Investigation and Reduction of Road Noise due to transient road inputs in Electric Vehicle

Higher road noise is perceived in the cabin when the test vehicle encounters road irregularities like bump or pothole in the public roads. The sudden transfer of transient road inputs inside the body caused objectionable cabin noise. Measurements are conducted on the test track at different road surfaces to identify the patch where the objective data well correlated with the noise measured at the public road. Wavelet analysis is carried out to identify the frequency zones since the events are transient in nature. Transfer Path Analysis (TPA) is conducted in both time domain and frequency domain to identify the nature of the noise and the limitation in each of the methodologies are explained. The dominant path through which the transient road forces are transferring inside the body are also identified. Based on the outcome of TPA, various countermeasures like reduction of dynamic stiffness of suspension and cradle bushes , structural modifications on the path are proposed to reduce the structure borne noise and airborne noise. Criteria which need to be considered for reduction of cabin noise due to transient road inputs is also discussed.