CN106839965A - Label, measuring system and its application process for measuring metal component surface strain - Google Patents

Abstract

The invention discloses a label for measuring the surface strain of a metal component, a measuring system and an application method thereof. In order to break through the limitations of active and wired in traditional strain sensors, the present invention provides a new idea for the design of strain sensors by using Radio Frequency Identification (RFID) technology, which can realize non-contact sensor without external wired power supply. Strain measurement. The present invention is used to measure the RFID system of the surface strain measurement of metal component, and this system is made up of reader and the label that is used for measuring the surface strain of metal component, wherein the label that is used for measuring the surface strain of metal component is fixed on the metal component under test, and label comprises RFID antenna, chip. The RFID antenna includes an upper radiating patch, a lower radiating patch, a dielectric board, and a matching line. The label is bonded to the metal surface of the metal component under test through the lower radiating patch of the RFID antenna, and the chip passes through the matching line. It is connected with the upper radiation patch and the lower radiation patch.

Description

Label for measuring surface strain of metal components, measurement system and method of application thereof

technical field

The invention relates to the field of measuring the surface strain of a metal component.

Background technique

Currently commonly used strain sensors include resistive strain gauges, vibrating wire strain gauges and Bragg grating sensors. Resistive strain gauges can convert strain changes into resistance changes, and further convert them into voltage or current changes through the bridge; vibrating wire strain gauges use the relationship between the resonant frequency of the string and the strain to measure the strain; the principle of the Bragg grating sensor is It is based on the theory of fiber grating Bragg wavelength shift. These strain sensors have their own advantages. In practical engineering applications, the appropriate strain sensors can be selected according to the site conditions, but they also have insurmountable shortcomings: the sensor layout and signal acquisition are wired, the operation is complicated, there are many leads, and the acquisition equipment The price is expensive, although some wireless communication methods such as Zigbee and Wifi have been used to improve, but this shortcoming cannot be fundamentally overcome; real-time power supply is required during the signal acquisition process, and the structure may break down when it experiences a disaster. The problem of power failure caused the signal acquisition system to fail to obtain data when the disaster occurred.

Contents of the invention

In order to overcome the shortcomings of the above solutions, the present invention discloses a label for measuring the surface strain of a metal component, a measurement system and an application method thereof.

In order to break through the limitation of active and wired in traditional strain sensors, the present invention provides a new idea for the design of strain sensors by using radio frequency identification (Radio Frequency Identification, RFID) technology, which can realize non-contact strain sensor without external wired power supply. Measurement.

Technical solution one

The present invention is used to measure the RFID system of the surface strain measurement of metal component, and this system is made up of reader 8 and the label 10 that is used for measuring the surface strain of metal component,

The tag 10 for measuring the surface strain of the metal component is fixed on the metal component 1 to be tested, and the tag 10 includes an RFID antenna and a chip 2 . The RFID antenna includes an upper radiation patch 31, a lower radiation patch 32, a dielectric plate 4, and a matching line 5, and the tag 10 is bonded to the metal surface of the metal member 1 under test through the lower radiation patch 32 of the RFID antenna , the chip 2 is connected to the upper radiation patch 31 and the lower radiation patch 32 through a matching line 5 .

In strain measurement, the RFID antenna on the tag 10 acts as a sensing unit. When the tag 10 undergoes deformation, the size of the antenna will change, and its resonant frequency will drift; the RFID reader 8 detects the resonant frequency drift of the RFID tag 10 through its antenna 9, and calculates the antenna on the metal member 1 under test. strain.

To further refine the technical solution, the RFID antenna also includes conductive glue 6, and the lower radiation patch 32 is bonded to the metal surface of the metal component 1 under test by using the conductive glue 6.

The performance of the RFID strain sensor is related to the type of antenna on the tag. Optimizing the design of the antenna on the tag can reduce the size of the sensor and improve its sensitivity. For example, a half-wavelength rectangular patch antenna or a quarter-wavelength rectangular patch antenna is used.

Further optimization, compared with the 1/2 wavelength rectangular patch antenna, the present invention changes the 1/2 wavelength rectangular patch antenna into a 1/4 wavelength rectangular patch antenna as a preferred embodiment, so that the sensor size can be reduced Cut in half or double the sensitivity of the sensor. The present invention makes a quarter-wavelength rectangular patch antenna, which can be realized in any of the following ways:

1. Drill some via holes at one end of the half-wavelength rectangular patch antenna, and coat the via arm with conductive material to short-circuit the upper and lower radiation patches;

2. Adding a lateral short-circuit wall on one side of the antenna to short-circuit the upper and lower radiation patches can turn the half-wavelength rectangular patch antenna into a quarter-wavelength rectangular patch antenna;

3. It is also possible to use welding technology to connect the rectangular patch antenna to the surface of the metal component instead of pasting the rectangular patch antenna on the surface of the metal component with conductive glue. (for optimal implementation)

Technical solution two

A tag 10 for measuring surface strain of a metal component is fixed on a metal component 1 to be tested, and the tag 10 includes an RFID antenna and a chip 2 . The RFID antenna includes an upper radiation patch 31, a lower radiation patch 32, a dielectric plate 4, and a matching line 5, and the tag 10 is bonded to the metal surface of the metal member 1 under test through the lower radiation patch 32 of the RFID antenna , the chip 2 is connected to the upper radiation patch 31 and the lower radiation patch 32 through a matching line 5 .

Technical solution three

An application method for measuring the surface strain of a metal component, comprising the steps of:

Step 1, using radio frequency identification (Radio Frequency Identification, RFID) technology to design a strain sensor for installation and fixing on the surface of the metal component to be measured. The structure of the strain sensor is the structure of the label 10 .

Step 2. When measuring the surface strain of metal components, in order to convert the 1/2-wavelength rectangular patch antenna into a 1/4-wavelength rectangular patch antenna, use welding technology to connect the antenna's upper radiation patch and the The surfaces of the test metal components are connected by welds, so that the upper and lower radiation patches of the rectangular patch antenna are short-circuited to form a quarter-wavelength rectangular patch antenna.

Step 3: The RFID reader transmits modulated electromagnetic wave signals to the RFID tag at different frequencies. When the signal power received by the RFID tag reaches a threshold, the chip in the RFID tag can be activated. The minimum transmit power P _min (f) of the reader required to activate the tag is related to the frequency f of the signal transmitted by the reader. When the reader transmits the signal at the resonant frequency f _R of the rectangular patch antenna in the RFID tag, the minimum required to activate the tag The transmit power P _min (f _R ) is the minimum. The resonant frequency f _R of the antenna in the RFID tag can be determined by finding the transmission frequency that makes the minimum transmission power reach the minimum value.

Step 4, when the antenna undergoes strain, its resonant frequency drifts, and when the antenna experiences strain ε in the length direction, the resonant frequency f _R will exhibit an approximately linear relationship with the strain, given by the following formula

where c is the speed of light in vacuum, ε _e is the relative permittivity of the dielectric plate, L is the length of the upper radiation patch, and f _RO is the resonant frequency of the antenna in the initial strain state. By determining the amount by which the resonant frequency has shifted, the strain experienced by the tag can be calculated.

1. The present invention is suitable for measuring the strain on the surface of conductive metal components, including but not limited to steel structures and aluminum structures.

2. The 1/2 wavelength rectangular patch antenna must be pasted on the metal surface or welded to the metal surface with conductive adhesive, including but not limited to LED conductive silver glue.

3. Use the upper radiation patch of the welding seam antenna to connect with the metal surface, and the flux includes but not limited to copper-aluminum flux-cored welding wire.

4. Ensure that all the above connections have good electrical conductivity.

Beneficial effects brought by the technical solution:

1. Compared with the half-wavelength rectangular patch antenna as the sensing unit of the sensor, the quarter-wavelength rectangular patch antenna can reduce the size of the sensor or improve the sensitivity of the sensor;

2. Welding method is used for short circuit, so that the strain sensor is relatively firm and not easy to be damaged;

5. The original scheme needs to be processed in an antenna processing factory. This scheme relaxes the processing restrictions and can be processed in an ordinary environment.

Description of drawings

Figure 1 is a schematic diagram of the entire system.

Fig. 2 is a schematic diagram of a label in a preferred embodiment.

Metal components under test 1, chip 2, upper radiation patch 31, lower radiation patch 32, dielectric board 4, matching line 5, conductive glue 6, weld seam 7, reader 8, reader antenna 9, for measuring metal Labeling of Component Surface Strain 10

detailed description

The technical solution of the present invention will be introduced further below in conjunction with the accompanying drawings.

Example

The system of the present invention is composed of RFID tags and RFID readers. The RFID tag is pasted on the surface of the metal component under test with conductive glue. In the RFID tag, a quarter-wavelength rectangular patch antenna short-circuited through the weld is used as the sensing unit. When the surface of the metal component under test undergoes strain, the patch The change of the antenna size causes the resonant frequency to drift; the code information of the tag is carried in the chip, and the RFID reader is used to transmit the modulated electromagnetic wave signal to the tag, and the code of the tag can be identified. When multiple RFID tags are arranged in the scanning range of the RFID reader, the reading The device can mark the strain value of each measuring point according to the code of each label.

The RFID used in this system is specially designed, and its principle of measuring the surface strain of metal components is as follows: the RFID reader transmits modulated electromagnetic wave signals to the RFID tag at different frequencies, when the signal power received by the RFID tag reaches the threshold, the RFID tag The chip in will be activated. The minimum transmit power P _min (f) of the reader required to activate the tag is related to the frequency f of the signal transmitted by the reader. When the reader transmits the signal at the resonant frequency f _R of the rectangular patch antenna in the RFID tag, the minimum required to activate the tag The transmit power P _min (f _R ) is the minimum. The resonant frequency of the antenna in the RFID tag can be determined by finding the transmission frequency that minimizes the minimum transmission power.

When the antenna experiences strain, its resonant frequency drifts, and when the antenna experiences strain ε in the length direction, the resonant frequency f _R will exhibit an approximately linear relationship with the strain, given by the following formula

where c is the speed of light in vacuum, ε _e is the relative permittivity of the dielectric plate, L is the length of the upper radiation patch, and f _RO is the resonant frequency of the antenna in the initial strain state. By determining the amount by which the resonant frequency has shifted, the strain experienced by the tag can be calculated.

Best Practices

The invention aims to provide a simple, reliable, convenient processing, practical and economical short-circuited one-half-wavelength rectangular patch antenna to make a quarter-wavelength rectangular patch antenna for measuring the surface strain of metal components.

When measuring the surface strain of metal components, in order to realize the conversion of the 1/2 wavelength rectangular patch antenna into the 1/4 wavelength rectangular patch antenna, the technical scheme of the present invention first converts the 1/2 wavelength rectangular patch antenna Paste it on the surface of the metal component under test with conductive glue; and then use welding technology to connect the upper radiation patch of the antenna with the surface of the metal component under test through the weld 7 . To ensure good conductivity of the conductive adhesive and weld seam, the upper and lower radiating patches of the rectangular patch antenna can be short-circuited to form a quarter-wavelength rectangular patch antenna.

Claims (6)

1. An RFID system for measuring the surface strain of a metal component is characterized in that the system is made up of a reader (8) and a tag (10) for measuring the surface strain of the metal component, Wherein the tag (10) for measuring the surface strain of the metal member is fixed on the metal member (1) to be tested, and the tag (10) includes an RFID antenna, a chip (2); the RFID antenna includes an upper radiation patch (31), The lower radiation patch (32), the dielectric plate (4), the matching line (5), the label (10) is bonded to the metal surface of the metal component (1) through the lower radiation patch (32) of the RFID antenna , the chip (2) is connected to the upper radiation patch (31) and the lower radiation patch (32) through a matching line (5). 2. system as claimed in claim 1, is characterized in that, described RFID antenna also comprises conductive glue (6), and radiation patch (32) is bonded to the metal surface of described measured metal member (1) by adopting The conductive glue (6) is realized. 3. The system according to claim 1, characterized in that a half-wavelength rectangular patch antenna or a quarter-wavelength rectangular patch antenna is used. 4. The system according to claim 1, wherein making a quarter-wavelength rectangular patch antenna can be realized in any of the following ways: Drill some via holes at one end of the half-wavelength rectangular patch antenna, and coat the via arm with conductive material to short-circuit the upper and lower radiation patches; or Adding a lateral short-circuit wall on one side of the antenna to short-circuit the upper and lower radiation patches can turn the half-wavelength rectangular patch antenna into a quarter-wavelength rectangular patch antenna; or Using welding technology to connect the rectangular patch antenna to the surface of the metal component instead of pasting the rectangular patch antenna on the surface of the metal component with conductive glue. 5. A label (10) for measuring the surface strain of a metal component is characterized in that it is fixed to the measured metal component (1), and the label (10) includes an RFID antenna, a chip (2); the RFID antenna includes The upper radiation patch (31), the lower radiation patch (32), the dielectric board (4), the matching line (5), and the label (10) are bonded to the tested device through the lower radiation patch (32) of the RFID antenna. On the metal surface of the metal member (1), the chip (2) is connected to the upper radiation patch (31) and the lower radiation patch (32) through a matching line (5). 6. An application method for measuring the surface strain of a metal member, comprising the steps of: Step 1, using radio frequency identification (Radio Frequency Identification, RFID) technology to design a strain sensor for installation and fixing on the surface of the metal component to be measured. The structure of the strain sensor is the structure of the label (10). Step 2. When measuring the surface strain of metal components, in order to convert the 1/2-wavelength rectangular patch antenna into a 1/4-wavelength rectangular patch antenna, use welding technology to connect the antenna's upper radiation patch and the The surfaces of the test metal components are connected by welds, so that the upper and lower radiation patches of the rectangular patch antenna are short-circuited to form a quarter-wavelength rectangular patch antenna. Step 3: The RFID reader transmits modulated electromagnetic wave signals to the RFID tag at different frequencies. When the signal power received by the RFID tag reaches a threshold, the chip in the RFID tag can be activated. The minimum transmit power P _min (f) of the reader required to activate the tag is related to the frequency f of the signal transmitted by the reader. When the reader transmits the signal at the resonant frequency f _R of the rectangular patch antenna in the RFID tag, the minimum required to activate the tag The transmit power P _min (f _R ) is the minimum. The resonant frequency f _R of the antenna in the RFID tag can be determined by finding the transmission frequency that makes the minimum transmission power reach the minimum value. Step 4, when the antenna undergoes strain, its resonant frequency drifts, and when the antenna experiences strain ε in the length direction, the resonant frequency f _R will exhibit an approximately linear relationship with the strain, given by the following formula ${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; \&ap;</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}<span\; class="notranslate">\; \&ap;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; )</span>$ where c is the speed of light in vacuum, ε _e is the relative permittivity of the dielectric plate, L is the length of the upper radiation patch, and f _RO is the resonant frequency of the antenna in the initial strain state. By determining the amount by which the resonant frequency has shifted, the strain experienced by the tag can be calculated.