formation mechanism of structure-borne noise.It has important guiding significance for vibration and noise reduction work and is the basis of vibration and noise control.Firstly,the FEM of vehicle was established based on the finite element theory,including trimmed body system,cavity system,steering system,suspension system,powertrain system and transmission system.A physical prototype of the body-in-white was fabricated,and a modal test was carried out.The modal test result shows that the FEM of the body-in-white meets the application requirements.Secondly,the excitation of engine was calculated based on engine dynamics.At the same time,multi-body dynamics software was used to model the crank-link mechanism,and the excitation of engine was calculated under idling condition.The results show that the excitation obtained by multi-body analysis is consistent with the theoretical calculation,which offers a foundation for the analysis of interior structure-borne noise under idling condition.Then,the interior structure-bore noise was simulated based on the FEM of vehicle and the engine excitation under idling condition.The direct method was used to extract the working load.At the same time,the frequency response functions of the system can be easily obtained by numerical simulation method.Then the traditional TPA method was used to find the critical path with significant contribution to structure-borne noise.The critical path was decomposed into the noise transfer function and the working load to find the root causes of the structure-borne noise.Finally,the modal contribution of the critical path noise transfer function was analyzed,and the main structural modes which contribute a lot to the noise transfer function were found.The structure that affects these modes was found using the sensitivity analysis.The inter ior structure-borne noise was controlled by improving pertinently the body structure.