Engineering topics

Weidner, D. J.

Publications and source records attributed to Weidner, D. J..

3 records

DOE OSTI2020

Bulk modulus measurement at mHz frequencies and high-pressure using synchrotron x-ray radiation

We report an experimental protocol for measuring the frequency dependence of the bulk modulus carried out in a synchrotron x-ray facility based multi-anvil high-pressure apparatus. An oscillating pressure perturbation characterized by x-ray diffraction produces a volume strain measured by imaging. Together, these yield the bulk modulus of the sample. In this work, we report data at 3 mHz as an example of the possibility of providing these data for the frequency range of 1 mHz–100 mHz.

47 OTHER INSTRUMENTATION↗

DOE OSTI2020

Full waveform analysis for high pressure ultrasonic measurement

In this paper we report a data analysis protocol for ultrasonic velocity measurements carried out in a synchrotron x-ray facility based multi-anvil high-pressure apparatus. Synthetic ultrasonic signals for the time period between echoes from the two ends of the sample assembly are created with a few simple parameters as the echo waveform is modeled by the first echo from the anvil-assembly boundary. Each echo is modeled as a delta function with an amplitude and arrival time and convolved with this waveform. The final waveform, fit to the data, enables analysis of signals with overlapped echoes as they are common in small cell assemblies and high pressure.

47 OTHER INSTRUMENTATION↗

NASA NTRS1972

Elastic properties of alpha quartz and the alkali halides based on an interatomic force model.

A two-body central-force atomic model can be used to describe accurately the elastic properties of alpha quartz if the nontetrahedral O:O forces are included. The strength of the Si:O interaction has little effect on the bulk modulus. The technique is sufficiently general to allow calculations of the elastic properties of a specified structure under arbitrary pressure from a complete description of the interatomic forces. The elastic constants for the NaCl structure and the CsCl structure are examined. Our model includes two-body, central, anion-anion, anion-cation, and electrostatic interactions.

Weidner, D. J.↗