Optical fiber sensing-capacitor energy storage-composite integrated structure and forming method thereof

Abstract

The application provides an optical fiber sensing-capacitor energy storage-composite material integrated structure and a forming method thereof. An optical fiber grating sensor is embedded and solidified on a carbon fiber composite material structure as a composite material substrate. A composite material super capacitor is integrated on the composite material substrate in a secondary solidification mode. The optical fiber grating sensor is embedded and solidified on the carbon fiber composite material structure, and then the composite material super capacitor is integrated on the composite material substrate in the secondary solidification mode. The application realizes the integrated integration of sensing, energy storage and force bearing structures.

Description

Technical Field

[0001] This invention relates to an integrated structure of fiber optic sensing, capacitor energy storage, and composite materials, and its molding method. Background Technology

[0002] my country's helicopter equipment has developed rapidly, especially with the pre-research and finalization of a number of key equipment and major models, which has placed increasingly higher demands on multi-functional structures that combine structural and functional characteristics.

[0003] The integrated structural-functional technology combines structural and non-structural functions, breaking through the functional limitations of traditional single structures. On the one hand, it can reduce the weight and volume of the entire system and improve the overall efficiency of the system; on the other hand, it can improve the integrity of the equipment system. Summary of the Invention

[0004] Purpose of the invention:

[0005] This invention relates to an integrated structure of fiber optic sensing, capacitor energy storage, and composite materials, and its molding method. A fiber optic grating sensor is embedded and cured into a carbon fiber composite material structure, and then a composite supercapacitor is integrated onto a composite material panel using a secondary curing process. This invention achieves integrated sensing, energy storage, and load-bearing structure.

[0006] This invention provides an integrated structure of fiber optic sensing, capacitor energy storage, and composite material. The fiber optic grating sensor is embedded and solidified in the carbon fiber composite material structure as a composite material substrate. The composite supercapacitor is integrated on the composite material substrate by a secondary curing method.

[0007] This invention also provides a method for molding an integrated structure of fiber optic sensing, capacitor energy storage, and composite materials, comprising:

[0008] The first heat-shrinkable tube is placed on the pigtail of the bare optical fiber sensor after the tube has been removed. Epoxy resin is applied to the end of the first heat-shrinkable tube and then a capillary tube is inserted from the end. The second heat-shrinkable tube is then placed from the end of the capillary tube. Epoxy resin is used to seal the ends of the capillary tube and the second heat-shrinkable tube and the tube is cured for a preset time.

[0009] A certain amount of fiber fabric prepreg is laid as a substrate for embedding the fiber optic sensor. The fiber optic sensor is laid parallel to the fiber direction of the top layer of the substrate. A layer of fiber fabric prepreg is laid parallel to the direction of the fiber optic sensor. The remaining fiber fabric prepreg is laid to obtain a composite material substrate. The substrate is then pressed to allow the fiber optic to be embedded in the gaps between the fibers.

[0010] The mold is closed and placed into a hot press for hot pressing and molding;

[0011] A capacitor energy storage device and two layers of prepreg are applied and laid on a composite material substrate;

[0012] The composite substrate with the implanted capacitor energy storage device is vacuum-sealed and pressurized, then placed in a temperature chamber for heat preservation and cooling.

[0013] Optionally, the pressure of the vacuum bag sealing pressurization should not exceed 90 kPa.

[0014] Optionally, before applying adhesive to the composite substrate and laying the capacitor energy storage device and two layers of prepreg, the method further includes:

[0015] Seal the capacitor energy storage device with an insulating membrane;

[0016] Correspondingly, the pressure applied to the vacuum bag during sealing should not exceed 120 kPa.

[0017] Optionally, a capacitor energy storage device and two layers of prepreg are coated and laid on a composite material substrate, including:

[0018] Prepare epoxy resin AB glue and let it stand for a certain period of time;

[0019] Apply a first layer of adhesive evenly to the composite substrate using a brush, place the capacitor energy storage device at a predetermined position, apply adhesive evenly to the capacitor energy storage device, and lay the first layer of prepreg.

[0020] Apply a second layer of adhesive evenly, and then lay down the second layer of prepreg.

[0021] Optionally, the composite material substrate with the embedded capacitor energy storage device is vacuum-bag sealed and pressurized, including:

[0022] On the operating platform, polyimide film, absorbent felt, and breathable cloth are laid out in sequence. The composite material substrate with the embedded capacitor energy storage device is placed in the middle position and covered with breathable cloth, absorbent felt, and polyimide film in sequence.

[0023] Place the entire item into a vacuum bag and use a vacuum sealer to vacuum and seal it.

[0024] Optionally, the composite substrate is integrated using carbon fibers with a layup of [902 / 04 / 902 / 04]s.

[0025] Optionally, the composite substrate has 22-40 layers, and the fiber optic sensor is implanted parallel to the 20th / 21st layer along 0°.

[0026] Optionally, the length of the capillary steel tube inserted into the composite material is 10~15mm, and the length extending out of the composite material is 5~10mm.

[0027] This invention provides an integrated structure and molding method for fiber optic sensing, capacitor energy storage, and composite materials, which not only possesses fiber optic sensing capabilities but also electrical energy storage and load-bearing functions. This method of integrating embedded optical fibers maintains a high fiber survival rate without compromising the load-bearing capacity of the composite material structure. After integration, both mechanical and electrical properties remain at a high level. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the optical fiber extraction process of the present invention;

[0029] Figure 2 This is a schematic diagram of the lead-out protection scheme for an implanted fiber optic sensor.

[0030] Figure 3 Physical sample of an extraction protection scheme for an implanted fiber optic sensor. Figure 1 ;

[0031] Figure 4 Physical sample of an extraction protection scheme for an implanted fiber optic sensor. Figure 2 ;

[0032] Figure 5 This is a schematic diagram of the integrated fiber optic sensing-capacitor energy storage-composite material structure layup of the present invention. Detailed Implementation

[0033] like Figure 1-5 As shown, the present invention provides an integrated structure of fiber optic sensing, capacitor energy storage, and composite material, and its molding method.

[0034] The integrated design of embedded fiber optic sensors and composite material structures includes:

[0035] 1) Process selection and fiber protection

[0036] The embedded fiber optic sensor is integrated with the composite material structure using a thermoforming process. This process requires applying pressure to the upper and lower surfaces of the composite material sheet using a rigid mold. Surface-extracted fiber optic cables are easily damaged by the mold; therefore, the method of extending the fiber optic cable from the end face is compatible with the thermoforming process. See [link / reference]. Figure 1 .

[0037] A small-diameter, bare optical fiber with its sheath removed is implanted parallel to the fiber direction of the upper and lower prepreg layers. Simultaneously, the fiber optic sensor's pigtail is led out from the side of the composite material plate. To protect the fiber at the composite material's lead-out end, a capillary tube is used to protect the fiber optic sensor's pigtail. The capillary tube is implanted into the composite material for a length of 10-15 mm and extends out of the composite material for a length of 5-10 mm, effectively protecting the fiber from bending damage at the lead-out port. Furthermore, a polymer heat-shrink tubing with a diameter slightly larger than the capillary tube is used inside the capillary tube to provide load-bearing protection for the exposed fiber, preventing breakage at the capillary tube's protruding end. See [link to product details]. Figure 1-4 .

[0038] The specific implantation steps for the embedded fiber optic sensor are as follows:

[0039] (a) Pre-processing of fiber optic grating sensor: The first heat-shrinkable tube is placed on the fiber optic sensor. Epoxy resin with a certain degree of adhesion is attached to the capillary steel tube insertion end of the first heat-shrinkable tube. The capillary steel tube is inserted, and the second heat-shrinkable tube is placed from the tail end of the capillary steel tube. Epoxy resin is used to seal the port of the second heat-shrinkable tube outside the capillary steel tube. The tube is then cured for 24 hours.

[0040] (b) Laying out the fiber optic grating sensor: First, cut a fiber prepreg of a predetermined area, plan the fiber optic implantation layers, and pre-lay a certain number of layers as the substrate for the fiber optic sensor implantation. Mark the fiber implantation positions and lay them on the composite material substrate parallel to the fiber direction with a certain pre-tightening force. Then carefully lay the remaining fiber prepreg and press it appropriately to make the fiber embed into the fiber gaps.

[0041] (c) Mold closing and placement in hot press: Since there is a certain height difference between the side wall groove of the hot press mold used for optical fiber lead-out and the bottom of the mold, the optical fiber will be directly squeezed during mold closing, causing the optical fiber to become inactive. Therefore, according to the planned molding thickness of the composite material and the mold depth, iron plates and pads should be placed at the bottom and around the mold to reduce the shear force on the optical fiber at the mold lead-out outlet.

[0042] The optical fiber is well protected by using fiber protection and applying pre-tension. For embedded optical fibers, carbon fiber with a layup of [902 / 04 / 902 / 04]s is used for integration. The fiber grating sensor is inserted parallel to the 0° direction between the 20th and 21st layers and the sample is prepared by one-time hot-press curing. The fiber survival rate is not less than 90%.

[0043] The integrated supercapacitor made of composite materials and the carbon fiber composite structure includes:

[0044] Structural layup such as Figure 5 As shown, the curing integration process is as follows:

[0045] (a) First curing: The composite material structure is first cured according to the above-mentioned fiber / structure integration method to form a composite material structure substrate with state sensing capability.

[0046] (b) Pretreatment: The composite substrate structure is pretreated by cleaning and polishing to ensure that the surface is clean and dust-free and to improve adhesion.

[0047] (c) Implanting the energy storage device: Prepare epoxy resin AB glue according to the product specifications and let it stand for a certain period of time to achieve a certain level of adhesion. Use a brush to evenly apply the first layer of glue to the substrate, place the energy storage device in the predetermined position, and evenly apply glue to the energy storage device; lay down the first layer of prepreg, use a squeegee to lightly smooth the prepreg, and then evenly apply the second layer of glue; lay down the second layer of prepreg, and continue to lightly smooth the prepreg with a squeegee.

[0048] (d) Vacuum Bag Sealing: Lay polyimide film, absorbent felt, and breathable fabric in sequence on an iron plate (the breathable fabric needs to be treated with a release agent beforehand). Place the composite material substrate with the embedded energy storage device in the center, and cover it with the breathable fabric, absorbent felt, and polyimide film in sequence. Place the entire assembly into a vacuum bag and use a vacuum sealing machine to perform vacuuming and sealing. During vacuuming, press down on the wrinkled areas as much as possible to ensure that atmospheric pressure is applied evenly to the composite material structure. Different treatments are applied to the energy storage elements to create two different energy storage capacities. Using an isolation film seal, with an applied pressure not exceeding 120 kPa, a 100% energy storage capacity retention rate can be achieved. Without an isolation film seal, with an applied pressure not exceeding 90 kPa, a capacity retention rate of not less than 80% can be achieved.

[0049] (e) Secondary curing in a temperature chamber: The vacuum-treated integrated energy storage / composite material structure is placed in a temperature chamber, kept at 80°C for 2 hours, and then allowed to cool naturally.

[0050] (f) Quality inspection: Grinding, polishing or other surface treatments shall be performed as needed to meet the appearance and performance requirements of the final product; quality inspections shall be carried out on composite material structures and integrated energy storage devices, including tests on dimensions, shape, surface condition and physical properties, to ensure that all design and performance specifications are met.

[0051] like Figure 5As shown, by integrating an embedded fiber optic sensor with the composite material structure to form a substrate, most of the mechanical properties of the composite material structure are preserved. Based on this, a composite supercapacitor is then integrated with the carbon fiber composite structure. This process reduces the loss of overall composite material mechanical properties. Verification was performed according to ASTM D3309 testing standards, with tensile test specimen dimensions of 250mm × 25mm × 2.15mm. Verification was performed according to ASTM D6641 testing standards, with compression test specimen dimensions of 140mm × 13mm × 2.15mm. The mechanical property retention rate is no less than 96%. Simultaneously, during loading, the substrate formed by the integrated embedded fiber optic sensor and composite material structure bears limited load, and the capacitor performance remains stable before failure, exhibiting good charge and discharge capabilities.

Claims

1. A molding method for an integrated fiber optic sensing-capacitor energy storage-composite material structure, wherein a fiber optic grating sensor is embedded and solidified on a carbon fiber composite material structure as a composite material substrate, and a composite material supercapacitor is integrated on the composite material substrate using a secondary curing method, characterized in that... The method includes: The first heat-shrinkable tube is placed on the pigtail of the bare optical fiber sensor after the tube has been removed. Epoxy resin is applied to the end of the first heat-shrinkable tube and then a capillary tube is inserted from the end. The second heat-shrinkable tube is then placed from the end of the capillary tube. Epoxy resin is used to seal the ends of the capillary tube and the second heat-shrinkable tube and the tube is cured for a preset time. A certain amount of fiber fabric prepreg is laid as a substrate for embedding the fiber optic sensor. The fiber optic sensor is laid parallel to the fiber direction of the top layer of the substrate. A layer of fiber fabric prepreg is laid parallel to the direction of the fiber optic sensor. The remaining fiber fabric prepreg is laid to obtain a composite material substrate. The substrate is then pressed to allow the fiber optic to be embedded in the gaps between the fibers. The mold is closed and placed into a hot press for hot pressing and molding; A capacitor energy storage device and two layers of prepreg are applied and laid on a composite material substrate; The composite material substrate with the implanted capacitor energy storage device is vacuum-sealed and pressurized, then placed in a temperature chamber for heat preservation and cooling. A capacitor energy storage device and two layers of prepreg are applied and laid on a composite material substrate, including: Prepare epoxy resin AB glue and let it stand for a certain period of time; Apply a first layer of adhesive evenly to the composite substrate using a brush, place the capacitor energy storage device at a predetermined position, apply adhesive evenly to the capacitor energy storage device, and lay the first layer of prepreg. Apply a second layer of adhesive evenly, and then lay the second layer of prepreg. Vacuum bag sealing and pressurization of the composite material substrate with the implanted capacitor energy storage device, including: On the operating platform, polyimide film, absorbent felt, and breathable cloth are laid out in sequence. The composite material substrate with the embedded capacitor energy storage device is placed in the middle position and covered with breathable cloth, absorbent felt, and polyimide film in sequence. Place the entire item into a vacuum bag and use a vacuum sealer to vacuum and seal it.

2. The method according to claim 1, characterized in that, The pressure applied during vacuum bag sealing and pressurization should not exceed 90 kPa.

3. The method according to claim 1, characterized in that, Before applying adhesive and laying the capacitor energy storage device and two layers of prepreg on the composite substrate, the method further includes: Seal the capacitor energy storage device with an insulating membrane; Correspondingly, the pressure applied to the vacuum bag during sealing should not exceed 120 kPa.

4. The method according to claim 1, characterized in that, The composite substrate is integrated using carbon fibers with a layup of [902 / 04 / 902 / 04]s.

5. The method according to claim 4, characterized in that, The composite substrate has 22-40 layers, and the fiber optic sensor is implanted parallel to the 20th / 21st layer along 0°.

6. The method according to claim 1, characterized in that, The length of the capillary steel tube inserted into the composite material is 10~15mm, and the length extending out of the composite material is 5~10mm.

Images