Method for real-time inspection of structural components

Patent metadata

Field	Value
Publication number	US-11022429-B2
Application number	US-201816219581-A
Country	US
Kind code	B2
Filing date	Dec 13, 2018
Priority date	Dec 18, 2017
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A multi-mode approach for real-time inspection of structural components may be applied to rapid, wide area measurement of thickness of thick plate-like structures using full-field multi-mode response measurement and analysis. The approach may allow estimation of thickness from full-field multi-mode response to single-tone ultrasonic excitation in thick plates. The approach may utilize wavenumber information across all available wave modes in order to make wavenumber spectroscopy sensitive to changes in thickness for a broader range of nominal initial thicknesses.

First claim

What is claimed is:

1. A method of determining a thickness of a structure, the method comprising:
(a) exciting the structure using one or more single-tone ultrasonic signals;
(b) measuring a resulting steady-state multi-mode response in the structure;
(c) producing transformed data corresponding to a two-dimensional Fourier representation of measurement data obtained from step (b);
(d) extracting a one-dimensional summary of wavenumbers from the transformed data;
(e) forming a set of one-dimensional templates corresponding to a set of possible thicknesses, wherein each one-dimensional template represents an expected one-dimensional summary of theoretical wavenumbers computed for the structure having one of the set of possible thicknesses, each theoretical wavenumber corresponding to an individual wave mode of a mechanical wave propagating through the structure having one of the set of possible thicknesses; and
(f) extracting a best estimate of the thickness of the structure from a selected one-dimensional template in the set of one-dimensional templates, the selected one-dimensional template determined to fit the one-dimensional summary of wavenumbers better than any other one-dimensional template in the set of one-dimensional templates.

2. The method of claim 1 , wherein the structure is a plate.

3. The method of claim 1 , wherein the structure is excited in step (a) using one or more of an ultrasonic transducer and a pulse laser.

4. The method of claim 3 further comprising performing a post-processing on the measurement data, the post-processing including making a correction for a measured angle of incidence of a laser beam corresponding to the scanning laser-Doppler vibrometer.

5. The method of claim 1 , wherein the resulting steady-state multi-mode response is measured using one or more of a scanning laser-Doppler vibrometer and a transducer.

6. The method of claim 5 , wherein the one-dimensional summary includes the transformed data corresponding to a single angle in the polar coordinates.

7. The method of claim 5 , wherein the one-dimensional summary includes an average of the transformed data over a prescribed set of angles in the polar coordinates.

8. The method of claim 5 , wherein the one-dimensional summary includes the transformed data corresponding to an angle in which the Fourier representation of the data carries the maximum energy.

9. The method of claim 5 , wherein the one-dimensional summary includes the transformed data, where a prescribed norm is applied to the transformed data with respect to an angle in the polar coordinates.

10. The method of claim 1 , wherein the two-dimensional Fourier representation of the measurement data is produced in polar coordinates.

11. A method of determining a thickness of a structure, the method comprising:
(a) receiving measurement data obtained from a measurement of a steady steady-state multi-mode response resulting from an excitation of the structure using one or more single-tone ultrasonic signals;
(b) producing transformed data corresponding to a two-dimensional Fourier representation of the measurement data;
(c) extracting a one-dimensional summary of wavenumbers from the transformed data;
(d) forming a set of one-dimensional templates corresponding to a set of possible thicknesses, wherein each one-dimensional template represents an expected one-dimensional summary of theoretical wavenumbers computed for the structure having one of the set of possible thicknesses, each theoretical wavenumber corresponding to an individual wave mode of a mechanical wave propagating through the structure having one of the set of possible thicknesses; and
(e) extracting a best estimate of a thickness of the structure from a selected one-dimensional template in the set of one-dimensional templates, the selected one-dimensional template determined to fit the one-dimensional summary of wavenumbers better than any other one-dimensional templates in the set of one-dimensional templates.

12. The method of claim 11 , wherein the theoretical wavenumbers are computed using Rayleigh-Lamb equations.

13. The method of claim 11 , further comprising estimating at least one unknown parameter for the set of one-dimensional templates, such that a given one-dimensional template best fits the one-dimensional summary.

14. The method of claim 13 , wherein the at least one unknown parameter comprises a relative mode amplitude.

15. The method of claim 13 , wherein a best fit is based on one or more of a least squares or maximum likelihood fitting scheme.

16. The method of claim 11 , wherein the selected one-dimensional template is determined to fit the one-dimensional summary of wavenumbers better than any other one-dimensional template in the set of one-dimensional templates based on estimation of relative mode amplitudes of the template and the summary.

17. A system configured to determine a thickness of a structure, the system comprising:
electronic storage; and
one or more physical computer processors configured by machine-readable instructions to:
(a) receive, from the electronic storage, measurement data obtained from a measurement of a steady steady-state multi-mode response resulting from an excitation of the structure using one or more single-tone ultrasonic signals;
(b) produce, using the one or more physical computer processors, transformed data corresponding to a two-dimensional Fourier representation of the measurement data;
(c) extract, using the one or more physical computer processors, a one-dimensional summary of wavenumbers from the transformed data;
(d) form, using the one or more physical computer processors, a set of one-dimensional templates corresponding to a set of possible thicknesses, wherein each one-dimensional template represents an expected one-dimensional summary of theoretical wavenumbers computed for the structure having one of the set of possible thicknesses, each theoretical wavenumber corresponding to an individual wave mode of a mechanical wave propagating through the structure having one of the set of possible thicknesses; and
(e) extract, using the one or more physical computer processors, a best estimate of a thickness of the structure from a selected one-dimensional template in the set of one-dimensional templates, the selected one-dimensional template determined to fit the one-dimensional summary of wavenumbers better than any other one-dimensional templates in the set of one-dimensional templates.

18. The system of claim 17 , wherein the structure is a plate that is thicker than 10 MHz-μm.

19. The system of claim 17 , wherein the theoretical wavenumbers are computed using Rayleigh-Lamb equations.

20. The system of claim 17 , wherein the one-dimensional summary includes an average of the transformed data over a prescribed set of angles.

Assignees

• Triad Nat Security Llc

Inventors

• Stull Nicholas D
• Flynn Eric Brian
• Mascarenas Matthew David

Classifications

• G01B11/0666 Primary

  using an exciting beam and a detection beam including surface acoustic waves [SAW] · CPC title

• G01B9/02084

  Processing in the Fourier or frequency domain when not imaged in the frequency domain · CPC title