Vehicle-to-Vehicle NVH Performance Variance

The effect of vehicle-to-vehicle variance on a comprehensive set of NVH performance measures is investigated. A complete experimental assessment of full vehicle NVH performance is often limited to a single vehicle due to test complexity, vehicle availability, and/or program timing constraints. However vehicle-to-vehicle performance variation is inherently present due to factors such as manufacturing variability, nonlinear response of component systems, and component mode coupling with vehicle structure. In past studies, NVH variability was investigated utilizing sample sizes up to one hundred vehicles but on a limited set of localized NVH input/response characteristics [1]. In this paper, the statistical sample size is reduced to five vehicles in order to study vehicle-to-vehicle variance on a more comprehensive set of NVH performance measures: structural modal and operational response. Modal response is evaluated at both the global vehicle and component levels. The variance in operational performance is evaluated both in vibration and acoustic response under road and powertrain inputs. The details of these test methodologies and results are presented. A discussion of recommended sample sizes for each test methodology is provided.