Health Monitoring Method and System for Composite Material Preform Based on Carbon-Based Nanoscale Sensors

Abstract

The present invention relates to the technical field of composite material health monitoring, and particularly to a method and system for health monitoring of composite material preforms based on carbon-based nanosensors. In the present invention, carbon-based nanosensors are implanted into the composite material preforms without significantly affecting the performance of the preforms themselves. The implantation method of the sensors is unified with the forming process of the composite material preforms. The use of these sensors does not increase the difficulty of the forming process, realizes the internal health monitoring of the composite material preforms, and avoids problems such as sensor damage that may be caused by the implantation method of other sensors as foreign objects, greatly improving the success rate of sensor implantation.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material health monitoring, and particularly to a method and system for monitoring the health of composite material preforms based on carbon-based nanosensors. Background Art

[0002] Due to their superior physical properties such as light weight and high specific strength, composite materials are widely used in the fields of aerospace, automotive, shipbuilding, rail transit, etc. However, traditional laminated composite materials have poor interlayer properties and are prone to defects such as interlayer delamination, edge warping, and delamination. Three-dimensional braided carbon fiber composite materials greatly enhance the longitudinal strength of composite materials on the basis of the light weight and high strength characteristics of the composite materials themselves. However, the forming process of three-dimensional braided composite materials is complex, traditional sensors are difficult to implant, and there is a lack of effective real-time monitoring methods for internal states. Therefore, there are certain difficulties in the structural stability assessment of three-dimensional braided composite material preforms.

[0003] In the health monitoring of laminated composite materials, guided wave piezoelectric ceramic sensors and fiber Bragg grating sensors are the two most common types of sensors. However, the monitoring accuracy of guided wave piezoelectric ceramic sensors is limited, while fiber Bragg grating sensors are widely used, but they are brittle and prone to failure during the forming process of composite materials. On the other hand, the forming process of three-dimensional braided composite materials is more complex than that of laminated composite materials. Usually, the gap between adjacent fiber bundles in the preform is about 0.2 mm, and it is impossible to arrange devices to protect the sensors. Moreover, the diameter of the smaller fiber Bragg grating sensors on the market is about 1 mm, which is difficult to implant into the interior of the preform. Forcibly embedding them will seriously affect the final forming quality of the preform and have a greater impact on its mechanical properties. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a method and system for monitoring the health of composite material preforms based on carbon-based nanosensors, enabling the sensors of the composite material preforms to be successfully implanted into the composite material preforms to monitor the stress distribution state of the preforms without having a greater impact on the performance of the composite material preforms.

[0005] Technical Solution:

[0006] The method for monitoring the health of composite material preforms based on carbon-based nanosensors provided by the present invention can adopt the following technical solutions, including the following steps:

[0007] (1) Provide a composite material preform with special fiber bundles, and the special fiber bundles are fiber bundles with a number of carbon-based nanosensors; and the carbon-based nanosensors are distributed from beginning to end in the special fiber bundles;

[0008] (2) The carbon-based nanosensors in the special fiber bundles are electrically connected to the monitoring module;

[0009] (3) Input the calibrated response coefficients of each special fiber bundle into the monitoring module, measure the resistance change of the special fiber bundle, so as to monitor the stress distribution state in the composite preform.

[0010] Further, in step (1), the preparation method of the special fiber bundle includes:

[0011] (1.1) Prepare a carbon nanotube liquid dispersion. Through continuous agitation by ultrasonic pulses, multi-walled carbon nanotubes and graphene oxide are dispersed into ionic water to make a CNTs / GO solution.

[0012] (1.2) Send the carbon fiber bundle to the CNTs / GO solution, reduction solution, water washing tank and drying station in sequence to prepare a carbon-based special fiber bundle, collect and wind it on a carbon fiber roller, take a section of the fiber bundle for response coefficient calibration test and number and mark the special fiber bundle.

[0013] Further, arrange the special fiber bundles at the corresponding positions on the roller stand according to a pre-designed grid structure as the woven fiber bundles at the parts of the composite preform to be monitored for health, and the arranged special fiber bundles gradually form a sensor grid structure as the weaving process proceeds.

[0014] Further, in step (3), calibrate the special fiber bundle through a tensile test to calibrate the stress-strain range and resistance response change coefficient applicable to the carbon-based nanosensor; the stress-strain applicable range is the range where the response shows a linear change, and calibrate the response coefficient of the whole special fiber bundle. The formula is as follows:

[0015]

[0016]

[0017] ρ 0 is the resistivity of the special fiber bundle, L 0 is the length of the special fiber bundle, S 0 is the cross-sectional area of the special fiber bundle; XY is the response coefficient of the special fiber bundle; ΔR is the resistance change value, R 0 is the initial resistance value; dε is the strain.

[0018] Further, the monitoring module includes a state data acquisition module, a data demodulation module, a data transmission module, a user display module and a power supply module;

[0019] The state data acquisition module is used to connect to the carbon-based nanosensor, collect the state parameter data of the composite preform, and transmit it to the data demodulation module;

[0020] The data demodulation module is used to demodulate the data transmitted by the status data acquisition module, convert it into digital data, and transmit the data to the data transmission module;

[0021] The data transmission module is responsible for sending the collected status data to each user display module to achieve long-distance transmission;

[0022] The user display module is used to convert the transmitted data into specific status parameter data for display;

[0023] The power supply module is used to provide power.

[0024] Further, in step (3), the specific method for monitoring the stress distribution state in the composite material preform through the resistance change of the special fiber bundle is as follows: according to the XY value of the special fiber bundle calibrated in the calibration test and the resistance change value of the special fiber bundle in the preform, the strain value dε of the position range where the special fiber bundle is located in the preform is obtained. The formula is as follows:

[0025]

[0026] XY is the response coefficient of the special fiber bundle, obtained from the calibration test; ΔR is the resistance change value, and R 0 is the initial resistance value;

[0027] Beneficial effects:

[0028] (1) The present invention proposes a special fiber bundle coated with a carbon-based nanosensor, which solves the problem of implanting the sensor into the composite material preform and does not cause a great impact on the performance of the preform itself. The implantation method of the carbon-based nanosensor is unified with the forming process of the composite material preform. The use of the carbon-based nanosensor does not increase the difficulty of the forming process, realizing the internal health monitoring of the composite material preform.

[0029] (2) The special fiber bundle proposed by the present invention can continue to play the function of health monitoring after the preform is impregnated with resin.

[0030] (3) The carbon-based nanosensor is successfully woven into the composite material preform, avoiding problems such as sensor breakage that may be caused by the implantation method of other sensors as foreign objects, and improving the implantation success rate of the carbon-based nanosensor.

[0031] The present invention also provides a technical solution for a health monitoring system of a composite material preform based on a carbon-based nanosensor:

[0032] It includes a composite material preform with a special fiber bundle and a monitoring module;

[0033] The special fiber bundle is a fiber bundle with a number of carbon-based nanosensors; and the carbon-based nanosensors are distributed throughout the special fiber bundle from beginning to end; the carbon-based nanosensors in the special fiber bundle are electrically connected to the monitoring module;

[0034] The monitoring module stores the calibrated response coefficients of each special fiber bundle. The monitoring module monitors the stress distribution state in the composite preform by measuring the resistance change on the special fiber bundle.

[0035] Further, the monitoring module includes a status data acquisition module, a data demodulation module, a data transmission module, a user display module, and a power supply module;

[0036] The status data acquisition module is used to connect to the carbon-based nanosensors, collect the status parameter data of the composite preform, and transmit it to the data demodulation module;

[0037] The data demodulation module is used to demodulate the data transmitted by the status data acquisition module, convert it into digital data, and transmit the data to the data transmission module;

[0038] The data transmission module is responsible for sending the collected status data to each user display module to achieve long-distance transmission;

[0039] The user display module is used to convert the transmitted data into specific status parameter data for display;

[0040] The power supply module is used to provide power.

[0041] Further, in the preform, conductive silver paste is applied and cured at the special fiber bundle to form an electrode connected to the monitoring module. Description of the Drawings

[0042] Figure 1 It is a flowchart of the health monitoring of the implantable composite preform;

[0043] Figure 2 It is a flowchart of the preparation process of the carbon-based sensor carbon fiber bundle;

[0044] Figure 3 It is a schematic diagram of the fiber bundle arrangement during the forming process of the preform of the present invention;

[0045] Figure 4 It is a schematic diagram of the health monitoring system of the composite preform of the present invention. Detailed Embodiments

[0046] The present invention will be further described in detail below with reference to the drawings and embodiments, but the protection scope of the present invention should not be limited thereby.

[0047] Embodiment 1

[0048] This embodiment provides a method for health monitoring of a composite preform based on a carbon-based nanosensor, comprising the following steps:

[0049] (1) Provide a composite preform with a special fiber bundle, where the special fiber bundle is a fiber bundle with a number of carbon-based nanosensors; and the carbon-based nanosensors are distributed throughout the special fiber bundle from beginning to end.

[0050] In step (1), the preparation method of the special fiber bundle includes:

[0051] (1.1) Prepare a carbon nanotube liquid dispersion. By continuously agitating with ultrasonic pulses, a number of carbon nanotubes (CNTs) and graphene oxide (GO) are dispersed into ionic water. The pulses are cycled in a 10-second period to make a CNTs / GO solution.

[0052] In this example of the present invention, 500 mg of carbon nanotubes (CNTs) and 200 mg of graphene oxide (GO) are dispersed into 500 mL of ionic water through an ultrasonic pulse instrument in a 10-s period to make a carbon nanotube liquid dispersion.

[0053] (1.2) As Figure 2 shown, the carbon fiber bundle is sequentially conveyed to the CNTs / GO solution, reduction solution, water washing tank, and drying station through a stepper motor and a pulley to prepare a special fiber bundle, which is collected and wound on a carbon fiber drum. Take a section of the special fiber bundle for a response coefficient calibration test and number and mark the special fiber bundle. In this step, the prepared fiber bundle of the carbon-based sensor is arranged at the corresponding position on the drum rack according to a predetermined designed grid structure as the woven fiber bundle at the part of the composite preform to be subjected to health monitoring. The arranged special fiber bundle will gradually form a sensor grid structure as the weaving process progresses.

[0054] In the embodiment of the present invention, a 30-m long carbon fiber bundle is used, and the transmission speed of the stepper motor is 15 mm / min; the reducing agent used is a hydroiodic acid solution, the temperature is 75 °C, and the reduction process lasts for 22 min; the solution used in the water washing process is ethanol; the drying process is carried out in a drying oven device at 65 °C; the response coefficient of the whole special fiber bundle is calibrated, and the formula is as follows:

[0055]

[0056]

[0057] ρ 0 is the resistivity of the special fiber bundle, L 0 is the length of the special fiber bundle, S 0 is the cross-sectional area of the special fiber bundle; XY is the response coefficient of the special fiber bundle; ΔR is the resistance change value, R0 is the initial resistance value; dε is the strain. The XY values of the 16 bundles of sensor carbon fiber bundles used in the examples of the present invention are 1.67, 1.34, 1.45, 1.46, 1.57, 1.41, 1.39, 1.27, 2.03, 1.78, 1.57, 1.97, 1.64, 1.36, 1.41, 1.74 respectively.

[0058] In the embodiment of the present invention, the preform is formed by 125*125 guiding array weaving. A total of 16 bundles of sensing fiber bundles are distributed in two forming directions of X and Y. 8 bundles in each direction are fixed on the woven cylinder, which serves as both a weaving raw material and a sensor. Conductive silver paste is applied and cured at the special fiber bundles to be detected in each layer of the preform as an electrode connected to the monitoring module; after the composite material preform is woven and formed, the electrode is connected to the preform health monitoring system to complete the connection between the sensor and the monitoring system. In the examples of the present invention, the number of layers of the preform is 300, the conductive silver paste is applied once every 60 layers, a total of 5 layers, and 32 places in each layer.

[0059] (2) The carbon-based nanosensors in the special fiber bundles are electrically connected to the monitoring module.

[0060] (3) Input the calibrated response coefficients of each special fiber bundle into the monitoring module, measure the resistance change on the special fiber bundle, so as to monitor the stress distribution state in the composite material preform.

[0061] In this embodiment, the monitoring module includes a status data acquisition module, a data demodulation module, a data transmission module, a user display module and a power supply module;

[0062] The status data acquisition module is used to connect to the carbon-based nanosensors, collect the status parameter data of the composite material preform, and transmit it to the data demodulation module;

[0063] The data demodulation module is used to demodulate the data transmitted by the status data acquisition module, convert it into digital data, and transmit the data to the data transmission module;

[0064] The data transmission module is responsible for sending the collected status data to each user display module to achieve long-distance transmission;

[0065] The user display module is used to convert the transmitted data into specific status parameter data for display;

[0066] The power supply module is used to provide power.

[0067] Example 2

[0068] This embodiment provides a health monitoring system for a composite material preform based on carbon-based nanosensors: including a composite material preform with special fiber bundles and a monitoring module;

[0069] The special fiber bundle is a fiber bundle with a number of carbon-based nanosensors; and the carbon-based nanosensors are distributed throughout the special fiber bundle from head to tail; the carbon-based nanosensors in the special fiber bundle are electrically connected to the monitoring module;

[0070] The monitoring module stores the calibrated response coefficients of each special fiber bundle. The monitoring module monitors the stress distribution state in the composite material preform by measuring the change in resistance on the special fiber bundle.

[0071] Same as the monitoring module in Embodiment 1, the monitoring module includes a state data acquisition module, a data demodulation module, a data transmission module, a user display module, and a power supply module;

[0072] The state data acquisition module is used to connect to the carbon-based nanosensors, collect the state parameter data of the composite material preform, and transmit it to the data demodulation module;

[0073] The data demodulation module is used to demodulate the data transmitted by the state data acquisition module, convert it into digital data, and transmit the data to the data transmission module;

[0074] The data transmission module is responsible for sending the collected state data to each user display module to achieve long-distance transmission;

[0075] The user display module is used to convert the transmitted data into specific state parameter data for display;

[0076] The power supply module is used to provide power.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements should all be within the protection scope determined by the patent claim.

Claims

1. A method for health monitoring of a composite preform based on a carbon-based nanosensor, characterized in that, it includes the following steps: (1) Provide a composite preform with a special fiber bundle, and the special fiber bundle is a fiber bundle with several carbon-based nanosensors; and the carbon-based nanosensors are distributed from beginning to end in the special fiber bundle; arrange the special fiber bundle at the corresponding position on the roller stand according to a predetermined designed grid structure, as the woven fiber bundle of the part of the composite preform to be subjected to health monitoring, and the arranged special fiber bundle gradually forms a sensor grid structure as the weaving process progresses; (2) Electrically connect the carbon-based nanosensors in the special fiber bundle to the monitoring module; (3) Input the calibrated response coefficients of each special fiber bundle into the monitoring module, measure the resistance change of the special fiber bundle, so as to monitor the stress distribution state in the composite preform; In step (1), the preparation method of the special fiber bundle includes: (1.1) Prepare a carbon nanotube liquid dispersion body, and disperse multi-walled carbon nanotubes and graphene oxide into ionic water through continuous agitation by ultrasonic pulses to make a CNTs / GO solution; (1.2) Send the carbon fiber bundle to the CNTs / GO solution, reduction solution, water washing tank and drying station in sequence, prepare a carbon-based special fiber bundle and wind it on a carbon fiber roller, take a section of the fiber bundle for a response coefficient calibration test and number and mark the special fiber bundle.

2. The method for health monitoring of a composite preform according to claim 1, characterized in that: In step (3), calibrate the special fiber bundle through a tensile test, and calibrate the stress-strain range and resistance response change coefficient applicable to the carbon-based nanosensors; the stress-strain applicable range is the range where the response shows a linear change, and calibrate the response coefficient of the whole special fiber bundle, and the formula is as follows: ρ 0 is the resistivity of the special fiber bundle, L 0 is the length of the special fiber bundle, S 0 is the cross-sectional area of the special fiber bundle; XY is the response coefficient of the special fiber bundle; ΔR is the resistance change value, and R 0 is the initial resistance value; dε is the strain.

3. The method for health monitoring of a composite preform according to claim 1, characterized in that: The monitoring module includes a state data acquisition module, a data demodulation module, a data transmission module, a user display module and a power supply module; The state data acquisition module is used to connect the carbon-based nanosensors, collect the state parameter data of the composite preform, and transmit it to the data demodulation module; The data demodulation module is used to demodulate the data transmitted by the state data acquisition module, convert it into digital data, and transmit the data to the data transmission module; The data transmission module is used to be responsible for sending the collected state data to each user display module to achieve long-distance transmission; The user display module is used to convert the transmitted data into specific state parameter data for display; The power supply module is used to provide power.

4. The method for health monitoring of a composite preform according to claim 2, characterized in that: In step (3), the specific method for monitoring the stress distribution state in the composite preform through the resistance change of the special fiber bundle is: according to the XY value of the special fiber bundle calibrated as a whole and the resistance change value of the special fiber bundle in the preform, calculate the strain value dε of the position range where the special fiber bundle is located in the preform, and the formula is as follows: XY is the response coefficient of the special fiber bundle, which is obtained from the calibration test; ΔR is the resistance change value, and R 0 is the initial resistance value.

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