Method, system, device and medium for online monitoring of plane stress field without baseline data based on piezoelectric transducer array

Patent metadata

Field	Value
Publication number	US-12203818-B2
Application number	US-202217704090-A
Country	US
Kind code	B2
Filing date	Mar 25, 2022
Priority date	Jan 19, 2022
Publication date	Jan 21, 2025
Grant date	Jan 21, 2025

Abstract

The disclosure provides a method, system, device and medium for online monitoring of a plane stress field without baseline data based on a piezoelectric transducer array. Since Lamb waves have complex multi-mode characteristics, a suitable excitation frequency needs to be selected according to geometric dimensions of the structure to be measured, and then, only low-order mode Lamb waves are excited inside the measured structure to avoid serious waveform aliasing. For isotropic measured objects, anisotropic characteristics will be generated under the action of pre-stresses, that is, the propagation velocities of ultrasonic waves in all directions are different, but there is a linear relationship between velocity changes in different propagation directions and stresses. Therefore, there is still a linear relationship between the difference of velocity changes in different propagation directions and the stress. According to this characteristic, a characterization method of an absolute stress field without baseline data can be implemented. The method of the disclosure can make full use of the low attenuation characteristics of the Lamb waves to realize online monitoring of the plane stress field with a large coverage area.

First claim

What is claimed is:

1. A method for online monitoring of a plane stress field without baseline data, based on a piezoelectric transducer array, comprising:
according to geometric dimensions and material parameters of a measured object, establishing a dispersion curve of Lamb waves, determining a cut-off frequency of a first-order Lamb wave mode, then selecting a suitable frequency within the cut-off frequency to excite piezoelectric wafers, and generating pure S0-mode Lamb waves by means of symmetrical excitation;
according to the invariant property of acoustoelastic coefficients of isotropic materials in different coordinate systems, obtaining acoustoelastic equations in different propagation directions, then calculating a difference to obtain a linear relationship between a difference of velocity changes in different directions and stress, and at the same time, according to a linear superposition relationship between stresses in different directions, calculating a magnitude of a plane stress field of the measured object through a difference of three groups of velocity changes in different directions, thereby finally realizing characterization of the plane stress field by means of measurement results of the piezoelectric transducer array in different directions; and
exciting and receiving Lamb wave signals inside the measured object, performing Hilbert transform on the received signals, extracting signal envelopes, then calculating acoustic time differences in different propagation directions through a cross-correlation algorithm, according to a linear relationship between acoustic time differences and velocity differences, determining that there is still a linear relationship between stresses and acoustic time differences in different propagation directions, and then, substituting three groups of acoustic time differences in different directions into pre-calibrated acoustoelastic equations to solve the plane stress field of the measured object.

2. The method according to claim 1 , wherein according to the geometric dimensions and the material parameters of the measured object, the dispersion curve of Lamb waves is established, and a Lamb wave dispersion equation of a free plate is a Rayleigh-Lamb wave dispersion equation, which meets:

tan
⁡
(
qh
)

tan
⁡
(
ph
)

=

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⁢

k
2

⁢
pq

(

q
2

-

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)

2

,

(
1
)

tan
⁡
(
qh
)

tan
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(
ph
)

=

-

(

q
2

-

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⁢

k
2

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pq

,

(
2
)

wherein p and q are respectively expressed as:

p
=

ω
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c
L
2

-

k
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,

(
3
)

q
=

ω
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c
T
2

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k
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Assignees

• Harbin Inst Technology

Inventors

• Shi Weijia
• Zhao Bo
• Tan Jiubin

Classifications

• G01N2203/0676

  Force, weight, load, energy, speed or acceleration · CPC title

• G01N2203/0017

  Tensile · CPC title

• G01M5/0066

  by exciting or detecting vibration or acceleration (vibration testing of structures G01M7/00) · CPC title

• G01N29/44

  Processing the detected response signal {, e.g. electronic circuits specially adapted therefor (digital signal processing per se G06F17/00)} · CPC title

• G01N2203/0003

  Steady · CPC title