Intercalation material for health monitoring of carbon fiber composite material structure and application of intercalation material

Abstract

The invention provides an intercalation material for health monitoring of a carbon fiber composite material structure and application, and belongs to the technical field of high-performance composite materials. The intercalation material is a sandwich structure membrane and comprises an upper PMIA nanofiber membrane, a lower PMIA nanofiber membrane and a middle CNT-loaded PMIA nanofiber membrane. According to the invention, real-time and in-situ structure health monitoring of the carbon fiber composite material can be realized. For I-type interlayer fracture damage, the resistance gain factor of the PMIA-CNT piezoresistive monitoring network reaches up to 220% in the whole crack propagation process, and the method is remarkably superior to a traditional method. The preparation process is simple and convenient, the expandability of the PMIA-CNT is extremely high, and the method is suitable for in-situ structure health monitoring of large-size carbon fiber composite structures in the fields of aerospace, low-altitude aircrafts, wind power blades and the like.

Description

TECHNICAL FIELD

[0001] The application relates to an intercalation material for monitoring the health of a carbon fiber composite structure and an application, and belongs to the technical field of high-performance composite materials. BACKGROUND

[0002] In recent years, nanofiber membranes prepared by electrospinning technology have various fiber structures, rich spinning material types, high porosity, controllable structure and high specific strength, and have wide application prospects in the fields of aerospace, new energy batteries and intelligent fabrics. During the actual service process of laminated carbon fiber reinforced composite structures, interlaminar damage is easy to occur, and damage accumulation can cause overall structural failure accidents. The current commonly used structure health monitoring methods, including resistance strain gauges, displacement gauges, vibration sensors, ultrasonic detection systems and fiber Bragg grating sensors, face technical bottlenecks such as complicated sensor installation process, insufficient damage identification resolution, difficult data analysis and dynamic response lag in practical application. In recent years, self-sensing networks developed by using the piezoresistive effect of nanocarbon materials have become a hot direction, but there are problems such as dispersion difficulty and insufficient monitoring sensitivity.

[0003] The finished carbon fiber laminated plate of CN107674385A forms an electrically conductive / toughening second phase by VARTM molding at high temperature and dissolving, and the component nanofiber membrane has a complicated preparation process and low stability; the nanofiber membrane is collected by a carbon fiber cloth negative electrode, which limits the continuity of the composite size and the forming process, and greatly increases the influence of the multi-step process on the apparent physical and chemical properties of the membrane. During the high-temperature curing process, the melting and dissolving behaviors of the thermoplastic TPU and PA are significantly uncontrollable, and the movement characteristics of the molecular chains and the change law of the melting viscosity with temperature are essentially different from those of the thermosetting epoxy resin, so that the mixed system spontaneously separates into a heterogeneous structure with the epoxy resin as the continuous phase and the TPU / PA as the dispersed phase, the particle size of the dispersed phase is uncontrollable, and the interface transition zone lacks effective chemical bonding, which easily leads to the deterioration of the mechanical properties of the composite system. The membrane is only distributed in the interlaminar (in-plane) region of the carbon fiber, and cannot form a uniform dispersion network in the thickness direction (out-of-plane). Therefore, although the I-type fracture toughness is improved by 50%, the actual II-type fracture toughness is improved by only 40%, and the I-type fracture toughness value is only 0.81 KJ / m 2 The mechanical property evaluation is incomplete.

[0004] CN 118372535 A preparation involves at least 6 main processes, the process is complicated, time-consuming; graphene, carbon nanotube and other nanofiller cost is high, and the intermediate phase pitch-based carbon fiber price is significantly higher than ordinary PAN-based carbon fiber; ultrasonic mixing is difficult to ensure the uniform dispersion of graphene / carbon nanotube in the spinning solution; the "pitch-based carbon fiber layer→carbon nanofiber film layer" formed by the alternating stacking forms a multi-dimensional heat conduction network; but this film is only distributed in the interlayer region (in-plane direction) area, and cannot form a uniform dispersion network in the thickness direction (out-of-plane direction). When the interlayer region is rigidly reinforced, there is a significant mechanical property gradient difference between the high-strength, high-modulus carbon nanofiber and the epoxy resin matrix, with a difference of 2-3 orders of magnitude, resulting in a sharp performance mismatch, resulting in a lack of mechanical property gradient transition from the rigid reinforcing agent to the flexible matrix at the interface. When stressed, the stress concentrates suddenly at the interface, and cannot be uniformly transmitted through gradient buffering. SUMMARY

[0005] Therefore, the present application first provides an intercalation material for carbon fiber composite material structure health monitoring, which can simply and efficiently realize in-situ structure health monitoring of the composite material.

[0006] Specifically, the present application is realized by the following scheme: An intercalation material for carbon fiber composite material structure health monitoring, the intercalation material is a sandwich structure film, comprising upper and lower PMIA nanofiber films, and a middle layer of CNT-loaded PMIA nanofiber film.

[0007] The intercalation material provided by the above scheme is based on a sandwich structure intercalation of poly-m-phenylene isophthalamide (PMIA) and carbon nanotubes (CNT), which realizes the method of carbon fiber reinforced composite material structure health monitoring, and is particularly suitable for high-end equipment structures with high safety and reliability requirements, such as aerospace, automobiles, electronics and energy fields.

[0008] Further, as preferred: The CNT is deposited on the PMIA nanofiber film.

[0009] The intercalation material is PMIA nanofiber film-(CNT-PMIA nanofiber film-CNT)-PMIA nanofiber film, PMIA nanofiber film-(CNT-PMIA nanofiber film)-PMIA nanofiber film, or PMIA nanofiber film-(PMIA nanofiber film-CNT)-PMIA nanofiber film.

[0010] The fiber diameter of the PMIA nanofiber film is 100-300 nm.

[0011] The second aspect of the application is to provide the application of the above-mentioned intercalation material in the in-situ structural health monitoring of carbon fiber composite materials, and the steps are as follows: Step one, PMIA nanofiber membrane with ultra-fine fiber skeleton is prepared by electrospinning of PMIA spinning solution; Step two, carbon nanotubes are deposited on the surface of the PMIA nanofiber membrane by ultrasonic atomization spraying process to form a PMIA nanofiber membrane loaded with CNTs, and the CNTs cooperate with the PMIA nanofiber membrane to form a piezoresistive network structure; Step three, the PMIA nanofiber membrane obtained in step one is packaged with the PMIA nanofiber membrane loaded with CNTs obtained in step two to form a sandwich structure membrane; Step four, the sandwich structure membrane is inserted between the layers of carbon fiber fabric or prepreg and integrated; Step five, based on the functional interlayer double cantilever beam, the resistance change of the carbon fiber composite material in the loading process is monitored in real time throughout the process to realize the in-situ structural health monitoring of the carbon fiber composite material.

[0012] Preferably: In step one, The PMIA fiber is dissolved in a LiCl / DMAc solution to obtain a PMIA spinning solution.

[0013] In the electrospinning process, the surface weight is 1.5-16.4 g / m 2 , and the thickness of the PMIA nanofiber membrane is 6-71 μm.

[0014] In the electrospinning process, the spinneret and voltage are adjusted to obtain a PMIA nanofiber membrane with the desired thickness by controlling the spinning time.

[0015] In step two, the packaging adopts a hot pressing process, and the PMIA nanofiber membrane loaded with CNTs is sandwiched between two layers of PMIA nanofiber membranes to synthesize a sandwich structure material.

[0016] In step four, The carbon fiber fabric or prepreg layer is 12 layers of unidirectional carbon fiber cloth, and the sandwich structure membrane is inserted between the 6th layer and the 7th layer.

[0017] The integrated integration adopts co-curing molding: pouring resin under vacuum conditions, first curing at 120 ℃ for 3 h, and then heating to 160 ℃ for 1 h.

[0018] In step five, the structural health monitoring includes damage location and extent, etc.

[0019] The above-mentioned carbon fiber composite material is a large-size carbon fiber composite material in the fields of aerospace, low-altitude aircraft, wind power blades, etc.

[0020] Compared with the prior art, the present application has the following beneficial effects Real-time structural health monitoring function: the CNT functional layer forms a three-dimensional conductive network, which can reflect the whole process of crack propagation in real time through the resistance change rate, and the gain factor reaches 220%. Compared with the gain (below 30%) of traditional methods, the monitoring sensitivity and reliability are significantly improved.

[0021] The process is simple and suitable for large-scale production. The electrospinning and ultrasonic atomization spraying technology has the characteristics of high efficiency and controllability, and is suitable for batch production. By adjusting the spinning time, spraying times and hot pressing parameters, the performance of the material can be flexibly adjusted. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 It is a schematic diagram of the intercalation material for carbon fiber composite material structural health monitoring in the present application, ①Electrospinning device for preparing PMIA nanofiber membrane; ②Ultrasonic atomizer for spraying CNT; ③Schematic diagram of sensing layer; ④Schematic diagram of real-time structural health detection of double cantilever beam; Figure 2 It is a schematic diagram of the application process of the intercalation material of the present application; Figure 3 It is a real-time change curve of DCB whole process structural health monitoring; Figure 4 It is a time-loading displacement-relative resistance change curve diagram of the whole process of DCB; Figure 5 It is a mapping relationship curve diagram of crack propagation and relative resistance change.

[0024] In the figure, the labels are: 1. High-voltage power supply; 2. High-precision syringe pump; 3. Roller collector; 4. Ultrasonic atomization nozzle; 5. PMIA nanofiber membrane loaded with CNT; 6. Intercalation material. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the technical solutions in the embodiments of the present application will be further described in detail below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the technical solutions of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0026] The present embodiment provides an intercalation material for carbon fiber composite structure health monitoring with high detection sensitivity. The present embodiment will be described below with reference to the accompanying drawings.

[0027] Reference is made to Figure 1 , Figure 1 The preparation flowchart of the intercalation material of the present embodiment is shown. The steps are as follows: Step 1: Dissolve 0.2 g LiCl in 17.8 g DMAc, after stirring for 10 min, add 2 g PMIA chopped fibers, fully dissolve at 100 ℃ to obtain a uniform spinning solution.

[0028] Step 2: Inject the spinning solution into the electrospinning equipment, inject the PMIA spinning solution into the electrospinning equipment, the spinning head scanning distance is 25 cm. Control the voltage of high voltage power supply 1 to be 25 kV, by controlling the electrospinning time to be 4 h, the PMIA nanofiber is obtained by the high-precision syringe pump 2, the PMIA nanofiber is collected by the drum type collector 3, a PMIA nanofiber membrane with a thickness of 24 μm and a surface weight of 5.8 g / m 2 is prepared, named PMIA-4.

[0029] Step 3: Vacuum dry the PMIA-4 nanofiber membrane at 160 ℃ for 24 h to completely remove the solvent. Then, under the nitrogen atmosphere, the CNT dispersion liquid is sprayed on PMIA-4 through the ultrasonic atomization spray head 4, the ultrasonic power is set to 15 W, the spraying area is set to 20x10 cm, and the CNT is uniformly distributed on the PMIA interlayer by continuous spraying twice, the bottom plate temperature is set to 60 ℃, the spraying interval is 10 s, the water is fully volatilized, and the PMIA nanofiber membrane loaded with CNT 5 is formed, recorded as PMIA-CNT.

[0030] Step 4: Clamping the PMIA-CNT nanofiber membrane 5 between the upper and lower two layers of PMIA-4 film to form a sandwich structure intercalation material 6.

[0031] Step 5: For carbon fiber reinforced polymer (CFRP) specimens, 12 layers of unidirectional carbon fiber cloth are laid along the 0° direction. The intercalation material 6 and a 12 μm polyimide film coated with a release agent (to initiate initial cracking) are embedded between layers 6 and 7. The CFRP is co-cured and integrally formed using the VARTM process. After the apparatus is completely vacuumed, resin is injected and cured at 120°C for 3 h and then at 160°C for 1 h.

[0032] Step 6: In the Type I double cantilever beam (DCB) test, record the change in the electrical resistance of the composite material, perform in-situ structural health monitoring (SHM) on the composite material that integrates PMIA-CNT and CFRP structure, evaluate the health status, and determine the degree and location of damage to the composite material.

[0033] Test results as follows Figure 3 , 4 As shown in Figure 5, the entire crack propagation process is highly correlated with the rate of change of resistance, with a resistance gain factor of 220%.

[0034] This demonstrates that the sandwich structure intercalation material prepared in the above embodiments exhibits excellent monitoring performance in the structural health monitoring of carbon fiber composite materials, with high monitoring sensitivity and signal stability.

[0035] The above-described embodiments are merely illustrative of several feasible implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention, nor are the embodiments intended to limit the scope of protection in the claims of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention. All equivalent implementations or changes that do not depart from the present invention should be included in the technology of the present invention.

Claims

1. An intercalation material for structural health monitoring of carbon fiber composite materials, characterized in that: The intercalation material is a sandwich structure membrane, comprising upper and lower PMIA nanofiber membranes, and a middle PMIA nanofiber membrane loaded with CNTs.

2. The intercalation material for structural health monitoring of carbon fiber composite materials according to claim 1, characterized in that: The CNTs are deposited on the PMIA nanofiber membrane.

3. The intercalation material for structural health monitoring of carbon fiber composite materials according to claim 1, characterized in that: The intercalation material is PMIA nanofiber membrane-(CNT-PMIA nanofiber membrane-CNT)-PMIA nanofiber membrane, PMIA nanofiber membrane-(CNT-PMIA nanofiber membrane)-PMIA nanofiber membrane, or PMIA nanofiber membrane-(PMIA nanofiber membrane-CNT)-PMIA nanofiber membrane.

4. The intercalation material for structural health monitoring of carbon fiber composite materials according to claim 1, characterized in that: The PMIA nanofiber membrane has a fiber diameter of 100~300nm.

5. An application of the intercalation material for health monitoring of carbon fiber composite structures as described in claim 1, characterized in that, The steps are as follows: Step 1: PMIA nanofiber membranes with an ultrafine fiber skeleton are prepared by electrospinning of PMIA spinning solution. Step 2: Carbon nanotubes are deposited on the surface of the PMIA nanofiber membrane using an ultrasonic atomization spraying process to form a CNT-loaded PMIA nanofiber membrane. Step 3: The PMIA nanofiber membrane obtained in Step 1 is encapsulated with the CNT-loaded PMIA nanofiber membrane obtained in Step 2 to form a sandwich structure membrane. Step four: Insert the sandwich structure membrane between the carbon fiber fabric or prepreg layers and integrate it as a whole; Step 5: Monitor the resistance change of the carbon fiber composite material during the loading process to achieve in-situ structural health monitoring of the carbon fiber composite material.

6. The application of the intercalation material for structural health monitoring of carbon fiber composite materials according to claim 5, characterized in that: In step one, PMIA fibers are dissolved in a LiCl / DMAc solution to obtain a PMIA spinning solution.

7. The application of the intercalation material for structural health monitoring of carbon fiber composite materials according to claim 5, characterized in that: In step four, the carbon fiber fabric or prepreg has 12 layers, and the sandwich structure membrane is inserted between the 6th and 7th layers.

8. The application of the intercalation material for structural health monitoring of carbon fiber composite materials according to claim 5, characterized in that: In step four, the integrated process adopts co-curing molding: resin is poured under vacuum conditions, first cured at 120 ℃ for 3 h, and then the temperature is raised to 160 ℃ for 1 h.

9. The application of the intercalation material for health monitoring of carbon fiber composite structures according to claim 5, characterized in that: In step five, the structural health monitoring includes the location and extent of damage.

10. The application of the intercalation material for structural health monitoring of carbon fiber composite materials according to claim 5, characterized in that: The carbon fiber composite material is used in the fields of aerospace, low-altitude aircraft, and wind turbine blades.

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