CN212540225U

CN212540225U - Passive wireless piezoelectricity driven composite coating damage detection sensor

Info

Publication number: CN212540225U
Application number: CN202021883450.7U
Authority: CN
Inventors: 吴楠; 王泉
Original assignee: Shantou University
Current assignee: Shantou University
Priority date: 2020-09-02
Filing date: 2020-09-02
Publication date: 2021-02-12
Anticipated expiration: 2030-09-02

Abstract

The embodiment of the utility model discloses passive wireless piezoelectricity driven composite biocoating damage detection sensor, including insulating coating, detection conductive coating, piezo-electric unit, the detection zone territory surface of testee is scribbled to insulating coating, piezo-electric unit with insulating coating faces the coating mutually, detect conductive coating and scribble on the insulating coating surface, and make the testee with piezo-electric unit surface connects into a closed loop circuit, detect conductive coating with piezo-electric unit meets. Adopt the utility model discloses, have real-time high efficiency, simple installation, it is with low costs small, can be used to different material surfaces and motion structure or the damage of part advantage such as survey.

Description

Passive wireless piezoelectricity driven composite coating damage detection sensor

Technical Field

The utility model relates to a structural damage detects technical field, especially relates to a passive wireless piezoelectricity driven composite biocoating damage detection sensor.

Background

Conventional structural damage detection techniques include vibration testing, ultrasonic inspection, optical coating, image processing, and the like.

The vibration test is the structural damage detection method with the longest application time and the most extensive use, and is closer to the scheme method and the starting point of the utility model, so the main description will be made. Vibration testing flaw detection is mainly based on the change of the natural frequency of a structure and the vibration response frequency spectrum to see the generation and development of damage. The material damage or structure loosening can cause the reduction of the structural rigidity or the rubbing phenomenon during the structural vibration, the natural frequency reduction or frequency doubling during the free vibration of the structure can be caused by the phenomenon, the most common application is to use the knocking of a train wheel rail and to check the damage and the loosening of the parts according to the sound frequency. First, flaw detection methods based on structural natural frequencies and modal changes have been commonly studied and applied to a variety of engineering structures by researchers all over the world over the past decades. However, the local damage (such as cracks and bolt loosening) of the structure often only causes the response of the local rigidity change of the structure to the whole structure to be less influenced, for example, a crack or a groove on a cantilever beam may only change 3% or even less than 1% of the natural frequency of the beam, which results in lower flaw detection sensitivity of the vibration testing method based on the change of the natural frequency of the structure. In order to improve the sensitivity of the method, the utility model people and research groups thereof have proposed an active control method using intelligent materials, which is also the current advanced natural frequency vibration test method.

Secondly, a frequency domain analysis method for observing the structural vibration response spectrum change is also a widely used flaw detection method. For example, it is well known in the vibration testing industry that the generation of closed cracks and the opening and closing processes of the cracks caused by vibration can cause the frequency doubling of the vibration spectrum, and the loosening of the structure can also cause similar phenomena. In addition, local material non-linearities due to material damage also alter the vibration spectrum of the structure causing it to shift. However, such frequency doubling and spectral shift phenomena are often weak under small cracks (< 10% of the structural thickness), and in order to improve the sensitivity of flaw detection based on frequency change, it is often necessary to develop and introduce advanced data signal processing methods such as wavelets to amplify the influence of damage on spectral change.

Thirdly, advanced time-domain vibration signal analysis methods are also available for structural damage detection, for example, utility model people and their teams have developed a flaw detection method based on time-domain signal chaos determination, which has a high sensitivity for the detection of micro-cracks (< 5% structural thickness). The combination of the time domain signal chaos and the vibration sensor signal comparison method can detect the micro-cracks with the structure thickness less than 3% and judge the expansion trend of the micro-cracks. In an experiment, the vibration sensor needs to be in real-time contact with data processing software through a wire or a wireless module controlled by a single chip microcomputer, so that the expansion of damage can be efficiently predicted, but the application range and convenience of the vibration sensor are limited by data transmission, a complex data signal processing module and energy supply. Furthermore, in most inspection applications, the primary requirement is to determine the occurrence of a flaw and to signal an early warning. How to develop a small vibration damage detection sensor integrating a damage sensor, a wireless early warning transmitter and an energy supply module becomes a practical requirement in the field of structural damage detection. This is also the problem to be solved by the present invention.

In addition to the most common vibration analysis methods, ultrasonic detection is another advanced flaw detection method. This method determines possible structural damage by transmitting and observing the propagation of mechanical waves in the structure. For example, mechanical waves reflect and diffract at the location of a crack or hole in the structure, and the presence and location of damage can be detected and noted by detecting these reflected waves. However, if the structural design itself has many holes or irregular shapes or even spatial variations of material properties, propagation of mechanical waves will inevitably be disturbed and hindered, so that ultrasonic inspection of different complex structures or materials is still under development and exploration. Although the ultrasonic detection can realize non-contact nondestructive inspection theoretically, the detection requirement is close to the measured object, the requirement on the working environment is high, and the detection equipment is fine and expensive. These practical problems often limit the application of ultrasonic inspection to large engineering structures.

Optical coatings and image processing inspection methods are based on image analysis for inspection. The basic principle of optical coatings is to highlight cracks by penetration of fine particles of the coating into possible cracks in the structure. And then the computer automatically identifies the generation and the position of the crack through image processing. The image processing method can also monitor the structure loosening problem by detecting appearance changes generated by loosening of the structural bolts. Both methods require direct contact or visual inspection of the site where structural damage occurs and require high light conditions.

Based on the above analysis, the main disadvantages of the prior art are: conventional signal acquisition techniques result in high system and material costs due to energy requirements and are not easily implemented for large and mobile structures. The disadvantages and causes of the different methods are as follows:

the vibration analysis method comprises the following steps: in both frequency domain and time domain signal analysis methods, due to the complexity of different vibration signals, environmental noise, and the selected and developed signal processing methods and algorithms have a great influence on the accuracy of damage determination. For the detection of structural damage under different working conditions, the traditional method based on vibration signal analysis still has instability factors. The method usually needs the assistance of computer software, and the sensor does not have the damage early warning capability.

The ultrasonic detection method comprises the following steps: although the method can detect the internal damage of the structure, the stability and the accuracy of the method are not ideal for the application of complex structures and materials in high-noise environments, and even if an advanced data processing and analyzing algorithm is introduced, the detection result cannot be confirmed by 100%.

Conventional optical coating and strain testing methods: the method has high requirements on the smoothness of the structure surface and the visibility of the working environment, and the cost of the coating material and the detection equipment is high.

The traditional image analysis processing method comprises the following steps: the method has high requirement on environment visibility, and needs a high-performance graphic workstation, so that real-time monitoring is difficult to realize due to huge calculation amount.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a technical problem that will solve lies in, provides a passive wireless piezoelectricity driven composite biocoating damage detection sensor, and the damage that damages is surveyed with low cost, small-size mode.

In order to solve the technical problem, the embodiment of the utility model provides a passive wireless piezoelectricity driven composite biocoating damage detection sensor, including insulating coating, detection conductive coating, piezo-electric unit, the detection zone surface of testee is scribbled to insulating coating, piezo-electric unit with insulating coating faces the coating mutually, detect conductive coating and scribble insulating coating surface, and make the testee with piezo-electric unit surface connects into a closed loop circuit, detect conductive coating with piezo-electric unit meets.

The device comprises a conductive base layer coated on the surface of a measured object, and the insulating coating, the detection conductive coating and the piezoelectric unit are arranged on the conductive base layer.

The detection area is more than two, and the insulation coating and the detection conductive coating are connected in series or in parallel.

And a detection circuit is connected in series or in parallel between the piezoelectric unit and the detection conductive coating.

Wherein the detection circuit is a transmitting coil.

And a resonant capacitor is also connected in series between the transmitting coil and the piezoelectric unit.

Implement the embodiment of the utility model provides a, real-time high efficiency, the simple installation, it is with low costs, can be used to the damage detection of different material surfaces and motion structure or part. The concrete advantages and implementation means are as follows:

low cost and small volume: the reasonable utilization of the piezoelectric material can realize the requirements of low cost and easy installation and operation. The simple radio wave generating circuit and device (only an inductance coil and a capacitance element are needed) also ensure the characteristics of low cost and small volume.

High stability and reliability: the novel coating design (without complex data signal processing process) and the simple sensor structure make the sensor extremely high in working stability, and the sensor coating design is tested for a long time of actual working conditions (on a heavy passenger vehicle, the working condition is tested for more than 4 months at the working condition of-20-30 ℃, and the coating sensor works stably and can accurately detect possible damage of the structure). The simple circuit design also ensures the working stability and durability of the circuit;

no external energy consumption: the use of the piezoelectric material realizes that the sensor can directly generate radio waves;

universality: the selection of different coating materials according to different structures and materials can make the flaw detection sensor suitable for various materials and working environments. The flexible morphological design characteristics of piezoelectric materials allow the sensor to be used for damage detection of a variety of moving structures and components, such as rotating components.

Multi-point flaw detection: the coating design can help achieve flexible placement of sensor coverage and location to achieve the capability of simultaneous multi-point inspection.

Drawings

FIG. 1 is a schematic diagram of the structure of the present invention;

FIG. 2 is a schematic structural diagram of the detection circuit of the present invention with a series connection mode;

FIG. 3 is a schematic structural diagram of the detection circuit of the present invention in a parallel connection mode;

FIG. 4 is a schematic structural view of the present invention for detecting the damage of the whole solder joint;

FIG. 5 is a schematic structural view of the present invention for detecting local damage at a welding site;

FIG. 6 is a schematic structural view of the multi-solder-spot series damage detection of the present invention;

FIG. 7 is a schematic structural view of the multi-pad parallel damage detection of the present invention;

fig. 8 is the utility model discloses be applied to the not hard up structural schematic who surveys of bolt.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings.

Reference is made to the schematic structural diagram shown in fig. 1.

The utility model discloses passive wireless piezoelectricity driven composite biocoating damage detection sensor, its basic form includes insulating coating 1, detect conductive coating 2, piezo-element 3, insulating coating 1, detect conductive coating 2 and all coat in the testee 4 surface, the regional surface of detection of testee 4 is coated in insulating coating 1, keep apart with detecting conductive coating 2 in the detection region, piezo-element 3 faces the coating with insulating coating 2 mutually, detect conductive coating 2 and coat insulating coating 1 surface, and connect testee and piezo-element 3.

The piezoelectric unit is used as an electric signal generating coating, the anode and the cathode of the piezoelectric unit are linked by a conductive object to be detected and a detection conductive coating to form a closed loop circuit, and the detection conductive coating and the surface of a detection area of the object to be detected are isolated by an insulating layer. When the structure is healthy, the positive and negative electrodes of the piezoelectric unit are in short circuit, and when the structure works, the surface potential of the piezoelectric unit is zero. When damage occurs in the coverage range of the coating sensor, the insulating coating of the conductive coating is detected to be disconnected at the same time, the positive electrode and the negative electrode of the piezoelectric unit are disconnected, the surface charge of the piezoelectric unit is nonzero when the structure operates, the damage occurs to the structure, and the nonzero potential can be linked to the AB two points through a link to output an early warning signal through a detection circuit.

The piezoelectric unit 3 can be selected as a piezoelectric coating or a ceramic piezoelectric sheet according to actual use requirements.

The measured object 4 is conducting material, when the measured object is non-conducting material, can further select to scribble the electrically conductive basic unit again on the additional survey thing surface to make the measured object and detect conductive coating and link and form a closed loop circuit, thereby the extension the utility model discloses an application scope.

The detection circuit can be an LED indicator light or a transmitting coil, and the embodiment is described as being implemented by the transmitting coil.

As shown in fig. 2, the end of the detection conductive coating 2 connected to the piezoelectric unit 3 is an a end, the end connected to the object to be detected is an B end, and the transmitting coil L is connected in series between the a end of the detection conductive coating 2 and the piezoelectric unit 3, so that the capacitors formed between the coatings form a radio wave oscillating circuit to transmit the detection signal, preferably, in order to make the oscillating frequency resonate and overlap with the oscillation generated by the operating condition of the object to be detected, the transmitting coil L is preferably connected in series with a capacitor C, so that the resonant frequency of the circuit needs to be consistent with or close to the oscillating frequency of the vibration received by the piezoelectric unit 2 (i.e. the frequency of the piezoelectric signal) to generate a strong oscillating electromagnetic wave, and the resistance in the oscillating circuit needs to be as small as possible to obtain a high Q factor and a strong electromagnetic wave, so that the oscillating circuit needs to be adjusted according to the operating condition, in the normal working condition of the embodiment, the circuit works when the end A and the end B are in a short circuit state, and when damage occurs, the end A and the end B are in an open circuit state, and the circuit stops working.

As shown in fig. 3, another connection mode of the detection circuit is shown, the transmitting coil L and the capacitor C are connected in series and then connected to two ends of the piezoelectric unit 3, when the surface of the detection area is damaged, the terminals a and B are in an open circuit state, the circuit starts to work, and the damage sends a warning signal.

The transmitting coil L and the capacitor C of the detection circuit in the series connection and parallel connection modes are attached to the surface of the object to be detected 4, wireless signal transmission is achieved, and the transmitting coil L can be printed and attached to the surface of the object to be detected 4 in an insulation mode.

As shown in fig. 4, the insulating coating 1 and the detecting conductive coating 2 are coated on the welding spots of the object to be detected 4, and the coating coverage detection is performed on the whole welding spots 5.

As shown in fig. 5, when a certain position of a welding spot needs to be detected with emphasis, a wire coating mode can be used, so that the insulating coating 1 and the detecting conductive coating 2 cover the position point of interest.

As shown in fig. 6, if a plurality of solder joints are required to be detected and a single solder joint damage emits an early warning signal, a single coating passes through the plurality of solder joints in a serial manner.

As shown in fig. 7, if it is necessary to detect multiple welding spots and the multiple welding spots are damaged at the same time to emit warning signals, multiple coatings may be used to cover the multiple welding spots in parallel.

As shown in fig. 8, the utility model discloses can be applied to and detect the bolt not hard up, the bolt not hard up can be the torsion of bolt or nut or the axial deformation of bolt itself leads to, and no matter which kind of not hard up all can lead to compound lead coating, the damage of electrical insulation coating and the on-surface nonzero electric potential of piezo-electric unit, and this nonzero electric potential can be through detection circuitry's radio signal transmission early warning signal.

In addition to the above embodiment, the utility model discloses still can be applicable to the damage detection of rotating machinery. The piezoelectric unit can be arranged on the side wall of the bearing inner ring and is connected with a tested part such as a rotating shaft and the like through an electrode and a composite coating (a detection conductive coating and an insulation coating) to form a closed short circuit. The wireless coil and the flat capacitor can be arranged on the rotating shaft in a shaft sleeve mode, when the structure is damaged (such as cracks on the rotating shaft), the composite coating is disconnected, the piezoelectric unit is disconnected, the non-zero potential on the surface of the coating can transmit an early warning signal of electromagnetic waves with specific frequency through a radio signal transmitting circuit, and a distributed electrode can be used on the piezoelectric layer to extract a part of strain on the surface of the piezoelectric unit to generate potential; the same piezoelectric unit can simultaneously detect damage of a plurality of rotating parts or a plurality of positions (such as different angles of the rotating shaft) through a plurality of distributed electrodes and composite coatings.

The utility model is suitable for a solder joint, bolt and the sensor design that rotates mechanical damage and survey, the capture device of signal receiving end demand high sensitivity low frequency radio wave signal, the utility model discloses can also be applied to the damage of machinery and the solder joint of civil structure (like car automobile body, aircraft surface, and bridge structure frame) and fastener and survey and rotate mechanical damage and survey. The method can also be used for detecting the damage of rough surfaces of irregular structures such as concrete high-rise buildings and the like and the damage of other mechanical moving parts.

The utility model discloses with prior art comparison key point and utility model point detail description as follows:

1. the design and application scheme of the piezoelectric driving composite coating is as follows: compare with methods such as vibration analysis flaw detection method, optical coating flaw detection method and ultrasonic wave and image processing based on vibration sensor traditionally, in the technical realization, the utility model provides a brand-new method that utilizes piezoelectric material and composite coating to supply and cut off the power supply, realized independent flaw detection sensor design and need not peripheral data acquisition and analytical equipment and confirm the emergence of damage. And, the utility model discloses based on piezoelectricity composite coating has provided the multiple spot detection design to different structural damage (like solder joint, fastener and moving part etc.), realized the commonality of sensor of detecting a flaw.

2. The piezoelectric driving wireless signal without energy consumption is generated and transmitted: the wireless vibration sensor is also applied and developed in recent years, but the traditional wireless signal transmission technology is mainly based on an analog-digital conversion circuit and a wireless signal generator controlled by a single chip microcomputer to transmit wireless signals, and the technology is often used with corresponding electronic components and batteries. The utility model provides a radio wave signal production all realizes through the piezoelectric material of piezoelectricity composite coating itself with the transmission, thereby radio coil and electric capacity part all can attach in piezoelectric material or the coating has reduced the sensor volume greatly to no energy demand's radio early warning signal transmission has been realized.

The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.

Claims

1. The utility model provides a passive wireless piezoelectricity driven composite biocoating damage detection sensor which characterized in that, includes insulating coating, detects conductive coating, piezo-element, insulating coating coats the detection zone surface of testee, piezo-element with insulating coating faces the coating mutually, detect conductive coating and coat insulating coating surface, and make the testee with piezo-element surface connects into a closed loop circuit, detect conductive coating with piezo-element meets.

2. The passive wireless piezoelectric driven composite coating damage detection sensor according to claim 1, wherein a detection circuit is connected in series or in parallel between the piezoelectric unit and the detection conductive coating.

3. A passive wireless piezo-electrically driven composite coating damage detection sensor according to claim 2, characterized in that the detection circuit is a transmitting coil.

4. The passive wireless piezoelectric driven composite coating damage detection sensor according to claim 3, wherein a resonant capacitor is further connected in series between the transmitting coil and the piezoelectric unit.

5. A passive wireless piezoelectric driven composite coating damage detection sensor according to any one of claims 1-4, wherein the detection area is more than two, and the insulation coating and the detection conductive coating are connected in series or in parallel.

6. The passive wireless piezoelectric driven composite coating damage detection sensor according to claim 5, further comprising a conductive base layer coated on the surface of the object to be detected, wherein the insulating coating, the detection conductive coating and the piezoelectric unit are arranged on the conductive base layer.

7. The passive wireless piezoelectric driven composite coating damage detection sensor according to any one of claims 1 to 4, further comprising a conductive base layer coated on the surface of the object to be detected, wherein the insulating coating, the detection conductive coating and the piezoelectric unit are arranged on the conductive base layer.