Active doublet method for measuring small changes in physical properties

Patent · Sat Jan 01 00:00:00 EST 1994

OSTI ID:869629

Roberts, Peter M ^[1]; Fehler, Michael C ^[1]; Johnson, Paul A ^[2]; Phillips, W Scott ^[2]

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1. Los Alamos, NM
2. Santa Fe, NM

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.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 5369997
• OSTI ID: 869629
• Country of Publication: United States
• Language: English

Related Subjects

active
doublet
method
measuring
changes
physical
properties
material
piece
detected
elastic
wave
velocity
attenuation
repeatable
source
generate
coda
responses
temporally
displaced
analyzing
progressive
relative
phase
amplitude
function
elapsed
time
accurate
determinations
change
occurring
sample
region
periods
excitation
origin
times
called
doublets
produce
delay
portion
scattered
waves
trend
changing
easier
detect
isolated
based
single
arrival
provides
direct
measure
arising
changed
elapsed time
relative phase
physical properties
time period
material properties
time periods
wave velocity
accurate determination
elastic wave
direct measure
source generate
delay based
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