A Microwave Damage Detection Method and System Based on Spatial Phase Difference

Abstract

The present invention discloses a microwave damage detection method and system based on spatial phase difference, which relates to the field of damage detection. The method includes obtaining the synthetic microwave signals at different detection unit positions of the object to be measured; determining the phase shift generated by the object to be measured on the microwave according to the synthetic microwave signals at different detection unit positions; and determining the damage position of the object to be measured according to the phase shift. The present invention can achieve high-precision detection of materials.

Description

Technical Field

[0001] The present invention relates to the field of damage detection, and particularly to a microwave damage detection method and system based on spatial phase difference. Background Art

[0002] Non-metallic materials such as glass fiber reinforced composites and polyethylene are widely used in various fields such as aerospace, navigation, construction, and medicine. With the further expansion of the application scope of non-metallic materials and the increasingly strict requirements for safety in their application fields, the detection of their damage and performance degradation has received more and more attention.

[0003] During this period, a large number of scholars at home and abroad have carried out in-depth research on the non-destructive testing of non-metallic materials. The testing technologies include ultrasonic testing technology, microwave testing technology, X-ray technology, and infrared thermal imaging testing technology, etc. Among various testing technologies, the ultrasonic testing technology and the microwave testing technology have higher testing efficiency and wider scope. Among them, microwave testing has been gradually well applied because of its portable equipment, simple operation, low maintenance cost, and can realize real-time and rapid detection, and is non-contact and does not require a coupling agent.

[0004] The influence of the damage of the object under test on the reflected wave includes the changes in the reflection intensity and phase. The change in the reflection intensity is usually relatively weak and is easily submerged by the transmitted signal in the transmission measurement. This detection method is also the currently commonly used detection method. In order to improve the detection sensitivity, it is necessary to obtain the phase signal. However, the currently used vector analyzers and the like realize phase analysis by accurately obtaining the entire microwave waveform, and there are problems such as complex system, large volume, and expensive equipment.

[0005] However, the current detection based on radiation intensity has the problem of low detection accuracy. Summary of the Invention

[0006] The purpose of the present invention is to provide a microwave damage detection method and system based on spatial phase difference, which can realize high-precision detection of materials.

[0007] To achieve the above purpose, the present invention provides the following solutions:

[0008] A microwave damage detection method based on spatial phase difference, comprising:

[0009] Obtaining the combined microwave signals at different detection unit positions of the object under test;

[0010] Determining the phase shift generated by the object under test on the microwave according to the combined microwave signals at different detection unit positions;

[0011] Determining the damage position of the object under test according to the phase shift.

[0012] Optionally, the phase shift generated by the object under test on the microwave is determined according to the synthesized microwave signals at different detector positions, specifically including:

[0013] Determine the squared amplitude of the synthesized microwave signal at the first detector position and the squared amplitude of the synthesized microwave signal at the second detector position according to the synthesized microwave signals at different detector positions;

[0014] Determine the phase shift generated by the object under test on the microwave according to the difference between the squared amplitude of the synthesized microwave signal at the first detector position and the squared amplitude of the synthesized microwave signal at the second detector position.

[0015] Optionally, the expression for the phase shift generated by the object under test on the microwave is:

[0016]

[0017] where ||S0||(t,z1) is the synthesized microwave signal at the first detector position, ||S0||(t,z2) is the synthesized microwave signal at the second detector position, Ae is the emission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, L is the position of the object under test, is the phase shift, z1 is the first detector position, z2 is the second detector position, and t is the time.

[0018] The present invention also provides a microwave damage detection system based on spatial phase difference, including:

[0019] An acquisition module for acquiring the synthesized microwave signals at different detector positions of the object under test;

[0020] A phase shift determination module for determining the phase shift generated by the object under test on the microwave according to the synthesized microwave signals at different detector positions;

[0021] A damage position determination module for determining the damage position of the object under test according to the phase shift.

[0022] Optionally, the phase shift determination module specifically includes:

[0023] An amplitude squared determination unit for determining the squared amplitude of the synthesized microwave signal at the first detector position and the squared amplitude of the synthesized microwave signal at the second detector position according to the synthesized microwave signals at different detector positions;

[0024] A phase shift determination unit for determining the phase shift generated by the object under test on the microwave according to the difference between the squared amplitude of the synthesized microwave signal at the first detector position and the squared amplitude of the synthesized microwave signal at the second detector position.

[0025] Optionally, the expression for the phase shift generated by the object under test on the microwave is:

[0026]

[0027] Among them, ||S0||(t, z1) is the synthesized microwave signal at the position of the first detection unit, ||S0||(t, z2) is the synthesized microwave signal at the position of the second detection unit, Ae is the transmission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, L is the position of the object to be measured, is the phase shift, z1 is the position of the first detection unit, z2 is the position of the second detection unit, and t is the time.

[0028] According to the specific embodiments provided by the present invention, the following technical effects are disclosed:

[0029] The present invention obtains the synthesized microwave signals at different detection unit positions of the object to be measured; determines the phase shift generated by the object to be measured on the microwave according to the synthesized microwave signals at different detection unit positions; and determines the damage position of the object to be measured according to the phase shift. By using microwaves to detect the object to be measured and determining the damage position of the object to be measured through the method of coherent wave difference, high-precision detection of materials can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 is the flow chart of the damage detection method provided by the present invention;

[0032] Figure 2 is the schematic structural diagram of the microwave detection device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0034] The purpose of the present invention is to provide a microwave damage detection method and system based on spatial phase difference, which can achieve high-precision detection of materials.

[0035] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] As Figure 1 shown, a microwave damage detection method based on spatial phase difference provided by the present invention includes:

[0037] Step 101: Obtain the synthesized microwave signals at different detection unit positions of the object to be measured.

[0038] As Figure 2 shown, a continuous microwave signal is emitted through the microwave signal. The object to be measured will generate a reflected wave. Multiple microwave detection units pick up the microwave detection signals. Since there are both transmitted waves and reflected waves in space, and the two waveforms have the same frequency; the signal read by the microwave detection unit is the signal after the interference of two coherent waves. The signal after the interference of the two coherent waves in the present invention refers to the synthesized microwave signal. The microwave detection unit is (such as: horn antenna), detector, etc.

[0039] Step 102: Determine the phase shift generated by the object to be measured for the microwave according to the synthesized microwave signals at different detection unit positions.

[0040] Step 102 specifically includes: determining the square of the amplitude of the synthesized microwave signal at the first detection unit position and the square of the amplitude of the synthesized microwave signal at the second detection unit position according to the synthesized microwave signals at different detection unit positions; determining the phase shift generated by the object to be measured for the microwave according to the difference between the square of the amplitude of the synthesized microwave signal at the first detection unit position and the square of the amplitude of the synthesized microwave signal at the second detection unit position.

[0041] The envelope of the microwave signal, that is, the amplitude value, is obtained by the detection unit reading the microwave detection unit. Using the microwave transmission line theory, the microwave signals existing in space are analyzed. Let the direction from the microwave transmitting unit to the object to be measured be the z direction, where the microwave transmitting unit is at 0, the object to be measured is at L, and the detection unit positions are z1, z2; let the intensity emitted by the transmitting unit be Ae, the microwave frequency be ω, and the speed of light be c; the distribution formula of the transmitted wave Se in space can be described as:

[0042]

[0043] Let the reflection intensity be Ar, and the phase shift generated by the material for the microwave be The distribution formula of the reflected wave Sr in space can be described as:

[0044]

[0045] Then, the synthesized microwave signal S0 distributed in space can be expressed as

[0046]

[0047] The amplitude square of the synthesized microwave signal S0 can be expressed as

[0048]

[0049] Signal extraction is performed on the microwave signal distribution in space. Through the analysis of the spatial microwave signal, it can be known that the signals of the microwave detection unit are respectively

[0050]

[0051]

[0052] Usually, the difference between the two signals can be calculated, and this value will be basically unaffected by the reflection signal intensity, mainly reflecting the phase change situation.

[0053] Further analysis is performed on the two signals

[0054]

[0055] When: where N is an integer, the expression for the phase shift generated by the object under test on the microwave is:

[0056]

[0057] where ||S0||(t,z1) is the synthesized microwave signal at the position of the first detection unit, ||S0||(t,z2) is the synthesized microwave signal at the position of the second detection unit, Ae is the emission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, L is the position of the object under test, is the phase shift, z1 is the position of the first detection unit, z2 is the position of the second detection unit, and t is the time.

[0058] When L, z1, and z2 are fixed, the phase shift generated by the material on the microwave can be measured variation. In the present invention, the case where the emission intensity and the reflection intensity are equal is considered.

[0059] Step 103: Determine the damage position of the object under test according to the phase shift.

[0060] By fixing the microwave transmitting and detecting units together to form a detecting unit, and by moving the detecting unit or the object under test, the phase shift value of the entire object to be inspected can be scanned to find the position where the material may be damaged. Scanning detection is performed, and the amplitude and phase signals can be obtained during the scanning process. The position where the amplitude or phase signal is different is the damage position.

[0061] When microwaves are incident on a material, reflection and refraction occur; changes in the microstructure and macroscopic damage of the material (such as the crystal structure and molecular weight state of polyethylene materials, delamination of fiber composites, etc.) will cause changes in the overall microwave response of the material; by measuring the changes in the reflected wave, microscopic or macroscopic damage to the object under test can be detected. Specifically, the damage to the object under test affects the reflected wave in terms of changes in reflection intensity and phase. The change in reflection intensity is usually relatively weak and is easily submerged by the transmitted signal in transmission measurement, and this detection method is also the commonly used detection method at present. To improve the detection sensitivity, it is necessary to obtain the phase signal. However, currently used vector analyzers and the like achieve phase analysis by accurately acquiring the entire microwave waveform, which have problems such as complex systems, large volumes, and expensive equipment. A method based on coherent wave difference provided by the present invention realizes the extraction of information on the phase change of microwaves by the material.

[0062] The present invention also provides a microwave damage detection system based on spatial phase difference, including:

[0063] An acquisition module for acquiring the combined microwave signals at different detection unit positions of the object under test.

[0064] A phase shift determination module for determining the phase shift generated by the object under test for microwaves according to the combined microwave signals at different detection unit positions.

[0065] A damage position determination module for determining the damage position of the object under test according to the phase shift.

[0066] As an optional implementation manner, the phase shift determination module specifically includes:

[0067] An amplitude square determination unit for determining the amplitude square of the combined microwave signal at the first detection unit position and the amplitude square of the combined microwave signal at the second detection unit position according to the combined microwave signals at different detection unit positions.

[0068] A phase shift determination unit for determining the phase shift generated by the object under test for microwaves according to the difference between the amplitude square of the combined microwave signal at the first detection unit position and the amplitude square of the combined microwave signal at the second detection unit position.

[0069] As an optional implementation manner, the expression for the phase shift generated by the object under test for microwaves is:

[0070]

[0071] where ||S0||(t,z1) is the combined microwave signal at the first detection unit position, ||S0||(t,z2) is the combined microwave signal at the second detection unit position, Ae is the emission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, and L is the position of the object under test. where $\Delta\varphi$ is the phase shift, $z_1$ is the position of the first detection unit, $z_2$ is the position of the second detection unit, and $t$ is the time.

[0072] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0073] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A microwave damage detection method based on spatial phase difference, characterized in that Including: Obtaining the synthetic microwave signal at different positions of the microwave detection units of the object under test; There are both transmitted waves and reflected waves in space, and the two waveforms have the same frequency; the microwave detection unit reads the signal after the interference of two coherent waves, and the signal after the interference of two coherent waves refers to the synthetic microwave signal; the transmission intensity and the reflection intensity are equal; Determining the phase shift generated by the object under test on the microwave according to the synthetic microwave signal at different positions of the microwave detection units; Determining the damage position of the object under test according to the phase shift; by fixing the microwave transmitting and detecting units together to form a microwave detection unit, by moving the microwave detection unit or the object under test, the phase shift value of the entire object under test can be scanned to find the position where the material may be damaged; When: where N is an integer, the expression for the phase shift generated by the object under test with respect to the microwave is: Among them, ||S0||(t, z1) is the synthesized microwave signal at the position of the first microwave detection unit, ||S0||(t, z2) is the synthesized microwave signal at the position of the second microwave detection unit, Ae is the transmission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, L is the position of the object to be measured, is the phase shift, z1 is the position of the first microwave detection unit, z2 is the position of the second microwave detection unit, and t is the time.

2. A microwave damage detection system based on spatial phase difference, characterized in that, Including: An acquisition module, configured to obtain the synthetic microwave signal at different positions of the microwave detection units of the object under test; there are both transmitted waves and reflected waves in space, and the two waveforms have the same frequency; the microwave detection unit reads the signal after the interference of two coherent waves, and the signal after the interference of two coherent waves refers to the synthetic microwave signal; the transmission intensity and the reflection intensity are equal; A phase shift determination module, configured to determine the phase shift generated by the object under test on the microwave according to the synthetic microwave signal at different positions of the microwave detection units; A damage position determination module, configured to determine the damage position of the object under test according to the phase shift; by fixing the microwave transmitting and detecting units together to form a microwave detection unit, by moving the microwave detection unit or the object under test, the phase shift value of the entire object under test can be scanned to find the position where the material may be damaged; When: where N is an integer, the expression for the phase shift generated by the object under test with respect to the microwave is: Among them, ||S0||(t,z1) is the synthesized microwave signal at the position of the first microwave detection unit, ||S0||(t,z2) is the synthesized microwave signal at the position of the second microwave detection unit, Ae is the emission intensity, Ar is the reflection intensity, ω is the microwave frequency, c is the speed of light, L is the position of the object under test, is the phase shift, z1 is the position of the first microwave detection unit, z2 is the position of the second microwave detection unit, and t is the time.

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