Nondestructive ultrasonic testing of materials
AssigneeBattelle Memorial Institute
InventorBernard P. Hildebrand
Life of this patent
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Abstract
Reflection wave forms obtained from aged and unaged material samples can be compared in order to indicate trends toward age-related flaws. Statistical comparison of a large number of data points from such wave forms can indicate changes in the microstructure of the material due to aging. The process is useful for predicting when flaws may occur in structural elements of high risk structures such as nuclear power plants, airplanes, and bridges.
Claims10
A method of detecting changes in a material between a top surface and a bottom surface due to aging, comprising the steps of:
- (a) introducing an ultrasonic wave of a known frequency into a material to be tested prior to substantial aging of the material, such that a reflection wave form of the ultrasonic wave passing from one surface through the material to the other surface is generated and stored;
- (b) periodically passing an ultrasonic wave of the same frequency as in above from one surface through the material to the other surface at various periods of aging and retrieving and storing the reflection wave form of the ultrasonic wave passed through the aged material;
- and
- (c) statistically comparing the reflection wave form generated in (a) with the reflection wave form generated in (b) above in order to determine structural changes in the material.
A method of detecting changes in a material due to aging, comprising the steps of:
- (a) introducing an ultrasonic wave having a frequency of from about 1 to about 100 MHz into a material to be tested at a plurality of locations on the material, at a time prior to substantial aging of the material;
- (b) recording a reflection wave form of the ultrasonic wave at each of the plurality of locations;
- (c) introducing an ultrasonic wave of the same frequency as in (a) above into the same material at a time after aging of the material has occurred, and recording a reflection wave form of said wave;
- (d) statistically comparing the reflection wave form of (b) to the reflection wave form of (c) by
- (i) deflecting a minor portion of the reflection wave form in each of (a) and (b) above, between a front and back surface reflection for each of the plurality of locations,
- (ii) determining the peak signal in the minor portion of each of the plurality of locations, and
- (iii) comparing the peak signals of each of the plurality of locations to one another to determine changes in the peak signals for at least one period of aging of the material;
- and
- (e) detecting a difference in the reflection wave forms of steps (b) and (c) above by the statistical comparison of step (d), as an indication of changes in the structure of the material resulting from aging.
A method of nondestructive testing to predict changes in a material due to aging, comprising the steps of:
- (a) passing an ultrasonic wave of a known freuqency through an upper surface of the material to a lower surface of the material to be tested prior to substantial aging of the material, such that a reflection wave form of the ultrasonic wave passing through the material is generated and stored;
- (b) subjecting the material to enhanced aging conditions in order to accelerate the aging of the material;
- (c) periodically passing an ultrasonic wave through the material during the enhanced aging conditions at the same freuqency as in (a) above and retrieving and storing a reflection wave form of the ultrasonic wave;
- and
- (d) statistically comparing the reflection wave from generated in (a) and (c) in order to determine structural changes in the material prior to the formation of failurerelated flaws.
Dependencies are inferred from the claim text.