阅读说明：本技术 一种曲面压电复合材料的温度弯曲形变的测量 (Measurement of temperature bending deformation of curved surface piezoelectric composite material ) 是由 王改丽 申丽丽 廖擎伟 康冰琳 李晋忠 张晶晶 肖文杰 孙悦 王丽坤 桑作钧 单 于 2019-11-08 设计创作，主要内容包括：本发明提供一种曲面压电复合材料的温度弯曲形变的测量方法,包括提供形成有光栅的光纤；确定待测曲面试样的被测位置,通过粘接方式将各光栅紧密贴敷于待测试样各表面；测量各被测位置光纤与待测试样粘接的粘结区长度；改变环境温度,监测各温度下所述光栅反射光的波长,根据光栅反射光的波长变化量与光纤光栅的应变的关系计算各光纤光栅的应变,得到各被测位置的测量应变；以及根据各被测位置光栅长度、粘结区长度和对应的测量应变,得到各温度下待测试样的平均应变值。本发明的方法为换能器用压电复合材料的检测提供了可靠依据,同时为曲面压电复合材料设计和制备工艺的改进提供了有效的检验手段,可提升换能器及声呐系统的环境适应性。(The invention provides a method for measuring temperature bending deformation of a curved piezoelectric composite material, which comprises the steps of providing an optical fiber with a grating; determining the measured position of the curved surface sample to be measured, and closely attaching each grating to each surface of the sample to be measured in an adhesion mode; measuring the length of a bonding area for bonding each measured position optical fiber with a sample to be measured; changing the ambient temperature, monitoring the wavelength of the grating reflected light at each temperature, and calculating the strain of each fiber grating according to the relationship between the wavelength variation of the grating reflected light and the strain of the fiber grating to obtain the measurement strain of each measured position; and obtaining the average strain value of the sample to be measured at each temperature according to the length of each measured position grating, the length of the bonding area and the corresponding measured strain. The method of the invention provides reliable basis for the detection of the piezoelectric composite material for the transducer, and simultaneously provides effective inspection means for the improvement of the design and preparation process of the curved surface piezoelectric composite material, thereby improving the environmental adaptability of the transducer and a sonar system.)

1. A method for measuring the temperature bending deformation of a curved piezoelectric composite material comprises

Providing an optical fiber formed with a grating;

determining the measured position of the curved surface sample to be measured, and closely attaching each grating to each surface of the sample to be measured in an adhesion mode;

measuring the length of a bonding area for bonding each measured position optical fiber with a sample to be measured;

changing the ambient temperature, monitoring the wavelength of the grating reflected light at each temperature, and calculating the strain of each fiber grating according to the relationship between the wavelength variation of the grating reflected light and the strain of the fiber grating to obtain the measurement strain of each measured position; and

and obtaining the average strain value of the sample to be measured at each temperature according to the length of the grating at each measured position, the length of the bonding area and the corresponding measured strain.

2. The method of claim 1, wherein a plurality of gratings are fabricated on the same optical fiber, and the strain at each measured location is measured using the plurality of gratings on the same optical fiber, and the average strain value is multiplied by the total length or the total area to obtain the total strain.

3. The method according to claim 1, wherein the measured positions are set on respective surfaces of the sample to be measured, and the average strain value of each surface is measured.

4. The method according to claim 3, wherein the average strain ε of a curved surface of the sample to be measured at each temperature T is calculated according to the following equation_T

Wherein n is the number of the measured positions of the curved surface, epsilon_T1,ε_T2,…,ε_Ti,…,ε_TnMeasuring strain for the grating axial direction of each measured position of the curved surface at the temperature T;

l1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, … and n is the number of the measured positions.

5. The method of claim 2 further comprising monitoring the wavelength of light reflected from the compensation grating at each temperature and calculating the strain of the compensation grating at each temperature T, and calculating the strain of the measured position temperature compensated piezoelectric composite material as follows

ε_TEi＝ε_Ti-ε_TE

Wherein epsilon_TEiIs the temperature-compensated measured strain, ε, at each measured location at a temperature T_TiIs the grating axial measurement strain at each measured position at the temperature T, i is 1, …N, n is the number of the measured positions, epsilon_TEIs to compensate the grating axial measurement strain of the grating.

6. The method according to claim 5, wherein the temperature compensated average strain ε of a curved surface of the curved surface sample to be measured at each temperature T is calculated according to the following formula_TE

L1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, … and n is the number of the measured positions.

7. The method of claim 1, wherein the adhesive is selected from the group consisting of 401 glue, 353ND glue and DB420 glue.

8. The method for measuring the temperature bending deformation curvature radius of the curved surface piezoelectric composite material is characterized by comprising the following steps

The method for measuring the temperature bending deformation of the curved piezoelectric composite material according to claim 1, obtaining the average strain value of the curved sample to be measured at each temperature,

calculating the curvature radius R of the sample to be measured at each temperature according to the initial curvature radius of the sample to be measured and the average strain value of the sample to be measured at each temperature_T

R_T＝(1+ε_T)×R

Wherein R is the initial curvature radius of the curved surface sample to be measured, epsilon_TMeasuring strain axially by the grating at the measured position at the temperature T; or

The measured positions are arranged on the inner surface and the outer surface of the curved surface sample to be measured,

respectively calculating the curvature radius R of the middle surface of the sample to be measured at each temperature based on the measured strain of the inner surface and the outer surface of the sample to be measured at each temperature_{Middle surface T}，

R_{Outer surface T}＝(1+ε_{Outer surface T})×R_{Outer surface}

R_{Inner surface T}＝(1+ε_{Inner surface T})×R_{Inner surface}

Wherein the content of the first and second substances,

R_{outer surface}Is the initial outer surface curvature radius, R, of the sample to be measured_{Outer surface T}Is the radius of curvature, epsilon, of the outer surface of the sample to be measured at the temperature T_{Outer surface T}The strain is measured on the outer surface of the sample to be measured at the temperature T;

R_{inner surface}Is the initial radius of curvature, R, of the inner surface of the sample to be measured_{Inner surface T}Radius of curvature, epsilon, of the inner surface of the sample to be measured at temperature T_{Inner surface T}The strain is measured on average on the inner surface of the sample to be measured at the temperature T.

9. The measurement method according to claim 8, characterized in that the method further comprises,

curvature K of sample to be tested_TComprises the following steps:

10. The measurement method according to claim 8, characterized in that the method further comprises,

at least one grating on the optical fiber is not contacted with the sample to be measured to be used as a compensation grating, the wavelength of the reflected light of the compensation grating at each temperature is monitored, the strain of the compensation grating at each temperature is calculated, and the average strain value of the sample to be measured with the measured position subjected to temperature compensation is calculated according to the following formula

ε_TEi＝ε_Ti-ε_TE

Wherein epsilon_TEiIs the temperature-compensated measured strain, ε, at each measured location at a temperature T_TiIs the grating axial measurement strain of each measured position at the temperature T, i is 1, …, n, n is the number of measured positions, epsilon_TEIs to compensate the grating axial measurement strain of the grating.

Technical Field

The invention belongs to the field of material deformation measurement, and particularly relates to a method for measuring temperature bending deformation of a curved surface piezoelectric composite material.

Background

Transducers are devices that convert energy, and are devices that convert energy in one form into another. Because the sound wave is the only carrier which is mastered by human beings so far and can transmit information and energy in vast sea in a long distance, underwater detection, communication, navigation, mapping and the like mostly rely on an underwater acoustic transducer at present. The currently used underwater acoustic transducer is mainly a piezoelectric transducer, and a piezoelectric element (i.e. a transducer element) is a core component of the piezoelectric transducer, which directly determines the performance of the transducer.

With the expansion of the application environment of the transducer, new requirements are put on the shape and various performance parameters of the transducer. For example, a spherical piezoelectric transducer generally employs a piezoelectric composite spherical shell as its piezoelectric element, which utilizes radial vibration of the piezoelectric composite spherical shell. The piezoelectric composite material is formed by compounding piezoelectric ceramics and polymers according to a certain rule, and the volume-temperature expansion (contraction) coefficient of the piezoelectric ceramics is different from that of the polymers, so that the piezoelectric composite material generates deformation of different degrees when the temperature changes. Different from the piezoelectric composite material, the piezoelectric ceramic material is a compact single-phase material sintered into ceramic, has small deformation, almost has negligible influence on the performance of the transducer, and therefore, the deformation of the transducer does not need to be tested. Because the bending deformation of the piezoelectric composite material can affect the transducer and the sonar system as follows: (1) frequency drift affects the frequency consistency of the transducer array elements, resulting in the performance degradation of the transducer array; (2) the beam opening angle of the transducer is changed, so that the positioning accuracy of the sonar system is reduced; (3) the piezoelectric composite material is peeled from the back lining of the transducer, so that the water pressure resistance of the transducer is reduced; (4) severe deformation can fracture the piezoelectric composite, resulting in complete transducer failure. Therefore, quantitative measurement of temperature deformation of piezoelectric composite materials, particularly of piezoelectric composite materials having curved surface shapes, is a problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a method for measuring temperature bending deformation of a curved piezoelectric composite material.

According to one aspect of the invention, a method for measuring the temperature bending deformation of a curved piezoelectric composite material is provided, which comprises the following steps

Providing an optical fiber formed with a grating;

determining the measured position of the curved surface sample to be measured, and closely attaching each grating to each surface of the sample to be measured in an adhesion mode;

measuring the length of a bonding area for bonding each measured position optical fiber with a sample to be measured;

changing the ambient temperature, monitoring the wavelength of the grating reflected light at each temperature, and calculating the strain of each fiber grating according to the relationship between the wavelength variation of the grating reflected light and the strain of the fiber grating to obtain the measurement strain of each measured position; and

and obtaining the average strain value of the sample to be measured at each temperature according to the length of the grating at each measured position, the length of the bonding area and the corresponding measured strain.

Preferably, a plurality of gratings are made on the same optical fiber, the strain of each measured position is measured by using the plurality of gratings on the same optical fiber, and the average strain value is multiplied by the total length or the total area to obtain the total deformation.

Preferably, the measured positions are arranged on the surfaces of the sample to be measured, and the average strain value of each surface is measured.

Preferably, the average strain value epsilon of a curved surface of the sample to be measured at each temperature T is calculated according to the following formula_T

Wherein n is the number of the measured positions of the curved surface, epsilon_T1,ε_T2,…,ε_Ti,…,ε_TnMeasuring strain for the grating axial direction of each measured position of the curved surface at the temperature T;

l1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, … and n is the number of the measured positions.

Preferably, the method further comprises the steps of enabling at least one grating on the optical fiber not to be in contact with a sample to be tested to be used as a compensation grating, monitoring the wavelength of light reflected by the compensation grating at each temperature, calculating the strain of the compensation grating at each temperature T, and calculating the strain value of the piezoelectric composite material with the measured position subjected to temperature compensation according to the following formula

ε_TEi＝ε_Ti-ε_TE

Wherein epsilon_TEiIs the temperature-compensated measured strain, ε, at each measured location at a temperature T_TiIs the grating axial measurement strain of each measured position at the temperature T, i is 1, …, n, n is the number of measured positions, epsilon_TEIs to compensate the grating axial measurement strain of the grating.

Preferably, the average strain value epsilon of the curved surface sample to be measured after temperature compensation at each temperature T is calculated according to the following formula_TE

L1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, … and n is the number of the measured positions.

Preferably, the adhesive is selected from the group consisting of 401 glue, 353ND glue and DB420 glue.

According to another aspect of the present invention, there is provided a method of measuring a temperature bending deformation curvature radius of a curved piezoelectric composite material, the method comprising

According to the method for measuring the temperature bending deformation of the curved surface piezoelectric composite material, the average strain value of the curved surface sample to be measured at each temperature is obtained,

calculating the curvature radius R of the sample to be measured at each temperature according to the initial curvature radius of the sample to be measured and the average strain value of the sample to be measured at each temperature_T

R_T＝(1+ε_T)×R

Wherein R is the initial curvature radius of the curved surface sample to be measured, epsilon_TMeasuring strain axially by the grating at the measured position at the temperature T; or

The measured positions are arranged on the inner surface and the outer surface of the curved surface sample to be measured,

respectively calculating the curvature radius R of the middle surface of the sample to be measured at each temperature based on the measured strain of the inner surface and the outer surface of the sample to be measured at each temperature_{Middle surface T}，

R_{Outer surface T}＝(1+ε_{Outer surface T})×R_{Outer surface}

R_{Inner surface T}＝(1+ε_{Inner surface T})×R_{Inner surface}

Wherein the content of the first and second substances,

R_{outer surface}Is the initial outer surface curvature radius, R, of the sample to be measured_{Outer surface T}Is the radius of curvature, epsilon, of the outer surface of the sample to be measured at the temperature T_{Outer surface T}The strain is measured on the outer surface of the sample to be measured at the temperature T;

R_{inner surface}Is the initial radius of curvature, R, of the inner surface of the sample to be measured_{Inner surface T}Radius of curvature, epsilon, of the inner surface of the sample to be measured at temperature T_{Inner surface T}The inner surface of the sample to be measured is flat when the temperature T isThe strain was measured.

Preferably, the method further comprises the step of,

curvature K of sample to be tested_TComprises the following steps:

or

Preferably, the method further comprises the step of,

at least one grating on the optical fiber is not contacted with the sample to be measured to be used as a compensation grating, the wavelength of the reflected light of the compensation grating at each temperature is monitored, the strain of the compensation grating at each temperature is calculated, and the average strain value of the sample to be measured with the measured position subjected to temperature compensation is calculated according to the following formula

ε_TEi＝ε_Ti-ε_TE

Wherein epsilon_TEiIs the temperature-compensated measured strain, ε, at each measured location at a temperature T_TiIs the grating axial measurement strain of each measured position at the temperature T, i is 1, …, n, n is the number of measured positions, epsilon_TEIs to compensate the grating axial measurement strain of the grating.

The invention has the following beneficial effects:

the invention provides a method for quantitatively testing the temperature bending deformation of a curved surface piezoelectric composite material based on a fiber grating sensing method, aiming at the quantitative testing requirement of the temperature bending deformation of the curved surface piezoelectric composite material for a transducer. According to the method, the measurement positions are arranged on the surfaces of the curved surface piezoelectric composite material, and the contact length between the optical fiber part of the grating and the piezoelectric composite material at each measurement position is accurately measured, so that the precision control of the quantitative test of the temperature bending deformation of the curved surface piezoelectric composite material is realized, the problem of the quantitative test of the temperature deformation of the curved surface piezoelectric composite material is solved, and the related performance parameters of the curved surface piezoelectric composite material are accurately measured. The testing method can provide reliable basis for the detection of the piezoelectric composite material for the transducer, and simultaneously provides an effective testing means for the improvement of the design and preparation process of the curved surface piezoelectric composite material, thereby improving the environmental adaptability of the transducer and a sonar system.

Drawings

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings:

FIG. 1 shows a schematic view of a fiber grating according to an example of the present invention;

FIGS. 2A and 2B are schematic diagrams showing the layout of a fiber grating according to the testing method of the present invention;

FIG. 3 shows a schematic view of a fiber grating bonding area according to the testing method of the present invention;

fig. 4A-4C show the average temperature strain in each direction of the curved piezoelectric composite obtained by the testing method of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The fiber grating is a diffraction grating formed by axially periodically modulating the refractive index of the fiber core, and is a passive filter device. The grating fiber has the advantages of small volume and full compatibility with the fiber, and the resonance wavelength of the grating fiber is sensitive to the change of external environments such as temperature, strain and the like, so the grating fiber is widely applied to the sensing field. The relationship between the wavelength variation of the reflected light of the fiber grating and the strain of the fiber grating is as follows:

wherein, λ is the wavelength of the reflected light of the fiber grating, Δ λ is the wavelength variation of the reflected light of the fiber grating, ε is the axial strain of the grating, and P is the Poisson's ratio of the optical fiber. And tightly attaching the optical fiber to the tested sample of the piezoelectric composite material, so that the strain of the optical fiber is the same as that of the test sample, and the measured axial measurement strain of the grating is the strain of the tested position of the tested sample. The wavelength lambda of the reflected light of the fiber grating is monitored by a fiber grating demodulator, and the test data is calculated, analyzed and processed by the formula, so that the strain value of the test sample can be obtained.

The test method according to the present invention is specifically described below with reference to fig. 1 to 3. In order to reduce the error caused by the inconsistency of the process, the grating on the same optical fiber is preferably used for testing the strain of the sample in the three-dimensional direction or each curved surface. The grating period suitable for sample test is designed, and the grating length and the space between the grating and the grating can be designed according to the specific requirements of the sample test. FIG. 1 shows a grating fiber according to an example of the present invention. The length of each grating is 3mm and the grating spacing is set as required to be 5mm-300mm, for example 15mm, 30mm, 50mm, 150mm, 200mm etc. The measured positions are arranged on each surface of the curved surface test sample, including the outer curved surface, the inner curved surface, the thickness direction, the width direction and the like, and the positions and the number of the measured points are determined according to the size of the surface. For example, the fiber grating layout of the curved surface piezoelectric composite material should be laid out and attached on the outer curved surface and the inner curved surface of the curved surface piezoelectric composite material at the same time, the directions of the inner surface layout and the outer surface layout are preferably the same, each surface is preferably laid out in two mutually perpendicular directions, such as the x direction and the y direction, at the same time, the fiber grating layout is laid out in the thickness direction of the curved surface piezoelectric composite material at the same time, so as to monitor the temperature deformation of different positions of the curved surface piezoelectric composite material. For the accuracy of the test, a plurality of gratings should be laid out in each direction or on each surface to be tested. Fig. 2A and 2B illustrate a curved piezoelectric composite, a fiber grating, and a fiber grating placement method according to an embodiment of the present invention.

In order to eliminate the variation of the fiber grating caused by the change of environmental factors, when the grating cloth is attached to the test point, at least one grating needs to be suspended and not attached to the surface of the piezoelectric composite material, so that the strain of the grating is only affected by environmental changes such as environmental temperature, and the grating cloth is used for carrying out environmental compensation on the grating of the test point. After the test is finished, the grating data attached to the curved surface piezoelectric composite material is subtracted from the grating data for environmental compensation, so that the environmental factors can be eliminated, and the optical fiber test can be carried outThe influence of the amount. The compensation grating may be located anywhere on the fiber, for example, the grating located at the end of the fiber may be used to make measurements for environmental compensation, as shown in fig. 1-2, where the first grating located at the end of the fiber is used as the compensation grating. The test temperature was varied and the measured strain at each temperature was recorded. For example, the strain measured at temperature T at test site 1 of the piezoelectric composite material is ε_T1The strain measured by the fiber grating for environmental compensation is epsilon_TETemperature compensated measured strain epsilon of the temperature Ttest site i_TEiIs composed of

ε_TEi＝ε_Ti-ε_TE

Wherein epsilon_TiThe measured strain measured by the sample test point i at the temperature T; epsilon_TEI is the measured position selected from 1-n, which is the strain of the fiber grating caused by environmental factors at the temperature T.

The fiber grating is adhered to the position to be measured by using quick-drying glue, preferably glue with temperature deformation basically negligible, such as 401 glue, 353ND glue or DB420 glue, so that the fiber grating and the curved surface piezoelectric composite material are tightly attached without relative displacement. For each test point, due to the limitation of a binder coating process or an applying process, the bonding length of the cementing layer along the detection direction is difficult to be completely equal to the grating length, and in order to obtain an accurate strain value of the test sample, the influence of the cementing area on the strain of the test sample is considered. Measuring the length l of the bonding area of each test point, namely measuring the length of the bonding area between the optical fiber of each tested point and the piezoelectric composite material to be tested, as shown in FIG. 3, to obtain l₁，l₂，…，l_nBond area length for each measured location; measuring the length l of each corresponding grating_{Grid 1}，l_{Grid 2}，…，l_{Grid n}And obtaining n as the number of the test points. The ratio of the length of the bonding area at each measuring position to the length of the grating at the corresponding position is used for correcting the measuring strain of the grating at the measuring position, so that the strain of the curved surface piezoelectric composite material can be represented more accurately. And dividing the measured strain of each test point measured by the grating by the length of the cementing layer of the test point to obtain a strain value at the test point. Testing each test point of a certain direction or a certain curved surface according to the following formulaAfter the quantity strain is averaged, the average strain value epsilon of the sample in the direction is obtained_T，

Wherein n is the number of the measured positions of the curved surface, epsilon_T1,ε_T2,…,ε_Ti,…,ε_TnMeasuring strain for the grating axial direction of each measured position of the curved surface at the temperature T;

l1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, … and n is the number of the measured positions.

And multiplying the average strain value of the tested sample by the total length or the total area of the tested sample to obtain the total deformation E.

According to the preferred embodiment of the invention, under the condition that the compensation grating is adopted to carry out environmental compensation on the measured strain of each fiber bragg grating by considering environmental factors, the average strain value epsilon of the curved surface sample to be measured after temperature compensation at each temperature T is calculated according to the following formula_TE

ε_TEiThe measured strain of each measured position i after temperature compensation at the temperature T, L1, L2, …, Li, … and Ln are the ratio of the bonding area length of each measured position of the curved surface to the grating length of the corresponding position, i is 1, …, n, and n is the number of the measured positions.

Preferably, for a curved surface sample, the relationship between the measured strain and the radius of curvature of the fiber grating is:

R_T＝(1+ε_T)×R

wherein R is the initial curvature radius of the curved surface sample, epsilon_TIs the average axial strain, R, of a curved surface sample at a temperature T_TThe radius of curvature of the curved surface sample at temperature T is shown.

At this time, the curvature K of the curved piezoelectric composite material is obtained_TComprises the following steps:

according to the preferred embodiment of the invention, for the curved surface in the x direction, the curvature radius of the middle position of the inner surface and the outer surface is used for representing the change of the curved surface piezoelectric composite material in the x direction, then

R_{Outer surface T}＝(1+ε_{Outer surface T})×R_{Outer surface}

R_{Inner surface T}＝(1+ε_{Inner surface T})×R_{Inner surface}

R_{Outer surface}Is the initial outer surface curvature radius, R, of the sample to be measured_{Outer surface T}Is the radius of curvature, epsilon, of the outer surface of the sample to be measured at the temperature T_{Outer surface T}The strain is measured on the outer surface of the sample to be measured at the temperature T;

R_{inner surface}Is the initial radius of curvature, R, of the inner surface of the sample to be measured_{Inner surface T}Radius of curvature, epsilon, of the inner surface of the sample to be measured at temperature T_{Inner surface T}The strain is measured on average on the inner surface of the sample to be measured at the temperature T.

At this time, the curvature K of the curved piezoelectric composite material_TComprises the following steps:

the curvature of the curved surface in the y direction can be calculated as described above.

The measuring method is realized by utilizing a testing system for temperature deformation of the piezoelectric composite material. The test system comprises a high-temperature and low-temperature experimental box for creating a use environment with the temperature of the piezoelectric composite material rising; the demodulator is used for monitoring the wavelength of the reflected light of the fiber bragg grating; the impedance analyzer is used for measuring performance parameters such as resonant frequency, capacitance and the like of the piezoelectric composite material; and the computer is used for calculating, analyzing and processing the test data obtained by the demodulator and the impedance analyzer to obtain a strain value and a deformation value.

The test method according to the present invention will be specifically described below with reference to examples.

An optical fiber sensor having 12 gratings formed on the same optical fiber is selected, and the grating layout is shown in fig. 1. Selecting radius of curvature R_{Inner surface}＝45.00mm，R_{Outer surface}As shown in fig. 2, the grating at the end is used as an environmental compensation grating, and the other 11 gratings are closely attached to the surface of the piezoelectric composite material by 401 glue. The bond area length was measured for each test point as shown in the table below

The strain of each test point is measured at-40 deg.C, -20 deg.C, 0 deg.C, 20 deg.C, 40 deg.C, 60 deg.C, 80 deg.C and 100 deg.C respectively, and calculated according to the above formula 2, to obtain the average temperature curved surface strain of the piezoelectric composite material in X direction, Y direction and thickness Z direction, which is subjected to temperature compensation and removed of the influence of the length of the adhesive layer in the bonding region, as shown in FIGS. 4A-4C. As can be seen from the strain in each direction and the deformation in each direction, the curve is basically linear, and the result verifies the feasibility of testing the temperature bending deformation of the curved piezoelectric composite material by adopting the fiber grating sensing method.

In fig. 4A-4C, comparative data are presented for average temperature bending strain compensated for temperature without considering the effect of bond line length in the bond area, and are calculated as:

ε_TEiis the temperature compensated measurement strain of each measured position i at the temperature T, i is 1, …, n, n is the number of measured positions.

As can be seen from fig. 4A-4C, the average strain calculated without considering the bond line length effect is about one order of magnitude greater than the average strain considered with the bond line effect, deviating from reality. Therefore, the temperature bending strain must be calculated taking into account the effect of the bond line length.

The invention provides a test method for measuring the temperature bending deformation of the curved surface piezoelectric composite material based on the fiber grating method by researching the layout, point sampling, calculation and data processing of the optical fiber on the curved surface, solves the problem of quantitative test of the temperature deformation of the curved surface piezoelectric composite material, accurately detects the related performance parameters of the curved surface piezoelectric composite material, and controls the quality of the transducer using the curved surface piezoelectric composite material. The invention can provide reliable basis for the detection of the piezoelectric composite material for the transducer, and can promote the improvement of the design and preparation process of the curved surface piezoelectric composite material, thereby improving the environmental adaptability of the transducer and a sonar system.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.