Gauge sensitivity indices for vehicle body structure assessment and optimisation

Reducing the weight of the primary structure in vehicles is an effective way to improve fuel efficiency and kinematic performance. The most direct approach to achieve such reductions is to decrease the thickness, or gauge, of the vehicle sheet metal stock. This article describes the development of numerical indices for assessing the sensitivity of vehicle body structure architectures to changes in noise, vibration and harshness (NVH) characteristics associated with thickness changes resulting from either same material down-gauging or material substitutions. A rigorous mathematical analysis is used to derive relationships between the indices and NVH parameters, such as structural stiffness and fundamental natural frequencies of critical deformation modes. The derivation also suggests algorithms for computational implementation. The work concludes with a series of validation case studies illustrating application and interpretation of the gauge sensitivity indices.