Method for detecting solid rocket engine liner curing based on fiber bragg grating

Abstract

The application discloses a solid rocket engine lining curing detection method based on a fiber Bragg grating, and comprises the following steps: S1, preparing a lining slurry according to process requirements, spraying or coating the lining slurry on an adiabatic surface according to engine technical index requirements, and feeding into a constant-temperature rotary curing furnace for constant-temperature rotary curing; S2, feeding a detection device into the engine, and placing the detection device on the lining surface; S3, acquiring grating sensor signal changes in a detection process by using a fiber detection system, and judging the lining curing state according to detection data and a data processing algorithm. The application has the advantages of small size, high precision, low cost and intrinsic safety, can effectively detect the physical characteristics such as strain, temperature and pressure of the structure, overcomes the defects such as large occupation area and high price of ultrasonic and infrared ray methods and equipment, and realizes in-situ and nondestructive detection of the lining curing state.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing, specifically to a method for testing the curing of solid rocket motor liner based on fiber Bragg gratings. Background Technology

[0002] Solid rocket motors are the main power units of modern aerospace equipment. As an important adhesive transition layer between the propellant and the insulation layer in the engine combustion chamber, the liner's adhesive performance directly affects the quality of the propellant charge and has a significant impact on the integrity of the engine structure and its operational reliability.

[0003] The curing process of the liner is a long-term, mild phase transition from liquid to solid. During curing, the liner's thickness, morphology, viscoelasticity, density, impedance, modulus, and other characteristic parameters change to varying degrees. Its appearance changes from an initial viscous flow state to a stringy state, then to a slightly sticky "semi-cured" state, and finally to a non-sticky, fully cured state. Based on the changes in the physical and appearance properties of the liner during curing, existing research has developed techniques such as ultrasonic methods, manual methods, and infrared spectroscopy to detect the curing process. However, these methods have limitations such as high cost, complex operation, and inability to detect in situ. Summary of the Invention

[0004] This invention provides a method for detecting the curing of solid rocket motor liner based on fiber Bragg gratings, which effectively solves the problems of high cost, complex operation, and insufficient or excessive curing caused by manual judgment in traditional methods.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for detecting the curing of solid rocket motor liner based on fiber Bragg gratings includes the following detection steps:

[0007] S1. Prepare the lining slurry according to the process requirements, and spray or scrape the lining slurry onto the heat insulation surface according to the engine technical specifications, and send it into the curing oven for constant temperature rotary curing.

[0008] S2. Insert the testing device into the engine and place it on the liner surface.

[0009] S3. Use the fiber optic detection system to acquire the changes in the grating sensor signal during the detection process, and determine the curing state of the liner based on the detection data and data processing algorithm.

[0010] As a preferred embodiment of the above scheme, in step S1, the liner is a solid engine liner, including conventional liners of HTPB / IPDI and HTPB / TDI thermosetting systems, as well as novel liners.

[0011] As a preferred embodiment of the above scheme, in step S2, the detection device includes a grating sensor, an optical fiber holder, a counterweight, and an optical fiber cutter. The grating sensor is held by the optical fiber holder, a counterweight is provided on the top of the optical fiber holder, and an optical fiber cutter is provided on the inner wall of one side of the optical fiber holder.

[0012] As a preferred embodiment of the above scheme, in step S2, the grating sensor is pre-applied with a constant clamping force by the fiber optic holder, the grating sensor is in direct contact with the liner, and the grating sensor is embedded in the liner by a counterweight.

[0013] As a preferred embodiment of the above scheme, in step S2, for engines of the same model, size and liner manufacturing process, the diameter of the grating sensor carried by the detection device, the coating, and the clamping force applied by the detection device to the sensor, i.e., the weight of the counterweight, should be kept consistent.

[0014] As a preferred embodiment of the above scheme, step S2 specifically includes:

[0015] S21. The grating sensor is clamped in the fiber optic holder, with the center of the grating area and the center of gravity of the counterweight on the same straight line. The clamping force of the sensor is controlled by a micro motor.

[0016] S22. Select a suitable location in the internal lining of the solid rocket motor, send the detection device into the designated location, press down the counterweight, and embed the grating sensor into the lining.

[0017] S23. Use a fiber optic cutter to cut one side of the grating sensor, and connect the other side of the grating sensor to the fiber optic detection system.

[0018] As a preferred embodiment of the above scheme, in step S3, the optical fiber detection system includes a demodulation module and a data analysis module that are interconnected. The demodulation module is connected to the grating sensor and is used to measure the optical fiber signal generated by the grating sensor retracting in the substrate and transmit the data to the data analysis module.

[0019] As a preferred embodiment of the above scheme, in step S3, the signal data generated by the retraction of the grating sensor in the liner is used to realize the liner curing detection.

[0020] As a preferred embodiment of the above scheme, step S3 specifically includes:

[0021] S31. Based on multiple tests, fiber optic signal data were obtained during the process of the liner changing from liquid to solid phase. Normalized curves λ(t) and k(t) of grating wavelength change Δλ and wavelength change rate k during the shrinkage process were established with respect to the liner curing time. Curing index and curing time curve ψ(t) were also constructed during the liner curing process.

[0022] S32. Install a fiber optic detection system in an engine of the same model and size to obtain the sensor model characteristics during the sensor retraction process, and calculate the measured solidification index ψ(t) corresponding to the i-th test. i ), through comparative analysis ψ(t) i ) and ψ(t) determine the current curing state of the liner.

[0023] As a preferred embodiment of the above scheme, the grating wavelength change Δλ=|λ1-λ2|, where λ1 is the wavelength value after the sensor is implanted at the interface, and λ2 is the wavelength value after the sensor is cut and retracted to stabilize; the grating wavelength change rate k=Δλ / ΔT, where ΔT is the retraction time of the sensor in the liner; the curing index ψ(t)=λ(t)+k(t), where t is time.

[0024] Due to the above structure, the beneficial effects of the present invention are as follows:

[0025] (1) Based on the advantages of fiber Bragg gratings such as small size, high precision, low cost and intrinsic safety, this invention can effectively detect the physical characteristics of the structure such as strain, temperature and pressure. The grating sensor is embedded in the liner and the physical characteristics of viscosity change during the liner curing process are used to analyze the signal generated by the grating sensor retracting in the liner. This overcomes the defects of ultrasonic and infrared methods such as large equipment footprint and high price, and realizes in-situ non-destructive testing of the liner curing state.

[0026] (2) This invention analyzes the grating signal data in depth, extracts the grating signal characteristics caused by viscosity during the grating retraction process, and quantitatively analyzes the curing state of the liner. This solves the problem that relying on manual judgment can easily lead to insufficient or excessive curing, and provides scientific support for subsequent processes such as loading. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0028] Figure 1 This is a flowchart of the curing and testing process of the present invention;

[0029] Figure 2 This is a schematic diagram of the detection device of the present invention;

[0030] Figure 3 This is a schematic diagram illustrating the principle of determining the curing of the liner in this invention. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, this embodiment provides a method for detecting the curing of solid rocket motor liner based on fiber Bragg gratings, including the following detection steps:

[0033] S1. Prepare the lining slurry according to the process requirements, and spray (scrape) the lining slurry onto the heat insulation surface according to the engine technical specifications. Then, send it into the curing oven for constant temperature rotary curing. The lining is a solid engine lining, including conventional linings and novel linings of HTPB / IPDI and HTPB / TDI thermosetting systems. That is, any lining involving liquid-to-solid phase transformation can be cured using the method of this invention.

[0034] S2. Insert the testing device 000 into the engine, placing it on the liner surface; wherein, as... Figure 2 As shown, the detection device 000 includes a grating sensor 001, an optical fiber holder 002, a counterweight 003, and an optical fiber cutter 4. The grating sensor 001 is held by the optical fiber holder 002. The counterweight 003 is located on the top of the optical fiber holder 002, and the optical fiber cutter 4 is located on the inner wall of one side of the optical fiber holder 002. A constant clamping force is pre-applied to the grating sensor 001 by the optical fiber holder 002. The grating sensor 001 is in direct contact with the liner, and the counterweight 003 embeds the grating sensor 001 into the liner. For engines of the same model, size, and liner manufacturing process, the diameter, coating, and clamping force applied by the detection device 000 to the sensor (i.e., the weight of the counterweight 003) of the grating sensor 001 carried by the detection device 000 are kept consistent. The specific steps include:

[0035] S21. Clamp the grating sensor 001 in the fiber optic holder 002. The center of the grating area and the center of gravity of the counterweight 003 are on the same straight line. The sensor clamping force is controlled by a micro motor. The sensors (diameter, coating) implanted in solid rocket motors of the same type and size have the same clamping force.

[0036] S22. Select a suitable location in the internal lining of the solid rocket engine, send the detection device 000 into the designated location, press down the counterweight 003, and embed the grating sensor 001 into the lining. The weight and duration of the counterweight 003 of the solid rocket engine of the same type and size should be consistent.

[0037] S23. Use fiber optic cutter 4 to cut one side of the grating sensor 001, and connect the other side of the grating sensor 001 to the fiber optic detection system. After the measurement is completed, pull up the counterweight 003 and remove the fiber optic detection device 000.

[0038] S3. The fiber optic detection system acquires the signal changes of the grating sensor 001 during the detection process, and determines the curing state of the liner based on the detection data and data processing algorithms. The fiber optic detection system includes a demodulation module 100 and a data analysis module 200 connected to each other. The demodulation module 100 is connected to the grating sensor 001 and measures the fiber optic signal generated by the grating sensor 001 retracting within the liner, transmitting the data to the data analysis module 200. The liner curing detection is achieved using the signal data generated by the grating sensor 001 retracting within the liner. Specifically, the following steps are included:

[0039] S31. For a specific type and size engine liner, install a fiber optic detection system to acquire fiber optic signal data during the liner's transition from a liquid to a solid phase. The test results of grating sensor 001 are as follows: Figure 3 As shown, the wavelength value of the grating sensor 001 after implantation at the interface is λ1, and the wavelength value after shearing and retraction stabilization is λ2. The sensor retraction time is ΔT. Calculate the grating wavelength change Δλ = λ1 - λ2| and the wavelength change rate k = Δλ / ΔT. Multiple tests were conducted during the curing process of the engine liner of this model and size. Normalized curves λ(t) and k(t) of Δλ and k versus curing time t were established during the liner curing process. A curve ψ(t) of the curing index versus curing time during the liner curing process was constructed. The index ψ(t) of the i-th test... i )=λ(t i )+k(t i The values ​​of the curing index ψ1 and ψ2 of the lining were analyzed within the optimal bonding performance time period, where ψ1 < ψ2.

[0040] S32. Install a fiber optic detection system in an engine of the same model and size to obtain the sensor model characteristics during the sensor retraction process, and calculate the measured solidification index ψ(t) corresponding to the i-th test. i ), by comparing ψ(t) i ) and ψ(t) determine the current curing state of the liner.

[0041] This embodiment leverages the advantages of fiber Bragg gratings, such as small size, high precision, low cost, and intrinsic safety, to effectively detect physical characteristics of structures, including strain, temperature, and pressure. By embedding the grating sensor into the liner and utilizing the physical characteristics of viscosity changes during the liner curing process, the signal generated by the grating sensor retracting within the liner is analyzed. This overcomes the drawbacks of ultrasonic and infrared methods, such as large equipment footprint and high cost, enabling in-situ, non-destructive testing of the liner curing state.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., 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 detecting the curing of solid rocket motor liner based on fiber Bragg gratings, characterized in that: The following testing steps are included: S1. Prepare the lining slurry according to the process requirements, and spray or scrape the lining slurry onto the heat insulation surface according to the engine technical specifications, and send it into the curing oven for constant temperature rotary curing. S2. Insert the testing device into the engine and place it on the liner surface. S3. Use the fiber optic detection system to acquire the changes in the grating sensor signal during the detection process, and determine the curing state of the liner based on the detection data and data processing algorithm. In step S2, the detection device includes a grating sensor, an optical fiber holder, a counterweight, and an optical fiber cutter. The grating sensor is held by the optical fiber holder, a counterweight is provided on the top of the optical fiber holder, and an optical fiber cutter is provided on the inner wall of one side of the optical fiber holder. In step S2, the grating sensor is pre-applied with a constant clamping force by the fiber optic holder, the grating sensor is in direct contact with the liner, and the grating sensor is embedded in the liner by the counterweight. Step S3 specifically includes: S31. Based on multiple tests, obtain fiber optic signal data during the process of the liner changing from liquid to solid phase, and establish the grating wavelength change during the retraction process. and wavelength change rate Normalized curve of curing time of liner With k Curves of curing indices versus curing time during the lining curing process were constructed. ; S32. Install a fiber optic detection system in an engine of the same model and size to acquire sensor signal characteristics during the sensor retraction process, and calculate the measured solidification index corresponding to the i-th test. Through comparative analysis and Determine the current curing status of the lining; Grating wavelength change In the formula This refers to the wavelength value after the sensor is implanted into the interface. The wavelength value after the sensor is cut back and stabilized; the grating wavelength change rate. , For sensor retraction time in the liner; curing index For time.

2. The method for detecting the curing of solid rocket motor liner based on fiber Bragg grating according to claim 1, characterized in that: In step S1, the liner is a solid engine liner.

3. The method for detecting the curing of solid rocket motor liner based on fiber Bragg grating according to claim 1, characterized in that: Step S2 specifically includes: S21. The grating sensor is clamped in the fiber optic holder, with the center of the grating area and the center of gravity of the counterweight on the same straight line. The clamping force of the sensor is controlled by a micro motor. S22. Select a suitable location in the internal lining of the solid rocket motor, send the detection device into the designated location, press down the counterweight, and embed the grating sensor into the lining. S23. Use a fiber optic cutter to cut one side of the grating sensor, and connect the other side of the grating sensor to the fiber optic detection system.

4. The method for detecting the curing of solid rocket motor liner based on fiber Bragg grating according to claim 1, characterized in that: In step S3, the fiber optic detection system includes a demodulation module and a data analysis module that are interconnected. The demodulation module is connected to the grating sensor and is used to measure the fiber optic signal generated by the grating sensor retracting in the substrate and transmit the data to the data analysis module.

5. The method for detecting the curing of solid rocket motor liner based on fiber Bragg grating according to claim 1, characterized in that: In step S3, the curing detection of the liner is achieved by using the signal data generated by the retraction of the grating sensor in the liner.

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