Piezoresistance response of ytterbium foil gauges shocked to 45 kbar in fused silica matrix

• Published in: Journal of applied physics 1987-02, Vol.61 (4), p.1304-1310
• Main Authors: BRAR, N. S, GUPTA, Y. M
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical instruments, equipment and techniques; Physics
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.338108

Resistance change at peak stress and the residual resistance change of ytterbium foil gauges embedded at different depths in fused silica matrix were determined under shock loading to a stress of 45 kbar. The results show that for a given peak stress, the gauge response was unchanged for an order of magnitude variation (103–104 kbar/μs) in the loading rate. Measured resistance change at peak stress and upon unloading agree very well with the analytic model calculations for stresses up to 30 kbar in the fused silica. Peak resistance change values in the present work have been reconciled with earlier ytterbium data in a polymethylmethacrylate (PMMA) matrix on the basis of differences in longitudinal stress in the gauge foils for the two materials (polymethylmethacrylate and fused silica) and differences in the electromechanical constants of the two sets of foils. Above 30 kbar stress in the fused silica, measured resistance values are lower than the calculated values. This difference is attributed to changes in the ytterbium as a result of the initiation of the fcc to bcc phase transition. The resistance change-time profile from the 45-kbar experiment shows a strongly time-dependent behavior suggesting that a significant fraction of the material has been transformed.