Surface Pressure Reconstruction in Shock Tube Tests Using the Virtual Fields Method

Abstract

This study investigates full-field, dynamic pressure reconstruction during shock-structure interactions using optical measurements and the virtual fields method (VFM). Shock wave impacts pose severe challenges to experimental measurement techniques due to the substantial, almost instantaneous pressure rises they induce. Their effects are typically measured pointwise using pressure transducers or as total force using load cells. Here, surface deformations were measured on the blind side of a flat steel plate in pure bending using a deflectometry setup. Pressure was reconstructed from the deformations induced by an impacting shock wave using a piecewise VFM approach. Different shock wave symmetries were used in order to investigate the capabilities of identifying spatial distributions reliably under the experimental conditions in the shock tube. Pointwise pressure transducer measurements allowed a validation of the results. It was found that different shapes of load distributions on the sample surface can be identified qualitatively, but that the comparability of both measurement techniques is limited due to filter and sampling capabilities.