Strain rate dependency in paratransit bus rollover

Abstract

This paper examines the effect of structural steel strain rate dependency on the outcome of the FDOT/ECE-R66 bus rollover test. Bending and impact tests were performed on structural tubing in order to evaluate strain rate dependency parameters. Several mesh densities were used to investigate the influence of mesh size on the final outcome of the analysis. Two strain rate dependency formulations, Cowper-Symonds and Johnson-Cook, were calibrated and then implemented in the finite element analysis of a paratransit bus rollover. Unlike strain rate effect on other types of impact such as the frontal crash, the results show that the strain rate has no significant effect on the FDOT/ECE-R66 rollover test. Therefore, the current approach used by researchers investigating bus rollovers, to validate finite element models based on quasi-static experiments, is well-grounded and the strain rate dependent effects may be ignored for the global deformation response in the ECE-R66 bus rollover.