Active doublet method for measuring small changes in physical properties
US5369997A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 1993 |
| Grant date | Dec 6, 1994 |
| Priority date | — |
| Expiry date | Jan 4, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/02827
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Small changes in material properties of a work piece are detected by measuring small changes in elastic wave velocity and attenuation within a work piece. Active, repeatable source generate coda wave responses from a work piece, where the coda wave responses are temporally displaced. By analyzing progressive relative phase and amplitude changes between the coda wave responses as a function of elapsed time, accurate determinations of velocity and attenuation changes are made. Thus, a small change in velocity occurring within a sample region during the time periods between excitation origin times (herein called "doublets") will produce a relative delay that changes with elapsed time over some portion of the scattered waves. This trend of changing delay is easier to detect than an isolated delay based on a single arrival and provides a direct measure of elastic wave velocity changes arising from changed material properties of the work piece.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.