CN116985500A

CN116985500A - Acoustic emission sensor and method for manufacturing same

Info

Publication number: CN116985500A
Application number: CN202311242749.2A
Authority: CN
Inventors: 任丹阳; 尹永刚; 施钧辉; 钟亮; 王钰琪; 高大
Original assignee: Zhejiang Lab
Current assignee: Zhejiang Lab
Priority date: 2023-09-25
Filing date: 2023-09-25
Publication date: 2023-11-03
Anticipated expiration: 2043-09-25
Also published as: CN116985500B

Abstract

The application provides an acoustic emission sensor and a preparation method thereof. The acoustic emission sensor is used for detecting damage and defects of the wind power blade when assembled on the surface of the wind power blade of the wind power generator. The acoustic emission sensor includes: a fiber composite layer, a piezoelectric composite layer, an acoustic attenuation composite layer, and a built-in circuit module. One side of the fiber composite material layer is used for contacting with the outer surface of the wind power blade, and the other side is laminated and compounded with the piezoelectric composite material layer and the sound attenuation composite material layer. The sound attenuation composite material layer is compounded on the outer side of the piezoelectric composite material layer in a surrounding mode. The built-in circuit module is connected to the piezoelectric composite material layer and the fiber composite material layer. Wherein the difference between the acoustic impedance of the fiber composite layer and the acoustic impedance of the composite material constituting the wind power blade ranges from 0 to 3.5 MRayl. The precision of wind power blade damage and defect detection can be effectively improved.

Description

Acoustic emission sensor and method for manufacturing same

Technical Field

The application relates to the field of health monitoring of wind power blades, in particular to an acoustic emission sensor and a preparation method thereof.

Background

Along with the rapid increase of the installed capacity of wind power in recent years, higher requirements are put on the safety and reliability of wind power equipment. The wind power blade is taken as the most important component in the wind generating set, and the health state of the wind power blade has important influence on the safe and reliable operation of the whole wind generating set. In the service process of the wind power blade, the wind power blade needs to bear external corrosion such as ultraviolet irradiation, rain and snow, strong wind load, atmospheric oxidation and the like for a long time, and the complex and severe environment causes great threat to the safety and reliability of the wind power blade. Therefore, in order to ensure safe and stable operation of the wind power blade, reduce great economic loss and the like, an effective method is adopted, so that the method has important significance and wide application prospect for monitoring the health state of the wind power blade. The composite material for forming the wind power blade comprises resin, a reinforcing material, other composite materials, natural fibers and the like, wherein the reinforcing material mainly comprises glass fibers and carbon fibers. Although the mechanical property, the light weight and the like of the carbon fiber are superior to those of the glass fiber, most of wind power blade reinforcing materials still take the glass fiber as the main material at present because the carbon fiber is relatively expensive in China. Therefore, the sound waves generated when the wind power blade is damaged and the defects inside the wind power blade mainly propagate in the composite material of the wind power blade. The acoustic emission sensor has special sensitivity to the initiation and expansion of defects caused by materials or components, has dynamic detection capability, and is one of effective methods for detecting damage of composite materials. The structure of the existing acoustic emission sensor in direct contact with the wind power blade is an alumina plate with an insulating layer, so that the strength of a detected sound wave is weakened, and the extremely early and tiny defects and damages of the wind power blade are difficult to detect in time.

Disclosure of Invention

The application provides an acoustic emission sensor and a preparation method thereof, which can effectively monitor damage of a wind power blade.

The application provides an acoustic emission sensor which is used for being assembled on the surface of a wind power blade of a wind driven generator; the acoustic emission sensor includes: a fiber composite layer, a piezoelectric composite layer, an acoustic attenuation composite layer, and a built-in circuit module;

one side of the fiber composite material layer is used for contacting with the outer surface of the wind power blade, and the other side is laminated and compounded with the piezoelectric composite material layer and the sound attenuation composite material layer; the sound attenuation composite material layer is circumferentially compounded on the outer side of the piezoelectric composite material layer; the built-in circuit module is connected with the piezoelectric composite material layer and the fiber composite material layer; wherein the difference between the acoustic impedance of the fiber composite layer and the acoustic impedance of the composite material constituting the wind blade ranges from 0 to 3.5 MRayl.

Further, the difference in acoustic impedance of the fiber composite layer and the piezoelectric composite layer ranges between 0 and 2.4 MRayl.

Further, the fiber composite material layer is made of a fiber composite material; the fiber composite material comprises glass fiber, epoxy resin and cellulose nanocrystalline which are compounded; wherein the mass percent of the glass fibers of the fiber composite material ranges from 35wt% to 45 wt%; the mass percent of the epoxy resin of the fiber composite material ranges from 15wt% to 25 wt%; the mass percentage of the cellulose nanocrystalline of the fiber composite material ranges from 30wt% to 40 wt%.

Further, the piezoelectric composite material layer is made of a piezoelectric composite material; the piezoelectric composite material comprises glass fiber, a piezoelectric active phase and cellulose which are compounded.

Further, the piezoelectric active phase comprises an organic piezoelectric phase and an inorganic piezoelectric phase which are compounded; the piezoelectric active phase comprises a three-dimensional communicated foam network structure formed by the inorganic piezoelectric phase; the organic piezoelectric phase, the glass fibers and the cellulose are filled in pores of the three-dimensional communicated foam network structure; wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 35wt% to 50 wt%; the mass percentage of the cellulose of the piezoelectric composite material ranges from 20wt% to 30 wt%; the mass percent of the glass fiber of the piezoelectric composite material ranges from 25wt% to 40 wt%.

Further, the piezoelectric active phase comprises an organic piezoelectric phase and an inorganic piezoelectric phase which are compounded; the inorganic piezoelectric phase is dispersed in the organic piezoelectric phase in the form of 0-dimensional particles; wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 10wt% to 18 wt%; the mass percentage of the cellulose of the piezoelectric composite material ranges from 4wt% to 12 wt%; the mass percentage of the glass fiber of the piezoelectric composite material is 8-15 wt%, and the mass percentage of the inorganic piezoelectric phase of the piezoelectric composite material is 55-65 wt%.

Further, the sound attenuating composite layer is made of a sound attenuating composite; the sound attenuating composite material includes polyurethane.

The application provides a preparation method of an acoustic emission sensor, which is used for preparing the acoustic emission sensor according to any embodiment; the preparation method comprises the following steps:

taking the fiber composite material layer as a substrate, and laminating and compositing the piezoelectric composite material layer on one side of the fiber composite material layer;

assembling the fiber composite material layer and the piezoelectric composite material layer in a shell, and taking the fiber composite material layer as the bottom surface of the shell;

pouring an acoustic attenuation composite into the housing to obtain an acoustic attenuation composite layer;

and installing a built-in circuit module inside the shell, and connecting the built-in circuit module with the piezoelectric composite material layer and the fiber composite material layer.

Further, the step of laminating and compounding the piezoelectric composite material layer on one side of the fiber composite material layer by using the fiber composite material layer as a substrate comprises the following steps:

taking the fiber composite material layer as a substrate, dripping conductive silver paste on one side of the fiber composite material layer, and uniformly coating to form a film so as to obtain a composite structure;

And compositing the piezoelectric composite material layer on the composite structure through conductive silver paste.

Further, before the piezoelectric composite layer is laminated on one side of the fiber composite layer with the fiber composite layer as a substrate, the method further includes:

dispersing cellulose nanocrystals in epoxy resin glue, and stirring to obtain a first mixed solution;

dispersing glass fibers in the first mixed solution, and stirring to obtain a second mixed solution;

adding an epoxy resin curing agent into the second mixed solution, stirring, pouring into a mold, and curing and molding;

and demolding and polishing after curing and forming to obtain the fiber composite material layer.

dissolving lead (II) acetate trihydrate in acetic acid, stirring and cooling to obtain a third mixed solution;

adding the zirconium n-propoxide solution and the tetrabutyl titanate solution into the third mixed solution, and stirring to obtain a fourth mixed solution;

adding glycol into the fourth mixed solution, and stirring to obtain sol;

Soaking a polyurethane foam template in the sol;

taking out the soaked polyurethane foam template, pressing and drying the polyurethane foam template to convert sol wrapped on the polyurethane foam template into gel;

sintering the polyurethane foam template wrapped around the gel to form a foam network structure, and placing the foam network structure in a mold;

dissolving glass fiber, carboxymethyl cellulose and organic piezoelectric phase powder in an organic dispersion solvent, and stirring to obtain a fifth mixed solution;

injecting the fifth mixed solution into the mold, and drying after covering the foam network structure;

demolding and polishing after drying to obtain the piezoelectric composite material layer.

Further, the polyurethane foam template has a porosity of 55%; and/or

The pore diameter of the polyurethane foam template is 20um; and/or

The range of the through porosity of the polyurethane foam template is more than 98 percent.

dissolving glass fiber, carboxymethyl cellulose and organic piezoelectric phase powder in an organic dispersion solvent, and stirring and oscillating to obtain a sixth mixed solution;

Adding inorganic piezoelectric phase powder into the sixth mixed solution, and stirring and oscillating to obtain a seventh mixed solution;

injecting the seventh mixed solution into a mould and drying;

The acoustic emission sensor provided by the application comprises a fiber composite material layer, a piezoelectric composite material layer, an acoustic attenuation composite material layer and a built-in circuit module, wherein one side of the fiber composite material layer is used for being in contact with the outer surface of a wind power blade. And the difference between the acoustic impedance of the fiber composite layer and the acoustic impedance of the composite material of the wind power blade ranges from 0 to 3.5 MRayl. Therefore, the phenomenon that the sound wave energy is greatly weakened due to the fact that the weak defect signals are mismatched through the acoustic impedance between the wind power blade and the sensor is avoided, so that the wind power blade has high sensitivity to detection of extremely weak defect signals in the wind power blade, the accuracy of damage and defect detection of the wind power blade can be effectively improved, and early fault diagnosis of the wind power blade can be achieved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application as claimed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

FIG. 1 is a schematic diagram of an acoustic emission system according to an embodiment of the present application;

FIG. 2 is a schematic diagram of an acoustic emission sensor according to an embodiment of the present application;

FIG. 3 illustrates a method of manufacturing an acoustic emission sensor in accordance with an embodiment of the present application;

FIG. 4 is a sub-flowchart of a method of manufacturing the acoustic emission sensor shown in FIG. 3;

FIG. 5 illustrates a method of preparing a fiber composite layer in the method of preparing the acoustic emission sensor of FIG. 3;

FIG. 6 illustrates a method of fabricating a piezoelectric composite layer in the fabrication of the acoustic emission sensor of FIG. 3;

fig. 7 shows another method for preparing a piezoelectric composite layer in the method for preparing the acoustic emission sensor shown in fig. 3.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application as detailed in the accompanying claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The terms "first," "second," and the like in the description and in the claims, are not used for any order, quantity, or importance, but are used for distinguishing between different elements. Likewise, the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "plurality" means two or more. Unless otherwise indicated, the terms "front," "rear," "lower," and/or "upper" and the like are merely for convenience of description and are not limited to one location or one spatial orientation. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

FIG. 1 is a schematic diagram of an acoustic emission system 19 according to an embodiment of the present application. Referring to fig. 1, the acoustic emission system 19 includes a data acquisition module 20, a data processing module 21, and an acoustic emission sensor 10, with the data acquisition module 20 being coupled to the data processing module 21 and the acoustic emission sensor 10. The acoustic emission sensor 10 is intended to be fitted to the surface of a wind blade of a wind turbine. The acoustic emission sensor 10 may be used to detect defects or damage inside a wind blade. The number of acoustic emission sensors 10 may be plural. The data acquisition module 20 is configured to receive acoustic signals representing internal defects or damage of the wind turbine blade detected by the plurality of acoustic emission sensors 10, and transmit the acoustic signals to the data processing module 21, where the data processing module 21 can calculate and locate a specific position of the defect or damage inside the wind turbine blade according to the data transmitted by the plurality of acoustic emission sensors 10, so that fault diagnosis of the wind turbine blade can be achieved.

Fig. 2 shows a schematic diagram of an acoustic emission sensor 10 according to an embodiment of the present application. Referring to fig. 2, the acoustic emission sensor 10 includes a fiber composite layer 11, a piezoelectric composite layer 12, an acoustic attenuation composite layer 13, and a built-in circuit module 14. One side of the fiber composite material layer 11 is used for contacting with the outer surface of the wind power blade, and the other side is laminated and compounded with the piezoelectric composite material layer 12 and the sound attenuation composite material layer 13. One side of the fibre composite layer 11 may be used in direct contact with a wind blade. The piezoelectric composite layer 12 is used to receive the acoustic signal transmitted from the fiber composite layer 11 and convert the acoustic signal into an electrical signal to be transmitted to the built-in circuit module 14. The built-in circuit module 14 is connected to the piezoelectric composite layer 12 and the fiber composite layer 11. The built-in circuit module 14 may be connected to the piezoelectric composite layer 12 and the fiber composite layer 11 by wires 18, respectively. The built-in circuit module 14 is used for performing bandpass filtering and amplification processing on the electric signal transmitted by the piezoelectric composite material layer 12. The sound attenuating composite layer 13 is wrapped around the outside of the piezoelectric composite layer 12. The acoustic attenuation composite layer 13 is used for absorbing the transmission of acoustic signals in the areas outside the fiber composite layer 11 and the piezoelectric composite layer 12, so as to inhibit the measurement distortion of effective acoustic waves caused by the phenomena of acoustic wave interference and the like caused by the multiple reflections of the ineffective acoustic waves in the acoustic emission sensor 10. Wherein the difference between the acoustic impedance of the fiber composite layer 11 and the acoustic impedance of the composite material constituting the wind blade ranges between 0 and 3.5 MRayl. It is understood that the acoustic impedance of the fiber composite material layer 11 may be equal to or greater than that of the composite material of the wind power blade, or the acoustic impedance of the composite material of the wind power blade may be equal to or greater than that of the fiber composite material layer 11. Therefore, the phenomenon of acoustic signal loss caused by serious mismatch of acoustic impedance between the acoustic emission sensor 10 and the wind power blade can be effectively avoided, and the sensitivity of the acoustic emission sensor 10 to detection of defects or damages inside the wind power blade can be improved.

When the sound wave is transmitted from the wind power blade to the acoustic emission sensor 10, if the acoustic impedance of the wind power blade is large in difference with the acoustic impedance of the side, which is contacted with the wind power blade, of the acoustic emission sensor 10, reflection of a large amount of sound wave can occur at the interface where the wind power blade is connected, and only a small part of sound wave can be transmitted to the acoustic emission sensor 10.

Wherein, the liquid crystal display device comprises a liquid crystal display device,acoustic impedance for wind power blade->For acoustic impedance of the surface of the acoustic emission sensor 10 in direct contact with the wind blade, +.>The transmission of sound waves for the wind blade to the acoustic emission sensor 10. Wind blades are known having acoustic impedances ranging between 3MRayl and 8 MRayl.

In the related art, the surface of the acoustic emission sensor, which is in direct contact with the wind power blade, is an alumina plate, and the acoustic impedance of the alumina plate ranges from 30MRayl to 40 MRayl. Therefore, the energy transmitted from the sound wave energy inside the wind power blade to the sound emission sensor is 26% of the initial energy, so that the sound wave intensity which can be detected by the sound emission sensor is weakened, the extremely early and tiny defects and damages of the wind power blade are difficult to detect in time, and the health monitoring and the advance of advance pre-supporting of the wind power blade are greatly reduced.

According to the acoustic emission sensor 10 provided by the application, the difference between the acoustic impedance of the fiber composite material layer 11 in direct contact with the wind power blade and the acoustic impedance of the composite material of the wind power blade is between 0 and 3.5MRayl, so that when the difference between the acoustic impedance of the fiber composite material layer 11 and the acoustic impedance of the composite material of the wind power blade is 0, the energy transmitted to the fiber composite material layer 11 by the acoustic energy in the wind power blade is 100% of the initial energy, and when the difference between the acoustic impedance of the fiber composite material layer 11 and the acoustic impedance of the composite material of the wind power blade is 3.5MRayl, the energy transmitted to the fiber composite material layer 11 by the acoustic energy in the wind power blade is 92% of the initial energy. Therefore, the problem of acoustic signal loss caused by serious mismatch of interface acoustic impedances between the acoustic emission sensor 10 and the wind power blade can be effectively avoided, the strength of signals detected by the acoustic emission sensor 10 can be effectively improved, and the sensitivity of the acoustic emission sensor 10 to detection of defects or damages inside the wind power blade is further improved.

In some embodiments, the difference in acoustic impedance of the fiber composite layer 11 and the piezoelectric composite layer 12 ranges between 0 and 2.4 MRayl. The acoustic impedance of the fiber composite material layer 11 is matched with that of the piezoelectric composite material layer 12, so that the transmission efficiency of acoustic signals in the acoustic emission sensor 10 can be effectively improved, and the detection sensitivity of the acoustic emission sensor 10 to defects or damage of the wind power blade can be effectively improved. When the difference between the acoustic impedance of the fiber composite layer 11 and the acoustic impedance of the piezoelectric composite layer 12 is in the range of 0, the energy transmitted from the acoustic wave energy passing through the fiber composite layer 11 to the piezoelectric composite layer 12 is 100% of the initial energy. When the difference between the acoustic impedance of the fiber composite layer 11 and the acoustic impedance of the piezoelectric composite layer 12 is 2.4MRayl, the energy of the acoustic wave transmitted through the fiber composite layer 11 to the piezoelectric composite layer 12 is 95% of the initial energy.

In some embodiments, the acoustic emission sensor 10 further includes a housing 15. The housing 15 may be a cylinder. The housing 15 includes a receiving cavity 16. The fiber composite layer 11, the piezoelectric composite layer 12, the sound attenuating composite layer 13, and the built-in circuit module 14 are disposed within the accommodation chamber 16. An opening 17 is provided below the housing 15, the opening 17 communicates with the accommodating chamber 16, and the fiber composite layer 11 is provided at the opening 17 and sealed to the opening 17. The shell 15 can play a role in protecting the piezoelectric composite material layer 12, the sound attenuation composite material layer 13 and the built-in circuit module 14, and the fiber composite material layer 11 is arranged at the opening 17, so that the fiber composite material layer 11 can be used as the bottom surface of the shell 15, and the fiber composite material layer 11 can be in direct contact with the wind power blade, and the structure is simple.

In some embodiments, the fiber composite layer 11 is made of a fiber composite. The fiber composite material comprises glass fiber, epoxy resin and cellulose nanocrystalline which are compounded. The cellulose nanocrystalline is the main component of natural fibers in the composite material of the wind power blade. Glass fiber is the main component of the reinforcing material in the composite material of the wind power blade. The epoxy resin is the main component of the resin in the composite material of the wind power blade. Wherein the mass percent of the glass fiber of the fiber composite material ranges from 35wt% to 45 wt%; the mass percent of the epoxy resin of the fiber composite material ranges from 15wt% to 25 wt%; the mass percent of the cellulose nanocrystals of the fiber composite material ranges from 30wt% to 40 wt%. The difference value between the acoustic impedance of the fiber composite material layer 11 made of the fiber composite material and the acoustic impedance of the composite material of the wind power blade can be in the range of 0 to 3.5MRayl, so that the problem of acoustic signal loss caused by interface acoustic impedance mismatch between the acoustic emission sensor 10 and the wind power blade can be effectively avoided.

Experiments show that when the mass percentage of the glass fiber is 35wt%, the mass percentage of the cellulose nanocrystalline is 25wt%, and the mass percentage of the epoxy resin is 40wt%, the acoustic impedance of the obtained fiber composite material layer 11 is 4.5MRayl.

When the mass percentage of the glass fiber was 45wt%, the mass percentage of the cellulose nanocrystal was 15wt%, and the mass percentage of the epoxy resin was 40wt%, the acoustic impedance of the obtained fiber composite material layer 11 was 4.8MRayl.

When the mass percentage of the glass fiber was 40wt%, the mass percentage of the cellulose nanocrystal was 25wt%, and the mass percentage of the epoxy resin was 30wt%, the acoustic impedance of the obtained fiber composite material layer 11 was 4.7MRayl.

In some embodiments, the piezoelectric composite layer 12 is made of a piezoelectric composite. The piezoelectric composite material comprises glass fiber, a piezoelectric active phase and cellulose which are compounded. In some embodiments, the piezoelectrically active phase comprises a composite organic piezoelectric phase and an inorganic piezoelectric phase. The functional groups on the surface of the cellulose can form hydrogen bonds with F atoms of the organic piezoelectric phase, which is helpful for improving the arrangement orientation and crystallinity of the organic piezoelectric phase, so that the piezoelectric performance and electromechanical coupling performance of the piezoelectric composite material layer 12 can be improved, and the bonding strength between the piezoelectric composite material components can be improved by chemical bond bonding. Glass fiber is the main component of the reinforcing material in the composite material of the wind power blade. Cellulose is the main component of natural fibers in the composite material of the wind power blade. The acoustic impedance of the piezoelectric composite material layer 12 made of the piezoelectric composite material is matched with the acoustic impedance of the composite materials of the fiber composite material layer 11 and the wind power blade, so that the transmission efficiency of acoustic signals in the acoustic emission sensor 10 can be effectively improved, and the detection sensitivity of the acoustic emission sensor 10 to defects or damages of the wind power blade can be effectively improved.

In some embodiments, the piezoelectrically active phase comprises a three-dimensionally interconnected foam network structure of inorganic piezoelectric phases. In some embodiments, the backbone of the foam network structure is composed of dense inorganic piezoelectric phase grains, which may be 3 μm in diameter. The organic piezoelectric phase, glass fibers and cellulose are filled in the pores of the three-dimensionally connected foam network structure. Wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 35wt% to 50 wt%; the mass percent of the cellulose of the piezoelectric composite material ranges from 20wt% to 30 wt%; the mass percent of the glass fiber of the piezoelectric composite material ranges from 25wt% to 40 wt%. The difference in acoustic impedance of the piezoelectric composite layer 12 thus made of the piezoelectric composite material and the acoustic impedance of the fiber composite layer 11 may range between 0 and 2.4 MRayl. The transmission efficiency of the acoustic signals in the acoustic emission sensor 10 can be effectively improved, and the detection sensitivity of the acoustic emission sensor 10 to defects or damage of the wind power blade can be effectively improved.

Experiments show that when the mass percentage of the organic piezoelectric phase is 35wt%, the mass percentage of the cellulose is 30wt%, and the mass percentage of the glass fiber is 35wt%, the acoustic impedance of the obtained piezoelectric composite material layer 12 is 5.5MRayl.

When the mass percentage of the organic piezoelectric phase was 50wt%, the mass percentage of the cellulose was 20wt%, and the mass percentage of the glass fiber was 30wt%, the acoustic impedance of the obtained piezoelectric composite layer 12 was 5.4MRayl.

The acoustic impedance of the piezoelectric composite layer 12 obtained was 5.2MRayl when the mass percentage of the organic piezoelectric phase was 45wt%, the mass percentage of the cellulose was 30wt%, and the mass percentage of the glass fiber was 25 wt%.

When the mass percentage of the organic piezoelectric phase was 35wt%, the mass percentage of the cellulose was 25wt%, and the mass percentage of the glass fiber was 40wt%, the acoustic impedance of the obtained piezoelectric composite layer 12 was 5.9MRayl.

In other embodiments, the inorganic piezoelectric phase is dispersed in the organic piezoelectric phase in the form of 0-dimensional particles. The 0-dimensional particles may refer to three-dimensional dimensions in space that are both hundred nanometers and micrometers, such as hundred nanometers or micrometer-scale particles, clusters of atoms, and the like. The inorganic piezoelectric phase may be uniformly dispersed in the form of 0-dimensional particles in the polymer substrate of the organic piezoelectric phase. Wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 10wt% to 18 wt%; the mass percentage of cellulose of the piezoelectric composite material ranges from 4wt% to 12 wt%; the mass percentage of the glass fiber of the piezoelectric composite material is 8 to 15 percent, and the mass percentage of the inorganic piezoelectric phase of the piezoelectric composite material is 55 to 65 percent. The difference in acoustic impedance of the piezoelectric composite layer 12 thus made of the piezoelectric composite material and the acoustic impedance of the fiber composite layer 11 may range between 0 and 2.4 MRayl. The transmission efficiency of the acoustic signals in the acoustic emission sensor 10 can be effectively improved, and the detection sensitivity of the acoustic emission sensor 10 to defects or damage of the wind power blade can be effectively improved.

Experiments show that when the mass percentage of the organic piezoelectric phase is 18wt%, the mass percentage of the cellulose is 12wt%, and the mass percentage of the glass fiber is 15wt%, the mass percentage of the inorganic piezoelectric phase is 55wt%, and the acoustic impedance of the obtained piezoelectric composite material layer 12 is 6.6MRayl.

When the mass percentage of the organic piezoelectric phase was 10wt%, the mass percentage of the cellulose was 11wt%, and the mass percentage of the glass fiber was 14wt%, the mass percentage of the inorganic piezoelectric phase was 65wt%, and the acoustic impedance of the obtained piezoelectric composite layer 12 was 6.9MRayl.

When the mass percentage of the organic piezoelectric phase was 18wt%, the mass percentage of the cellulose was 4wt%, and the mass percentage of the glass fiber was 15wt%, the mass percentage of the inorganic piezoelectric phase was 63wt%, and the acoustic impedance of the obtained piezoelectric composite layer 12 was 6.8MRayl.

When the mass percentage of the organic piezoelectric phase was 18wt%, the mass percentage of the cellulose was 12wt%, and the mass percentage of the glass fiber was 8wt%, the mass percentage of the inorganic piezoelectric phase was 62wt%, and the acoustic impedance of the obtained piezoelectric composite layer 12 was 6.7MRayl.

In some embodiments, the sound attenuating composite layer 13 is made of a sound attenuating composite. The sound attenuating composite material comprises polyurethane. The polyurethane has good elasticity, can effectively weaken or reduce the propagation of sound wave energy, and has good effect of inhibiting the measurement distortion of effective sound waves.

In some embodiments, when the mass percentage of glass fiber is 35wt%, the mass percentage of cellulose nanocrystals is 25wt%, and the mass percentage of epoxy is 40wt%, a cellulose composite layer 11 with an acoustic impedance of 4.5Mrayl is obtained. When the mass percentage of the organic piezoelectric phase was 45wt%, the mass percentage of the cellulose was 30wt%, and the mass percentage of the glass fiber was 25wt%, the piezoelectric composite layer 12 having an acoustic impedance of 5.2MRayl was obtained. If the acoustic impedance of the wind power blade is 3MRayl, the energy transmitted to the fiber composite layer 11 by the acoustic energy in the wind power blade is 96% of the initial energy. The energy transmitted by the acoustic wave energy passing through the fiber composite layer 11 to the piezoelectric composite layer 12 is 99.5% of the initial energy. The energy detected by the acoustic emission sensor 10 is 94.5% of the initial energy, the acoustic wave energy loss is small, and most of acoustic wave energy can be used for completing conversion between mechanical energy such as acoustic energy and electric energy, so that the detection sensitivity of the sensor is greatly improved.

Fig. 3 illustrates a method of manufacturing an acoustic emission sensor 10 in accordance with an embodiment of the present application. Referring to fig. 2 and 3, a method of manufacturing the acoustic emission sensor 10 may be used to manufacture the acoustic emission sensor 10 of the above-described examples and embodiments. The preparation method comprises the steps S101-S104.

In step S101, the piezoelectric composite layer 12 is laminated and compounded on one side of the fiber composite layer 11 with the fiber composite layer 11 as a substrate. The piezoelectric composite layer 12 may be adhesively bonded to one side of the fiber composite layer 11 by a conductive adhesive.

In step S102, the fiber composite material layer 11 and the piezoelectric composite material layer 12 are assembled in the housing 15, and the fiber composite material layer 11 is used as the bottom surface of the housing 15. The fiber composite layer 11 and the piezoelectric composite layer 12 may be assembled within the housing 15. The two-sided electrodes of the piezoelectric composite layer 12 may be led out of the housing 15 after being assembled to the housing 15.

In step S103, an acoustic attenuation composite is poured into the housing 15 to obtain the acoustic attenuation composite layer 13. Polyurethane excellent in elasticity may be poured into the case 15 to obtain the sound attenuation composite layer 13 composited around the outside of the piezoelectric composite layer 12. Wherein the space defined by the housing 15, the fiber composite layer 11 and the piezoelectric composite layer 12 may be filled with an acoustic attenuation composite.

In step S104, the built-in circuit module 14 is mounted inside the case 15, and the built-in circuit module 14 is connected to the piezoelectric composite material layer 12 and the fiber composite material layer 11. After the built-in circuit module 14 is mounted, the top of the housing 15 may be packaged. The method of assembling the acoustic emission sensor 10 according to the embodiment of the present application can be applied to the acoustic emission sensor 10 of the above-described embodiment and implementation. The preparation method is simple.

Fig. 4 shows a sub-flowchart of a method of manufacturing the acoustic emission sensor 10 shown in fig. 3. Referring to fig. 2 and 4, in some embodiments, the fiber composite layer 11 is used as a substrate, and the piezoelectric composite layer 12 is laminated and compounded on one side of the fiber composite layer 11, which includes steps S201 to S202.

In step S201, the fiber composite material layer 11 is used as a substrate, and the conductive silver paste is dropped on one side of the fiber composite material layer 11 and uniformly glued to form a film, so as to obtain a composite structure. The fiber composite material layer 11 can be taken as a substrate in a spin coater, conductive silver paste is dripped on one side of the fiber composite material layer 11, and after the conductive silver paste is uniformly coated on the surface of one side of the fiber composite material layer 11 by the spin coater, the conductive silver paste can form a uniform film so as to obtain a composite structure of the fiber composite material layer 11 and the conductive silver paste.

In step S202, the piezoelectric composite layer 12 is compounded on the composite structure by conductive silver paste. A composite structure of the fiber composite layer 11, the conductive silver paste and the piezoelectric composite layer 12 can be obtained. The piezoelectric composite material layer 12 can be laminated and compounded on one side of the fiber composite material layer 11 through the conductive silver paste, and the connection mode is simple and has good conductive performance.

Fig. 5 shows a method for producing the fiber composite layer 11 in the method for producing the acoustic emission sensor 10 shown in fig. 3. Referring to fig. 2 and 5, in some embodiments, before the fiber composite layer 11 is used as a substrate and the piezoelectric composite layer 12 is laminated and compounded on one side of the fiber composite layer 11, the method further includes steps S301 to S304.

In step S301, cellulose nanocrystals are dispersed in epoxy glue, and a first mixed solution is obtained after stirring. The cellulose nanocrystals with the corresponding mass percentages can be weighed and dispersed in the epoxy resin glue, and the cellulose nanocrystals are uniformly mixed in the epoxy resin glue after stirring so as to obtain a first mixed solution in which the cellulose nanocrystals and the epoxy resin glue are mixed.

In step S302, glass fibers are dispersed in the first mixed solution, and a second mixed solution is obtained after stirring. Dispersing glass fibers in the first mixed solution, and uniformly mixing the glass fibers in the first mixed solution after stirring to obtain a second mixed solution. The surface of the cellulose nanocrystalline has hydroxyl functional groups and hydrophobic and oleophilic properties, so that the aggregation phenomenon of glass fibers in epoxy resin can be effectively avoided, and the uniform dispersion of the components of each composite material is facilitated.

In step S303, an epoxy resin curing agent is added to the second mixed solution, stirred, and poured into a mold for curing and molding. In this way, the second mixed solution can be converted into a solid state after being solidified and molded in the mold from a liquid state. Wherein the mold may be an annular mold. So that the fiber composite material layer 11 obtained after the curing molding has a disc shape.

In step S304, demolding and polishing are performed after the curing molding to obtain the fiber composite material layer 11. The composite material obtained after the curing molding is demolded and sanded with sand paper to obtain the fiber composite material layer 11. The mode of obtaining the fiber composite layer 11 is simple, and the acoustic impedance of the obtained fiber composite layer 11 can be matched with that of the composite material of the wind power blade.

Fig. 6 illustrates a method of manufacturing the piezoelectric composite layer 12 in the method of manufacturing the acoustic emission sensor 10 illustrated in fig. 3. Referring to fig. 2 and 6, in some embodiments, before the piezoelectric composite layer 12 is laminated and compounded on one side of the fiber composite layer 11 using the fiber composite layer 11 as a substrate, the method further includes steps S401 to S409.

In step S401, lead (II) acetate trihydrate is dissolved in acetic acid, stirred and cooled to obtain a third mixed solution. Lead (II) acetate trihydrate may be dissolved in acetic acid, stirred at a set temperature until the solution assumes a transparent state, and cooled to room temperature to obtain a third mixed solution. Wherein the set temperature may be 80 ℃.

In step S402, zirconium n-propoxide is added) Solution and tetrabutyl titanate) And adding the solution into the third mixed solution, and stirring to obtain a fourth mixed solution. In the fourth mixed solution obtained, pb: zr: the ratio of the amounts of substances of ions of Ti was 1:0.52:0.48.

in step S403, ethylene glycol is added to the fourth mixed solution, and the sol is obtained after stirring. Ethylene glycol was added to the fourth mixed solution to obtain PZT (Pb (zr0.52ti0.48) O3) sol. The PZT sol solution may be stirred at room temperature for one hour to disperse it uniformly.

In step S404, the polyurethane foam template is immersed in the sol. The polyurethane foam template can be fully soaked in the sol, and the polyurethane foam template can be fully soaked in the PZT sol, so that the PZT sol is fully adsorbed by the polyurethane foam template through capillary effect. In some embodiments, the polyurethane foam template has a porosity of 55%. In some embodiments, the pore diameter of the polyurethane foam template is 20um. In some embodiments, the polyurethane foam template has a porosity in the range of greater than 98%. Wherein porosity may refer to the total volume of cells divided by the total volume of the polyurethane foam template. The porosity may refer to a volume ratio of a plurality of pores to a plurality of pores.

In step S405, the soaked polyurethane foam template is taken out, pressed and dried to convert the sol wrapped around the polyurethane foam template into gel. The polyurethane foam template that had saturated the adsorption sol after soaking can be removed. The polyurethane foam template after being taken out can be pressed at least twice by hands uniformly, and then placed in a drying oven for drying, and can be dried in the drying oven for 1 hour at 60 ℃. This allows the PZT sol encapsulated in polyurethane to be converted into PZT gel. The weight of the converted PZT gel-coated polyurethane foam template can be increased by a factor of 6 compared to the original polyurethane foam template.

In step S406, the gel-encased polyurethane foam template is sintered to form a foam network structure, and the foam network structure is placed within a mold. Wherein the mold may be a circular mold. The polyurethane foam template and the gel can be placed in a muffle furnace, and can be sintered for 2 hours at 1000 ℃, and the solvent in the PZT gel and the polyurethane foam template volatilize in the high-temperature sintering process until a single PZT foam network structure is prepared. The morphology of the polyurethane foam template will remain in the sintered PZT foam network. The porosity of the foam network thus obtained was 55%. The pores of the foam network had a diameter of 20um. The range of porosity of the foam network structure is greater than 98%.

In step S407, glass fiber, carboxymethyl cellulose, and organic piezoelectric phase powder are dissolved in an organic dispersion solvent, and stirred to obtain a fifth mixed solution. The glass fiber, the carboxymethyl cellulose and the organic piezoelectric phase powder can be dissolved in an organic dispersion solvent, stirred and oscillated to be uniformly dispersed, and a fifth mixed solution of the glass fiber, the carboxymethyl cellulose and the organic piezoelectric phase is obtained. Wherein the organic piezoelectric phase powder is selected from one of PVDF and P (VDF-TrFE).

In step S408, the fifth mixed solution is injected into a mold, and after covering the foam network structure, it is dried. The fifth mixed solution may be injected into the mold, after the foam network structure is completely covered, placed in a drying oven, and dried at 50 ℃ for 4 hours to completely cure the overall structure.

In step S409, demolding and polishing are performed after drying to obtain the piezoelectric composite layer 12. And after drying, the resulting structure is demolded and sanded to obtain the composite piezoelectric composite layer 12. The inorganic piezoelectric phase can be used as a framework of the piezoelectric composite material, and the organic piezoelectric phase, cellulose and glass fibers are uniformly dispersed in a foam framework formed by the inorganic piezoelectric phase as a filling structure. The skeleton of the foam network structure is formed by inorganic piezoelectric phase grains, and has higher compactness, piezoelectric performance and electromechanical coupling performance. The three-dimensional communicated foam network structure is beneficial to the transmission of voltage after the application of polarization voltage, and is beneficial to the full polarization of the piezoelectric composite material, so that the piezoelectric performance and the electromechanical coupling performance are improved.

Fig. 7 shows another method of manufacturing the piezoelectric composite layer 12 in the method of manufacturing the acoustic emission sensor 10 shown in fig. 3. Referring to fig. 2 and 7, in some embodiments, before the piezoelectric composite layer 12 is laminated and combined on one side of the fiber composite layer 11 using the fiber composite layer 11 as a substrate, the method further includes steps S501 to S504.

In step S501, glass fiber, carboxymethyl cellulose, and organic piezoelectric phase powder are dissolved in an organic dispersion solvent, and stirred and oscillated to obtain a sixth mixed solution. The organic piezoelectric phase powder can be one of PVDF and P (VDF-TrFE). And dissolving glass fiber, carboxymethyl cellulose and organic piezoelectric phase powder in an organic dispersion solvent, stirring and oscillating to uniformly disperse the materials, and obtaining a sixth mixed solution.

In step S502, the inorganic piezoelectric phase powder is added to the sixth mixed solution, and stirred and oscillated to obtain a seventh mixed solution. Wherein, the inorganic piezoelectric phase can be one of PZT, PMN-PT and PZN-PT. The inorganic piezoelectric phase powder may be added to the sixth mixed solution and then stirred and oscillated to uniformly disperse the inorganic piezoelectric phase powder, thereby obtaining a seventh mixed solution in which the glass fiber, the cellulose, the organic piezoelectric phase and the inorganic piezoelectric phase are mixed.

In step S503, the seventh mixed solution is injected into a mold and then dried. The seventh mixed solution may be injected into the circular ring-shaped mold. The seventh mixed solution after being injected into the mold may be placed in a drying oven and dried at 50 c for 4 hours to complete the curing.

In step S504, demolding and polishing are performed after drying to obtain the piezoelectric composite layer 12. Demolding may be performed after drying and sanding to obtain the piezoelectric composite layer 12 and polarizing. Thus, the inorganic piezoelectric phase may be dispersed in the organic piezoelectric phase in the form of 0-dimensional particles, and the glass fibers and cellulose may be uniformly distributed in the inorganic piezoelectric phase. The manner in which the piezoelectric composite layer 12 is thus obtained is simple, and the acoustic impedance of the obtained piezoelectric composite layer 12 can be matched to that of the fiber composite layer 11.

Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It is to be understood that the application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. An acoustic emission sensor, characterized by being adapted to be mounted to a surface of a wind power blade of a wind power generator; the acoustic emission sensor includes: a fiber composite layer, a piezoelectric composite layer, an acoustic attenuation composite layer, and a built-in circuit module;

2. The acoustic emission sensor of claim 1, wherein the difference in acoustic impedance of the fiber composite layer and the piezoelectric composite layer ranges between 0 and 2.4 MRayl.

3. The acoustic emission sensor of claim 1, wherein the fiber composite layer is made of a fiber composite material; the fiber composite material comprises glass fiber, epoxy resin and cellulose nanocrystalline which are compounded; wherein the mass percent of the glass fibers of the fiber composite material ranges from 35wt% to 45 wt%; the mass percent of the epoxy resin of the fiber composite material ranges from 15wt% to 25 wt%; the mass percentage of the cellulose nanocrystalline of the fiber composite material ranges from 30wt% to 40 wt%.

4. The acoustic emission sensor of claim 1, wherein the piezoelectric composite layer is made of a piezoelectric composite material; the piezoelectric composite material comprises glass fiber, a piezoelectric active phase and cellulose which are compounded.

5. The acoustic emission sensor of claim 4, wherein the piezoelectrically active phase comprises a composite of an organic piezoelectric phase and an inorganic piezoelectric phase; the piezoelectric active phase comprises a three-dimensional communicated foam network structure formed by the inorganic piezoelectric phase; the organic piezoelectric phase, the glass fibers and the cellulose are filled in pores of the three-dimensional communicated foam network structure; wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 35wt% to 50 wt%; the mass percentage of the cellulose of the piezoelectric composite material ranges from 20wt% to 30 wt%; the mass percent of the glass fiber of the piezoelectric composite material ranges from 25wt% to 40 wt%.

6. The acoustic emission sensor of claim 4, wherein the piezoelectrically active phase comprises a composite of an organic piezoelectric phase and an inorganic piezoelectric phase; the inorganic piezoelectric phase is dispersed in the organic piezoelectric phase in the form of 0-dimensional particles; wherein the mass percent of the organic piezoelectric phase of the piezoelectric composite material ranges from 10wt% to 18 wt%; the mass percentage of the cellulose of the piezoelectric composite material ranges from 4wt% to 12 wt%; the mass percentage of the glass fiber of the piezoelectric composite material is 8-15 wt%, and the mass percentage of the inorganic piezoelectric phase of the piezoelectric composite material is 55-65 wt%.

7. The acoustic emission sensor of claim 1, wherein the acoustic attenuation composite layer is made of an acoustic attenuation composite; the sound attenuating composite material includes polyurethane.

8. A method of manufacturing an acoustic emission sensor for manufacturing an acoustic emission sensor as claimed in any one of claims 1 to 7; the preparation method is characterized by comprising the following steps:

9. The method of manufacturing an acoustic emission sensor as claimed in claim 8, wherein the laminating the piezoelectric composite layer on one side of the fiber composite layer with the fiber composite layer as a substrate comprises:

10. The method of manufacturing an acoustic emission sensor as claimed in claim 8, wherein prior to the lamination of the piezoelectric composite layer to one side of the fiber composite layer with the fiber composite layer as a substrate, the method further comprises:

11. The method of manufacturing an acoustic emission sensor as claimed in claim 8, wherein prior to the lamination of the piezoelectric composite layer to one side of the fiber composite layer with the fiber composite layer as a substrate, the method further comprises:

adding glycol into the fourth mixed solution, and stirring to obtain sol;

soaking a polyurethane foam template in the sol;

12. The method of manufacturing an acoustic emission sensor of claim 11, wherein the polyurethane foam template has a porosity of 55%; and/or

The pore diameter of the polyurethane foam template is 20um; and/or

13. The method of manufacturing an acoustic emission sensor as claimed in claim 8, wherein prior to the lamination of the piezoelectric composite layer to one side of the fiber composite layer with the fiber composite layer as a substrate, the method further comprises:

Injecting the seventh mixed solution into a mould and drying;