CN111486880A - Molding self-monitoring intelligent composite material and monitoring method thereof - Google Patents
Molding self-monitoring intelligent composite material and monitoring method thereof Download PDFInfo
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- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35309—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
- G01D5/35316—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using a Bragg gratings
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
Abstract
The invention discloses a forming self-monitoring intelligent composite material, which relates to the field of composite material manufacturing and comprises a composite material main body and a sensing system; the composite material main body is a woven composite material; the sensing system comprises a multifunctional sensing probe and a fiber bragg grating demodulator; the multifunctional sensing probe can monitor temperature and stress simultaneously and comprises a temperature sensing part and a stress sensing part; the temperature sensing part consists of a fiber grating, a capillary tube and a sealant, wherein the fiber grating is packaged in the capillary tube through the sealant; the stress sensing component is an optical fiber embedded part; the multifunctional sensing probe is embedded in the woven composite material and is connected with the fiber bragg grating demodulator through the optical fiber.
Description
Technical Field
The invention relates to the field of composite material manufacturing, in particular to a forming self-monitoring intelligent composite material based on embedded fiber bragg grating and data processing and a monitoring method thereof.
Background
In recent years, fiber grating sensors have been extensively studied. The fiber grating sensor has the advantages of small volume, light weight and large monitoring amount, has excellent multiplexing capability, high temperature resistance and electromagnetic interference resistance, and can be embedded into a composite material to monitor the molding process.
The fiber grating sensor reflects the Bragg wavelength lambda of incident light by writing a diffraction grating which causes the refractive index of the fiber core of the optical fiber to be modulated in an axial periodic mannerBAnd light in the vicinity thereof, Bragg wavelength lambdaBExpressed as:
λB＝2neffΛ
wherein n iseffΛ is the grating period for effective index.
When the fiber grating is subjected to temperature change Δ T or axial strain, the grating period Λ and effective refractive index n caused by grating region elongation and photoelastic effecteffResulting in strain response, thermal expansion of the fiber itself and effective refractive index neffThe temperature dependence of (a) results in a temperature response. Effective refractive index neffAnd the change in grating period Λ results in a Bragg wavelength shift Δ λBExpressed as:
ΔλB＝K+KTΔT
wherein, KAnd KTThe sensitivity coefficients of strain and temperature, respectively. When fiber gratings are used as temperature sensors, it is often necessary to use packaging techniques to remove the strain effects.
In the field of monitoring of composite material molding based on fiber gratings, the current technology mainly focuses on monitoring thermosetting composite materials made of unidirectional prepregs with molding temperatures below 220 ℃. However, the use of thermoplastic composites generally requires higher molding temperatures to ensure that the matrix is sufficiently molten during the molding process. For example, composites such as polyetherimides have molding temperatures as high as 332 ℃. At such high temperatures, conventional fiber gratings exhibit an irreversible wavelength shift of about-0.2 nm (corresponding to-241 μ or 24 ℃), and a temperature T and Bragg wavelength drift Δ λBIn a non-linear relationship fromResulting in measurement errors. In addition to high temperatures, a significant portion of thermoplastic composites are woven composites. The microstructure is much more complex than that of a composite material formed by stacking unidirectional prepregs, and the embedded fiber grating is extruded under high pressure, so that the reflectivity is reduced, signals cannot be identified, and even the fiber grating is damaged. In addition, the hot press molding process of thermoplastic woven composites requires a large pressure, 2MPa for polyetherimide matrix composites, which can lead to failure of embedded sensors using fragile ceramic or silica capillaries. The high temperature, micro-weave structure and high pressure all make the molding process of thermoplastic woven composites more difficult to monitor.
Disclosure of Invention
The invention discloses a forming self-monitoring intelligent composite material based on embedded fiber bragg grating and data processing, aiming at the blank of the prior art in the monitoring of forming temperature and stress of a woven composite material. The intelligent composite material can monitor the temperature and stress changes of the composite material in the high-temperature and high-pressure forming process in real time.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
the invention discloses a molding self-monitoring intelligent composite material, which comprises a composite material main body and a sensing system, wherein the composite material main body is provided with a plurality of cavities; the composite material main body is a woven composite material laminated structure; the sensing system comprises a multifunctional sensing probe and a fiber bragg grating demodulator; the multifunctional sensing probe is embedded in the woven composite material laminated structure through an optical fiber, and the multifunctional sensing probe is connected with the fiber bragg grating demodulator through the optical fiber outside the woven composite material laminated structure; the multifunctional sensing probe comprises a temperature sensing part and a stress sensing part; the temperature sensing component comprises a fiber grating, a capillary tube and a sealant, wherein the fiber grating is packaged in the capillary tube through the sealant; the monitoring part of the stress sensing part is an optical fiber embedded part. The multifunctional sensing probe can monitor temperature and stress simultaneously. The technology of the invention eliminates the influence of strain on the fiber grating by using a high-temperature and high-pressure resistant packaging technology, and can realize real-time monitoring of temperature and stress in the forming process based on the sensitivity of the fiber grating to temperature and the light loss effect caused by weaving a composite material micro-woven structure; and because the embedded encapsulated fiber grating has the advantages of small volume and light weight, the embedded encapsulated fiber grating has excellent multiplexing capability, high temperature resistance and electromagnetic interference resistance, has reliable monitoring result, has little influence on the mechanical property of the composite material, and can also realize multi-point monitoring.
Further, the reinforcing phase of the woven composite material laminated structure comprises glass fiber and carbon fiber, the matrix comprises thermosetting resin and thermoplastic resin, and the weaving mode comprises plain weave, twill weave and satin weave.
Furthermore, the temperature sensing component is divided into a single-head temperature sensing component and a double-head temperature sensing component; the single-head temperature sensing component is made by packaging a fiber grating with one end cut off and the other end connected with an optical fiber in a capillary, and the cut-off end of the fiber grating is freely suspended and does not accept strain;
the double-head temperature sensing component is made by packaging the fiber bragg grating with two ends connected with the optical fiber in the capillary, and the fiber bragg grating is prestressed to enable the fiber bragg grating to be bent in the capillary during packaging.
Furthermore, the capillary tube is of a hollow tubular structure and is made of high-temperature and high-pressure resistant materials, namely the temperature resistance is higher than 332 ℃, and the pressure resistance is higher than 2 MPa. Further, the sealant is a high temperature resistant sealant, i.e., resistant at temperatures >332 ℃. The temperature sensing part is formed by encapsulating a high-temperature (332 ℃) resistant sealant and a high-temperature (332 ℃) resistant high-pressure (2 MPa) capillary tube, so that the temperature sensing part has the capability of working at the temperature of more than 332 ℃, can resist larger local stress, and realizes the self-monitoring of the molding temperature of the thermoplastic woven composite material with high molding temperature and pressure and complex microstructure.
Furthermore, the multifunctional sensing probe is formed by connecting one or a plurality of temperature sensing parts and a stress sensing part in series; or multiple multi-functional sensing probes embedded in a woven composite laminate structure.
The invention also discloses a monitoring method of the forming self-monitoring intelligent composite material, which is characterized by comprising the following steps:
1) carrying out high-temperature pre-annealing on the multifunctional sensing probe before embedding the multifunctional sensing probe into the braided composite material laminated structure;
2) carrying out temperature calibration, load test and embedding performance test on the multifunctional sensing probe;
2.1, temperature calibration: delta lambda shift due to temperature T and Bragg wavelength at high temperatureBThe relation of (a) is nonlinear, and a cubic polynomial is required for fitting, and the specific form is as follows:
T＝K0+K1ΔλB+K2ΔλB 2+K3ΔλB 3(1)
wherein, K0，K1，K2And K3Is a fitting coefficient;
2.2, load test method: respectively applying transverse and axial loads on the temperature sensing component of the multifunctional sensing probe if the Bragg wavelength is lambdaBIf no obvious change exists, the temperature sensing component is not influenced by external load;
2.3, embedding performance test: embedding the multifunctional sensing probe into prepreg, putting the prepreg into a hot press, gradually increasing the embedding depth and pressurizing, and according to the reflectivity R of different embedding depthsfDetermining a proper embedding depth;
3) the initial data monitored by the temperature sensing part in the composite material forming process is Bragg wavelength drift delta lambdaBReconstructing an actual temperature curve through a formula;
4) stress sensing member through reflectance change Δ RfReflecting the internal stress change of the composite material.
Furthermore, when the intelligent composite material takes thermoplastic resin as a matrix: in the cooling process, when the temperature is lower than the glass transition temperature T of the resingWhen the resin is gradually converted into a glass state, the embedded portion of the optical fiber is slightly bent due to the gradual increase of the internal stress and the influence of the micro-woven structure of the woven composite material laminated structure, resulting in a change in reflectivity Δ Rf；
When the intelligent composite material takes thermosetting resin as a matrix: in the process of resin curing and cooling after curing, due to the gradual increase of internal stress and the influence of the micro-woven structure of the woven composite material laminated structure, the embedded part of the optical fiber is slightly bent, so that the reflectivity change delta R is causedf。
Further, the stress change inside the composite material can also be simulated according to the weaving form and the resin type of the laminated structure of the woven composite material to obtain a specific value of the stress change.
Furthermore, the multifunctional sensing probe is formed by connecting one or a plurality of temperature sensing parts and a stress sensing part in series, so that multiplexing is realized; or a plurality of multifunctional sensing probes are embedded in the woven composite material laminated structure to carry out multi-point multi-physical quantity forming self-monitoring.
The beneficial effects of the invention and the prior art are as follows:
1. the existing monitoring technology based on FBG can only realize the monitoring of the molding temperature of the unidirectional fiber prepreg laminated composite material with lower molding temperature and pressure and simple microstructure; the temperature sensing probe disclosed by the invention can effectively eliminate irreversible wavelength drift generated by the Bragg wavelength above 300 ℃ through high-temperature pre-annealing; through cubic polynomial fitting, a temperature response curve can be accurately obtained, and the influence of the nonlinear relation between the Bragg wavelength and the temperature is eliminated. By eliminating errors through the two methods, the accuracy of monitoring the temperature can reach +/-2 ℃.
2. Compared with the prior art, the strain and the stress of the composite material in the forming process can be monitored, and an additional sensing unit is required; the stress sensing component realizes stress monitoring in the forming process by utilizing the light loss effect caused by micro bending of the optical fiber pigtail in the forming process for the first time; the invention does not need to add an additional sensing unit, is beneficial to reducing the initial damage to the composite material, reduces the complexity of the sensor system and increases the reliability of the sensing system.
Drawings
FIG. 1 is a schematic diagram of a molded self-monitoring intelligent composite material based on embedded fiber grating and data processing according to the present invention;
FIG. 2 is a schematic view of a single-ended temperature sensing component of the present invention;
FIG. 3 is a schematic view of a dual-head temperature sensing component of the present invention;
FIG. 4 is a schematic view of a multi-functional sensing probe of the present invention;
FIG. 5 is a graph illustrating exemplary Bragg wavelength shift and post-reconstruction temperature in an embodiment of the present invention;
FIG. 6 is a graph illustrating temperature and reflectivity (stress) monitoring results according to an embodiment of the present invention;
the sensor comprises a 1-woven composite material laminated structure, a 2-multifunctional sensing probe, a 3-fiber grating demodulator, a 4-temperature sensing component, a 5-stress sensing component, a 6-fiber grating, a 7-capillary tube, an 8-sealant, a 9-optical fiber embedded part, a 10-single-head temperature sensing component and a 11-double-head temperature sensing component.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be noted that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in FIG. 1, FIG. 1 is a schematic diagram of a self-monitoring intelligent composite material formed based on embedded fiber bragg grating and data processing, and a multifunctional sensing probe 2 is embedded in a woven composite material laminated structure 1 and connected with a fiber bragg grating demodulator 3 through an optical fiber, wherein the woven composite material laminated structure 1 of the embodiment is a glass fiber woven composite material, a matrix is polyetherimide, and the thickness of the composite material is 20 layers of 200 × 200mm2The prepreg is formed by unidirectional laying.
As shown in fig. 2, fig. 2 is a schematic view of a single-head temperature sensing component 10, in this embodiment, the single-head temperature sensing component 10 is made by packaging a fiber grating 6, one end of which is cut off and the other end of which is connected with an optical fiber, in a 304 stainless steel capillary 7 with an inner diameter of 300 μm, an outer diameter of 500 μm and a length of 15mm, wherein a sealant 8 is an aluminosilicate high-temperature-resistant sealant, the maximum use temperature is 1300 ℃, and the cut-off end of the fiber grating 6 is freely suspended and does not receive strain. As shown in fig. 3, the double-head temperature sensing component (11) is made by packaging the fiber grating (6) with both ends connected with optical fibers in the capillary (7), and the fiber grating (6) is pre-stressed to be bent in the capillary (7) during packaging.
As shown in fig. 4, fig. 4 is a schematic view of the multi-functional sensing probe 2, the multi-functional sensing probe 2 in this embodiment includes only 1 single-head temperature sensing component 10, and the stress sensing component 5 is an optical fiber embedded portion 9. In this embodiment, the fiber grating 6 and the fiber embedded portion 9 have a core diameter of 9 μm and a cladding outer diameter of 125 μm. The length of the fiber grating 6 is 5mm, the coating layer is stripped off, and the Bragg wavelength lambda is at normal temperatureBIs 1550 nm; the outer diameter of the coating layer of the optical fiber embedded portion 9 was 250 μm.
The multifunctional sensing probe 2 of the embodiment needs to be subjected to high-temperature pre-annealing before embedding, and then needs to be subjected to temperature calibration, load test and embedding performance test.
The high-temperature pre-annealing method comprises the following steps: and (3) putting the multifunctional sensing probe 2 into high-temperature equipment, heating to 350 ℃, keeping for 2 hours, and naturally cooling to room temperature along with the furnace.
The temperature calibration method comprises the following steps: the multifunctional sensing probe 2 is put into high-temperature equipment, heated to 350 ℃, then naturally cooled to room temperature along with the furnace, and the Bragg wavelength drift delta lambda of the multifunctional sensing probe is recorded by the fiber grating demodulator 3 in the processBThe temperature T is recorded by a thermocouple. Due to temperature T above 150 ℃ and Bragg wavelength drift Delta lambdaBFor non-linearity, a cubic curve is required for fitting, the specific form being:
T＝K0+K1ΔλB+K2ΔλB 2+K3ΔλB 3(1)
wherein, K0，K1，K2And K3Are fitting coefficients.
The load test method comprises the following steps: applying transverse and axial loads, respectively, on the temperature sensing member 4 of the multi-function sensing probe 2 if the Bragg wavelength λBThe temperature sensing part 4 is not considered to be changed without any significant changeAffected by external loads.
The embedding performance test method comprises the following steps: embedding the multifunctional sensing probe 2 into the prepreg, placing the prepreg and the multifunctional sensing probe into a hot press, gradually increasing the embedding depth and pressurizing, and according to the reflectivity R of different embedding depthsfAn appropriate embedding depth is determined. In this example, when the embedding depth D is less than 40mm, the reflectance R isfThe embedding depth D is set to 40mm for > 0.1.
The forming process and the multi-physical quantity self-monitoring method are specifically as follows:
the method comprises the following steps: embedding the multifunctional sensing probe 2 along the warp direction or the weft direction of the woven composite material laminated structure 1, and putting the embedded multifunctional sensing probe into a hot press;
step two: recording buried grating Bragg wavelength λ with integrated grating demodulation systemBAnd the reflectivity R of the optical fiberf；
Step three: setting the temperature of the hot press to 332 ℃;
step four: after the temperature reaches 332 ℃ and is constant, applying the pressure of 2MPa, and keeping the temperature and the pressure for 40 minutes;
step five: naturally cooling to room temperature, then releasing the pressure intensity and demoulding;
as shown in fig. 5, K is given by the formula T ═ K0+K1ΔλB+K2ΔλB 2+K3ΔλB 3Can be shifted by the Bragg wavelength by Delta lambdaBReconstructing a temperature T-time T curve of the braided composite material laminated structure 1 in the forming process by using the time T curve;
as shown in FIG. 6, the glass transition temperature of the polyetherimide is 217 ℃ at which the polyetherimide is in a uniform stress state, and micro-bending does not occur in the optical fiber embedded portion 9 under uniform stress; at 217 ℃ or lower, the polyetherimide gradually turns into a glassy state, the internal stress is not uniform, and since the braided composite laminated structure 1 has a micro-braided structure, the optical fiber embedded portion 9 starts to be subjected to non-uniform stress and is slightly bent to cause light loss, and the reflectance becomes gradually small, whereby the change of the stress inside the composite can be monitored.
The foregoing is only a preferred embodiment of the present invention. It should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the scope of the present invention.
Claims (10)
1. The formed self-monitoring intelligent composite material is characterized by comprising a composite material main body and a sensing system;
the composite material main body is a woven composite material laminated structure (1);
the sensing system comprises a multifunctional sensing probe (2) and a fiber grating demodulator (3); the multifunctional sensing probe (2) is embedded into the woven composite material laminated structure (1) through an optical fiber, and the multifunctional sensing probe (2) is connected with the fiber bragg grating demodulator (3) through the optical fiber outside the woven composite material laminated structure (1);
the multifunctional sensing probe (2) comprises a temperature sensing part (4) and a stress sensing part (5), namely, the temperature and the stress are monitored simultaneously; the temperature sensing component (4) comprises a fiber grating (6), a capillary tube (7) and a sealant (8), wherein the fiber grating (6) is packaged in the capillary tube (7) through the sealant (8); the monitoring part of the stress sensing component (5) is an optical fiber embedded part (9).
2. A shaped self-monitoring smart composite as claimed in claim 1, characterized in that the reinforcing phase of the woven composite laminate structure (1) comprises glass and carbon fibers, the matrix comprises thermosetting and thermoplastic resins, and the weave comprises plain, twill and satin.
3. The intelligent composite material for molding self-monitoring according to claim 1, wherein the temperature sensing component (4) is divided into a single-head temperature sensing component (10) and a double-head temperature sensing component (11);
the single-head temperature sensing component (10) is made by packaging a fiber grating (6) with one end cut off and the other end connected with an optical fiber in a capillary (7), and the cut-off end of the fiber grating (6) is freely suspended and does not accept strain;
the double-head temperature sensing component (11) is made by packaging a fiber grating (6) with two ends connected with optical fibers in a capillary tube (7), and the fiber grating (6) is prestressed to be bent in the capillary tube (7) during packaging.
4. The shaped self-monitoring smart composite material according to claim 1, wherein the capillary tube (7) is a hollow tubular structure made of a material resistant to high temperature and high pressure, i.e. resistant to temperature >332 ℃ and resistant to pressure >2 MPa.
5. The shaped self-monitoring smart composite as claimed in claim 1, wherein the sealant (8) is a high temperature resistant sealant, i.e. temperature resistant >332 ℃.
6. The shaped self-monitoring smart composite material as claimed in claim 1, wherein the multifunctional sensor probe (2) is composed of one or more temperature sensing elements (4) in series with a stress sensing element (5); or embedding a plurality of multifunctional sensing probes (2) in the woven composite material laminated structure (1).
7. A monitoring method for a formed self-monitoring intelligent composite material is characterized by comprising the following steps:
1) carrying out high-temperature pre-annealing on the multifunctional sensing probe (2) before embedding the multifunctional sensing probe into the braided composite material laminated structure (1);
2) carrying out temperature calibration, load test and embedding performance test on the multifunctional sensing probe (2);
2.1, temperature calibration: delta lambda shift due to temperature T and Bragg wavelength at high temperatureBThe relation of (a) is nonlinear, and a cubic polynomial is required for fitting, and the specific form is as follows:
T＝K0+K1ΔλB+K2ΔλB 2+K3ΔλB 3(1)
wherein, K0，K1，K2And K3Is a fitting coefficient;
2.2, load test method: applying a transverse and an axial load on the temperature sensing member (4) of the multi-functional sensing probe (2), respectively, if the Bragg wavelength λ isBIf no obvious change exists, the temperature sensing component (4) is not influenced by external load;
2.3, embedding performance test: embedding the multifunctional sensing probe (2) into the prepreg, putting the prepreg into a hot press, gradually increasing the embedding depth and pressurizing, and according to the reflectivity R of different embedding depthsfDetermining a proper embedding depth;
3) the initial data monitored by the temperature sensing part (4) in the composite material forming process is Bragg wavelength drift delta lambdaBReconstructing an actual temperature curve through the formula (1);
4) the stress sensing member (5) changes by a reflectivity Delta RfReflecting the internal stress change of the composite material.
8. The monitoring method of the self-monitoring intelligent composite material as claimed in claim 7, wherein when the intelligent composite material takes the thermoplastic resin as the matrix: in the cooling process, when the temperature is lower than the glass transition temperature T of the resingWhen the resin is gradually converted into a glass state, the optical fiber embedded part (9) is slightly bent due to the gradual increase of the internal stress and the influence of the micro-woven structure of the woven composite material laminated structure (1), resulting in a change in reflectivity Δ Rf；
When the intelligent composite material takes thermosetting resin as a matrix: in the process of resin solidification and cooling after solidification, due to the gradual increase of internal stress and the influence of the micro-woven structure of the woven composite material laminated structure (1), the optical fiber embedded part (9) is slightly bent, so that the reflectivity change delta R is causedf。
9. The monitoring method for the self-monitoring intelligent composite material molding according to claim 7, wherein the stress variation inside the composite material can also be simulated to obtain a specific value of the stress variation according to the weaving form and the resin type of the woven composite material laminated structure (1).
10. The monitoring method of the self-monitoring intelligent composite material as claimed in claim 7, wherein the multifunctional sensing probe (2) is composed of one or more temperature sensing components (4) and a stress sensing component (5) which are connected in series to realize multiplexing; or a plurality of multifunctional sensing probes (2) are embedded in the woven composite material laminated structure (1) to carry out multi-point multi-physical quantity forming self-monitoring.
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