Determination of system vibratory response characteristics applying a spectral-based inverse sub-structuring approach. Part II: motor vehicle structures

The spectral-based inverse sub-structuring theory formulated in part 1 [1] is applied here to investigate the vibration transmissibility and frequency response characteristics of motor vehicle structures. Analysis assumes a vehicle model that comprised of two sub-structures representing the body and chassis/suspension. Measured structural-acoustic and vibration spectra acquired from a relatively direct experimental setup are utilized to compute the relevant force transmissibility and path contribution functions at the discrete coupling points. Furthermore, the free sub-structure response characteristics and mount dynamic stiffnesses are expressed directly in terms of coupled system responses. These studies are performed using four real-life vehicles. For each case, the constructed system response functions are shown to match well with experimental data. Comparisons of the results derived from these vehicle examples reveal useful relationships between coupled system responses, free sub-structure characteristics and coupling compliances.