Spectral-based multicoordinate substructuring model for vehicle noise, vibration, and harshness refinement

Abstract

The success of vehicle NVH (noise, vibration, and harshness) refinement often depends on the ability to identify and understand noise and vibration transmission paths within the mid-frequency range, i.e., 200–1000 Hz, throughout the assembled structure. Due to the complexity of the dynamics in this frequency range, most modal or finite element-based methods do not possess the fidelity needed. To address this gap, a multicoordinate substructuring theory applying measured structural-acoustic and vibration spectra is applied. Three forms of substructuring formulation, namely the nondiagonal, block-diagonal, and purely diagonal coupling cases, are developed. The performances of these approaches are studied numerically, and the net effects of these coupling formulations on the predicted joint and free substructure dynamic characteristics, and system response, are determined. Conditions for applying the simpler coupler that can simplify the testing process and overcome computational deficiencies are also derived. When the measured data is noise contaminated, the singular value decomposition (SVD) algorithm is found to be quite helpful. Using an actual vehicle, a comprehensive analysis of the measured and predicted vehicle system responses is performed. The results are employed to develop an understanding of the primary controlling factors and transfer paths and to cascade system requirements to the substructure level.