A method and system for online monitoring of fiber pressure bearing during composite material molding process

Abstract

This invention discloses a method and system for online monitoring of fiber pressure bearing during composite material molding, belonging to the field of composite material molding and preparation. The method includes: S1, embedding an online fiber pressure bearing monitoring sensor into the interlayer of the composite material to be monitored; the online fiber pressure bearing monitoring sensor is a porous conductive network thin-film sensor with piezoresistive effect; S2, applying pressure in the thickness direction of the composite material during molding; S3, monitoring the resistance change of the online fiber pressure bearing monitoring sensor to reflect the change in fiber pressure bearing during the composite material molding process. This invention eliminates the influence of resin pressure on the sensor signal output during composite material molding, achieving accurate online monitoring of fiber pressure bearing during the composite material molding process. Furthermore, the monitoring process does not affect the molding process or quality of the composite material, and does not reduce the service performance of the molded composite material, or even improve the interlayer mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding and preparation, and more specifically, relates to a method and system for online monitoring of fiber pressure during composite material molding process. Background Technology

[0002] Fiber-reinforced composites possess outstanding advantages such as high specific strength and high specific modulus, and are widely used in aerospace, rail transportation, and other fields. However, the molding process of fiber composites is complex, and improper parameter control during molding can easily lead to defects such as porosity, delamination, and warping, thereby affecting the mechanical properties and service reliability of composite components. Pressure is a crucial parameter in fiber composite molding, applied to the composite material and borne by both the fibers and resin, directly influencing resin flow and fiber density. Improper pressure control during molding, resulting in excessively dense or sparse fibers in certain areas, will lead to uneven distribution of fiber and resin content, affecting the performance of composite components. Therefore, online monitoring of fiber pressure bearing within the composite layer is essential and of great significance for controlling the molding quality of composite components.

[0003] Currently, only fiber optic micro-bending pressure sensors can monitor fiber pressure during the molding process of fiber composite materials. However, fiber optic sensors are expensive, fragile, and difficult to operate. Furthermore, the diameter of the fiber is several times that of the fiber, which can easily cause localized fiber deformation and resin accumulation, thus affecting the molding quality and monitoring accuracy of the composite material. At the same time, due to the irregular distribution of fibers and pressure, the output signal generated by the fiber micro-bending cannot obtain an accurate quantitative relationship; the system can only qualitatively analyze changes in fiber pressure. Summary of the Invention

[0004] In view of the shortcomings of existing technologies and the need for improvement, this invention provides a method and system for online monitoring of fiber pressure during composite material molding process, with the aim of improving the accuracy and quality of composite material molding monitoring.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for online monitoring of fiber pressure bearing capacity during composite material molding process is provided, comprising:

[0006] S1. Embed the fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a porous conductive network structure thin film sensor with piezoresistive effect;

[0007] S2. Perform composite material molding, and apply pressure in the thickness direction of the composite material during the composite material molding process;

[0008] S3. Monitor the resistance change of the fiber pressure-bearing online monitoring sensor to reflect the fiber pressure-bearing changes during the composite material molding process.

[0009] Furthermore, in S3, the resistance change of the fiber pressure-bearing online monitoring sensor is inversely proportional to the fiber pressure-bearing change.

[0010] Furthermore, S1 also includes: leading out the wires of the fiber pressure online monitoring sensor and connecting them to a signal acquisition device; the signal acquisition device is used to acquire the resistance change data of the fiber pressure online monitoring sensor.

[0011] Furthermore, the fabrication steps of the fiber pressure-bearing online monitoring sensor include:

[0012] S11. An insulating material is selected as the matrix, and the matrix is ​​pretreated to obtain a first precursor.

[0013] S12. Add conductive filler to the first precursor, stir and disperse evenly to obtain the second precursor;

[0014] S13. The second precursor is molded to obtain a porous conductive network structure film with piezoresistive effect;

[0015] S14. Using the thin film as a sensing element, connect flexible wires to both sides of the sensing element to obtain the fiber pressure-bearing online monitoring sensor.

[0016] Furthermore, in S13, the second precursor is shaped using any one of the following molding methods: electrospinning, template method, thermally induced phase separation method, sol-gel method, and laser 3D printing.

[0017] Further, in S12, the conductive filler includes one or more of the following: carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, or metal powder.

[0018] Further, in S11, the insulating material includes any one of polyvinylidene fluoride, copolymers of polyvinylidene fluoride, polyether ether ketone, nylon, polyurethane, alumina, silicon dioxide, and titanium dioxide.

[0019] Furthermore, the flexible wire is connected to both sides of the sensing element via conductive silver paste.

[0020] According to another aspect of the present invention, an online monitoring system for fiber pressure bearing during composite material molding process is provided, comprising:

[0021] An embedded module is used to embed a fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a porous conductive network structure thin film sensor with piezoresistive effect;

[0022] A composite material molding module is used to perform composite material molding, wherein pressure is applied in the thickness direction of the composite material during the composite material molding process;

[0023] The monitoring module is used to monitor the resistance change of the fiber pressure-bearing online monitoring sensor to reflect the fiber pressure-bearing changes during the composite material molding process.

[0024] Furthermore, it also includes a quantitative calculation module for calculating the change in fiber pressure based on the change in resistance; wherein the change in resistance is inversely proportional to the change in fiber pressure.

[0025] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0026] (1) The method of the present invention employs a porous conductive network structure thin film sensor with piezoresistive effect. During the composite material molding process, the resin can flow freely inside the porous conductive network structure of the sensor. At the same time, the sensor is wetted by the resin liquid. Under the action of resin pressure, the fiber skeleton of the composite material is subjected to a uniform force. The distance between the fiber skeletons will not change under the action of resin pressure. That is, the resin pressure will not change the conductive network structure inside the sensor and will not affect the change of the sensor's resistance signal. Only when the fiber pressure of the composite material acts on the sensor will the sensor deform in the thickness direction, change the conductive path of the conductive network, and thus generate a changed resistance signal, thereby accurately monitoring the fiber pressure. The method of the present invention eliminates the influence of resin pressure on the sensor's electrical signal output during the fiber composite material molding process, which can improve the molding quality and monitoring accuracy of the composite material.

[0027] (2) In the method of the present invention, the resistance change of the sensor is inversely proportional to the pressure change of the fiber, and an accurate quantitative relationship can be obtained.

[0028] (3) In the method of the present invention, since the sensor is a porous thin film, after being embedded inside the composite material, the porous thin film and the fiber layer inside the composite material are of the same size, and the fiber structure and distribution of the composite material will not be changed. The porous structure of the sensor ensures that the resin can flow freely inside the sensor, without affecting the flow rate of the resin and the wetting effect of the fiber cloth during the molding process, and has little impact on the molding process of the composite material. Compared with existing sensors, the present invention embeds the porous thin film inside the composite material, making the molding process of the composite material closer to the actual situation. Therefore, the fiber pressure monitored by the sensor is also closer to the true value.

[0029] (4) The method of the present invention does not affect the internal fiber structure of the composite material and has little impact on the molding process. Therefore, it will not affect the mechanical properties of the composite material component after molding, and can ensure the normal service of the component. At the same time, after the resin impregnates the porous film, it can further form resin bridging between the fiber layers of the composite material, which will improve the interlayer mechanical properties of the composite material.

[0030] (5) Compared with expensive and complex fiber optic sensors, the present invention uses a porous thin film sensor for monitoring. The production cost of the substrate material of the sensor is low, the raw materials required for preparation are diverse, and the process is stable. The porous thin film prepared using it can also be controlled at a low cost. At the same time, the operation of the sensor to monitor the pressure during the molding process by embedding it between the composite material layers is simple, which greatly saves time and has a broader application prospect. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the online monitoring method for fiber pressure bearing during the composite material molding process of the present invention.

[0032] Figure 2 This is a schematic diagram illustrating the use of an online fiber pressure monitoring sensor in an embodiment of the present invention to monitor fiber pressure.

[0033] Figure 3 This is an image of a PVDF porous fiber membrane used for monitoring the pressure bearing capacity of composite fiber in an embodiment of the present invention, under a SEM microscope.

[0034] Figure 4 This is a schematic cross-sectional view of a PVDF porous fiber membrane structure used for monitoring the pressure bearing capacity of composite fiber in an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram illustrating the sensor embedded between composite fiber layers in an embodiment of the present invention, subjected to pressure from glass fibers and resin.

[0036] Figure 6(a) is a schematic diagram of the sensor in a free state before vacuuming in an embodiment of the present invention.

[0037] Figure 6(b) is a schematic diagram of the sensor in a compressed state after vacuuming in an embodiment of the present invention.

[0038] Figure 7 This is a schematic diagram showing the resistance values ​​output by the sensor before and after being compressed in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In this invention, the terms "first," "second," etc., used in the invention and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0041] like Figure 1 , Figure 2 As shown, the online monitoring method for fiber pressure bearing during the composite material molding process of the present invention mainly includes:

[0042] S1. Embed the fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a porous conductive network structure thin film sensor with piezoresistive effect;

[0043] S2. Perform composite material molding. During the composite material molding process, apply pressure in the thickness direction of the composite material.

[0044] S3. Monitor the resistance change of a porous conductive network thin-film sensor with piezoresistive effect to reflect the fiber pressure change during the composite material molding process. Specifically, if the resistance of the fiber pressure monitoring sensor decreases, it indicates that the fiber pressure during the composite material molding process increases; if the resistance of the fiber pressure monitoring sensor increases, it indicates that the fiber pressure during the composite material molding process decreases.

[0045] S1 also includes: leading out the wires of the porous conductive network structure thin film sensor and connecting them to the signal acquisition device;

[0046] S3 also includes: acquiring and storing the resistance changes of the porous conductive network structure thin-film sensor through a signal acquisition device. The signal acquisition device can be an LCR bridge or other types of electrical signal acquisition devices.

[0047] The method of this invention employs a porous conductive network thin-film sensor with a piezoresistive effect. During the composite material molding process, the resin can flow freely within the porous conductive network structure of the sensor, while the sensor is simultaneously wetted by the resin liquid. Under the pressure of the resin, the fiber skeleton of the composite material is subjected to a uniform force, preventing macroscopic bending deformation of the fiber skeleton. The distance between the fiber skeletons does not change under the pressure of the resin, meaning that the resin pressure does not alter the conductive network structure inside the sensor and does not affect the change in the sensor's resistance signal. Only when the fiber pressure of the composite material acts on the sensor will it deform in the thickness direction, changing the conductive path of the conductive network and thus generating a changing resistance signal. This changing resistance signal is acquired and stored by a signal acquisition device and transmitted to computer software. Based on the change law of the resistance signal, the fiber pressure change of the fiber layer during the molding process is obtained, thereby accurately monitoring the fiber pressure. The method of this invention eliminates the influence of resin pressure on the sensor's electrical signal output during the fiber composite material molding process, improving the molding quality and monitoring accuracy of the composite material.

[0048] Specifically, the fabrication method of the porous conductive network structure thin-film sensor with piezoresistive effect in step S1 includes:

[0049] S11. An insulating material is selected as the sensor substrate, and the substrate is pretreated to obtain the first precursor.

[0050] S12. Add conductive filler to the first precursor, and stir and disperse evenly to obtain the second precursor;

[0051] S13. The second precursor is formed by molding to obtain a porous conductive network structure film with piezoresistive effect.

[0052] S14. Using the porous conductive network structure film as a sensing element, connect flexible wires suitable for composite materials to both sides of the sensing element to form a fiber pressure-bearing online monitoring sensor, that is, a porous conductive network structure film sensor with piezoresistive effect.

[0053] Specifically, in S11, the insulating material includes any one of organic materials such as polyvinylidene fluoride (PVDF), copolymers of polyvinylidene fluoride, polyether ether ketone, nylon, and polyurethane, as well as inorganic materials such as alumina, silicon dioxide, and titanium dioxide.

[0054] Specifically, in S12, the conductive filler includes one or more of carbon nanotubes (CNTs), graphene, graphene oxide, reduced graphene oxide, or metal powder.

[0055] Specifically, in S13, the molding method includes any one of the advanced molding technologies such as electrospinning, template method, thermally induced phase separation method, sol-gel method and laser 3D printing.

[0056] Specifically, in S14, a flexible wire suitable for composite materials is connected to both sides of the sensing element by a conductive silver paste with high conductivity. After the conductive silver paste cures, a fiber pressure-bearing online monitoring sensor is formed.

[0057] Flexible conductors suitable for composite materials include carbon fibers or glass fibers with a graphene coating.

[0058] Specifically, after S14, the following steps are also included:

[0059] S15. Calibrate the initial resistance and piezoresistive sensitivity of the porous conductive network structure thin film sensor with piezoresistive effect.

[0060] The method of the present invention will be further illustrated below with a specific application example. It should be noted that the method of the present invention is not limited to the specific materials provided in the embodiments; any materials that satisfy the principles of the present invention are acceptable.

[0061] 1) Take 16g of dimethylformamide (DMF) and acetone, and mix them evenly at a mass ratio of 3:2 to obtain a solvent; then take 4g of PVDF powder and pour it into the prepared solvent, and stir magnetically for 2 hours at 40℃ to obtain a PVDF solution for electrospinning, i.e., the first precursor; add CNTs to the PVDF solution at a mass fraction of 2%, and stir magnetically for 2 hours at 80℃, followed by ultrasonic dispersion for 30 minutes to obtain a PVDF solution containing CNTs, i.e., the second precursor; select a prepared aluminum foil, and roll it onto the collecting roller in the electrospinning equipment. The collecting roller speed is set to 50rpm, the voltage is set to 18kV, the distance between the tip of the syringe containing the solution and the collecting roller is 15cm, and the solution feed rate in the syringe is 1mm / h; after spinning for 5 hours, a PVDF porous fiber film containing CNTs (thickness of 0.06mm) is obtained on the surface of the aluminum foil, and placed aside for later use; the SEM image and structural schematic diagram of the porous fiber film are shown below. Figure 3-4 As shown.

[0062] 2) Cut several PVDF porous films with a size of 2cm*2cm according to the monitoring requirements during the molding process; take one of the films and place it on a horizontal table for simple fixation. Place two bundles of carbon fibers on both sides of the film respectively, and use Kingstar K-818 conductive silver paste to connect the carbon fibers to the PVDF porous film. After the conductive silver paste is cured, the fiber pressure online monitoring sensor is obtained.

[0063] 3) After the fiber pressure monitoring sensor is prepared, it is necessary to calibrate the initial resistance and piezoresistive sensitivity of the sensor. After calibration, the sensor can be used for fiber pressure monitoring in the composite material molding process.

[0064] Specifically, the composite material molding process includes:

[0065] 4) Prepare 20 sheets of pre-cut EWR200 woven fiberglass cloth (25cm*20cm); LY1564 epoxy resin and 375g of 22962 curing agent were mixed evenly at a ratio of 4:1 under heating conditions at 40℃, and then defoamed.

[0066] 5) Place a 3mm transparent tempered glass plate on a horizontal table. After cleaning the surface of the glass plate, spray a layer of release agent evenly on the surface. After spraying, place the glass plate in an oven at 100℃ and dry for 10 minutes. After the glass plate is removed and cooled, apply sealant to the four edges of the glass plate without peeling off the white paper on the surface of the sealant. Lay fiberglass cloth inside the sealant. In this embodiment of the invention, the sensor is placed on the 2nd and 10th layers of fiberglass cloth. A release cloth and a flow guide net are laid on the surface of the laid fiberglass cloth, followed by a vacuum bag film. The white paper on the surface of the sealant is then peeled off to form a sealed space. A vacuum pump is used to evacuate the sealed space to a vacuum state.

[0067] 6) Place the vacuum tube for resin filling into the resin solution prepared in step 4), open the vacuum valve, and fill the resin under vacuum. Under vacuum, the fiberglass cloth and resin are subjected to atmospheric pressure, while the sensor inside the fiberglass layer is only subjected to fiber pressure. When the fiber pressure changes, the internal conductive network of the sensor changes, resulting in a change in resistance signal. This signal is transmitted to the signal acquisition device via carbon fiber wires, and the fiber pressure during the glass fiber composite molding process can be monitored by observing the change in the sensor's resistance.

[0068] In the liquid molding process of fiber composite materials, the monitoring sensor embedded between the fiber layers of the composite material is subjected to the combined action of glass fiber pressure and resin pressure, as shown in the schematic diagram. Figure 5 As shown.

[0069] Because the sensor has a porous structure, the resin can flow freely inside the sensor during the composite material molding process. The resin pressure acts uniformly on the fiber skeleton inside the sensor, and the fiber diameter remains almost unchanged. Simultaneously, the sensor as a whole does not undergo macroscopic deformation due to the resin pressure. That is, the conductive network inside the sensor is formed based on the contact between CNTs (conductive fillers) on the surface of the PVDF fiber skeleton. When the sensor is wetted by the resin liquid, under the resin pressure, the PVDF fiber skeleton is subjected to a uniform force in the resin liquid. The distance between the PVDF fiber skeletons does not change, the conductive path formed by the CNT contact does not change, and the total resistance of the sensor does not change. This eliminates the influence of resin pressure on the sensor's electrical signal output during the fiber composite material molding process.

[0070] When the multi-layer fiber cloth of the composite material is subjected to pressure, its thickness will change significantly, the distance between the fiber layers will decrease, and the contact between the glass fibers will become tighter. When the sensor is placed between the glass fiber cloth layers, the pressure on the glass fiber layers will directly act on the sensor's skeleton structure through the contact between the glass fibers and PVDF fibers, causing the sensor to undergo compressive deformation in the thickness direction. This changes the distance between the CNTs attached to the PVDF fibers, alters the conductive network structure inside the sensor, and thus causes a change in resistance, enabling online monitoring of the fiber pressure during the composite material molding process.

[0071] Taking the sensor pressure conditions before and after vacuuming during the molding process as an example, the sensor monitoring results and analysis are explained in detail. As shown in Figure 6(a), before vacuuming, the glass fiber cloth and the internal sensor are in a free state, and the sensor resistance remains stable. As shown in Figure 6(b), after vacuuming, atmospheric pressure acts on the composite material, and the fibers bear all the atmospheric pressure. The sensor is located between the fiber layers of the composite material and is subjected to the pressure transmitted by the glass fiber, causing deformation in the thickness direction and resulting in a change in resistance. The resistance changes of the sensor before and after vacuuming are shown in Figure 6(b). Figure 7 As shown, when the pressure applied to the glass fiber layer changes, the pressure on the sensor changes accordingly, causing a change in the sensor's resistance. Based on this, the changes in fiber pressure during the molding process are monitored in real time, and the changes in resistance are used to quantitatively reflect the changes in fiber pressure.

[0072] This invention eliminates the influence of resin pressure on sensor signal output during composite material molding by preparing a porous film containing conductive filler, thereby achieving accurate online monitoring of fiber pressure during composite material molding and providing reliable data support for parameter control of composite material liquid molding process. At the same time, thanks to its ingenious structural design and excellent mechanical properties, the sensor has almost no impact on the molding process and quality of composite materials, does not reduce the mechanical properties of the composite material after molding, and even improves the interlaminar fracture toughness, thus providing effective protection for the service safety of composite materials.

[0073] According to another aspect of the present invention, an online monitoring system for fiber pressure bearing during composite material molding process is provided, comprising:

[0074] An embedded module is used to embed the fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a thin film sensor with a porous conductive network structure and piezoresistive effect;

[0075] The composite material molding module is used to mold composite materials, and during the molding process, pressure is applied in the thickness direction of the composite material.

[0076] The monitoring module is used to monitor the resistance changes of the fiber pressure-bearing online monitoring sensor to reflect the changes in fiber pressure-bearing during the composite material molding process.

[0077] The system also includes a quantitative calculation module for calculating the change in fiber pressure based on the change in resistance; wherein the change in resistance is inversely proportional to the change in fiber pressure.

[0078] Each module is used to perform each step in the above-mentioned online monitoring method for fiber pressure bearing in the composite material molding process.

[0079] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for online monitoring of fiber pressure bearing capacity during composite material molding process, characterized in that, include: S1. Embed the fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a porous conductive network structure thin film sensor with piezoresistive effect; S2. A composite material is formed. During the forming process, pressure is applied in the thickness direction of the composite material. During this process, resin flows freely within the porous conductive network structure of the fiber pressure-bearing online monitoring sensor. Simultaneously, the fiber pressure-bearing online monitoring sensor is impregnated by the resin liquid. Under the resin pressure, the fiber skeleton of the composite material is subjected to a uniform force, ensuring that the distance between the fiber skeletons does not change under the resin pressure, thus not affecting the resistance signal change of the fiber pressure-bearing online monitoring sensor. Applying pressure in the thickness direction of the composite material causes the fiber pressure-bearing online monitoring sensor to deform in the thickness direction, thereby altering the conductive path of the porous conductive network structure and generating a changing resistance signal. S3. Monitor the resistance signal of the fiber pressure monitoring sensor. The changing resistance signal is used to reflect the change in fiber pressure during the molding process of the composite material.

2. The method according to claim 1, characterized in that, In S3, the resistance change of the fiber pressure-bearing online monitoring sensor is inversely proportional to the fiber pressure-bearing change.

3. The method according to claim 1, characterized in that, S1 further includes: leading out the wires of the fiber pressure-bearing online monitoring sensor and connecting them to a signal acquisition device; the signal acquisition device is used to acquire the resistance change data of the fiber pressure-bearing online monitoring sensor.

4. The method according to claim 1, characterized in that, The fabrication steps of the fiber pressure-bearing online monitoring sensor include: S11. An insulating material is selected as the matrix, and the matrix is ​​pretreated to obtain a first precursor. S12. Add conductive filler to the first precursor, stir and disperse evenly to obtain the second precursor; S13. The second precursor is molded to obtain a porous conductive network structure film with piezoresistive effect; S14. Using the thin film as a sensing element, connect flexible wires to both sides of the sensing element to obtain the fiber pressure-bearing online monitoring sensor.

5. The method according to claim 4, characterized in that, In S13, the second precursor is shaped using any one of the following molding methods: electrospinning, template method, thermally induced phase separation method, sol-gel method, and laser 3D printing.

6. The method according to claim 4, characterized in that, In S12, the conductive filler includes one or more of the following: carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, or metal powder.

7. The method according to claim 4, characterized in that, In S11, the insulating material includes any one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, polyether ether ketone, nylon, polyurethane, alumina, silica, and titanium dioxide.

8. The method according to claim 4, characterized in that, The flexible wire is connected to both sides of the sensing element via conductive silver paste.

9. An online monitoring system for fiber pressure bearing during composite material molding process, characterized in that, include: An embedded module is used to embed a fiber pressure-bearing online monitoring sensor into the interlayer of the composite material to be monitored; wherein, the fiber pressure-bearing online monitoring sensor is a porous conductive network structure thin film sensor with piezoresistive effect; A composite material molding module is used for molding composite materials. During the molding process, pressure is applied in the thickness direction of the composite material. During molding, resin flows freely within the porous conductive network structure of the fiber pressure-bearing online monitoring sensor, while the sensor is impregnated with the resin liquid. Under resin pressure, the fiber skeleton of the composite material is subjected to a uniform force, ensuring that the distance between the fiber skeletons does not change under the pressure, thus not affecting the resistance signal of the sensor. Applying pressure in the thickness direction causes the sensor to deform, altering the conductive path of the porous conductive network structure and generating a changing resistance signal. The monitoring module is used to monitor the resistance signal of the fiber pressure monitoring sensor, and the changing resistance signal is used to reflect the change in fiber pressure during the molding process of the composite material.

10. The system according to claim 9, characterized in that, It also includes a quantitative calculation module for calculating the change in fiber pressure based on the change in resistance; wherein the change in resistance is inversely proportional to the change in fiber pressure.

Images