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Title: Method and apparatus for determining material structural integrity

A non-destructive method and apparatus for determining the structural integrity of materials by combining laser vibrometry with damping analysis techniques to determine the damping loss factor of a material. The method comprises the steps of vibrating the area being tested over a known frequency range and measuring vibrational force and velocity as a function of time over the known frequency range. Vibrational velocity is preferably measured by a laser vibrometer. Measurement of the vibrational force depends on the vibration method. If an electromagnetic coil is used to vibrate a magnet secured to the area being tested, then the vibrational force is determined by the amount of coil current used in vibrating the magnet. If a reciprocating transducer is used to vibrate a magnet secured to the area being tested, then the vibrational force is determined by a force gauge in the reciprocating transducer. Using known vibrational analysis methods, a plot of the drive point mobility of the material over the preselected frequency range is generated from the vibrational force and velocity measurements. The damping loss factor is derived from a plot of the drive point mobility over the preselected frequency range using the resonance dwell method and compared with amore » reference damping loss factor for structural integrity evaluation.« less
Inventors:
 [1]
  1. (Aiken, SC)
Issue Date:
OSTI Identifier:
870432
Assignee:
United States of America as represented by United States (Washington, DC) SRS
Patent Number(s):
US 5520052
Contract Number:
AC09-89SR18035
Research Org:
WESTINGHOUSE SAVANNAH RIVER CO
Country of Publication:
United States
Language:
English
Subject:
method; apparatus; determining; material; structural; integrity; non-destructive; materials; combining; laser; vibrometry; damping; analysis; techniques; determine; loss; factor; comprises; steps; vibrating; tested; frequency; range; measuring; vibrational; force; velocity; function; time; preferably; measured; vibrometer; measurement; depends; vibration; electromagnetic; coil; vibrate; magnet; secured; determined; amount; current; reciprocating; transducer; gauge; methods; plot; drive; mobility; preselected; generated; measurements; derived; resonance; dwell; compared; reference; evaluation; selected frequency; analysis techniques; analysis methods; magnetic coil; method comprises; frequency range; structural integrity; velocity measurements; analysis method; method comprise; non-destructive method; analysis technique; loss factor; electromagnetic coil; velocity measurement; integrity evaluation; determining material; /73/