CN107747900A - A kind of strain based on binary patch antenna array and crackle solution decoupling measuring device and method - Google Patents

Abstract

The invention discloses a kind of strain based on binary patch antenna array and crackle solution decoupling measuring device and method, this method comprises the following steps：S1, will compensation antenna and measurement antenna be respectively adhered on body structure surface to be measured；To compensation antenna and measurement antenna transmitting purpose sweep frequency electromagnetic ripple, its resonant frequency is obtained according to the signal reflected in real time respectively for S2, wireless interrogation device；S3, when body structure surface to be measured occur crackle when, the earth plate for compensating antenna has isolated influence of the body structure surface crackle to be measured to its resonant frequency, only perceive strain, measurement antenna perceive strain and crackle integrated information；According to compensation antenna and the real-time resonant frequencies of measurement antenna, with reference to its length and original resonance frequency, strain and the decoupling of crack information are realized.The present invention is realized using paster antenna to decoupling of the metal structure surface strain with crack information and accurate measurement, and has the advantages that apparatus structure is simple, is connected without wire.

Description

A strain and crack decoupling measurement device based on binary patch antenna array and method

technical field

The invention relates to the field of strain and crack measurement of metal structures, in particular to a strain and crack decoupling measurement device and method based on a binary patch antenna array.

Background technique

Common metal structure health monitoring sensors include foil strain gauges, fiber optic sensors, ultrasonic sensors, etc. These sensors can meet the needs of engineering applications to a certain extent, but there are also disadvantages such as cable connections, high cost, and complicated devices. In recent years, scholars at home and abroad have proposed the use of microstrip patch antennas in the field of strain and crack measurement of metal structures. The microstrip patch antenna has the characteristics of simple structure, light weight, low production cost, passive wireless interrogation, and easy conformity with curved surfaces. It can effectively overcome the shortcomings of the above-mentioned sensors and has a good engineering application prospect.

At present, the measurement of strain and cracks by patch antennas has not yet entered into engineering practice, and is only in the stage of laboratory research and development. The existing research results show that when the patch antenna is used as a strain sensor, its resonant frequency decreases linearly with the increase of strain; length and direction. However, the observation indicators of patch antennas to measure strain and cracks are all changes in resonance frequency. When used in actual metal structures, patch antenna sensors will be affected by structural strain and cracks at the same time, and the resonance frequency changes caused by strain and cracks Mutual coupling easily leads to misjudgment of strain and crack parameters. This coupling effect will greatly hinder the engineering application and promotion of the patch antenna sensor, especially when the strain and crack measurement accuracy is high, a suitable decoupling measurement method is particularly necessary.

Contents of the invention

The technical problem to be solved by the present invention is to provide a strain and crack decoupling measurement device and method based on a binary patch antenna array for the defect that it is difficult to accurately measure the surface stress and crack parameters of metal structures in the prior art.

The technical solution adopted by the present invention to solve its technical problems is:

The present invention provides a strain and crack decoupling measurement device based on a binary patch antenna array. The device includes a compensation antenna, a measurement antenna and a wireless interrogation device. The compensation antenna and the measurement antenna are two different structures and sizes. The rectangular patch antenna, the compensation antenna and the measurement antenna are respectively pasted on the surface of the structure to be tested; the compensation antenna and the measurement antenna are both resonant cavity structures, and the wireless interrogation device transmits frequency-sweeping electromagnetic waves to the compensation antenna and the measurement antenna respectively, and according to the reflected The resonant frequency of the signal is obtained respectively, and then according to the decoupling measurement of the resonant frequency, the strain magnitude at the place where the measurement antenna is pasted and the crack characteristics under the patch are obtained.

Further, the compensation antenna of the present invention includes a radiation patch, a substrate and a grounding plate, the substrate is arranged between the radiation patch and the grounding plate, and the underside of the grounding plate is pasted to the surface of the structure to be measured by superglue.

Further, the material of the substrate of the compensation antenna of the present invention is FR4, and the material of the radiation patch and the ground plate is copper, which is manufactured by depositing copper on the upper and lower surfaces of the FR4 substrate by using a printed circuit board process.

Furthermore, the measurement antenna of the present invention includes a radiation patch and a substrate, and the underside of the substrate is pasted to the surface of the structure to be measured by superglue.

Further, the material of the substrate of the measurement antenna of the present invention is FR4, and the material of the radiation antenna is copper, which is manufactured by depositing copper on the upper surface of the FR4 substrate by using a printed circuit board process.

Further, the wireless interrogation device of the present invention includes a horn antenna, a radio frequency circulator, a network analyzer and a data processing module, which are used to access the compensation antenna and the measurement antenna and obtain the real-time resonance frequency of the two.

The invention provides a strain and crack decoupling measurement method based on a binary patch antenna array, comprising the following steps:

S1. On the surface of the structure to be tested, paste the compensation antenna and the measurement antenna on the surface of the structure to be tested respectively, and record the initial resonance frequencies of the compensation antenna and the measurement antenna respectively;

S2. The wireless interrogation device transmits frequency-sweeping electromagnetic waves to the compensation antenna and the measurement antenna in real time, and obtains their resonance frequencies respectively according to the reflected signals;

S3. When cracks occur on the surface of the structure to be measured, the grounding plate of the compensation antenna isolates the influence of the crack on the surface of the structure to be measured on its resonance frequency, and only senses the strain, and the measurement antenna perceives the comprehensive information of strain and cracks; according to the compensation antenna and the measurement antenna Real-time resonant frequency, combined with its initial resonant frequency, enables decoupled measurement of strain and crack information.

Further, the method for calculating strain and crack information in step S3 of the present invention is:

After obtaining the real-time resonant frequencies f _A and f _B of the compensation antenna and the measurement antenna, calculate the strain ε according to the following formula:

Among them, the initial resonant frequency of the compensation antenna is f _0A , and the strain sensitivity of the compensation antenna is s _Aε ;

Then the resonant frequency caused by the crack is separated out as:

Wherein, the initial resonance frequency of the measurement antenna is f _0B , and the strain sensitivity of the measurement antenna is s _Bε .

The beneficial effects produced by the present invention are: the strain and crack decoupling measurement device and method based on the binary patch antenna array of the present invention, through the compensation antenna and the measurement antenna pasted on the surface of the structure to be measured, the strain and crack of the metal structure are realized Separation of information, through the wireless interrogation device to transmit frequency-sweeping electromagnetic waves to the compensation antenna and the measurement antenna in real time, obtain their resonant frequencies according to the reflected signals, and then accurately calculate the stress and crack characteristics on the surface of the structure to be measured according to the resonant frequency. The invention has simple structure and low cost, and the wireless method overcomes the problem of difficult wiring in the traditional method, and overcomes the coupling effect of measuring strain and crack by a single patch antenna sensor, thereby ensuring the accuracy of strain and crack measurement.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is the structural representation of the embodiment of the present invention;

2 is a schematic structural diagram of a compensation antenna and a wireless interrogation device thereof according to an embodiment of the present invention;

Fig. 3 is the schematic diagram of the specific embodiment of the present invention;

In the figure, 1-compensation antenna, 2-measurement antenna, 3-wireless interrogation device.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 1, the strain and crack decoupling measurement device based on the binary patch antenna array of the embodiment of the present invention includes a compensation antenna 1, a measurement antenna 2 and a wireless interrogation device 3, the compensation antenna 1 and the measurement antenna 2 is two rectangular patch antennas with different structures and sizes. The compensation antenna 1 and the measurement antenna 2 are pasted on the surface of the structure to be tested respectively; Sweeping electromagnetic waves are sent to the compensation antenna 1 and the measurement antenna 2 respectively, and their resonant frequencies are obtained according to the reflected signals, and then the strain at the pasted measurement antenna 2 and the crack characteristics under the patch are obtained according to the resonant frequency decoupling measurement.

The compensation antenna 1 and the measurement antenna 2 have different initial resonance frequencies, and the area of the measurement antenna 2 is larger than that of the compensation antenna 1, so that the measurement antenna 2 can cover more measurement areas.

The compensation antenna 1 includes a radiation patch, a matrix and a grounding plate, the matrix is arranged between the radiation patch and the grounding plate, and the underside of the grounding plate is pasted to the surface of the structure to be measured by superglue. The material of the substrate of the compensation antenna 1 is FR4, and the materials of the radiation patch and the ground plate are copper, which are manufactured by depositing copper on the upper and lower surfaces of the FR4 substrate by using a printed circuit board process.

The measurement antenna 2 includes a radiation patch and a matrix, and the underside of the matrix is pasted to the surface of the structure to be measured by superglue. The material of the substrate of the measurement antenna 2 is FR4, and the material of the radiating antenna is copper, which is manufactured by depositing copper on the upper surface of the FR4 substrate by using a printed circuit board process.

The wireless interrogation device 3 includes a horn antenna, a radio frequency circulator, a network analyzer and a data processing module, which are used to access the compensation antenna and the measurement antenna and obtain the real-time resonance frequency of the two.

The strain and crack decoupling measurement method based on the binary patch antenna array in the embodiment of the present invention includes the following steps:

S1. On the surface of the structure to be tested, paste the compensation antenna and the measurement antenna on the surface of the structure to be tested respectively, and record the initial resonance frequencies of the compensation antenna and the measurement antenna respectively;

S2. The wireless interrogation device transmits frequency-sweeping electromagnetic waves to the compensation antenna and the measurement antenna in real time, and obtains their resonance frequencies respectively according to the reflected signals;

S3. When cracks occur on the surface of the structure to be measured, the grounding plate of the compensation antenna isolates the influence of the crack on the surface of the structure to be measured on its resonance frequency, and only senses the strain, and the measurement antenna perceives the comprehensive information of strain and cracks; according to the compensation antenna and the measurement antenna Real-time resonant frequency, combined with its initial resonant frequency, enables decoupled measurement of strain and crack information.

Utilizing the above-mentioned devices, the present invention is realized by the following principle.

Let the working direction lengths of the radiation patches of the compensating antenna and measuring antenna be L _0A and L _0B respectively, the dielectric constant of the substrate FR4 be β, and the speed of light in vacuum be c. Then the initial resonant frequencies of the two sensors are f _0A and f _0B , and their expressions are:

When the metal structure is in a certain working state, the binary patch antenna array is subjected to strain along with the structure. Due to its own ground plate, the compensation antenna can isolate the influence of cracks on the surface of the metal structure, and its resonance frequency only changes with strain; while the measurement antenna is affected by both strain and cracks on the surface of the metal structure, and its resonance frequency changes include strain and cracks comprehensive information. Assuming that the strain in this working state is ε, and there is a crack perpendicular to its working direction under the measuring antenna, then the radiation patch of the compensation antenna bears the strain at this time, and its resonant frequency becomes f _A ; the radiation patch of the measuring antenna bears strain and its current path is disturbed by the crack, the resonant frequency becomes _fB . The expressions of f _A and f _B are (where ΔL _Aε and ΔL _Bε represent the change in the electrical length of the compensation antenna and the measuring antenna caused by the strain, and ΔL _Bcrack represents the change in the electrical length of the measuring antenna caused by the crack):

Suppose the strain sensitivity of the compensation antenna is s _Aε , the strain sensitivity of the measurement antenna is s _Bε , and the crack length sensitivity of the measurement antenna is s _Bcrack . After the design of the binary patch antenna array is completed, s _Aε , s _Bε and s _Bcrack are all Know the parameters. In a measurement, the values of f _A and f _B can be obtained by using the wireless interrogation device, at this time, the structural strain of the sticking place can be obtained according to formula (5). After measuring the strain, the resonant frequency change Δf _Bε of the measuring antenna caused by the strain can be calculated according to the formula (6), and then the resonant frequency change Δf _Bcrack of the measuring antenna caused by the crack can be calculated according to the formula (7).

Δf _Bε = εs _Bε (6)

Δf _Bcrack ＝f _B -f _0B -Δf _Bε (7)

which is

Therefore, the measured crack length l _crack under the antenna can be obtained according to formula (8):

When there is an oblique crack under the measurement antenna, two resonant frequencies corresponding to its length and width directions need to be observed. Subtract the strain component from the two resonance frequency changes to obtain the resonance frequency change caused by the crack alone, which can reflect the length and direction information of the crack.

Compared with the existing technical means, the beneficial effect of the present invention lies in: providing a strain and crack decoupling measurement method based on a binary patch antenna array, the method uses two rectangular patch antennas to realize the strain and crack information of metal structures The separation of the single patch antenna sensor overcomes the coupling effect of measuring strain and crack, and ensures the accuracy of strain and crack measurement.

In another specific embodiment of the present invention:

As shown in Figure 1, the designed binary patch antenna array is pasted to the area to be tested on the surface of the metal structure with super glue. The compensation antenna has its own ground plate to sense the strain information only, and the antenna senses the comprehensive information of strain and cracks. When the metal structure is in a certain working state, use the wireless interrogation device to access the compensation antenna and the measurement antenna, and obtain the resonant frequencies f _A and f _B of the two. According to the values of f _A and f _B and the design sensitivity parameters of the two patch antennas, the strain magnitude and the crack characteristics under the patch can be calculated in this working state.

Fig. 2 is a schematic diagram of the structure of the compensation antenna and its wireless interrogation device in the present invention. The radiation patch, matrix and ground plate of the compensation antenna form a resonant cavity, which can transmit frequency-sweeping electromagnetic waves to it through the wireless interrogation device, and obtain its resonant frequency according to the reflected signal. The wireless interrogation device is composed of a horn antenna, a radio frequency circulator, a network analyzer and corresponding signal processing modules.

Fig. 3 is a specific embodiment of the present invention. As shown in the figure, the binary patch antenna array is arranged on the surface of the steel structure, which is subjected to a load in the horizontal direction. Under the action of strain, the resonant frequency of the compensation antenna in the longitudinal direction decreases; the measuring antenna is subjected to strain, and there is a crack perpendicular to the longitudinal direction below, both the strain and the crack cause the resonant frequency of the longitudinal direction to decrease. After the sensor arrangement is completed, the steel structure is working normally. At a certain moment, the resonant frequencies f _A and f _B of the two patch antennas are measured by the wireless interrogation device, and are passed through the formula (5) according to the design parameters of the binary patch antenna array. —(8) Accurately calculate the strain at the paste and the crack length under the patch antenna.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (8)

1. a kind of strain and crack decoupling measurement device based on binary patch antenna array, it is characterized in that, this device comprises compensation antenna (1), measurement antenna (2) and wireless inquiry device (3), compensation antenna ( 1) and measurement antenna (2) are two rectangular patch antennas with different structures and sizes. The compensation antenna (1) and measurement antenna (2) are respectively pasted on the surface of the structure to be measured; the compensation antenna (1) and measurement The antennas (2) are resonant cavity structures, and the wireless interrogation device (3) transmits frequency-sweeping electromagnetic waves to the compensation antenna (1) and the measurement antenna (2) respectively, and obtains their resonant frequencies according to the reflected signals, and then according to the resonant frequency The decoupling measurement obtains the strain magnitude at the pasted measurement antenna (2) and the crack characteristics under the patch. 2. The strain and crack decoupling measurement device based on the binary patch antenna array according to claim 1, wherein the compensation antenna (1) comprises a radiation patch, a substrate and a ground plate, and the substrate is arranged on the radiation patch Between the grounding plate and the grounding plate, stick the lower part of the grounding plate to the surface of the structure to be tested with super glue. 3. the strain and crack decoupling measurement device based on binary patch antenna array according to claim 2, is characterized in that, the material of the matrix of compensating antenna (1) is FR4, and the material of radiation patch and ground plate is Copper, fabricated by depositing copper onto the upper and lower surfaces of the FR4 substrate using a printed circuit board process. 4. The strain and crack decoupling measurement device based on the binary patch antenna array according to claim 1, wherein the measuring antenna (2) comprises a radiation patch and a substrate, and the substrate is pasted below the substrate by superglue. Measure the surface of the structure. 5. the strain and crack decoupling measurement device based on binary patch antenna array according to claim 4, is characterized in that, the material of the matrix of measuring antenna (2) is FR4, and the material of radiation antenna is copper, adopts printing The circuit board process is made by depositing copper onto the upper surface of the FR4 substrate. 6. The strain and crack decoupling measurement device based on the binary patch antenna array according to claim 1, wherein the wireless interrogation device (3) includes a horn antenna, a radio frequency circulator, a network analyzer and a data processing Module for accessing the compensation and measurement antennas and obtaining their real-time resonant frequencies. 7. A method of measuring that adopts the strain and crack decoupling measurement device based on the binary patch antenna array of claim 1, is characterized in that, comprises the following steps: S1. On the surface of the structure to be tested, paste the compensation antenna and the measurement antenna on the surface of the structure to be tested respectively, and record the initial resonance frequencies of the compensation antenna and the measurement antenna respectively; S2. The wireless interrogation device transmits frequency-sweeping electromagnetic waves to the compensation antenna and the measurement antenna in real time, and obtains their resonance frequencies respectively according to the reflected signals; S3. When cracks occur on the surface of the structure to be measured, the grounding plate of the compensation antenna isolates the influence of the crack on the surface of the structure to be measured on its resonance frequency, and only senses the strain, and the measurement antenna perceives the comprehensive information of strain and cracks; according to the compensation antenna and the measurement antenna Real-time resonant frequency, combined with its initial resonant frequency, enables decoupled measurement of strain and crack information. 8. The strain and crack decoupling measurement method based on binary patch antenna array according to claim 7, wherein the method for calculating strain and crack information in step S3 is: After obtaining the real-time resonant frequencies f _A and f _B of the compensation antenna and the measurement antenna, calculate the strain ε according to the following formula: <mrow><mi>&amp;epsiv;</mi><mo>=</mo><mfrac><mrow><msub><mi>f</mi><mi>A</mi></msub><mo>-</mo><msub><mi>f</mi><mrow><mn>0</mn><mi>A</mi></mrow></msub></mrow><msub><mi>s</mi><mrow><mi>A</mi><mi>&amp;epsiv;</mi></mrow></msub></mfrac></mrow> Among them, the initial resonant frequency of the compensation antenna is f _0A , and the strain sensitivity of the compensation antenna is s _Aε ; Then, the change of resonance frequency caused by the separation of cracks is: <mrow><msub><mi>&amp;Delta;f</mi><mrow><mi>B</mi><mi>c</mi><mi>r</mi><mi>a</mi><mi>c</mi><mi>k</mi></mrow></msub><mo>=</mo><msub><mi>f</mi><mi>B</mi></msub><mo>-</mo><msub><mi>f</mi><mrow><mn>0</mn><mi>B</mi></mrow></msub><mo>-</mo><mrow><mo>(</mo><msub><mi>f</mi><mi>A</mi></msub><mo>-</mo><msub><mi>f</mi><mrow><mn>0</mn><mi>A</mi></mrow></msub><mo>)</mo></mrow><mfrac><msub><mi>s</mi><mrow><mi>B</mi><mi>&amp;epsiv;</mi></mrow></msub><msub><mi>s</mi><mrow><mi>A</mi><mi>&amp;epsiv;</mi></mrow></msub></mfrac></mrow> Wherein, the initial resonance frequency of the measurement antenna is f _0B , and the strain sensitivity of the measurement antenna is s _Bε .