Validation of Vehicle NVH Performance using Experimental Modal Testing and In-Vehicle Dynamic Measurements 2007-01-2320
NVH targets for future vehicles are often defined by utilizing a competitive benchmarking vehicle in conjunction with an existing production and/or reference vehicle. Mode management of full vehicle modes is one of the most effective and significant NVH strategies to achieve such targets. NVH dynamic characteristics of a full vehicle can be assessed and quantified through experimental modal testing for determination of global body mode resonance frequency, damping property, and mode shape. Major body modes identified from full vehicle modal testing are primarily dominated by the vehicle's body-in-white structure. Therefore, an estimate of BIW modes from full vehicle modes becomes essential, when only full vehicle modes from experimental modal testing exist. Establishing BIW targets for future vehicles confines the fundamental NVH behavior of the full vehicle. In addition to vehicle body structure, the tire/wheel assembly, suspension, and chassis system affect overall on-road NVH performance of the vehicle. Understanding body acoustic and tactile sensitivity from various suspension and chassis attachment locations, and utilizing standardized NVH load cases under vehicle operating conditions, also benefit full vehicle NVH development. This paper presents modal test results of various vehicle body structures at the fully trimmed and body-in-white configurations. Global body mode correlation between the two configurations is established, and the scatter band of the resonance frequency ratio between the two identified. In-vehicle NVH standardized test results are also presented to demonstrate the dynamic interaction of the vehicle to body structure modal behavior.