SAW (Surface Acoustic Wave) sensor for monitoring vibration of shockproof hammer in real time and monitoring method thereof

Abstract

The invention relates to the technical field of power transmission line fault monitoring, and provides an SAW sensor for monitoring vibration of a shockproof hammer in real time and a monitoring method thereof. The method comprises the following steps that 1, a vibration signal of the shockproof hammer excites the SAW sensor, a piezoelectric substrate of the SAW sensor generates surface acoustic waves, and the substrate of the SAW sensor is prepared from a flexible material; step 2, the vibration signal of the shockproof hammer causes the characteristic change of the piezoelectric substrate of the SAW sensor, and the propagation signal of the surface acoustic wave is changed; 3, receiving the changed propagation signal of the surface acoustic wave by an interdigital transducer of the SAW sensor, and converting the changed propagation signal of the surface acoustic wave into an electric signal for transmission; and 4, transmitting the electric signal to a signal receiver of the SAW sensor, and calculating the vibration displacement of the shockproof hammer. According to the scheme of the invention, based on the SAW technology, the characteristics of high frequency and high sensitivity of surface acoustic waves are utilized, and rapid capture and real-time monitoring of vibration signals of the shockproof hammer are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of power transmission line fault monitoring, and in particular relates to a SAW sensor for real-time monitoring of vibration of an anti-vibration hammer and a monitoring method thereof. Background Art

[0002] The transmission line anti-vibration hammer is a protective device set up to reduce the vibration of the transmission line due to the wind in the sky. Overhead transmission lines are mostly built in the wild natural environment. They are disturbed by wind, frost, rain and snow in the natural environment for a long time. The anti-vibration hammer will inevitably vibrate. When the vibration frequency and amplitude are too large, it will cause the anti-vibration hammer to slip and fall off, which will seriously endanger the stability and safety of my country's power transportation system. The traditional anti-vibration hammer inspection method is manual inspection, which is time-consuming, inefficient, and inaccurate. There is also a high risk of personnel safety, which makes it difficult to ensure the normal operation of the transmission line.

[0003] In view of the shortcomings and limitations of the traditional anti-vibration hammer inspection method, inspection robots for transmission lines have been developed at home and abroad. They are mounted on the transmission lines by hanging online, and use machine vision to realize online monitoring of anti-vibration hammer slippage, falling off and other problems. However, the monitoring method using inspection robots still has many shortcomings. First, the inspection robot relies on a complex mechanical structure and power system, which is costly and requires high equipment maintenance, making it unsuitable for large-scale popularization and application; second, the inspection robot usually conducts regular inspections, making it difficult to realize real-time monitoring of the vibration state of the anti-vibration hammer, and it is impossible to detect sudden vibration anomalies in time; in addition, the operation of the robot is greatly affected by the environment, and it may not work normally under severe weather conditions, further limiting its applicability in the complex natural environment of the transmission line; finally, the robot is easily corroded and damaged by the external environment during long-term use, resulting in instability in data collection. Summary of the invention

[0004] The present invention provides a SAW sensor for real-time monitoring of the vibration of a shock-absorbing hammer and a monitoring method thereof, which can improve the shortcomings of manual inspection of shock-absorbing hammers in related technologies, such as long time consumption, low efficiency, poor accuracy and high personnel safety risks, and it is difficult to ensure the normal operation of transmission lines. In addition, the monitoring method using inspection robots still has many technical problems.

[0005] In a first aspect, the present invention provides a monitoring method of a SAW sensor for real-time monitoring of vibration of an anti-vibration hammer, comprising the following steps:

[0006] Step 1: The vibration signal of the anti-vibration hammer excites the SAW sensor, and the piezoelectric substrate of the SAW sensor generates a surface acoustic wave. The SAW sensor is made of a flexible material to prepare the substrate;

[0007] Step 2: The vibration signal of the anti-vibration hammer causes the piezoelectric substrate characteristics of the SAW sensor to change, thereby changing the propagation signal of the surface acoustic wave;

[0008] Step 3: The interdigital transducer of the SAW sensor receives the changed propagation signal of the surface acoustic wave and converts the changed propagation signal of the surface acoustic wave into an electrical signal for transmission;

[0009] Step 4: The electrical signal is transmitted to the signal receiver of the SAW sensor, and after analyzing the electrical signal, the vibration displacement of the shock-absorbing hammer is calculated.

[0010] The present invention provides a monitoring method for a SAW sensor for real-time monitoring of the vibration of an anti-shock hammer, which has at least the following technical effects: based on SAW technology, utilizing the high frequency and high sensitivity characteristics of surface acoustic waves, rapid capture and real-time monitoring of the vibration signal of the anti-shock hammer can be achieved, effectively improving the timeliness of the monitoring of the vibration signal of the anti-shock hammer; adopting a wireless passive working mode, without the need for external power supply, avoiding the service life limitations and maintenance difficulties of traditional battery power supply methods, and improving the reliability and durability of the device; in addition, the substrate made of flexible materials can fit the complex curved structure of the anti-shock hammer, thereby improving the adaptability of the installation and reducing the requirements for the surface flatness of the SAW sensor.

[0011] Furthermore, in step 1, the flexible material is polyimide.

[0012] Furthermore, the propagation signal of the surface acoustic wave in step 1 includes wave velocity, frequency and wavelength.

[0013] Furthermore, in step 2, the propagation signal of the surface acoustic wave is analyzed by combining the piezoelectric equation, the wave equation and the coupled Maxwell electromagnetic equations, and the motion equation of the particle on the wave is:

[0014]

[0015] Where ρ is the material density; represents partial derivative; t is time; u i is the displacement of the material at position x at time t; T ij is the mechanical stress; x j is the coordinate component; i and j are two different directions;

[0016] The stress on the piezoelectric substrate is:

[0017] Where, T ij is the stress on the piezoelectric substrate; is the elastic stiffness constant when the electric field is constant; e kij is the piezoelectric constant; S kl is the strain tensor; E k is the electric field strength;

[0018] The electric field strength is:

[0019] In the formula, E k is the electric field strength; represents partial derivative; Φ is electric potential; x k is the coordinate component; k = 1, 2, 3, is the x, y, z axis coordinate in the spatial rectangular coordinate system;

[0020] The relationship between the strain of the piezoelectric substrate and the particle displacement is:

[0021] In the formula, S kl is the strain tensor; represents partial derivative; u i is the displacement of the material on the x-axis at time t; l is the coordinate component; k and l are two different directions;

[0022] The divergence of the electric displacement vector D is zero, expressed as:

[0023] In the formula, is the divergence of the electric displacement vector; represents partial derivative; x1 is the coordinate component of the x-axis; x2 is the coordinate component of the y-axis; x3 is the coordinate component of the z-axis; D1 is the component of the electric displacement vector in the x1 direction; D2 is the component of the electric displacement vector in the x2 direction; D3 is the component of the electric displacement vector in the x3 direction;

[0024] The equation for surface acoustic wave propagation on a piezoelectric substrate is:

[0025]

[0026] In the formula, is the elastic stiffness tensor; e jkl is the piezoelectric constant tensor; l k is the direction cosine component of the wave propagation direction in the k direction; l j is the direction cosine component of the wave propagation direction in direction i; l l is the direction cosine component of the wave propagation direction in the l direction; ρ is the material density; v is the propagation velocity of the surface acoustic wave; δ ik is the Kronecker function; α k is the amplitude factor related to wave propagation; i, j, k, l are the indices of the tensor, and their value range is 1, 2, 3.

[0027] Furthermore, the interdigital transducer in step 2 has an interdigital width of 30 μm, an interdigital half period of 60 μm, a thickness of 120 nm, an acoustic aperture of 800 μm, and an interdigital logarithm N. tThe metallization rate is 50%.

[0028] Furthermore, in step 4, the vibration of the anti-vibration hammer causes the strain of the SAW sensor, and the strain is

[0029] Where ε is the strain; ΔL is the linear length increment of the tiny linear unit, and L is the initial length of the tiny linear unit;

[0030] The resonant frequency of the SAW sensor is:

[0031] Where, f0 is the change in the resonant frequency of the SAW sensor; v is the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor;

[0032] When the surface acoustic wave is deformed by external force, the propagation path length of the SAW sensor and the interdigital width of the interdigital transducer will change, and the resonant frequency change Δf0 of the SAW sensor is:

[0033]

[0034] Where, Δf0 is v, the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor; Δλ is the change in the SAW wavelength;

[0035] The relationship between the resonant frequency change Δf0 of the SAW sensor and the strain of the SAW sensor is expressed as:

[0036] Where f0 is the resonant frequency of the SAW sensor; ε is the strain; Δf0 is the change in the resonant frequency of the SAW sensor; α is the strain coefficient, and the type and tangent of the piezoelectric substrate material determine the value of α.

[0037] Furthermore, the piezoelectric substrate material is 128° YX-cut lithium niobate, with a gauge coefficient α=0.2×10 -6 / με-0.5× 10-6 / με, 128°YX-cut lithium niobate as a piezoelectric substrate material can efficiently convert electrical signals and acoustic signals to each other, achieve high-sensitivity and real-time monitoring, and is stable in temperature differences and harsh environments, and is suitable for long-term vibration monitoring of power transmission lines under complex natural conditions.

[0038] In a second aspect, the present invention provides a SAW sensor for real-time monitoring of vibration of an anti-shock hammer, comprising:

[0039] A base layer, the base layer is a cube structure, with a length of 5 mm, a width of 5 mm, and a thickness of 30 um, and the base layer is made of polyimide;

[0040] A piezoelectric layer, the piezoelectric layer is located above the base layer, the piezoelectric layer is a cubic structure, with a length of 5 mm, a width of 5 mm, and a thickness of 50 um, and the piezoelectric layer is made of 128° YX-cut lithium niobate;

[0041] The electrode layer is located above the piezoelectric layer. The electrode layer is two pairs of vertically orthogonal interdigital transducers. The interdigital width of the interdigital transducer is 30um, the interdigital half-period is 60um, the thickness is 120nm, the acoustic aperture is 800um, and the electrode layer is made of aluminum.

[0042] Two pairs of perpendicular interdigital transducers can detect displacement in the x and y axes.

[0043] Furthermore, the preparation process of the SAW sensor comprises the following steps:

[0044] Step S1: cleaning the 128° YX-cut lithium niobate piezoelectric substrate;

[0045] Step S2: bonding 128° YX-cut lithium niobate with a thickness of 600 um to a UV film with a thickness of 150 um;

[0046] Step S3: thinning the 128° YX-cut lithium niobate to 50 um to obtain a single crystal thin film 128° YX-cut lithium niobate;

[0047] Step S4: Use acetone and isopropanol to clean the single crystal thin film 128° YX-cut lithium niobate in turn, then spin-coat the photoresist at a speed of 3000 rpm for 60 seconds, and then pre-bake at 105°C for 5 minutes; then perform UV exposure at 8mW / cm in Soft mode. 2 The power was used for exposure for 3 seconds; then the film was developed for 20 seconds and then rinsed with deionized water. After sufficient exposure and development, the film was hardened at 105°C for 3 minutes, and then a 120nm aluminum metal film was sputtered and finally the aluminum electrode was peeled off.

[0048] Step S5: UV exposure for 0.5 h, then immersion in acetone, and ventilation heating at 105°C for 0.5 h, until the UV film on the back of the single crystal thin film 128° YX-cut lithium niobate is removed;

[0049] Step S6: using a UV light source to illuminate the UV film to invalidate the viscosity of the UV film, and then using an acetone solution to remove the UV film;

[0050] Step S7: sequentially wash the polyimide flexible substrate with deionized water, acetone and isopropyl alcohol, and then dry the polyimide flexible substrate at 80-100°C.

[0051] Step S8: Spin-coat epoxy resin as an adhesive on the polyimide flexible substrate to form a uniform adhesive layer with a thickness of 5 um.

[0052] The use of low-cost flexible substrates and aluminum electrodes, optimized manufacturing processes and modular design can significantly reduce production and installation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0054] Figure 1 A flow chart of a monitoring method of a SAW sensor for real-time monitoring of vibration of an anti-vibration hammer provided by an embodiment of the present invention;

[0055] Figure 2 A three-dimensional view of a SAW sensor provided by an embodiment of the present invention;

[0056] Figure 3 A side view of a SAW sensor provided by an embodiment of the present invention;

[0057] Figure 4 A schematic diagram of the structure of the interdigital electrodes of the SAW sensor provided in an embodiment of the present invention;

[0058] Figure 5 A simulation mode diagram of a specific embodiment provided for an embodiment of the present invention;

[0059] Figure 6 A flow chart of a process for preparing a SAW sensor provided by an embodiment of the present invention;

[0060] Figure 7 A schematic diagram of the connection relationship between a SAW sensor and a shock-absorbing hammer according to a specific embodiment of the present invention.

[0061] Reference numerals:

[0062] 1. Base layer; 2. Piezoelectric layer; 3. Electrode layer. DETAILED DESCRIPTION

[0063] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments rather than limiting the present invention.

[0065] In order to improve the technical problems of low modeling efficiency and insufficient equivalent accuracy of new energy station modeling technology in related technologies, the embodiments of the present invention provide the following solutions.

[0066] In some embodiments, Figure 1 As shown, the present invention provides a monitoring method of a SAW sensor for real-time monitoring of vibration of an anti-vibration hammer, comprising the following steps:

[0067] Step 1: The vibration signal of the anti-vibration hammer excites the SAW sensor, and the piezoelectric substrate of the SAW sensor generates a surface acoustic wave. The SAW sensor uses a flexible material to prepare the substrate;

[0068] Step 2: The vibration signal of the anti-vibration hammer causes the piezoelectric substrate characteristics of the SAW sensor to change, thereby changing the propagation signal of the surface acoustic wave;

[0069] Step 3: The interdigital transducer of the SAW sensor receives the changed propagation signal of the surface acoustic wave and converts the changed propagation signal of the surface acoustic wave into an electrical signal for transmission;

[0070] Step 4: The electrical signal is transmitted to the signal receiver of the SAW sensor, and after analyzing the electrical signal, the vibration displacement of the shock-absorbing hammer is calculated.

[0071] Specifically, in step 1, the flexible material is polyimide.

[0072] Specifically, the propagation signal of the surface acoustic wave in step 1 includes wave velocity, frequency and wavelength.

[0073] It can be understood that the SAW sensor is affected by the vibration signal of the shock absorber, and the piezoelectric substrate material properties of the SAW sensor, such as density, elastic modulus, and geometric dimensions such as length, change, thereby causing the propagation characteristics of the surface acoustic wave, wave velocity, frequency and wavelength to change. The SAW sensor interdigital transducer converts the surface acoustic wave into an electrical signal and transmits it to the signal receiver of the SAW sensor. By analyzing the electrical signal, the vibration displacement of the shock absorber can be calculated.

[0074] Such a setting, based on SAW technology, utilizes the high frequency and high sensitivity characteristics of surface acoustic waves to realize rapid capture and real-time monitoring of the vibration signal of the shock-absorbing hammer, effectively improving the timeliness of the vibration signal monitoring of the shock-absorbing hammer; adopts a wireless passive working mode, without the need for external power supply, avoiding the service life limitations and maintenance difficulties of traditional battery power supply, and improving the reliability and durability of the device; in addition, the substrate made of flexible materials can fit the complex curved structure of the shock-absorbing hammer, improve the adaptability of the installation, and at the same time reduce the surface flatness requirements of the SAW sensor.

[0075] Specifically, in step 2, the propagation signal of the surface acoustic wave is analyzed by combining the piezoelectric equation, the wave equation and the coupled Maxwell electromagnetic equations, and the motion equation of the particle on the wave is:

[0076]

[0077] Where ρ is the material density; represents partial derivative; t is time; u i is the displacement of the material at position x at time t; T ij is the mechanical stress; x j is the coordinate component; i and j are two different directions;

[0078] The stress on the piezoelectric substrate is:

[0079] Where, T ij is the stress on the piezoelectric substrate; is the elastic stiffness constant when the electric field is constant; e kij is the piezoelectric constant; S kl is the strain tensor; E k is the electric field strength;

[0080] The electric field strength is:

[0081] In the formula, E k is the electric field strength; represents partial derivative; Φ is electric potential; x k is the coordinate component; k = 1, 2, 3, is the x, y, z axis coordinate in the spatial rectangular coordinate system;

[0082] The relationship between the strain of the piezoelectric substrate and the particle displacement is:

[0083] In the formula, S kl is the strain tensor; represents partial derivative; u i is the displacement of the material on the x-axis at time t; l is the coordinate component; k and l are two different directions;

[0084] The divergence of the electric displacement vector D is zero, expressed as:

[0085] In the formula, is the divergence of the electric displacement vector; represents partial derivative; x1 is the coordinate component of the x-axis; x2 is the coordinate component of the y-axis; x3 is the coordinate component of the z-axis; D1 is the component of the electric displacement vector in the x1 direction; D2 is the component of the electric displacement vector in the x2 direction; D3 is the component of the electric displacement vector in the x3 direction;

[0086] The equation for surface acoustic wave propagation on a piezoelectric substrate is:

[0087]

[0088] In the formula, is the elastic stiffness tensor; e jkl is the piezoelectric constant tensor; l k is the direction cosine component of the wave propagation direction in the k direction; l j is the direction cosine component of the wave propagation direction in direction i; l l is the direction cosine component of the wave propagation direction in the l direction; ρ is the material density; v is the propagation velocity of the surface acoustic wave; δ ik is the Kronecker function; α k is the amplitude factor related to wave propagation; i, j, k, l are the indices of the tensor, and their value range is 1, 2, 3.

[0089] Specifically, the interdigital transducer in step 2 has an interdigital width of 30 μm, an interdigital half-period of 60 μm, a thickness of 120 nm, an acoustic aperture of 800 μm, an interval of 60 μm, and an interdigital pair number N. t The metallization rate is 50%.

[0090] It can be understood that the interdigital transducer is a key component of the SAW sensor. Considering the propagation characteristics of the surface acoustic wave and the characteristics of the piezoelectric substrate material 128° YX-cut lithium niobate, the wavelength is set to 120um, the interdigital width a of the interdigital transducer is set to 30um, the interdigital half-period p is set to 60um, the thickness is set to 120nm, the acoustic aperture is set to 800um, the interval is set to 60um, and the number of interdigits is set to N t The acoustic aperture of the IDT is proportional to the amplitude of the surface acoustic wave and inversely proportional to the insertion loss. When the acoustic aperture is too large, the equivalent capacitance of the IDT increases, making the size larger and increasing the difficulty of the preparation process. When the acoustic aperture is too small, the diffraction phenomenon of the surface acoustic wave is aggravated and the device performance is reduced. Therefore, the acoustic aperture is set to 800um to balance the performance of the SAW sensor and the feasibility of the preparation process.

[0091] Furthermore, in step 4, the vibration of the anti-vibration hammer causes the strain of the SAW sensor, and the strain is

[0092] Where ε is the strain; ΔL is the linear length increment of the tiny linear unit, and L is the initial length of the tiny linear unit;

[0093] The resonant frequency of the SAW sensor is:

[0094] Where, f0 is the change in the resonant frequency of the SAW sensor; v is the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor;

[0095] When the surface acoustic wave is deformed by external force, the propagation path length of the SAW sensor and the interdigital width of the interdigital transducer will change, and the resonant frequency change Δf0 of the SAW sensor is:

[0096]

[0097] Where, Δf0 is v, the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor; Δλ is the change in the SAW wavelength;

[0098] The relationship between the resonant frequency change Δf0 of the SAW sensor and the strain of the SAW sensor is expressed as:

[0099] Where f0 is the resonant frequency of the SAW sensor; ε is the strain; Δf0 is the change in the resonant frequency of the SAW sensor; α is the strain coefficient, and the type and tangent of the piezoelectric substrate material determine the value of α.

[0100] It can be understood that there is a linear relationship between strain and the resonant frequency of the SAW sensor, which can be expressed as However, when the SAW sensor is deformed by external force, in addition to the change in the wavelength of the SAW sensor, the velocity of the surface acoustic wave will also change accordingly. Therefore, when the SAW sensor is subjected to external force, there is a strain proportional coefficient α between the ratio of the change in the resonant frequency of the SAW sensor to the initial resonant frequency and the magnitude of the strain. α is related to the type and tangent of the piezoelectric substrate material.

[0101] Specifically, the piezoelectric substrate material is 128° YX-cut lithium niobate, with a gauge coefficient α=0.2×10 -6 / με-0.5× 10-6 / με.

[0102] It can be understood that by using 128° YX-cut lithium niobate as the piezoelectric substrate material, the electrical signal and the acoustic signal can be efficiently converted to each other, high sensitivity and real-time monitoring can be achieved, and the SAW sensor can also be stable under temperature differences and harsh environments, which is suitable for long-term vibration monitoring of power transmission lines under complex natural conditions.

[0103] In some embodiments, the present invention provides a SAW sensor for real-time monitoring of vibration of an anti-shock hammer, comprising:

[0104] Base layer 1, the base layer 1 is a cubic structure, with a length of 5 mm, a width of 5 mm, and a thickness of 30 um, and the base layer 1 is made of polyimide;

[0105] A piezoelectric layer 2, the piezoelectric layer 2 is located above the base layer 1, the piezoelectric layer 2 is a cubic structure, with a length of 5 mm, a width of 5 mm, and a thickness of 50 um, and the piezoelectric layer 2 is made of 128° YX-cut lithium niobate;

[0106] The electrode layer 3 is located above the piezoelectric layer 2. The electrode layer 3 is two pairs of vertically orthogonal interdigital transducers. The interdigital width of the interdigital transducer is 30um, the interdigital half period is 60um, the thickness is 120nm, the acoustic aperture is 800um, and the electrode layer 3 is made of aluminum.

[0107] It can be understood that two pairs of perpendicular and orthogonal interdigital transducers can detect displacements in both the x-axis and y-axis directions.

[0108] With this arrangement, when external strain or vibration acts on the SAW sensor, the surface acoustic wave propagation paths in the x and y axis directions will change to varying degrees, causing the corresponding resonance frequency of the interdigital electrodes to shift. By detecting the frequency changes of the two pairs of interdigital electrodes respectively, the displacement or strain in the x and y axis directions can be accurately measured, thereby achieving comprehensive monitoring of the two-dimensional vibration or stress state, improving the adaptability and measurement capability of the SAW sensor, and being particularly suitable for vibration detection of anti-vibration hammers with curved surfaces.

[0109] Specifically, the preparation process of the SAW sensor includes the following steps:

[0110] Step S1: cleaning the 128° YX-cut lithium niobate piezoelectric substrate;

[0111] Step S2: bonding 128° YX-cut lithium niobate with a thickness of 600 um to a UV film with a thickness of 150 um;

[0112] Step S3: thinning the 128° YX-cut lithium niobate to 50 um to obtain a single crystal thin film 128° YX-cut lithium niobate;

[0113] Step S4: Use acetone and isopropanol to clean the single crystal thin film 128° YX-cut lithium niobate in turn, then spin-coat the photoresist at a speed of 3000 rpm for 60 seconds, and then pre-bake at 105°C for 5 minutes; then perform UV exposure at 8mW / cm in Soft mode. 2 The power was used for exposure for 3 seconds; then the film was developed for 20 seconds and then rinsed with deionized water. After sufficient exposure and development, the film was hardened at 105°C for 3 minutes, and then a 120nm aluminum metal film was sputtered and finally the aluminum electrode was peeled off.

[0114] Step S5: UV exposure for 0.5 h, then immersion in acetone, and ventilation heating at 105°C for 0.5 h, until the UV film on the back of the single crystal thin film 128° YX-cut lithium niobate is removed;

[0115] Step S6: using a UV light source to illuminate the UV film to invalidate the viscosity of the UV film, and then using an acetone solution to remove the UV film;

[0116] Step S7: sequentially wash the polyimide flexible substrate with deionized water, acetone and isopropyl alcohol, and then dry the polyimide flexible substrate at 80-100°C.

[0117] Step S8: Spin-coat epoxy resin as an adhesive on the polyimide flexible substrate to form a uniform adhesive layer with a thickness of 5 um.

[0118] It can be understood that the use of low-cost flexible substrates and aluminum electrodes, optimized manufacturing processes and modular design can significantly reduce production and installation costs.

[0119] Embodiment 1:

[0120] like Figure 5 As shown, the initial propagation velocity of the Rayleigh wave on the substrate surface in the simulation experiment is v0=3924m / s, and the initial resonant frequency is f0=32.514MHz. It can be seen that the high resonant frequency can significantly improve the sensor's detection sensitivity to tiny vibrations or strains, and can capture extremely small vibration changes, making monitoring more accurate.

[0121] Embodiment 2:

[0122] like Figure 7 As shown, by using polyimide as a material to prepare a flexible substrate for the SAW sensor, the sensor can be bent or attached to the irregular or curved structure of the shock-absorbing hammer to ensure the working stability of the SAW sensor. It can be fixed with a high-performance adhesive, such as a conductive adhesive or a double-sided adhesive film, to achieve strong bonding while avoiding damage to the sensor due to mechanical stress. It can also be combined with magnetic fixation, mechanical clamps or hot-melt attachment to enhance vibration resistance and environmental adaptability.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A monitoring method of a SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer, characterized in that: The following steps are involved: Step 1: The vibration signal of the anti-vibration hammer excites the SAW sensor, and the piezoelectric substrate of the SAW sensor generates a surface acoustic wave. The SAW sensor is made of a flexible material to prepare the substrate; Step 2: The vibration signal of the anti-vibration hammer causes the piezoelectric substrate characteristics of the SAW sensor to change, thereby changing the propagation signal of the surface acoustic wave; Step 3: The interdigital transducer of the SAW sensor receives the changed propagation signal of the surface acoustic wave and converts the changed propagation signal of the surface acoustic wave into an electrical signal for transmission; Step 4: The electrical signal is transmitted to the signal receiver of the SAW sensor, and after analyzing the electrical signal, the vibration displacement of the shock-absorbing hammer is calculated.

2. The monitoring method of a SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer according to claim 1, characterized in that: In the step 1, the flexible material is polyimide.

3. The monitoring method of a SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer according to claim 1, characterized in that: The propagation signal of the surface acoustic wave in step 1 includes wave velocity, frequency and wavelength.

4. The monitoring method of a SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer according to claim 1, characterized in that: In step 2, the propagation signal of the surface acoustic wave is analyzed by combining the piezoelectric equation, the wave equation and the coupled Maxwell electromagnetic equations. The motion equation of the particle on the wave is: Where ρ is the material density; represents partial derivative; t is time; u i is the displacement of the material at position x at time t; T ij is the mechanical stress; x j is the coordinate component; i and j are two different directions; The stress on the piezoelectric substrate is: Where, T ij is the stress on the piezoelectric substrate; is the elastic stiffness constant when the electric field is constant; e kij is the piezoelectric constant; S kl is the strain tensor; E k is the electric field strength; The electric field strength is: In the formula, E k is the electric field strength; represents partial derivative; Φ is electric potential; x k is the coordinate component; k = 1, 2, 3, is the x, y, z axis coordinate in the spatial rectangular coordinate system; The relationship between the strain of the piezoelectric substrate and the particle displacement is: In the formula, S kl is the strain tensor; represents partial derivative; u i is the displacement of the material on the x-axis at time t; l is the coordinate component; k and l are two different directions; The divergence of the electric displacement vector D is zero, expressed as: In the formula, is the divergence of the electric displacement vector; represents partial derivative; x1 is the coordinate component of the x-axis; x2 is the coordinate component of the y-axis; x3 is the coordinate component of the z-axis; D1 is the component of the electric displacement vector in the x1 direction; D2 is the component of the electric displacement vector in the x2 direction; D3 is the component of the electric displacement vector in the x3 direction; The equation for surface acoustic wave propagation on a piezoelectric substrate is: In the formula, is the elastic stiffness tensor; e jkl is the piezoelectric constant tensor; l k is the direction cosine component of the wave propagation direction in the k direction; l j is the direction cosine component of the wave propagation direction in direction i; l l is the direction cosine component of the wave propagation direction in the l direction; ρ is the material density; v is the propagation velocity of the surface acoustic wave; δ ik is the Kronecker function; α k is the amplitude factor related to wave propagation; i, j, k, l are the indices of the tensor, and their value range is 1, 2, 3.

5. The monitoring method of a SAW sensor for real-time monitoring of vibration of an anti-vibration hammer as claimed in claim 1, characterized in that: The interdigital transducer in step 2 has an interdigital width of 30 μm, an interdigital half period of 60 μm, a thickness of 120 nm, an acoustic aperture of 800 μm, and an interdigital logarithm N. t The metallization rate is 50%.

6. The monitoring method of a SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer according to claim 1, characterized in that: In step 4, the vibration of the anti-vibration hammer causes the strain of the SAW sensor, and the strain is Where ε is the strain; ΔL is the linear length increment of the tiny linear unit, and L is the initial length of the tiny linear unit; The resonant frequency of the SAW sensor is: Where, f0 is the change in the resonant frequency of the SAW sensor; v is the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor; When the surface acoustic wave is deformed by external force, the propagation path length of the SAW sensor and the interdigital width of the interdigital transducer will change, and the resonant frequency change Δf0 of the SAW sensor is: Where, Δf0 is v, the wave velocity of the SAW sensor; λ is the wavelength of the SAW sensor; Δλ is the change in the SAW wavelength; The relationship between the resonant frequency change Δf0 of the SAW sensor and the strain of the SAW sensor is expressed as: Where f0 is the resonant frequency of the SAW sensor; ε is the strain; Δf0 is the change in the resonant frequency of the SAW sensor; α is the strain coefficient, and the type and tangent of the piezoelectric substrate material determine the value of α.

7. The monitoring method of the SAW sensor for real-time monitoring of the vibration of the shock-absorbing hammer according to claim 6, wherein the piezoelectric substrate material is 128° YX-cut lithium niobate, and the strain coefficient α is 0.2×10 -6 / με-0.5× 10-6 / με.

8. A SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer, characterized in that: include: A base layer, the base layer is a cube structure, with a length of 5 mm, a width of 5 mm, and a thickness of 30 um, and the base layer is made of polyimide; A piezoelectric layer, the piezoelectric layer is located above the base layer, the piezoelectric layer is a cubic structure, with a length of 5 mm, a width of 5 mm, and a thickness of 50 um, and the piezoelectric layer is made of 128° YX-cut lithium niobate; The electrode layer is located above the piezoelectric layer. The electrode layer is two pairs of vertically orthogonal interdigital transducers. The interdigital width of the interdigital transducer is 30um, the interdigital half-period is 60um, the thickness is 120nm, the acoustic aperture is 800um, and the electrode layer is made of aluminum.

9. The SAW sensor for real-time monitoring of vibration of a shock-absorbing hammer as claimed in claim 7, characterized in that: The preparation process of the SAW sensor comprises the following steps: Step S1: cleaning the 128° YX-cut lithium niobate piezoelectric substrate; Step S2: bonding 128° YX-cut lithium niobate with a thickness of 600 um to a UV film with a thickness of 150 um; Step S3: thinning the 128° YX-cut lithium niobate to 50 um to obtain a single crystal thin film 128° YX-cut lithium niobate; Step S4: Use acetone and isopropanol to clean the single crystal thin film 128° YX-cut lithium niobate in turn, then spin-coat the photoresist at a speed of 3000 rpm for 60 seconds, and then pre-bake at 105°C for 5 minutes; then perform UV exposure at 8mW / cm in Soft mode. 2 The power was used for exposure for 3 seconds; then the film was developed for 20 seconds and then rinsed with deionized water. After sufficient exposure and development, the film was hardened at 105°C for 3 minutes, and then a 120nm aluminum metal film was sputtered and finally the aluminum electrode was peeled off. Step S5: UV exposure for 0.5 h, then immersion in acetone, and ventilation heating at 105°C for 0.5 h, until the UV film on the back of the single crystal thin film 128° YX-cut lithium niobate is removed; Step S6: using a UV light source to illuminate the UV film to invalidate the viscosity of the UV film, and then using an acetone solution to remove the UV film; Step S7: sequentially wash the polyimide flexible substrate with deionized water, acetone and isopropyl alcohol, and then dry the polyimide flexible substrate at 80-100°C. Step S8: Spin-coat epoxy resin as an adhesive on the polyimide flexible substrate to form a uniform adhesive layer with a thickness of 5 um.

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