Composite material curing observation device and method for prepreg vibration-assisted molding process

Abstract

The invention belongs to the technical field of composite material forming, and particularly relates to a composite material curing observation device and method for a prepreg vibration auxiliary forming process. According to the curing observation device, a prepreg part of a composite material to be observed is placed on a transparent objective table, a heating pad is placed on the top of the prepreg part, then the prepreg part is covered and sealed through a vacuum bag, and then the prepreg part is pressed through a vibration mechanism flexibly connected to the transparent objective table; the optical camera shoots an image of the prepreg workpiece from the position below the transparent objective table and then transmits the image to the upper computer, and the curing process of the composite material is observed. According to the curing observation method, multiple curing experiments are carried out by adopting a control variable method, optimal vibration parameters and corresponding image information corresponding to each temperature interval are acquired, and a corresponding relationship between the temperature and the vibration parameters of the vibration mechanism is established, so that a basis is provided for setting the vibration parameters of the vibration mechanism in a subsequent composite material curing process; and an image reference is provided, so that the curing process is optimized on line.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material molding, and in particular relates to a composite material curing observation device and method for a prepreg vibration-assisted molding process. Background Art

[0002] Fiber-reinforced resin-based composite materials have the advantages of light weight and high strength, and are widely used in aerospace and other fields. The composite prepreg molding process is a molding process in which the composite material is impregnated with a fiber layer to form a prepreg, and then the prepreg is used for plying, and finally cured to form a composite material part. The air entrained in the prepreg plying process and the gas dissolved in the resin matrix will form pore defects during the curing process, affecting the performance of the part. In order to facilitate the monitoring of the resin flow and fiber compaction behavior during the curing process of the composite material in the prepreg molding process, our team has previously developed a curing monitoring system for composite materials based on the prepreg molding process, and its patent announcement number is CN117863596B. This scheme arranges an observation mechanism and a high-temperature resistant camera on the stage to observe from the side of the prepreg part, and puts the observation mechanism and the high-temperature resistant camera together with the prepreg part on the workbench in the oven, but this scheme is not suitable for observing the vibration-assisted curing process. After prepreg laying, vibration assistance can effectively remove pores. Therefore, it is necessary to design corresponding observation devices to explore the influence of vibration assistance on the flow and pore evolution of composite prepreg parts during the curing process. Summary of the invention

[0003] The present invention provides a composite material curing observation device for a prepreg vibration-assisted molding process. The device arranges an optical camera outside a heating environment and a transparent stage, so that the installation of the optical camera is more convenient, the optical camera is not affected by the heating environment and the vibration environment, and the observation result is more accurate. It is possible to observe the composite material curing process by a non-destructive method without affecting the composite material curing molding process and the performance of the product, and provides help for the exploration and research of the vibration-assisted composite material prepreg curing molding process.

[0004] The device comprises a frame, a transparent stage, a heating pad, a vacuum bag, a vibration mechanism, an optical camera and a host computer; the transparent stage is fixed on the frame, and a prepreg workpiece of a composite material to be observed is placed on the transparent stage; the heating pad is placed on the top of the prepreg workpiece, the vacuum bag cover is arranged on the heating pad and the prepreg workpiece, and the four sides of the vacuum bag are sealed and fixed on the transparent stage; the vibration mechanism is flexibly connected to the transparent stage, and the vibration mechanism is pressed on the vacuum bag; the optical camera is arranged on the frame, and the optical camera is located below the transparent stage; the host computer is communicatively connected to the optical camera.

[0005] In a specific embodiment, a release layer is provided on the upper surface of the transparent stage, and the prepreg product is placed on the release layer.

[0006] In a specific embodiment, the release layer is a transparent release agent coating or a transparent release film.

[0007] In a specific embodiment, an isolation film is provided between the prepreg part and the heating pad.

[0008] In a specific embodiment, the four sides of the vacuum bag are sealed and fixed on the transparent stage by high-temperature glue.

[0009] In a specific embodiment, the heating pad is an electric heating pad, and the power supply wire of the electric heating pad passes through the high temperature glue and is connected to an external power source.

[0010] In a specific embodiment, the vibration mechanism includes: a vibration plate, an exciter and a flexible limiter, the vibration plate is pressed on the vacuum bag, the exciter is fixed on the top of the vibration plate, the top end of the flexible limiter is connected to the vibration plate, and the bottom end of the flexible limiter is connected to the transparent stage.

[0011] In a specific embodiment, the flexible limiting member is a rubber suction cup.

[0012] The present invention has at least the following beneficial effects: 1. The device sets the optical camera outside the heating environment and the transparent stage, which makes the installation of the optical camera more convenient, and the optical camera is not affected by the heating environment and the vibration environment, so the observation result is more accurate.

[0013] 2. The device can limit the vibration mechanism and reduce the leakage of vibration energy through the transparent stage by flexibly connecting the vibration mechanism to the transparent stage, so that the vibration energy acts on the prepreg parts as much as possible, and can also reduce the risk of damage to the transparent stage caused by direct action of the vibration mechanism, and can also reduce the large shaking of the transparent stage that affects the observation of the optical camera.

[0014] 3. It has been realized to observe the curing process of composite materials by non-destructive methods without affecting the curing molding process and product performance of composite materials, which provides help for the exploration and research of vibration-assisted composite prepreg curing molding process.

[0015] The present invention also provides a composite material curing observation method, which can obtain the corresponding relationship between temperature and vibration parameters of the vibration mechanism, provide a basis for dynamically adjusting the vibration parameters of the vibration mechanism during the subsequent curing process of the composite material, and realize online real-time optimization of the curing process.

[0016] The method comprises the following steps: S1, placing a composite material prepreg workpiece to be observed in a composite material curing observation device of a prepreg vibration-assisted molding process described in any one of the above, starting an optical camera and a host computer, and zooming in and photographing the prepreg workpiece with an optical lens; setting an image acquisition area, obtaining initial image information of the prepreg workpiece in the image acquisition area, and transmitting the obtained image information to the host computer for storage; S2, evacuating the vacuum bag, setting initial vibration parameters of the vibration mechanism, and starting a heating pad and a vibration mechanism, and continuously obtaining process image information of the image acquisition area with an optical lens and transmitting it to the host computer; dividing the entire curing process of the composite material into a plurality of temperature intervals, and waiting for the temperature of the composite material to rise to the starting value of the first temperature interval; When the image information is processed, the vibration parameters of the vibration mechanism are adjusted. The host computer analyzes and calculates the process image information and the initial image information to calculate the change value of the image information of the composite material in the first temperature interval; S3, multiple curing experiments are carried out, and different vibration parameters are adjusted at the starting value of the first temperature interval by the control variable method. The host computer calculates the change value of the image information of the composite material in the first temperature interval under different vibration parameters. The host computer records and saves the best vibration parameters and corresponding image information in the first temperature interval; S4, repeating steps S1 to S3, the host computer records and saves the best vibration parameters and corresponding image information of each temperature interval in the entire curing process of the composite material, and establishes the corresponding relationship between temperature and vibration parameters of the vibration mechanism.

[0017] In a specific embodiment, the image information is one or more of the number of pores in the image acquisition area, the average area of ​​each pore, the coordinate position of each pore, the circumference of each pore, the aspect ratio of each pore, or the coordinate position of the front curve of the composite material.

[0018] The present invention has at least the following beneficial effects: by adopting the control variable method to carry out multiple curing experiments, the optimal vibration parameters and corresponding image information corresponding to each temperature range are collected, and the corresponding relationship between temperature and vibration parameters of the vibration mechanism is established, which provides a basis for setting the vibration parameters of the vibration mechanism in the subsequent composite material curing process, and provides image reference to achieve online optimization of the curing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional structural diagram of the solidification observation device in an embodiment of the present invention.

[0020] Figure 2It is a cross-sectional view of the assembly structure of the prepreg component, heating pad, vacuum bag and vibration mechanism in an embodiment of the present invention.

[0021] Figure 3 2 is a structural diagram of a flexible limiter in an embodiment of the present invention.

[0022] Reference numerals: frame 1 , transparent stage 2 , heating pad 3 , vacuum bag 4 , vibration mechanism 5 , vibration plate 51 , exciter 52 , flexible limiter 53 , optical camera 6 , prepreg component 7 . DETAILED DESCRIPTION

[0023] See also Figure 1-3The present invention provides a composite material curing observation device for a prepreg vibration-assisted molding process, which includes a frame 1, a transparent stage 2, a heating pad 3, a vacuum bag 4, a vibration mechanism 5, an optical camera 6 and a host computer. The transparent stage 2 is fixed on the frame 1, and the transparent stage 2 can be made of a transparent acrylic material. A layer of transparent release agent is sprayed on the upper surface of the transparent stage 2 to form a release layer, and the prepreg part 7 of the composite material to be observed is laid on the release layer. The composite material is a resin, and the transparent release agent is an existing known technology. Of course, in other embodiments of the present invention, the transparent release agent can also be replaced by an existing transparent release film. The heating pad 3 is placed on the top of the prepreg part 7, and an isolation film is provided between the prepreg part 7 and the heating pad 3 to isolate the heating pad 3 from the prepreg part 7. The vacuum bag 4 is covered on the heating pad 3 and the prepreg part 7, and the four sides of the vacuum bag 4 are sealed and fixed on the transparent stage 2 by high-temperature glue to ensure the sealing performance of the vacuum bag 4. In an embodiment of the present invention, the heating pad 3 adopts an electric heating pad 3, and the power supply wire of the electric heating pad 3 passes through the high temperature glue and is connected to an external power supply. Of course, in other embodiments of the present invention, in order to reduce wiring operations and ensure the sealing performance of the high temperature glue, the heating pad 3 can also adopt a wireless structure, such as an induction heating method. The vibration mechanism 5 is flexibly connected to the transparent stage 2. The vibration mechanism 5 includes: a vibration plate 51, an exciter 52 and a flexible limiter 53. The vibration plate 51 is pressed on the vacuum bag 4, the exciter 52 is fixed on the top of the vibration plate 51, the top end of the flexible limiter 53 is connected to the vibration plate 51, and the bottom end of the flexible limiter 53 is connected to the transparent stage 2. This vibration mechanism 5 directly sets the exciter 52 on the vibration plate 51. During the experiment, the position of the exciter 52 can be adjusted according to the actual situation such as the shape and size of the prepreg product 7. Compared with the integrally packaged vibration mechanism 5, the vibration mechanism 5 of this scheme is more flexible when used in experiments. The flexible stopper 53 is a rubber suction cup. Compared with a spring structure, this structure is low-cost and easy to obtain. Moreover, this structure is simple and practical, and is easy to disassemble and assemble. The optical camera 6 is arranged on the frame 1, and the optical camera 6 is located below the transparent stage 2. By arranging the optical camera 6 in a heating environment and outside the transparent stage 2, the installation of the optical camera 6 is more convenient, the optical camera 6 is not affected by the heating environment and the vibration environment, and the observation result is more accurate. The host computer is connected to the optical camera 6 for recording, analyzing and saving data such as image information obtained by the optical camera 6.

[0024] The present invention has at least the following beneficial effects: 1. The device arranges the optical camera 6 outside the heating environment and the transparent stage 2, so that the installation of the optical camera 6 is more convenient, the optical camera 6 is not affected by the heating environment and the vibration environment, and the observation result is more accurate.

[0025] 2. The device flexibly connects the vibration mechanism 5 to the transparent stage 2, which can not only limit the vibration mechanism 5, but also reduce the leakage of vibration energy through the transparent stage 2, so that the vibration energy acts on the prepreg component 7 as much as possible, and can also reduce the risk of damage to the transparent stage 2 caused by direct action of the vibration mechanism 5, and can also reduce the large shaking of the transparent stage 2 to affect the observation of the optical camera 6.

[0026] 3. It has been realized to observe the curing process of composite materials by non-destructive methods without affecting the curing molding process and product performance of composite materials, which provides help for the exploration and research of vibration-assisted composite prepreg curing molding process.

[0027] The present invention also provides a composite material curing observation method, which adopts a control variable method to conduct multiple curing experiments, collects the optimal vibration parameters and corresponding image information corresponding to each temperature range, establishes a corresponding relationship between temperature and vibration parameters of a vibration mechanism, provides a basis for setting the vibration parameters of the vibration mechanism in a subsequent composite material curing process, and provides an image reference to achieve online optimization of the curing process, and specifically includes the following steps: First, the prepreg component 7 of the composite material to be observed is placed in the composite material curing observation device of the prepreg vibration-assisted molding process, the optical camera 6 and the host computer are started, the optical lens is magnified 10 times to 100 times to shoot the prepreg component 7, and a 100mm×100mm image acquisition area is drawn on the transparent stage 2, and the host computer obtains the initial image information of the prepreg component 7 in the image acquisition area.

[0028] Then, the vacuum bag 4 is evacuated, and the initial vibration parameters of the vibration mechanism 5 are set according to the vibration parameters corresponding to the better performance parts in the previous vibration-assisted molding process, and the heating pad 3 and the vibration mechanism 5 are started to start the curing process. During the curing process, the temperature of the composite material gradually rises, and the temperature rise rate is 2°C / min. The optical lens continuously obtains the process image information of the image acquisition area. When the temperature of the composite material rises to a specific value, such as 80°C, the vibration parameters of the vibration mechanism 5 are adjusted. Since the adjustment effect of the vibration parameters is not so quickly reflected on the image, the vibration parameters of the vibration mechanism 5 are adjusted at 80°C, and the changes in the image information during the period when the temperature of the composite material rises from 80°C to 90°C are observed. The image information is the number of pores in the image acquisition area, the average area of ​​each pore, the coordinate position of each pore, the perimeter of each pore, the aspect ratio of each pore, or the coordinate position of the front curve of the composite material. Changes in one or more information. Specifically, the host computer analyzes and calculates based on the continuously acquired process image information and initial image information, and calculates the change value of the image information during the period when the temperature of the composite material rises from 80°C to 90°C after the vibration parameters of the vibration mechanism 5 are adjusted at 80°C. For example, the rate of change of the number of pores in the image acquisition area is calculated, and the host computer saves the adjusted vibration parameters, temperature range values ​​and change values ​​of the image information.

[0029] Then, multiple curing experiments were carried out, and the control variable method was used to adjust the vibration parameters of different vibration mechanisms 5 at 80°C. The changes in image information under different vibration parameters during the period when the temperature of the composite material increased from 80°C to 90°C were compared, and the optimal vibration parameters were selected and recorded as the optimal vibration parameters of the composite material in the temperature range of 80°C to 90°C.

[0030] Repeat the above steps to select the best vibration parameters in other temperature ranges during the composite material curing process. The host computer records the best vibration parameters and corresponding image information corresponding to each temperature range, establishes the corresponding relationship between temperature and vibration parameters of the vibration mechanism 5, provides a basis for the subsequent vibration parameter setting of the vibration mechanism 5 in the composite material curing process, and provides image reference. Vibration parameters include vibration frequency, vibration amplitude and vibration magnitude.

[0031] When the host computer analyzes and calculates based on the process image information and the initial image information, the image information can be the number of pores in the image acquisition area, and the change rate of the number of pores in the image acquisition area is calculated. For example, the time taken for the composite material to heat up from the initial state to 80°C is 30 minutes, there are 12 pores in the initial image information obtained, and there are 8 pores in the process image information obtained at 80°C, then the pore change rate at 80°C is calculated to be (12-8) ÷ 30 = 0.133. The vibration parameters of the vibration mechanism 5 are adjusted at 80°C, and the time corresponding to the temperature of the composite material rising from 80°C to 90°C is 5 minutes. There are 6 pores in the process image information when the temperature of the composite material is at 90°C, then the pore change rate at 90°C is calculated to be (12-6) ÷ 35 = 0.171. It can be seen from the calculation results that after the vibration parameters of the vibration mechanism 5 are adjusted at 80°C, the pore change rate of the composite material during the period from 80°C to 90°C increases, indicating that after the vibration parameters of the vibration mechanism 5 are adjusted, the change of the number of pores is accelerated.

[0032] In an embodiment of the present invention, the 100mm×100mm image acquisition area can also be divided into 100 squares of 10mm×10mm in size, so as to draw coordinate values ​​for the 100mm×100mm image acquisition area, which is convenient for digital description and processing of the image.

[0033] In an embodiment of the present invention, the relationship between the curing temperature and the viscosity or curing degree of the composite material can be combined with the corresponding relationship between the temperature and the vibration parameters established above to obtain the corresponding relationship between the viscosity or curing degree and the vibration parameters, thereby providing more comprehensive information for the analysis of the curing process of the composite material.

[0034] The present invention has at least the following beneficial effects: by adopting the control variable method to carry out multiple curing experiments, the optimal vibration parameters and corresponding image information corresponding to each temperature range are collected, and the corresponding relationship between the temperature and the vibration parameters of the vibration mechanism 5 is established, which provides a basis for setting the vibration parameters of the vibration mechanism 5 in the subsequent composite material curing process, and provides image references to achieve online optimization of the curing process.

[0035] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A composite material curing observation device for a prepreg vibration-assisted molding process, characterized in that: It includes a frame, a transparent stage, a heating pad, a vacuum bag, a vibration mechanism, an optical camera and a host computer; the transparent stage is fixed on the frame, and the prepreg product of the composite material to be observed is placed on the transparent stage; the heating pad is placed on the top of the prepreg product, the vacuum bag cover is arranged on the heating pad and the prepreg product, and the four sides of the vacuum bag are sealed and fixed on the transparent stage; the vibration mechanism is flexibly connected to the transparent stage, and the vibration mechanism is pressed on the vacuum bag; the optical camera is arranged on the frame, and the optical camera is located below the transparent stage; the host computer is communicatively connected to the optical camera.

2. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 1, characterized in that: The upper surface of the transparent stage is provided with a demoulding layer, and the prepreg product is placed on the demoulding layer.

3. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 2, characterized in that: The demoulding layer is a transparent demoulding agent coating or a transparent demoulding film.

4. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 1, characterized in that: An isolation film is provided between the prepreg component and the heating pad.

5. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 1, characterized in that: The four sides of the vacuum bag are sealed and fixed on the transparent stage by high temperature glue.

6. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 5, characterized in that: The heating pad is an electric heating pad, and the power supply wire of the electric heating pad passes through the high temperature glue and is connected to an external power source.

7. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 1, characterized in that: The vibration mechanism includes: a vibration plate, an exciter and a flexible limiter, the vibration plate is pressed on the vacuum bag, the exciter is fixed on the top of the vibration plate, the top end of the flexible limiter is connected to the vibration plate, and the bottom end of the flexible limiter is connected to the transparent stage.

8. The composite material curing observation device for prepreg vibration-assisted molding process according to claim 7, characterized in that: The flexible limiting member is a rubber suction cup.

9. A composite material curing observation method, characterized in that: The steps include: S1. After placing the composite material prepreg workpiece to be observed in the composite material curing observation device of the prepreg vibration-assisted molding process according to any one of claims 1 to 8, start the optical camera and the host computer, and use the optical lens to zoom in and shoot the prepreg workpiece; set the image acquisition area, obtain the initial image information of the prepreg workpiece in the image acquisition area, and transmit the obtained image information to the host computer for storage; S2, evacuate the vacuum bag, set the initial vibration parameters of the vibration mechanism, start the heating pad and the vibration mechanism, and the optical lens continuously obtains the process image information of the image acquisition area and transmits it to the host computer; divide the entire curing process of the composite material into multiple temperature intervals, and when the temperature of the composite material rises to the starting value of the first temperature interval, adjust the vibration parameters of the vibration mechanism, and the host computer analyzes and calculates the change value of the image information of the composite material in the first temperature interval based on the process image information and the initial image information; S3, performing multiple curing experiments, using the control variable method, adjusting different vibration parameters at the starting value of the first temperature interval, the host computer calculates the change value of the image information of the composite material in the first temperature interval under different vibration parameters, and the host computer records and saves the optimal vibration parameters and corresponding image information in the first temperature interval; S4, repeating steps S1 to S3, the host computer records and saves the optimal vibration parameters and corresponding image information of each temperature range in the entire curing process of the composite material, and establishes the corresponding relationship between the temperature and the vibration parameters of the vibration mechanism.

10. The composite material curing observation method according to claim 9, characterized in that: The image information is one or more of the number of pores in the image acquisition area, the average area of ​​each pore, the coordinate position of each pore, the perimeter of each pore, the aspect ratio of each pore or the coordinate position of the front curve of the composite material.

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