Gauge sensitivity indices and application for assessing vehicle body structural stiffness

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Gauge sensitivity indices and application for assessing vehicle body structural stiffness

Zhang, Shengyong / Prater, Glen

Gauge sensitivity indices are a family of techniques for assessing the effect of thickness changes on automotive structural performance. They are particularly well suited to investigate the effect of material substitution or same material re-gauging upon vehicle body structures' NVH parameters. The gauge sensitivity result in Patton and Edwards (2002) and Prater et al. (2009) was based on a hypothetical twin-flange cantilever beam with negligible web elements. The assumption of negligible web in a beam is quite restrictive. This paper demonstrates gauge sensitivity results through a series of example cases with complex sections and different loading conditions, including flanged I-beam, general flanged beam, closed hat beam, hollow circular shaft and axially loaded members. It has been proved that structural gauge sensitivity values are always greater than or equal to unity. The specific and useful physical interpretation for gauge sensitivity indices is addressed for evaluating structural efficiency. Fundamentally, gauge sensitivity is a measure of the non-uniformity of the internal load distribution, with greater non-uniformities corresponding to higher gauge sensitivity values. The validation case study illustrates that architecture changes that decrease the non-uniformity of the internal load distribution will reduce gauge sensitivity and thus increase stiffness-to-weight ratio. In the application study, gauge sensitivity has been applied to predict changes in the stiffness of a light-duty truck cab over a range of steel gauge modifications. The prediction accuracy has been validated by FEA-based results.