Baseline method for structural vibration and noise optimization, partI: baseline sensitivity method

Abstract

This work investigates the availability of the baseline approach proposed in the previous researches, and expands the applicability of the method for noise and vibration optimization. Based on the s-plane extension theory, baseline was formed by introducing a virtual damping in the transfer function calculation formula. Sensitivity analysis based on baseline was conducted to predict the changing tendency by structure modification in the target frequency range. The validity of the proposed method is examined through numerical simulation with two finite element (FE) models. A simple hollow rectangular parallelepiped model was constructed for confirming the effect of baseline sensitivity analysis as a structural vibration reduction treatment. And a vehicle frame-panel structure was constructed for confirming the proposed method as a noise optimization example. In view of the model in discussion, the sum of squares sensitivity or root-mean-square sensitivity was calculated to determine the mass attachment location. The conventional sensitivity values using FRFs without virtual damping(FRF method) were also calculated for comparing with baseline sensitivity results. The FE models with mass attachment based on sensitivity analysis results were calculated for confirming the vibration reduction effects. The result shows that FRF method has a greater decrease at some single peak in the target frequency range, while the baseline method has a better reduction performance at multiple peaks in the target frequency range. The selection strategies of the two methods for the mass attachment location and the change of mode shape after mass attachment were discussed. The baseline sensitivity method presented in this study provides a feasible approach for noise and vibration performance improvement in the medium frequency band.