Network wavefield imaging methods for quantification of complex discontinuity in plate-like structures

Patent metadata

Field	Value
Publication number	US-11199524-B2
Application number	US-201916432159-A
Country	US
Kind code	B2
Filing date	Jun 5, 2019
Priority date	Jun 19, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

Network wavefield imaging methods are able to image significantly complex discontinuities or shapes in plate-like structures for superior ultrasonic structural health monitoring (SHM)/nondestructive evaluation (NDE). The imaging provides high-resolution location, shape and/or size images of a structure, and for discontinuities with more complicated profiles. Guided wave (GW) network wavefield imaging methods combine tomography and wavefield/wavenumber imaging algorithms. Metallic plate damage detection uses guided ultrasonic waves and non-contact laser vibrometry. Guided waves are generated by piezoelectric transducers (PZT). A non-contact scanning laser Doppler vibrometer (SLDV) measures the full velocity plate guided wave wavefields. Developed network wavefield imaging algorithms account for multiple-actuator excitations from different angles enclosing the discontinuity, with algorithms using intrinsic wave characteristics such as wavefield, wavenumber, or reconstructed wave energy. Determined locations, sizes and shapes of highlighted areas in wavefield, wavenumber and/or filter reconstructed energy-based images correlate with location, size and shape of damage in metallic plates.

First claim

What is claimed is:

1. Methodology for structural health monitoring (SHM)/nondestructive evaluation (NDE) testing of a plate-like structure to detect discontinuities therein, comprising:
providing a plurality of guided ultrasonic wave actuators;
arranging said plurality of actuators to enclose a designated scanning area of a target plate structure to be checked for a potential discontinuity therein;
selectively exciting said actuators to produce guided waves in said structure to be tested;
measuring a wavefield v(t,x) of guided waves in said structure generated upon excitation of the respective plurality of actuators; and
creating a synthetic image based on such wavefield v(t,x), to detect a discontinuity in said plate structure within said scanning area,
wherein said synthetic image comprises wavefield and/or wavenumber information of damage induced waves for damage detection and quantification, and
wherein creating said synthetic image includes at least one of:
A:
determining the maximum absolute value of the waveform at each point x, by:
v mag ( x )=max(abs( v ( t,x )));

exciting each actuator in turn so that a corresponding plurality of wavefield data v i (t,x) are obtained for each actuator; and
creating data for said synthetic wavefield image through performing one of a summation, multiplication, and weighting factor synthesis of the wavefield data; or
B:
determining at least in part from said wavefield data a spatial wavenumber image at a selected frequency range as:

k
*

⁡

(

x
_

)

=

1
N

⁢

∑

i
=
1

N

⁢



k
*

⁡

(

x
_

,

f
i

)



;

where f i (i=1,2,3 ... N) is the selected frequency band centered at the desired frequency f 0 , which corresponds to the particular guided wave mode, for N number of actuators; and
creating data for said synthetic wavenumber image through performing one of a summation, multiplication, and weighting factor synthesis of the wavenumber image; or
C:
determining at least in part from said wavefield data a frequency wavenumber representation as:

v
⁡

(

f
,
k

)

=

∫

-
∞

∞

⁢

∫

-
∞

∞

⁢

v
⁡

(

t
,
x

)

⁢

e

-

j
⁡

(

2
⁢
π
⁢

⁢
ft

-

k
·
x

)

⁢
dtdx

⁢

;

conducting a filtering process on said frequency wavenumber representation to obtain a filtered spectrum as:
V F ( f,k )= V ( f,k ) F ( f,k );

determining waves corresponding to the filtered spectrum Vf F (f,k) as:

v
F

⁡

(

t
,
x

)

=

1

(

2
⁢
π

)

2

⁢

∫

-
∞

∞

⁢

∫

-
∞

∞

⁢

Assignees

• Univ South Carolina

Inventors

• Yu Lingyu
• Ma Zhaoyun
• Xiao Wenfeng
• Tian Zhenhua

Classifications

• G01N29/2412 Primary

  using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18) · CPC title

• G01N2291/0289

  Internal structure, e.g. defects, grain size, texture · CPC title

• G01N2291/2632

  flat · CPC title

• G01N2291/106

  one or more transducer arrays · CPC title

• G01N29/069 Primary

  Defect imaging, localisation and sizing using, e.g. time of flight diffraction [TOFD], synthetic aperture focusing technique [SAFT], Amplituden-Laufzeit-Ortskurven [ALOK] technique · CPC title