Structural health monitoring method of composite material rotating component based on RFID
Through the RFID-based structural health monitoring method, RFID tags and vector network analyzers are used to detect changes in scattering parameters of rotating members, solving the problem of difficult to detect damage to rotating members, and achieving rapid non-destructive detection and timely alarms, with thin sensors and no impact on mechanical performance.
Patent Information
- Application Number
- CN202510401681.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-07-11
AI Technical Summary
The prior art is difficult to realize non-destructive testing on rotating components such as fan blades or aircraft propellers. In particular, there are challenges in the installation of wires and detection equipment, which leads to difficulty in detecting damage in a timely manner and affects mechanical strength.
Using RFID-based structural health monitoring method, the damage is detected by preparing RFID tags, using wire-wounded loop coils and vector network analyzers, scanning the scattering parameters of the rotating members of the composite material, and monitoring the attenuation changes of the scattering parameters.
实现了对旋转构件的快速无损检测,传感器薄且不影响碳纤维复合材料的力学性能,能够及时发现损伤并发出警报。
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Figure CN120294136A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for detecting a material, and more particularly to a method for structural health monitoring of a composite rotating member based on RFID, belonging to the technical field of non-destructive testing.
Background Art
[0002] Carbon fiber reinforced composites have excellent mechanical properties and are widely used in many fields. However, in actual applications, composites often suffer damage, which is almost invisible, resulting in a reduction in their mechanical strength. If the damage cannot be detected and repaired in time, it may lead to catastrophic consequences.
[0003] To solve this problem, many non-destructive testing methods have been invented, such as electrical impedance tomography, ultrasonic scanning, and infrared detection. However, in the application scenarios of rotating members such as fan blades or aircraft propellers, the installation of wires and detection equipment becomes a huge challenge.
[0004] Therefore, to solve the above problems, it is indeed necessary to provide an innovative method for structural health monitoring of a composite rotating member based on RFID to overcome the defects in the prior art.
Summary of the Invention
[0005] The purpose of the present invention is to provide a method for structural health monitoring of a composite rotating member based on RFID, which can achieve the structural health monitoring of carbon fiber reinforced composites in a rotating scenario without affecting the mechanical properties of carbon fiber reinforced composites.
[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a method for structural health monitoring of a composite rotating member based on RFID, which includes the following technological steps:
[0007] 1), Prepare RFID tags;
[0008] 2), Wind a wire into a toroidal coil, weld the toroidal coil to a coaxial connector, and connect the coaxial connector to the port of a vector network analyzer;
[0009] 3), Install the composite rotating member on the motor, place the vector network analyzer at the rear cover of the motor, and keep the toroidal coil close to the rotating member;
[0010] 4), Calibrate the vector network analyzer; then start the motor, and the toroidal coil continuously scans the composite rotating member. If the scattering parameters of the vector network analyzer within the scanning frequency do not decay significantly within a certain period of time, the monitoring system issues an alarm.
[0011] The structural health monitoring method of the composite rotating component based on RFID of the present invention further includes: The specific preparation method of the RFID tag in step 1) includes the following steps:
[0012] 1-1), Design a planar rectangular spiral inductor:
[0013]
[0014] Among them, L is the inductance value of the planar rectangular spiral inductor, d0 and d i are the outer length and inner length of the coil respectively, and N is the number of turns;
[0015] 1-2), Design interdigital electrodes:
[0016]
[0017] Among them, C is the capacitance value of the interdigital electrode; l is the length of the electrode; n is the number of electrodes; ε0 is the permittivity of free space; ε1 is the relative permittivity of the measured material; ε2 is the relative permittivity of the material between the electrodes; ε3 is the relative permittivity of the insulating film; K() is the first kind of elliptic integral; a is the spatial distance between the two electrodes; b is the distance between the centers of the two electrodes; h is the thickness of the electrode;
[0018] 1-3), Calculate the resonant frequency of the RFID tag:
[0019]
[0020] 1-4), Use conductive ink and screen printing technology to print a planar rectangular spiral coil and interdigital electrodes on the insulating film;
[0021] 1-5), After the conductive ink dries, apply vias at the unconnected ends of the inner ring electrode of the coil and the interdigital electrodes, and print conductive ink on the reverse side of the insulating film to connect the two vias.
[0022] The structural health monitoring method of the composite rotating component based on RFID of the present invention further includes: Before printing in step 1-4), first use laser etching method to process the shapes of interdigital electrodes and planar rectangular spiral inductors on a stainless steel plate with a thickness of 0.1 mm; then place the processed stainless steel plate on the insulating film.
[0023] The structural health monitoring method of the composite rotating component based on RFID of the present invention further includes: The insulating film is used as a substrate, specifically a PET film.
[0024] The structural health monitoring method of the composite rotating component based on RFID of the present invention further includes: In step 2), the wire used is specifically a copper wire.
[0025] The structural health monitoring method of the composite rotating component based on RFID of the present invention is further as follows: In step 3), three composite rotating components are selected as the blades of the fan and installed on the motor; a plastic plate is provided near the composite rotating component of the rear cover, and the annular coil is pasted on the plastic plate; during the installation process of the composite rotating component and the vector network analyzer, the distance l1 between the two when the composite rotating component is directly in front of the coil is recorded.
[0026] The structural health monitoring method of the composite rotating component based on RFID of the present invention is further as follows: Step 4) is specifically as follows:
[0027] 4-1), Keep a distance of l1 between the vector network analyzer and the composite rotating component without embedded RFID tags, and perform rotational scanning at a frequency of f0±x MHz; there is a maximum value of the scattering parameter S within the scanning range of f0±x, and the absolute value of the maximum value is used as the attenuation degree |S| of the scattering parameter when the vector network analyzer scans the carbon fiber composite rotating component without embedded RFID tags.
[0028] 4-2), Embed the RFID tag into the composite rotating component.
[0029] 4-3), After the motor is started, the vector network analyzer continuously scans the rotating component. If the resonant frequency of the RFID tag is within the scanning frequency range of the vector network analyzer, a large amount of the magnetic field energy output by the vector network analyzer will be absorbed by the tag, and the scattering parameter S will be greatly attenuated, indicating that the rotating component has not been damaged.
[0030] If the composite rotating component is damaged, resulting in the resonant frequency shifting out of the scanning frequency range of the vector network analyzer, the RFID tag will no longer absorb the magnetic field energy output by the vector network analyzer, and the magnetic field energy will only be absorbed by the carbon fiber composite plate, and the scattering parameter S will not be greatly attenuated; if the attenuation degree of the scattering parameter within the scanning frequency is lower than y|S| within a certain period of time, where 5>y>1, it can be determined that damage has occurred inside the rotating component, and at this time the monitoring system issues an alarm.
[0031] The structural health monitoring method of the composite rotating component based on RFID of the present invention is further as follows: It is characterized in that: in step 4-1), f0 = f, and x is not higher than 0.1f0.
[0032] The structural health monitoring method of the composite rotating member based on RFID of the present invention is further as follows: It is characterized in that: the specific step 4-2) is: First, stick PET tapes on the front and back sides of the RFID tag, and then place it in the middle layer of the composite rotating member. After curing, the resin inside the composite rotating member contacts the upper and lower sides of the RFID tag.
[0033] The structural health monitoring method of the composite rotating member based on RFID of the present invention can also be: In the step 4-3), when the attenuation degree of the scattering parameter is lower than 2|S| within 4 seconds, it can be determined that damage has occurred inside the rotating member.
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] 1. The structural health monitoring method of the composite rotating member based on RFID of the present invention uses interdigital electrodes and planar rectangular spiral inductors as sensors for the structural health monitoring of the carbon fiber composite rotating member. On the one hand, the sensors can be measured using a handheld vector network analyzer. By controlling the range of the scanning frequency and the number of scanning points, the measurement speed can be very fast; in addition, the handheld vector network analyzer device is small in size and light in weight, and these advantages enable the present invention to be applied to the structural health monitoring of scenarios such as fan blades or propellers; on the other hand, the thickness of the interdigital electrodes and planar rectangular spiral inductors can be made very thin, and it has little impact on the mechanical properties of the carbon fiber composite rotating member.
[0036] 2. The structural health monitoring method of the composite rotating member based on RFID of the present invention embeds the RFID tag into the carbon fiber reinforced composite material to achieve structural health monitoring. The energy of the tag is provided by the magnetic field generated by the external coil, so there is no need to connect through cables either; when the oscillation frequency of the coil is consistent with the resonance frequency of the tag, the scattering parameter of the vector network analyzer will attenuate significantly, and the damage condition of the carbon fiber composite rotating member can be monitored through the signal change of the scattering parameter, and it can realize the structural health monitoring of the carbon fiber reinforced composite rotating member on the premise of ensuring that it does not affect the mechanical properties of the carbon fiber reinforced composite material.
Description of the Drawings
[0037] Figure 1 It is a schematic structural diagram of the RFID tag prepared in step 1) of the present invention.
[0038] Figure 2 It is a schematic diagram of connecting the circular coil in step 2) of the present invention to the vector network analyzer.
[0039] Figure 3 It is a schematic diagram of embedding the RFID tag of the present invention into the carbon fiber composite rotating member.
[0040] Figure 4 It is a schematic diagram of the vector network analyzer of the present invention scanning a composite rotating member.
[0041] Figure 5 It is a comparison chart of the attenuation degree of the scattering parameters when the vector network analyzer of the present invention non-rotationally scans damaged and undamaged composite rotating members.
[0042] Figure 6 It is a comparison chart of the attenuation degree of the scattering parameters when the vector network analyzer of the present invention rotationally scans damaged and undamaged composite rotating members.
Detailed Implementation Manner
[0043] Please refer to the attached Figure 1 to the attached Figure 6 As shown, the present invention is a structural health monitoring method for a composite rotating member based on RFID, which includes the following process steps:
[0044] 1), Prepare an RFID (Radio Frequency Identification) tag 4, and its specific preparation method is as follows:
[0045] 1-1), Design a planar rectangular spiral inductor 2:
[0046]
[0047] Among them, L is the inductance value of the planar rectangular spiral inductor 2, d0 and d i are the outer length and inner length of the coil respectively, and N is the number of turns.
[0048] 1-2), Design interdigital electrodes 1:
[0049]
[0050] Among them, C is the capacitance value of the interdigital electrodes; l is the length of the electrodes; n is the number of electrodes; ε0 is the permittivity of free space; ε1 is the relative permittivity of the measured material; ε2 is the relative permittivity of the material between the electrodes; ε3 is the relative permittivity of the insulating film; K() is the first kind of elliptic integral; a is the spatial distance between the two electrodes; b is the distance between the centers of the two electrodes; h is the thickness of the electrodes;
[0051] 1-3), Calculate the resonant frequency of the RFID tag:
[0052]
[0053] It can be seen that by adjusting the inductance value L of the planar rectangular spiral inductor and the capacitance value C of the interdigital electrodes, the RFID tag operates within the high-frequency band (1 - 100 MHz).
[0054] 1 - 4), the planar rectangular spiral coil 2 and the interdigital electrodes 1 are printed on the insulating film 3 using conductive ink and screen printing technology. Before printing, the shapes of the interdigital electrodes and the planar rectangular spiral inductor are processed on a 0.1 mm thick stainless steel plate using laser etching; then the processed stainless steel plate is placed on the insulating film. The insulating film serves as the substrate, specifically a PET film.
[0055] 1 - 5), after the conductive ink dries, vias are applied to the unconnected ends of the inner ring electrode of the coil 2 and the interdigital electrodes 1, and conductive ink is printed on the reverse side of the insulating film 3 to connect the two vias, thus completing the preparation of the RFID tag.
[0056] In this embodiment, l is taken as 20 mm, N is taken as 40, ε0 is 8.854×10 -12 F / m, ε1 is taken as 4, ε2 is taken as 1, ε3 is taken as 3, a is taken as 0.4 mm, b is taken as 0.8 mm, h is taken as 0.04 mm, and the result is approximately 32 pF; similarly, d0 and d of the planar rectangular spiral inductor 2 i are taken as 35 mm and 10 mm respectively, N is taken as 15, and the result is approximately 4.89 μH; the RFID tag 4 operates within a frequency band of around 12.72 MHz.
[0057] 2), a toroidal coil 8 is wound using a wire, the toroidal coil 8 is welded to the coaxial connector 7, and the coaxial connector 7 is connected to the port of a vector network analyzer (vector network analyzer) 6. The wire used is specifically a copper wire.
[0058] 3), the composite material rotating member 5 is installed on the motor 10, the vector network analyzer 6 is placed at the rear cover of the motor 10, and the toroidal coil 8 is close to the rotating member.
[0059] Specifically, three composite material rotating members are selected as the blades of the fan and installed on the motor 10; there is a plastic plate 9 near the rear cover close to the composite material rotating member, and the toroidal coil 8 is pasted on the plastic plate 9. During the installation of the composite material rotating member 5 and the vector network analyzer 6, the distance l1 between the two when the composite material rotating member is directly in front of the coil is recorded. In this embodiment, l1 is taken as 3 cm.
[0060] 4), the vector network analyzer is calibrated; then the motor 10 is started, and the toroidal coil 8 continuously scans the composite material rotating member. If the scattering parameter S of the vector network analyzer within the scanning frequency does not decay significantly within a certain period of time, the monitoring system issues an alarm.
[0061] The scattering parameter is the ratio of the reflected wave to the incident wave in a vector network analyzer. The attenuation level is the energy loss of the vector network analyzer from the energy emitted from the port to the energy returned to the port. Since the vector network analyzer delivers energy to the coil, the coil will convert it into magnetic field energy, and the magnetic field energy will be absorbed by the conductive material or the coil of the LC resonance circuit with the same frequency. The conductive ability of the carbon fiber composite material plate itself will absorb a certain degree of electromagnetic energy, resulting in a small attenuation; when there is no attenuation, the scattering parameter should be 0, and the smaller the scattering parameter, the greater the attenuation level.
[0062] This step is specifically as follows:
[0063] 4-1), Keep a distance of l1 between the vector network analyzer and the composite rotating member without an embedded RFID tag, and perform a rotational scan at a frequency of f0 ± x MHz. Since the interference of external signals will cause the shift of the resonance point, in order to avoid false warnings of the monitoring system, therefore, the scan frequency is set to f0 ± x MHz, and f0 = f, and x is not higher than 0.1f0. At the same time, the number of scan points is as small as possible (within 10 scan points) without affecting the measurement results to reduce the measurement time of the vector network analyzer.
[0064] Within the scan range of f0 ± x, there is a maximum value of the scattering parameter S (S is negative), and the absolute value of the maximum value is taken as the attenuation level |S| of the scattering parameter when the vector network analyzer scans the carbon fiber composite rotating member without an embedded RFID tag.
[0065] 4-2), Embed the RFID tag into the composite rotating member; that is, first stick PET tapes on the front and back sides of the RFID tag to prevent short circuits. Then place it in the middle layer of the composite rotating member. After curing, the resin inside the composite rotating member comes into contact with the upper and lower sides of the RFID tag.
[0066] 4-3), After the motor starts, the vector network analyzer continuously scans the rotating member. If the resonance frequency of the RFID tag is within the scan frequency range of the vector network analyzer, the magnetic field energy output by the vector network analyzer will be largely absorbed by the tag, and the scattering parameter S will be largely attenuated (as shown by the solid line), indicating that the rotating member has no damage. Figure 5 as shown by the solid line), indicating that the rotating member has no damage.
[0067] If the composite rotating component is damaged, there will be an air gap between the tag 4 and the resin of the composite rotating component 5. At this time, ε1 should be the dielectric constant of air; due to the change in the dielectric constant, the capacitance of the interdigital electrode 1 will change, resulting in a change in the resonance frequency of the RFID tag 4, causing the resonance frequency to shift out of the scanning frequency of the vector network analyzer. Then the RFID tag no longer absorbs the magnetic field energy output by the vector network analyzer, and the magnetic field energy is only absorbed by the carbon fiber composite board, and the scattering parameter S will not be greatly attenuated (as Figure 5 shown by the dashed line); if the attenuation degree of the scattering parameter within the scanning frequency is lower than y|S| within a certain time, it can be determined that damage has occurred inside the rotating component. At this time, the monitoring system issues an alarm. Since the magnitude of |S| will fluctuate due to external signal interference, it is multiplied by the multiple y for amplification to avoid false alarms, and 5 > y > 1.
[0068] In this embodiment, after the motor 10 is started, the vector network analyzer 6 scans the rotating component 5 intermittently, as Figure 6 shown. It scans once every 0.02 s. Before 0.2 s, each time the rotating component 5 passes through the coil 8 of the vector network analyzer 6, the scattering parameter S of the vector network analyzer 6 will be greatly attenuated; at 0.2 s, due to delamination inside the rotating component 5, the resonance frequency decreases and exceeds the scanning range of the vector network analyzer 6. After that, when the rotating component 5 passes through the coil 8 of the vector network analyzer 6, since the resonance frequency of the tag 4 is inconsistent with the scanning range of the vector network analyzer 6 and cannot absorb the energy of the vector network analyzer 6, the scattering parameter S no longer attenuates significantly. And because the delamination damage is irreversible, once the resonance frequency shifts out of the scanning range of the vector network analyzer 6, the attenuation degree of the scattering parameter S will decrease until the time exceeds 4 s, and it can be determined that damage has occurred inside the rotating component 5. At this time, the monitoring system issues an alarm.
[0069] The above specific embodiments are only preferred embodiments of this creation and are not intended to limit this creation. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this creation shall be included within the protection scope of this creation.
Claims
1. A structural health monitoring method for a composite rotating component based on RFID, characterized in that: It includes the following technological steps: 1), Prepare RFID tags; 2), Wind a wire into a toroidal coil, weld the toroidal coil to a coaxial connector, and connect the coaxial connector to the port of a vector network analyzer; 3), Install the composite rotating member on the motor, place the vector network analyzer at the rear cover of the motor, and keep the toroidal coil close to the rotating member; 4), Calibrate the vector network analyzer; then start the motor, and the toroidal coil continuously scans the composite rotating member. If the scattering parameters of the vector network analyzer within the scanning frequency do not decay significantly within a certain period of time, the monitoring system issues an alarm.
2. The structural health monitoring method of the composite rotating component based on RFID according to claim 1, characterized in that: The specific preparation method of the RFID tag in step 1) includes the following steps: 1-1), Design a planar rectangular spiral inductor: where L is the inductance value of the planar rectangular spiral inductor, d0 and d i are the outer length and the inner length of the coil respectively, and N is the number of turns; 1-2), Design interdigital electrodes: Wherein, C is the capacitance value of the interdigital electrodes; l is the length of the electrodes; n is the number of electrodes; ε0 is the free space permittivity; ε1 is the relative permittivity of the material to be measured; ε2 is the relative permittivity of the material between the electrodes; ε3 is the relative permittivity of the insulating film; K() is the first kind of elliptic integral; a is the spatial distance between two electrodes; b is the distance between the centers of two electrodes; h is the thickness of the electrodes; 1-3), Calculate the resonant frequency of the RFID tag: 1-4), Use conductive ink and screen printing technology to print a planar rectangular spiral coil and interdigital electrodes on the insulating film; 1-5), After the conductive ink dries, apply vias at the unconnected ends of the inner ring electrode of the coil and the interdigital electrodes, and print conductive ink on the reverse side of the insulating film to connect the two vias.
3. The structural health monitoring method of the composite rotating component based on RFID according to claim 2, characterized in that: Before step 1-4) is printed, first use laser etching to process the shapes of the interdigital electrodes and the planar rectangular spiral inductor on a stainless steel plate with a thickness of 0.1 mm; then place the processed stainless steel plate on the insulating film.
4. The structural health monitoring method of the composite rotating component based on RFID according to claim 2, characterized in that: The insulating film is used as a substrate, specifically a PET film.
5. The structural health monitoring method of the composite rotating member based on RFID according to claim 1, characterized in that: In step 2), the wire used is specifically a copper wire.
6. The structural health monitoring method of the composite rotating member based on RFID according to claim 2, characterized in that: In step 3), select three composite rotating members as the blades of the fan and install them on the motor; there is a plastic plate near the composite rotating member at the rear cover, and the toroidal coil is pasted on the plastic plate; during the installation process of the composite rotating member and the vector network analyzer, record the distance l1 between the two when the composite rotating member is directly in front of the coil.
7. The structural health monitoring method for a composite rotating member based on RFID according to claim 6, characterized in that: Step 4) is specifically: 4-1), Keep a distance of l1 between the vector network analyzer and the composite rotating member without an embedded RFID tag, and perform rotational scanning at a frequency of f0 ± x MHz; there is a maximum value of the scattering parameter S within the scanning range of f0 ± x, and take the absolute value of the maximum value as the attenuation degree |S| of the scattering parameter when the vector network analyzer scans the carbon fiber composite rotating member without an embedded RFID tag; 4-2), Embed the RFID tag into the composite rotating member; 4-3), after the motor starts, the vector network analyzer continuously scans the rotating component. If the resonant frequency of the RFID tag is within the scanning frequency range of the vector network analyzer, a large amount of the magnetic field energy output by the vector network analyzer will be absorbed by the tag, and the scattering parameter S will be greatly attenuated, indicating that the rotating component has no damage; If the composite rotating component is damaged, resulting in the resonant frequency shifting out of the scanning frequency of the vector network analyzer, the RFID tag will no longer absorb the magnetic field energy output by the vector network analyzer. Then the magnetic field energy will only be absorbed by the carbon fiber composite board, and the scattering parameter S will not be greatly attenuated. If the attenuation degree of the scattering parameter within the scanning frequency is lower than y|S| within a certain time, where 5 > y > 1, it can be determined that damage has occurred inside the rotating component. At this time, the monitoring system issues an alarm.
8. The structural health monitoring method of the composite rotating member based on RFID according to claim 7, characterized in that: In the step 4-1), f0 = f, and x is not higher than 0.1f0.
9. The structural health monitoring method of the composite rotating member based on RFID according to claim 7, characterized in that: The step 4-2) is specifically as follows: First, stick PET tapes on the front and back sides of the RFID tag, and then place it in the middle layer of the composite rotating component. After curing, the resin inside the composite rotating component comes into contact with the upper and lower sides of the RFID tag.
10. The structural health monitoring method of the composite rotating component based on RFID according to claim 8, characterized in that: In the step 4-3), if the attenuation degree of the scattering parameter is lower than 2|S| within 4 seconds, it can be determined that damage has occurred inside the rotating component.