Resin-based mechanochromic glass fiber composite material as well as preparation method and application thereof

Abstract

The invention relates to a resin-based mechanochromic glass fiber composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing rhodamine 6G with absolute ethyl alcohol and anhydrous ethylenediamine to form a mixed solution, then carrying out heating reflux reaction on the mixed solution in an oil bath, and then sequentially filtering, cleaning and drying to obtain amino-functionalized rhodamine; mixing the amino-functionalized rhodamine with epoxy resin, and carrying out heating reaction in an oil bath to obtain rhodamine modified epoxy resin; and (2) injecting the rhodamine modified epoxy resin into the glass fiber by adopting a drainage method, fully impregnating, and then curing to obtain the resin-based mechanochromic glass fiber composite material. The resin-based mechanochromic glass fiber composite material prepared by the invention has good mechanical properties, and can realize visual response to mechanical stimulation, thereby achieving the purpose of real-time in-situ detection of structural damage.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced composite materials, and particularly to a resin-based force-induced color-changing glass fiber composite material and its preparation and application. Background Art

[0002] Advanced composite materials have occupied an important position in the industrial field, especially in the aerospace field, due to their excellent properties such as light weight, high strength, fatigue resistance, corrosion resistance, and strong designability. In aerospace engineering, reducing the structural weight is crucial for improving the performance of aircraft, reducing energy consumption, and operating costs. Among them, resin-based composite materials, as the fourth major aerospace structural material, have been widely and extensively used in the structures of new-generation aircraft. For example, in key parts such as aircraft wings and fuselages, resin-based composite materials can effectively reduce weight while ensuring structural strength, thereby improving the fuel efficiency and flight performance of the aircraft.

[0003] In recent years, fiber-reinforced epoxy resin has seen a significant increase in demand as a structural material due to its various excellent properties. However, this material also faces a series of technical problems in practical applications. As its scope of use continues to expand, how to ensure its safety and reliability during use has become an urgent problem to be solved. Especially in terms of damage detection and maintenance, traditional detection methods are difficult to meet the requirements of high efficiency, accuracy, and low cost. In fields such as aerospace where safety requirements are extremely high, if minor damages cannot be detected and repaired in a timely manner, it may lead to serious safety accidents, resulting in huge economic losses and casualties.

[0004] Traditional non-destructive testing methods include radiographic testing, ultrasonic testing, eddy current testing, and magnetic particle testing, but all have certain limitations. Radiographic testing equipment is large, requires a dedicated site for installation and operation, and is expensive. Radiation is harmful to the human body, and operators need strict protection, which increases costs and limits the detection efficiency. Moreover, its detection accuracy for complex structures or minor defects is relatively low. Ultrasonic testing relies on the propagation characteristics of sound waves in materials. For irregularly shaped or thin-walled structures, the reflection and scattering laws of sound waves become complex, resulting in inaccurate detection results. Eddy current testing is sensitive to the conductivity and surface state of materials. For structures with uneven surfaces or covered with non-conductive coatings, the detection is difficult. The sensitivity of magnetic particle testing is unstable, and its detection effect is closely related to the magnetization direction and defect direction. When the defect direction is parallel to the magnetization direction, it is difficult for magnetic particles to accumulate at the defect, easily causing missed detections. Moreover, the cleaning work after magnetic particle testing is relatively cumbersome, and the residual magnetic particles may have a certain impact on the material properties.

[0005] Therefore, there is an urgent need to develop a new advanced composite material suitable for damage detection and / or damage warning. Summary of the Invention

[0006] To solve the above technical problems, the object of the present invention is to provide a resin-based force-induced color-changing glass fiber composite material, its preparation method and application. The present invention utilizes the force-induced color-changing property of the rhodamine group, introduces it into the epoxy resin matrix, and composites it with glass fiber to prepare a resin-based glass fiber composite material. By optimizing the composition and preparation process of the material, while the composite material has good mechanical properties, it can achieve a visual response to mechanical stimuli, so as to achieve the purpose of real-time in-situ detection of structural damage.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] The first object of the present invention is to provide a preparation method of a resin-based force-induced color-changing glass fiber composite material, comprising the following steps:

[0009] (1) Mix rhodamine 6G with a solvent and anhydrous ethylenediamine to form a mixed solution, then heat and reflux the mixed solution, and then filter, wash and dry in sequence to obtain amino-functionalized rhodamine, that is, Rh-NH2; then mix the amino-functionalized rhodamine with epoxy resin and carry out a heating reaction to obtain rhodamine-modified epoxy resin, that is, DGEBA-Rh;

[0010] (2) Inject the rhodamine-modified epoxy resin into the glass fiber for sufficient impregnation, and then cure to obtain a resin-based force-induced color-changing glass fiber composite material.

[0011] The beneficial effects of the present invention are as follows: Utilizing the force-induced color-changing property of rhodamine, after amino-functionalizing it and introducing it into the epoxy resin matrix, the epoxy resin material can change its photophysical properties when stressed, having force-induced fluorescence color-changing performance, and the epoxy resin provides good matrix support for the glass fiber, enhancing the compressive performance of the resin-based force-induced color-changing glass fiber composite material, while the glass fiber provides an effective strengthening effect for the rhodamine-modified epoxy resin, improving the tensile performance of the resin-based force-induced color-changing glass fiber composite material. The present invention realizes the synergistic optimization between the mechanical properties and the force-induced color-changing properties of the resin-based force-induced color-changing glass fiber composite material through reasonable design and control of the preparation process. It not only ensures that the resin-based force-induced color-changing glass fiber composite material has sufficient load-bearing capacity under normal use conditions, but also enables it to emit optical signals in a timely manner when damage occurs, improving the safety and reliability of the use of the resin-based force-induced color-changing glass fiber composite material.

[0012] On the basis of the above technical solution, the present invention can also be improved as follows.

[0013] Further, the dosage ratio of the rhodamine 6G, the solvent, and the anhydrous ethylenediamine is 0.02 - 0.03 mol: 250 - 400 ml: 0.07 - 0.1 mol.

[0014] Further, the solvent includes absolute ethanol.

[0015] Further, the mass ratio of the amino-functionalized rhodamine to the epoxy resin is 2-4:40-60.

[0016] Further, the specific steps of the heating reflux reaction in step (1) are as follows: When the mixed solution is subjected to heating reflux reaction in an oil bath, the temperature of the oil bath is 75-90 °C, and the time of the heating reflux is 22-26 h.

[0017] Further, the glass fiber is at least one of SW80B, SW110C, SW210A, SW220B, and SW280F.

[0018] The beneficial effects of adopting the above further scheme are as follows: Parameters such as the organizational structure and density of the glass fiber have a significant impact on the mechanical properties and force-induced color change properties of the composite material. The glass fiber of the present invention provides an effective strengthening effect for the resin and improves the tensile property of the material.

[0019] Further, the mass ratio of the rhodamine-modified epoxy resin to the glass fiber in step (2) is 2-4:1.

[0020] Further, the impregnation time in step (2) is 5-15 min.

[0021] The beneficial effects of adopting the above further scheme are as follows: After the glass fiber is fully impregnated, the resin can better wrap the fiber, which can effectively improve the mechanical properties of the resin-based force-induced color change glass fiber composite material. For example, in terms of tensile strength, when the fully impregnated material is subjected to external tensile force, the fiber and the resin act synergistically, and it can withstand greater tensile force and is not easily broken. At the same time, it can also enhance the fatigue resistance of the composite material, enabling the material to still maintain good performance under the action of multiple cyclic stresses.

[0022] Further, the specific steps of the curing in step (2) are as follows: First, cure at 65 °C - 75 °C for 2 - 4 hours, then raise the temperature to 110 °C - 125 °C and cure for 1.5 - 2 hours, and finally post-cure at 130 °C - 160 °C for 0.8 - 2 hours to fully cure and form the composite material.

[0023] The second object of the present invention is to provide a resin-based force-induced color change glass fiber composite material.

[0024] The beneficial effects of the present invention are as follows: Rhodamine changes from a spiro structure to an open-ring structure under the action of an external force, visually changing the color or optical properties. The resin-based force-induced color change glass fiber composite material of the present invention can achieve a visual response to mechanical stimuli while having good mechanical properties.

[0025] The third object of the present invention is to provide an application of a resin-based force-induced color change glass fiber composite material, and use the described resin-based force-induced color change glass fiber composite material for damage detection and / or damage warning.

[0026] The beneficial effects of the present invention are as follows: The present invention successfully introduces a fluorescence response switch into the fiber composite system, realizing real-time in-situ damage detection with the naked eye. When the resin-based force-induced color change glass fiber composite material is subjected to an external force, the rhodamine group undergoes a force-induced color change reaction, and the damage area and degree inside the material can be intuitively displayed through the changes in color and fluorescence. This technology can be applied to detect the stress condition of materials and predict potential damage, and has broad application prospects in many fields such as aerospace, automobile manufacturing, and electronic products. This characteristic enables potential safety hazards to be detected in a timely manner during the use of the structure without the need to rely on complex external detection equipment, greatly improving the detection efficiency and convenience and reducing the detection cost. Description of the Drawings

[0027] Figure 1 It is the fluorescence spectrum curve graph of the resin-based force-induced color change glass fiber composite material of Example 1 of the present invention under different pressures;

[0028] Figure 2 It is the fluorescence spectrum curve graph of the resin-based force-induced color change glass fiber composite materials of Examples 1 to 5 of the present invention;

[0029] Figure 3 It is the fluorescence situation graph of the resin-based force-induced color change glass fiber composite materials of Examples 1 to 5 of the present invention under ultraviolet light. Detailed Embodiments

[0030] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specifying specific techniques or conditions in the examples, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments not indicating the manufacturer, they are all conventional products that can be purchased through regular channels.

[0031] Example 1: Preparation 1 of Resin-Based Force-Induced Color Change Glass Fiber Composite Material

[0032] (1) In a fume hood, add 0.021 mol of rhodamine 6G (Aladdin) to a three-necked flask containing 300 ml of absolute ethanol (Fuyu reagent). Turn on the stirrer and set the stirring speed to 350 rpm to fully dissolve rhodamine 6G to obtain an ethanol solution of rhodamine 6G. Slowly add 0.083 mol of anhydrous ethylenediamine (Damao) to the ethanol solution of rhodamine 6G. During the addition process, control the reaction temperature at 25 - 30 °C. After the addition is complete, connect the three-necked flask to an argon protection device and introduce argon to remove oxygen from the system. Heat the oil bath to 80 °C, place the three-necked flask in the oil bath, and heat under reflux for 24 hours. After the reaction is completed, naturally cool the reaction system to room temperature, then filter through a Buchner funnel. Wash the obtained solid product three times with absolute ethanol to obtain the washed product. Transfer the washed product to a vacuum oven and dry it at 80 °C for 3 hours to obtain Rh-NH2;

[0033] Accurately weigh 2.5 g of Rh-NH2 and 50 g of bisphenol A glycidyl ether DGEBA (Booker Chemical Industry) and add them to a dry three-necked flask. Again, introduce argon for protection. Heat the oil bath to 150 °C and heat with stirring for 3 hours to allow Rh-NH2 and DGEBA to fully react to obtain DGEBA-Rh resin. The process is as Figure 1 shown;

[0034] (2) Cut the fiberglass cloth SW280F (Nanjing Fiberglass Research Institute) with a warp density of 20 ends / cm, a weft density of 18 ends / cm, a warp breaking strength of 2000 N / 25 mm, a weft breaking strength of 1700 N / 25 mm, and a grammage of 280 g / m 2 into square composite specimens with a side length of 26 mm and a thickness of 0.25 mm. Stack the cut square composite specimens in a mold, ensuring that the square composite specimens are laid flat and without wrinkles. Pour the prepared DGEBA-Rh resin into the mold and use the drainage method to slowly impregnate the square composite specimens. The impregnation time is 5 - 15 min. After impregnation is completed, place the mold in an oven. First, pre-cure at 60 °C for 3 hours with a heating rate of 5 °C / min; then raise the temperature to 120 °C and cure for 2 hours with a heating rate of 5 °C / min; finally, post-cure at 150 °C for 1 hour with a heating rate of 5 °C / min. After curing is completed, take the mold out of the oven, naturally cool it to room temperature, and then carefully demold to obtain a resin-based mechanochromic fiberglass composite material, as Figure 2 shown.

[0035] Examples 2 - 5:

[0036] Examples 2 to 5 are different from the example only in that the types and thicknesses of the glass fiber cloths used are different, and the remaining steps, parameters, conditions, and raw materials are the same as those in Example 1. The specific types of glass fiber cloths used in Examples 2 to 5 are shown in Table 1 as follows:

[0037] Table 1

[0038]

[0039] Comparative Example 1: Preparation of Resin-Based Force-Induced Color Change Glass Fiber Composite

[0040] Comparative Example 1 is different from Example 1 only in that the heating reflux time in step (1) for preparing DGEBA-Rh is 12 h, and the remaining preparation steps, operating parameters, and raw materials are the same as those in Example 1.

[0041] Comparative Example 2: Preparation of Resin-Based Force-Induced Color Change Glass Fiber Composite

[0042] Comparative Example 2 is different from Example 1 only in that the heating reflux time in step (1) for preparing DGEBA-Rh is 48 h, and the remaining preparation steps, operating parameters, and raw materials are the same as those in Example 1.

[0043] Comparative Examples 3 to 5: Preparation of Resin-Based Force-Induced Color Change Glass Fiber Composite

[0044] Comparative Examples 3 to 5 are different from Example 1 only in that the dosage of DGEBA in step (1) for preparing Rh-NH2 is different, and the remaining preparation steps, operating parameters, and raw materials are the same as those in Example 1. The specific heating reflux times of Comparative Examples 3 to 5 are shown in Table 2 as follows:

[0045] Table 2

[0046] Comparative Example 3 Comparative Example 4 Comparative Example 5 DGEBA 12.5g 25g 75

[0047] Comparative Examples 6 to 8:

[0048] Comparative Examples 6 to 8 are different from Example 1 only in that the curing process in step (2) is different, and the remaining preparation steps, operating parameters, and raw materials are the same as those in Example 1. The curing processes of Comparative Examples 6 to 8 are shown in Table 3 as follows:

[0049] Table 3

[0050]

[0051] Performance Test:

[0052] 1. Mechanical Property Test

[0053] The uniaxial compression test and tensile test were carried out on the resin-based glass fiber composites prepared in Examples 1-5 by a universal mechanical material testing machine (LE5255-H800; Shanghai Lishi Scientific Instrument Co., Ltd.).

[0054] (1) Uniaxial compression test: The resin-based glass fiber composites prepared in Examples 1-5 were pressured at a constant loading rate of 10 MPa / s, with the inlet force of 20 MPa. The deformation of each material was measured at 0 MPa, 50 MPa, 100 Mpa, 150 Mpa, 200 MPa, 250 Mpa, and 300 MPa, and the fluorescence intensity of the resin-based glass fiber composites prepared in Examples 1-5 under the above pressures was detected by a fluorescence spectrometer (FL970 Plus; Shanghai Tianmei Scientific Instrument Co., Ltd.). Among them, the fluorescence intensity of the resin-based glass fiber composite prepared in Example 1 under the above pressures was as Figure 1 shown.

[0055] (2) Tensile test: The two ends of the resin-based glass fiber composites prepared in Examples 1-5 and Comparative Examples 6-8 were fixed respectively, and the specimens were stretched at a tensile rate of 2 mm / min. The tensile strength of the materials was obtained as shown in Table 4.

[0056] Each group was repeated five times and the average value was taken. The above results are shown in Table 4 and Figure 1 as follows:[[]]END]]

[0057] Table 4

[0058] Tensile strength Example 1 259 MPa Example 2 103 MPa Example 3 126 MPa Example 4 209 MPa Example 5 233 MPa Comparative Example 6 109 MPa Comparative Example 7 215 MPa Comparative Example 8 238 MPa

[0059] From Table 4 and Figure 1 it can be obtained that

[0060] (1) The test results show that the Rh mechanical group can be activated by scratching or uniaxial compression, showing reversible color change and red fluorescence turn-on response. By combining the Rh mechanical carrier with commercial epoxy resin, the stress-dependent color response under uniaxial compression was achieved. The Rh zwitterion formed under compressive stress makes the sample turn red. The ultraviolet-visible spectrum proves the differential activation under different degrees of compressive stress.

[0061] (2) There are differences in the tensile strength of different types of glass fiber composites, which are closely related to parameters such as the organizational structure, density, and breaking strength of the glass fiber. For example, the composite reinforced with SW280F glass fiber shows a higher strength value in the tensile test, because its higher density and breaking strength can better withstand external forces and provide more effective reinforcement for the resin.

[0062] (3) Among Examples 1 to 5, the only variable is the change in the type of glass fiber in the raw materials. From SW80B to SW280F, as its density, breaking strength, and gram weight increase, its tensile strength also increases;

[0063] (4) In Comparative Examples 6, 7, and 8, only the curing process was changed. From the results, it can be seen that different curing temperatures and holding times have a great impact on the tensile strength of the material. When only low-temperature curing is carried out, even if the holding time is the same, the tensile strength of the specimen is significantly lower than that of the material prepared in the present invention; when the high-temperature curing time is increased, the mechanical properties of the material are instead reduced.

[0064] 2. Optical property test

[0065] The fluorescence emission spectra of the resin-based force-induced color-changing glass fiber composites prepared in Examples 1 to 5 under a pressure of 600 MPa were measured using a fluorescence spectrometer (FL970 Plus; Shanghai Tianmei Scientific Instrument Co., Ltd.). The specific measurement method is as follows:

[0066] The resin-based force-induced color-changing glass fiber composites prepared in Examples 1 to 5 were respectively placed in the sample cell of the fluorescence spectrometer. The excitation light wavelength was set to the characteristic excitation wavelength of rhodamine, and the fluorescence emission spectra of the materials under the action of the same degree of external force were recorded. The changes in optical parameters such as fluorescence intensity and emission peak position were analyzed. The results are as Figure 2 shown;

[0067] From Figure 2 it can be obtained that:

[0068] Under ultraviolet light, the position of the fluorescence emission peak shows a certain shift. The fluorescence spectrum data measured by the fluorescence spectrometer further confirm this change law of optical properties. Most importantly, when the amount of the fluorescent dye rhodamine remains unchanged, its fluorescence intensity is significantly enhanced, indicating that the rhodamine content therein is significantly increased.

[0069] 3. Microstructure characterization

[0070] A strong light ultraviolet flashlight (ZF-7A; Shanghai Qigong Instrument and Equipment Co., Ltd.) and a high-power microscope (model LEICALAS X; Leica Microsystems GmbH, Germany) were used to observe the fluorescence of the resin-based force-induced color-changing glass fiber composites prepared in Examples 1 to 5 under ultraviolet light before and after being stressed at a pressure of 600 MPa, directly observing the changes in fluorescence color and intensity of the material before and after being stressed, as well as the distribution of the force-induced color-changing regions. The results are as Figure 3 shown. Observe the interfacial bonding situation between the glass fiber and the resin matrix, including whether the interface is clear, and whether there are defects such as pores or cracks.

[0071] From Figure 3 it can be obtained that:

[0072] The interface between the glass fiber and the resin matrix is well-bonded, without obvious defects such as pores or cracks. In the unloaded state, the material exhibits the initial color and fluorescence characteristics of rhodamine. When pressure is applied to the specimen, it can be observed under natural light that the color of the material changes from the initial color to red, and the degree of color change is related to the magnitude of the pressure.

[0073] Test Example 2:

[0074] The yields of Rh-NH2 during the preparation processes of Example 1, Comparative Examples 1-2 were detected respectively, and the results are shown in Table 5:

[0075] Table 5

[0076]

[0077]

[0078] It can be obtained from Table 5 that:

[0079] For the experiment of heating and refluxing the modified rhodamine in an oil bath at 80 °C, in Comparative Examples 1 and 2, only the heating and refluxing reaction time was changed: it can be seen from the results that insufficient reaction for 24 h will lead to a very obvious decrease in the yield; however, too long reaction time exceeding 24 h has little effect on the yield of amino-modified rhodamine. Although the yield of Comparative Example 2 is higher than that of Example 1, the time is longer and the cost is higher.

[0080] Test Example 3:

[0081] The fluorescence intensities of Example 1, Comparative Examples 3-8 under 600 Mpa were tested using a fluorescence spectrometer (FL970 Plus; Shanghai Tianmei Scientific Instrument Co., Ltd.). The parameter settings at room temperature were: the starting wavelength of Em was 360 nm, the ending wavelength was 680 nm, the fixed wavelength of Ex was 350 nm, and the PTM value was 470. The detection results are shown in Table 6:

[0082] Table 6

[0083] Fluorescence intensity Example 1 19372 Comparative Example 3 5565 Comparative Example 4 9815 Comparative Example 5 21093 Comparative Example 6 8184 Comparative Example 7 15355 Comparative Example 8 17801

[0084] It can be obtained from Table 5 that:

[0085] (1) In Comparative Examples 3, 4, and 5, only the mass ratio of the amino-functionalized rhodamine Rh-NH2 to the epoxy resin DGEBA was changed. It can be seen from the results that the fluorescence intensities of the specimens prepared with different mass ratios are also different under the same pressure. When the mass ratio is less than 1:20, as the mass ratio decreases, that is, the content of rhodamine in the composite material decreases, the fluorescence intensity also decreases; however, when the mass ratio is greater than 1:20, it has little effect on the fluorescence intensity.

[0086] (2) Comparative Examples 6, 7, and 8 only changed the curing process. The results show that different curing temperatures and holding times have a greater impact on the fluorescence intensity of the material under the same pressure. When only low-temperature curing is performed, even if the holding time is the same, the fluorescence intensity of the sample is significantly lower than that of the material prepared by the curing process of the present invention; when the high-temperature curing time is increased, the fluorescence intensity of the material is reduced.

[0087] In summary, the resin-based mechanochromic glass fiber composite material prepared by the method of the present invention can better wrap the fiber with the resin, and can effectively improve the mechanical properties and fatigue resistance of the resin-based mechanochromic glass fiber composite material. At the same time, it can realize a visual response to mechanical stimulation, and the method is simple and has high performance, thereby achieving the purpose of real-time in-situ detection of structural damage.

[0088] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A preparation method of a resin-based force-induced color-changing glass fiber composite material, characterized in that, The preparation method comprises the following steps: (1) Mix rhodamine 6G with a solvent and anhydrous ethylenediamine to form a mixed solution, then carry out a heating reflux reaction on the mixed solution, and then filter, wash and dry in sequence to obtain amino-functionalized rhodamine; mix the amino-functionalized rhodamine with epoxy resin and carry out a heating reaction to obtain rhodamine-modified epoxy resin; (2) Inject the rhodamine-modified epoxy resin into glass fiber for full impregnation, and then cure to obtain a resin-based force-induced color-changing glass fiber composite material.

2. The preparation method of a resin-based stress-responsive color-changing glass fiber composite material according to claim 1, characterized in that, The dosage ratio of the rhodamine 6G, the solvent and the anhydrous ethylenediamine is 0.02-0.03 mol: 250-400 ml: 0.07-0.1 mol.

3. The preparation method of a resin-based force-induced color-changing glass fiber composite material according to claim 1, characterized in that The mass ratio of the amino-functionalized rhodamine to the epoxy resin is 2-4: 40-60.

4. The preparation method of a resin-based stress-responsive color-changing glass fiber composite material according to claim 1, wherein, The specific steps of the heating reflux reaction in step (1) are as follows: carry out a heating reflux reaction on the mixed solution in an oil bath, the oil bath temperature is 75-90 °C, and the heating reflux time is 22-26 h.

5. The preparation method of a resin-based force-induced color change glass fiber composite material according to claim 1, wherein, The glass fiber is at least one of SW80B, SW110C, SW210A, SW220B, SW280F.

6. The preparation method of a resin-based stress-responsive color-changing glass fiber composite material according to claim 1, characterized in that, In step (2), the mass ratio of the rhodamine-modified epoxy resin to the glass fiber is 2-4:

1.

7. The preparation method of a resin-based force-induced color-changing glass fiber composite material according to claim 1, characterized in that, In step (2), the impregnation time is 5 min-15 min.

8. The preparation method of a resin-based force-induced color change glass fiber composite material according to claim 1, wherein The specific steps of the curing in step (2) are as follows: first cure at 65 °C-75 °C for 2-4 hours, then raise the temperature to 110 °C-125 °C and cure for 1.5-2 hours, and finally post-cure at 130 °C-160 °C for 0.8-2 hours to fully cure and form the composite material.

9. A resin-based force-induced color-changing glass fiber composite material, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

10. Application of a resin-based force-induced color change glass fiber composite material, characterized in that, Use the resin-based force-induced color-changing glass fiber composite material according to claim 9 for damage detection and / or damage warning.

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