Stress Perturbations Caused by Longitudinal Stress Gauges

摘要

In general, the diagnostics used to evaluate the shock state parameters in samples loaded by stress waves perturb the fields they are measuring. For example the insulating layers in which stress gauges have to be mounted in a conducting sample usually result in impedance mismatched interfaces. Similarly, velocity interferometry inevitable requires the wave to interact with a mismatch interface. In such situations wavelets generated by the parts of the wave that arrive early at the mismatch interface reflect back into the sample and interfere with the later-arriving parts of the wave. In principle, high resolution hydrocodes may be used to compute, and thereby potentially, take account of, the perturbations caused by intrusive diagnostics. For example Winter and Harris computed the perturbing effect of lateral stress gauges [1] and Huang and Assay [2] computed the effect of a mismatch boundary on velocimetry records. The confidence with which fine-mesh hydrocodes may be used to correct diagnostic records to their "in-situ" wave forms depends, of course, on the accuracy of the codes which, in turn, depends on factors such as the mesh size used and on the constitutive models of the materials in the configuration under investigation.