A partitioned carbon fiber composite material leakage behavior detection method and device

Abstract

This invention discloses a zoned method and device for detecting leakage behavior in carbon fiber composite materials, belonging to the field of composite material leakage detection technology. The invention employs a minimalist design of "dual detection zones + independent valves," with the two detection zones corresponding to the main load-bearing surface and side surface of the sample, respectively. Considering the layered structure characteristics of composite materials (low interlayer bonding strength and susceptibility to interlayer performance degradation on the side surface), once leakage is detected, simply closing the control valves of the corresponding zones and observing the changes in the helium mass spectrometer readings allows for rapid and accurate determination of the leakage location, thus distinguishing between high-pressure penetrating damage to the main load-bearing surface and damage caused by interlayer performance degradation on the side surface. It eliminates the need for complex sealing and shielding mechanisms, offering convenient operation and accurate positioning, completely solving the problems of existing technologies that can only detect leakage but cannot locate the leakage area or differentiate the damage type. This provides a precise basis for targeted performance improvement and repair work of composite materials.

Description

Technical Field

[0001] This invention relates to the field of composite material leakage detection technology, specifically to a partitioned carbon fiber composite material leakage behavior detection method and device. Background Technology

[0002] Carbon fiber / resin matrix composites are widely used in high-end equipment fields such as aerospace, new energy (e.g., liquid hydrogen / liquid nitrogen storage tanks), and rail transportation due to their excellent specific strength, specific modulus, fatigue resistance, and designability. In these applications, composite material samples (or components) often serve as core units for pressure-bearing or sealing components, and their airtightness is a key performance indicator to ensure the safety and reliable operation of the system. Especially in scenarios such as cryogenic propellant storage tanks in the aerospace field and hydrogen fuel cell storage cylinders in the new energy field, composite material structures need to operate for a long time under extremely low temperatures (e.g., 90K for liquid oxygen and 77K for liquid nitrogen) and cyclic loads. Any tiny cracks, pores, or interface defects can develop into channels leading to media leakage, and the leakage risk varies significantly in different areas (e.g., main load-bearing surfaces and sides). Once leakage occurs, it will lead to serious safety accidents and performance failures.

[0003] Currently, the main methods for detecting leakage in composite materials include the bubble method (water detection method) and the pressure decay method. While the bubble method is simple and intuitive, it has low sensitivity, making it difficult to detect minute leaks, and it is not suitable for materials whose properties change upon contact with water. The pressure decay method requires extremely high equipment sealing and faces two major scientific and technological challenges: first, it cannot pinpoint the leak point; it can only determine that leakage exists in the sample, but cannot pinpoint the specific area of ​​the sample where the leakage occurs (e.g., the main load-bearing surface or the side surface); second, it cannot distinguish between damage types, ignoring the core characteristics of the layered structure of composite materials. Specifically, the interlaminar bonding strength of composite materials is much lower than the intralaminar strength. The main load-bearing surface is susceptible to penetrating damage under high pressure, while the side surface is prone to non-penetrating leakage channels due to interlaminar performance degradation (e.g., delamination and cracking caused by low temperature and cyclic loading). The impact of these two damage types on the performance of composite materials and the direction of repair are completely different. Existing technologies cannot distinguish between the two, thus preventing targeted performance improvement and repair work for composite materials. Furthermore, existing testing devices mostly employ a single vacuum chamber design and are largely limited to room temperature testing, making it difficult to simulate the leakage characteristics of composite materials under low-temperature service conditions. At low temperatures, resin matrix shrinkage and fiber / matrix interface stress changes further exacerbate interlayer performance degradation, leading to enlarged side leakage channels or the generation of new interlayer defects. This results in significant differences in leakage characteristics at low temperatures compared to room temperature. Existing technologies cannot accurately reflect the sealing reliability under actual service conditions, nor can they capture the leakage patterns caused by interlayer damage.

[0004] Therefore, there is an urgent need to develop a method and device for detecting leakage behavior in composite materials. This device should possess a zoned detection structure, be able to accurately locate leakage damage in different areas (main load-bearing surface and side surfaces) of composite material samples through simple valve control, be able to distinguish between high-pressure penetration damage on the main load-bearing surface and interlaminar performance degradation damage on the side surfaces, be able to simulate a wide temperature range environment (with a focus on extreme low temperatures), be easy to operate, have an intuitive detection logic, and be suitable for engineering-scale batch screening. This is of significant scientific and engineering value for clarifying the damage mechanisms in different areas of composite materials, carrying out targeted performance improvement and repair work, and evaluating the sealing reliability of composite material structures under real service environments. It is also an urgent need in the current field of composite material performance evaluation. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for detecting leakage behavior of carbon fiber composite materials in a partitioned manner, so as to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A partitioned carbon fiber composite material leakage behavior detection device includes: an integrated sealed vacuum chamber, two independent detection zones (first detection zone and second detection zone), a fixture assembly, a vacuum pumping unit, a pressure regulating unit, a control valve, a helium mass spectrometry detection unit, a temperature control module, and a temperature sensor; the structure and connection relationship of each component are as follows:

[0008] Integrated sealed vacuum chamber: It has a sealed structure and is internally divided into a first detection zone and a second detection zone that are independent and do not communicate with each other, with no gas exchange and eliminating detection interference;

[0009] Testing zones: The first testing zone corresponds to the main bearing surface of the circular composite material sample and adopts an upper-lower double-clamping sealing structure to ensure that the main bearing surface of the sample is only connected to the first testing zone; the second testing zone corresponds to the side of the sample and adopts an annular sealing structure to ensure that the side of the sample is only connected to the second testing zone.

[0010] Fixture assembly: Used to clamp and seal the disc-shaped sample to be tested, achieving partitioned sealing and isolation between the sample and the two testing areas, ensuring reliable sealing;

[0011] Vacuum pumping unit and pressure regulation unit: Each of the two detection zones is equipped with an independent vacuum pumping unit and pressure regulation unit, which provide and maintain a stable high vacuum and target test pressure for the corresponding detection zone;

[0012] Control valves: Independent control valves are installed on each branch pipeline to control the connection / disconnection between the first detection zone, the second detection zone and the helium mass spectrometer detection unit. The valves can be manual or automatic.

[0013] Helium mass spectrometry detection unit: This is a high-precision helium mass spectrometer with a detection accuracy of up to 10^-9 Pa・m³ / s. Two detection areas share one unit, which is used to capture weak leakage signals, continuously monitor and record changes in readings.

[0014] Temperature control module and temperature sensor: The two detection areas share a set of temperature control modules. Each detection area is equipped with a temperature sensor. The temperature control module can adjust the low temperature environment by introducing liquid nitrogen to achieve a wide temperature range environment simulation from 90K (-183℃) to room temperature, with temperature fluctuations not exceeding ±2K, accurately monitoring and controlling the test environment temperature.

[0015] The sealing structure of this device is adapted to a wide temperature range: fluororubber or silicone rubber sealing rings are selected at room temperature, and indium rings are selected at low temperature to ensure sealing reliability at different temperatures and avoid leakage from interfering with the test results.

[0016] A method for detecting leakage behavior of carbon fiber composite materials in a partitioned manner:

[0017] Based on the above-described apparatus, the detection method of the present invention includes the following steps:

[0018] Installation and Sealing: The circular carbon fiber / composite material sample to be tested is clamped in the preset position of the integrated sealed vacuum chamber using the clamping assembly. The main bearing surface of the sample is isolated from the first detection area by the upper-lower double clamping sealing structure, and the side of the sample is isolated from the second detection area by the annular sealing structure. The control valves of the two detection areas are closed, and the two detection areas are initially evacuated. The vacuum degree is observed to be stable. If the vacuum degree does not drop significantly, the seal is considered qualified. Otherwise, the seal is checked and resealed.

[0019] Establish initial state: Open the control valves of the two detection zones to connect both detection zones to the helium mass spectrometry detection unit, start the vacuum pumping unit to simultaneously evacuate the two detection zones and maintain a stable high vacuum (preferably around -0.01 MPa); simultaneously fill the two detection zones with dry helium as the detection gas, and maintain the pressure in the detection zones at the target test pressure of 0.001 MPa to 1.5 MPa through the pressure regulating unit to form a driving pressure difference between the sample and the detection zone;

[0020] Wide temperature range monitoring: According to the test requirements, the temperature control module is activated to cool and stabilize the test environment at the target temperature between 90K and room temperature, and the temperature sensor monitors the temperature in real time; the helium mass spectrometry detection unit is activated to continuously monitor and record the changes in readings over time;

[0021] Positioning and Differentiation: If the reading of the helium mass spectrometer detection unit does not rise significantly, it is determined that there is no leakage in the sample; if the reading continues to rise, close the control valve of the first detection zone and observe the change in reading:

[0022] The reading dropped after the switch was turned off, indicating that the sample's main bearing surface had high-pressure penetrating damage and leakage.

[0023] If the reading continues to rise after the switch is closed, it is determined that the leakage is caused by the degradation of the interlayer properties on the side of the sample.

[0024] Optional verification steps: Close the control valve of the second detection zone, open the control valve of the first detection zone, and repeat the above observation steps to further verify the leakage area and damage type.

[0025] Furthermore, this method can also establish a quantitative relationship between the rate of change or amplitude of the helium mass spectrometer detection unit reading and the standard leak rate through a calibration procedure, thereby achieving a quantitative or semi-quantitative assessment of the sample leakage rate.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This invention employs a minimalist design of "dual detection zones + independent valves." The two detection zones correspond to the main load-bearing surface and the side surface of the sample, respectively. Considering the layered structure characteristics of composite materials (low interlayer bonding strength and susceptibility to interlayer performance degradation on the side surface), once leakage is detected, simply closing the control valves in the corresponding areas and observing the changes in the helium mass spectrometer readings allows for rapid and accurate determination of the leakage location. This distinguishes between high-pressure penetrating damage to the main load-bearing surface and damage caused by interlayer performance degradation on the side surface. It eliminates the need for complex sealing and shielding mechanisms, offering convenient operation and accurate positioning. This completely solves the problems of existing technologies that can only detect leakage but cannot locate the leakage area or differentiate the damage type, providing a precise basis for targeted performance improvement and repair of composite materials.

[0028] By adapting to a wide temperature range (focusing on extreme low temperatures), it closely matches real-world service conditions, filling the gap in low-temperature leak location. Overcoming the limitations of traditional leak detection methods, which are mostly conducted at room temperature, it enables direct testing in extreme low-temperature environments down to 90K, accurately capturing changes in leakage characteristics in different areas of the sample under low-temperature conditions (such as the expansion of leakage channels and the increase in leakage rate caused by low temperatures). At the same time, it can achieve precise location of leakage areas at low temperatures, which can more realistically reflect the sealing reliability of composite materials in actual low-temperature service environments. This is crucial for high-end equipment fields such as aerospace cryogenic storage tanks and superconducting magnet containers, where existing technologies cannot achieve precise location of leakage areas at low temperatures.

[0029] The dual-zone independent controllability is suitable for batch testing and differentiated testing. The two testing zones are independently sealed and can operate independently or work together, enabling batch synchronous testing of multiple samples, which greatly improves testing efficiency and meets the needs of engineering batch screening. At the same time, each zone is equipped with independent pressure regulation and valve control units, which can flexibly adjust the test parameters according to the testing needs of different zones to achieve differentiated testing and adapt to the testing of disc-shaped samples of different specifications and service conditions.

[0030] With its simple structure, controllable cost, and ease of engineering application, this device abandons complex sealing and shielding mechanisms and adopts a minimalist design of "dual detection zones + independent valves." Based on the direct physical principle of "differential pressure drive - signal monitoring - valve positioning," the detection logic is clear. The device has a simple and reliable structure, low manufacturing cost, and requires no complex precision components. It is easy to operate and maintain, significantly reducing detection costs compared to existing complex detection equipment. At the same time, it is suitable for batch detection needs in production lines and has extremely high engineering application value.

[0031] It boasts high sealing reliability and outstanding detection accuracy. Optimized sealing structure and materials are designed for wide-temperature-range detection needs. Fluororubber / silicone rubber sealing rings are used at room temperature, while indium rings are used at low temperatures, ensuring sealing reliability at different temperatures and preventing leakage from interfering with detection results and positioning accuracy. Furthermore, by pre-evacuating to high vacuum or low background pressure, combined with a high-sensitivity helium mass spectrometer, the signal-to-noise ratio for detecting weak leakage signals is greatly improved. After calibration, it can achieve a leap from qualitative judgment and precise positioning to quantitative assessment, with detection accuracy far exceeding existing conventional methods.

[0032] This invention effectively fills the gaps in existing technologies regarding low-temperature leakage detection, precise leakage area location, and damage mode differentiation. Focusing on the core scientific issue of interlaminar damage in composite materials, it clarifies the leakage differences between high-pressure penetration damage on the main load-bearing surface and interlaminar performance degradation damage on the sides. It provides a low-cost, high-efficiency, high-reliability, and refined method for evaluating the sealing performance of composite materials, adapting to the testing needs of composite materials. Its core value lies in its ability to differentiate between different regions and types of damage, providing targeted directions for improving the performance of composite materials (such as optimizing interlaminar bonding strength to improve side leakage and strengthening intralaminar strength to resist high-pressure penetration damage). This is of great significance for ensuring the service safety of high-end composite material structures in harsh environments and promoting the optimization and upgrading of composite material performance, and has broad application prospects in aerospace, new energy equipment, and rail transportation. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0035] Figure 2 This is a side view of the entire invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] To overcome the shortcomings of existing composite material leakage detection technologies, such as difficulty in simulating low-temperature conditions, complex equipment, low efficiency, inability to accurately locate leakage damage in different areas of composite material samples, and inability to distinguish different damage forms, this invention provides a partitioned carbon fiber / composite material leakage behavior detection method and device.

[0038] The core scientific issue lies in the layered structure of composite materials, where the interlayer bonding strength is far lower than the intralayer strength. The damage mechanisms in different regions differ fundamentally: the main load-bearing surface is susceptible to penetrating damage under high pressure, while the side surfaces are prone to non-penetrating leakage channels due to interlayer performance degradation (such as delamination and cracking caused by low temperatures and cyclic loading), unlike the penetrating damage under normal conditions. These two damage forms have drastically different impacts on the composite material's performance and require different repair methods. The core design of this invention involves constructing a vacuum testing chamber (containing two independent testing zones, corresponding to the main load-bearing surface and the side surfaces of the sample, respectively). Each zone is independently connected to the testing chamber, control valves, and a helium mass spectrometry unit. This allows for leakage detection across a wide temperature range, from room temperature to extremely low temperatures (90K), focusing on the composite material sample.

[0039] The core innovation lies in this: after detecting a leak, by closing the control valves in the corresponding areas and observing the changes in the helium mass spectrometer readings, it is possible to clearly determine which area of ​​the sample the leak occurred in, and thus distinguish whether the damage was caused by high-pressure penetration damage on the main load-bearing surface or by interlaminar performance degradation on the side. This solves the problem that existing technologies cannot accurately locate leak damage or distinguish the damage type, providing data support for targeted improvement of composite material performance, and is also suitable for engineering-scale batch screening scenarios.

[0040] See Figure 1 and Figure 2 The present invention discloses a partitioned method and apparatus for detecting leakage behavior of carbon fiber / composite materials. The core of this method lies in the partitioned structure of a "large integrated vacuum detection chamber (including a first detection zone and a second detection zone)". The two detection zones correspond to the main bearing surface and side surface of the sample, respectively, and are independently connected to a vacuum pumping unit, a pressure regulating unit, a control valve, and a helium mass spectrometry detection unit. Through partitioned vacuum pumping, pressurization, and signal monitoring, combined with a "valve closure - reading observation" positioning logic, targeted detection and precise positioning of leakage behavior in different areas of the circular sample are achieved. The specific steps are as follows:

[0041] Overall Description of the Detection Device: The core of the detection device of this invention is a large-scale integrated vacuum detection chamber with a sealed structure. The interior is divided into two independent detection zones (a first detection zone and a second detection zone), each corresponding to a key area of ​​the circular sample. The device is simple in structure and easy to operate, requiring no complex shielding mechanisms. The specific structure and connection relationships are as follows:

[0042] First testing area: Specifically designed for the main bearing surface (circular surface) of the disc-shaped sample, used to detect leakage behavior of the main bearing surface of the sample; adopting an "upper-lower double clamping seal" structure, the main bearing surface of the sample is sealed in this testing area, ensuring that the main bearing surface of the sample is only connected to the first testing area, simulating the pressure leakage scenario of the main bearing surface during actual service of the sample, and can quickly screen the sealing integrity of the main bearing surface.

[0043] The second testing area is specifically designed for the side of the circular sample and is used to detect leakage behavior on the side of the sample. It adopts a "ring seal" structure to seal the side of the sample within this testing area, ensuring that the side of the sample is only connected to the second testing area, simulating the service leakage scenario of the side of the sample.

[0044] Connection Relationship: The two detection zones are independent and not interconnected. Each zone is equipped with its own independent vacuum unit, pressure regulation unit, and manual / automatic control valves. The two detection zones share a single high-sensitivity helium mass spectrometry detection unit (or each zone has its own independent detection unit). The helium mass spectrometry detection unit is connected to the two detection zones via branch pipelines, each equipped with control valves to independently control the connection / disconnection between the two detection zones and the helium mass spectrometry detection unit. Both detection zones are equipped with temperature sensors and share a single temperature control module (e.g., liquid nitrogen), enabling independent simulation of a wide temperature range (90 K to room temperature).

[0045] Sealing structure: All cavities are sealed with a wide temperature range-adaptive sealing structure. Fluororubber or silicone rubber sealing rings are used at room temperature, and indium rings are used at low temperature to ensure sealing reliability at different temperatures and avoid leakage from interfering with test results. At the same time, it ensures that the main bearing surface of the sample is only connected to the first test area and the side is only connected to the second test area, preventing gas exchange between the two areas and providing a basis for subsequent leakage location.

[0046] Specific testing steps: Install the circular composite material sample to be tested in the preset position of the vacuum testing chamber, complete the double sealing, and ensure the zone isolation effect. The specific operation is as follows:

[0047] The main bearing surface of the sample is sealed in the first detection area through an upper-lower double clamping sealing structure, ensuring that the main bearing surface of the sample is tightly fitted and completely connected to the cavity of the first detection area, and that there is no leakage at the seal between the edge of the sample and the first detection area, thus preventing the gas in the first detection area from communicating with the outside or the second detection area.

[0048] The side of the sample is sealed in the second detection zone through an annular sealing structure, ensuring that the side of the sample is tightly fitted and completely connected to the cavity of the second detection zone, and that there is no leakage at the seal, thus preventing the gas in the second detection zone from communicating with the outside or the first detection zone.

[0049] Check the reliability of the seal: Close the control valves of the two detection zones, perform preliminary vacuuming on the two detection zones respectively, and observe whether the vacuum degree is stable. If the vacuum degree does not drop significantly, it means that the seal is qualified and you can proceed to the next step of the test; if the vacuum degree drops, check the seal and reseal it.

[0050] System initial setup: Open the control valves of the two detection zones to connect both zones to the helium mass spectrometry detection unit. Simultaneously, start the vacuum pumping units of both detection zones to evacuate them synchronously, achieving and maintaining a stable high vacuum (preferably around -0.01 MPa). This ensures that the background gas concentration in both detection zones is at an extremely low level, significantly improving the signal-to-noise ratio of weak leakage signals and preventing background gas from interfering with the detection results.

[0051] Subsequently, according to the test requirements (simulating the actual service pressure of the sample), a specific detection gas (preferably helium, as helium molecules have a small diameter and strong permeability, which can effectively detect tiny leakage channels and greatly improve detection sensitivity) is synchronously introduced into the two detection zones. The pressure of the two detection zones is then adjusted by the pressure regulating unit to maintain it between 0.001 MPa and 1.5 MPa (which can be flexibly adjusted according to the actual service pressure conditions of the material). If the "differential pressure drive" mode is adopted, the two detection zones can maintain a stable pressure higher than that of the external reference chamber, forming a controllable pressure difference, which provides a stable driving force for the gas to pass through the leakage channel of the sample, simulating the pressure leakage scenario during actual service.

[0052] Wide-temperature-range leakage detection and signal monitoring: According to the test requirements, the temperature control module is activated to adjust the test environment temperature: If it is room temperature test, there is no need to activate the temperature control module, just maintain the room temperature (25 ℃); if it is low temperature test (focusing on extreme low temperature), liquid nitrogen is introduced into the test chamber, and the temperature is monitored in real time by the temperature sensor to cool and stabilize the test environment and sample temperature at the target low temperature (any temperature in the range of 90 K to room temperature, focusing on adapting to extreme low temperature conditions such as liquid oxygen 90 K and liquid nitrogen 77 K), ensuring that the temperature fluctuation does not exceed ±2 K, simulating the real low temperature service environment.

[0053] After the temperature stabilizes, the helium mass spectrometry detection unit is activated to continuously monitor the reading changes of the helium mass spectrometer, and the reading-time curve is recorded to determine whether there is any leakage in the sample.

[0054] If the helium mass spectrometer reading remains at an extremely low background level without a significant increase, it indicates that the sample is leak-free and the sealing performance of the main bearing surface and the side is qualified, and the test is completed. If the helium mass spectrometer reading shows a significant increase and continues to rise, it indicates that the sample is leaking, but at this time it is impossible to determine whether the leak is occurring on the main bearing surface or the side, and the next step of precise leak area location should be performed.

[0055] Precise Leakage Location: This step utilizes the simple logic of "closing the corresponding valve and observing the changes in the helium mass spectrometer reading" to quickly and accurately locate the leakage damage area. The operation is convenient and requires no complex structure. The specific steps are as follows:

[0056] Step 1: Close the control valve of the first detection zone to disconnect the connection between the first detection zone and the helium mass spectrometer detection unit, leaving only the connection between the second detection zone and the helium mass spectrometer detection unit, and continuously observe the changes in the readings of the helium mass spectrometer.

[0057] Judgment Logic 1: If, after closing the valve in the first detection zone, the helium mass spectrometer reading rapidly decreases and returns to the background level, and remains stable, it indicates that leakage occurs on the main bearing surface of the sample. Because closing the valve in the first detection zone cuts off the leakage channel on the main bearing surface, no helium enters the detection unit, hence the decrease in reading.

[0058] Judgment Logic 2: If the helium mass spectrometer reading continues to rise without a significant decrease after the valve in the first detection zone is closed, it indicates that leakage is occurring on the side of the sample. Because the second detection zone remains connected to the detection unit, the leakage channel on the side is not cut off, and helium continues to enter the detection unit, hence the reading continues to rise.

[0059] Step 2 (Verification, optional): Close the control valve of the second detection zone, open the control valve of the first detection zone, and repeat the above observation steps to further verify the leakage area: if the reading decreases, it indicates that the leakage is on the side; if the reading increases, it indicates that the leakage is on the main bearing surface, ensuring that the positioning results are accurate.

[0060] Key parameter optimization: Detection gas: Helium is preferred. Helium molecules have small diameters and strong permeability, which can effectively detect tiny leakage channels, greatly improve detection sensitivity, and meet the needs of accurate detection and location of tiny leaks in samples.

[0061] Pressure range: The pressure adjustment range of both detection zones is 0.001 MPa to 1.5 MPa, which can be flexibly adjusted according to the actual service pressure conditions of the disc-shaped composite material to accurately simulate real service conditions.

[0062] Detection accuracy: A helium mass spectrometer with fast response capability is selected, and the detection accuracy can reach 10^-9 Pa·m³ / s. It can capture weak leakage signals in different regions of the sample within a wide temperature range, ensuring detection accuracy and positioning accuracy.

[0063] Sealing material: The sealing ring must be able to maintain its elasticity and sealing performance within the target test temperature range (e.g., room temperature to 90K). Fluororubber or silicone rubber is preferred at room temperature. Indium rings are used at low temperatures to solve the problem of embrittlement and sealing failure of conventional sealing materials at low temperatures, ensuring sealing reliability over a wide temperature range and providing a basis for zoned positioning.

[0064] Temperature range: Through the temperature control module, it can achieve a wide temperature range detection from 90 K (-183 ℃) to room temperature, which is mainly suitable for extreme low temperature service scenarios. It can accurately capture the differences in leakage characteristics of different areas of the sample at different temperatures, filling the gap in the existing technology that cannot accurately locate leakage areas at low temperatures.

[0065] Example 1:

[0066] The scenario set in this embodiment is as follows: leakage reference test of circular disc sample, dual-region collaboration, room temperature conditions.

[0067] 1. Prepare a T700 grade carbon fiber / epoxy resin composite disc plate with a diameter of 94 mm and a thickness of 2 mm as a test sample. After preliminary inspection by appearance and ultrasonic C-scan, it is confirmed that there are no obvious macroscopic defects in the sample. The focus is on verifying that there is no leakage on the main load-bearing surface and the side of the sample, and at the same time verifying the background stability of the detection system.

[0068] 2. Install the test sample in the preset position of the integrated vacuum testing chamber and complete the sealing: seal the main bearing surface of the sample to the first testing area through the upper-lower double clamping sealing structure, and seal the side of the sample to the second testing area through the annular sealing structure; close the control valves of the two testing areas, evacuate the two testing areas respectively, observe the vacuum degree stability, and confirm that the sealing is qualified.

[0069] 3. Open the control valves of the two detection zones to connect both detection zones to the helium mass spectrometry detection unit; start the vacuum pumping unit of the two detection zones, pump the vacuum to -0.01 MPa and stabilize it, then close the vacuum pump connection valve to maintain a stable background vacuum.

[0070] 4. Simultaneously fill the two detection zones with dry helium gas, adjust the pressure to stabilize at 0.5 MPa (gauge pressure), simulate the actual service pressure of the sample, and form a stable pressure difference.

[0071] 5. Maintain room temperature (25 ℃), start the helium mass spectrometry detection unit, continuously monitor the reading changes of the helium mass spectrometer, and continue testing for 30 minutes.

[0072] 6. Test results: The readings of the helium mass spectrometer remained at the background level (without significant increase), indicating that there was no leakage on the main bearing surface and sides of the sample, and the sealing performance was qualified; at the same time, it verified the background stability of the detection system and provided benchmark data for subsequent leakage detection and location.

[0073] Example 2:

[0074] The scenario set in this embodiment is: leakage detection and location of the main bearing surface of a circular sample, under room temperature conditions.

[0075] 1. Prepare a T700 grade carbon fiber / epoxy resin composite disc of the same specifications as in the example. Use a laser to pre-fabricate a through-hole with a diameter of 100 μm on the main bearing surface (circular surface) of the sample (simulating a leakage channel due to damage to the main bearing surface). Keep the sides free of defects. This is used to test the ability of the present invention to detect and locate leakage on the main bearing surface.

[0076] 2. Repeat steps 2-4 in Example 1 to complete the sample installation, sealing, vacuuming, and pressurization operations (both detection zone valves are opened and connected to the helium mass spectrometry detection unit).

[0077] 3. Start the helium mass spectrometry detection unit and continuously monitor at room temperature. If the reading of the helium mass spectrometer rises rapidly, it indicates that there is leakage in the sample. However, the leakage area cannot be determined at this time. Proceed to the localization step.

[0078] 4. Leakage Location: First, close the control valve of the first detection area (severing the connection between the main load-bearing surface detection area and the helium mass spectrometer detection unit), leaving only the second detection area (side) connected to the detection unit, and continue observation. It was observed that the helium mass spectrometer reading rapidly decreased, then recovered to the background level and remained stable within 10 minutes. Second, close the control valve of the second detection area and open the control valve of the first detection area. The helium mass spectrometer reading was observed to rise again, further verifying the location result.

[0079] 5. Detection Results: Based on the change in readings after valve closure, leakage was determined to occur on the main load-bearing surface of the sample. Continuous monitoring of the reading change curve for leakage on the main load-bearing surface, after calibration, allows for quantitative assessment of the leakage rate. These results demonstrate that this invention can rapidly detect leakage on the main load-bearing surface, and through a simple valve closure and reading observation operation, the leakage area can be accurately located, making the operation convenient and the location accurate.

[0080] Example 3:

[0081] The scenario set in this embodiment is: side leakage detection and location of a circular sample, under room temperature conditions.

[0082] 1. Prepare a T700 grade carbon fiber / epoxy resin composite disc of the same specifications as in Example 1. Simulate leakage channels caused by interlaminar performance degradation on the side (rather than penetrating microcracks) by interlaminar peeling treatment. Keep the main bearing surface free of defects. This is used to test the ability of the present invention to detect and locate leakage caused by interlaminar performance degradation on the side, and to fit the damage characteristics of the composite material layered structure.

[0083] 2. Repeat steps 2-4 in Example 1 to complete the sample installation, sealing, vacuuming, and pressurization operations (both detection zone valves are opened and connected to the helium mass spectrometry detection unit).

[0084] 3. Start the helium mass spectrometry detection unit and monitor continuously at room temperature. If the reading of the helium mass spectrometer rises rapidly, it indicates that there is leakage in the sample, and proceed to the positioning step.

[0085] 4. Leakage Location: First, close the control valve of the first detection zone, leaving only the second detection zone connected to the detection unit, and continue observation; it was found that the helium mass spectrometer reading continued to rise without a significant decrease. Second, close the control valve of the second detection zone and open the control valve of the first detection zone. It was observed that the helium mass spectrometer reading rapidly dropped to the background level, further verifying the location result.

[0086] 5. Detection Results: Based on the change in readings after the valve was closed, it was determined that the leakage occurred on the side of the sample; by continuously monitoring the reading change curve of the side leakage and after calibration, the leakage rate can be quantitatively assessed. These results demonstrate that the present invention can quickly detect side leakage, and its positioning logic is reliable and easy to operate, completely solving the problem of existing technologies being unable to locate leakage areas.

[0087] Example 4:

[0088] The scenario set in this embodiment is: leakage detection and location in a low-temperature environment, under extreme low-temperature conditions.

[0089] 1. Prepare two test samples: Sample 1 (the main bearing surface contains high-pressure penetrating microporous leakage channels, the same as in Example 2) and Sample 2 (the side contains leakage channels caused by interlaminar performance degradation, the same as in Example 3). These samples are used to simulate leakage detection and location in different areas and with different damage forms of composite materials under extreme low temperature conditions, to verify the wide temperature range adaptability, and to capture the leakage change pattern caused by the aggravation of interlaminar performance degradation at low temperatures.

[0090] 2. Install the two samples into the two detection devices respectively (or test them in batches on the same device), complete the sealing, vacuuming, and pressurization operations (pressure 0.5 MPa helium, vacuum degree -0.01 MPa), and open the control valve of the corresponding detection area to connect the detection area with the helium mass spectrometry detection unit.

[0091] 3. Activate the temperature control module, introduce liquid nitrogen into the detection chamber, adjust the liquid nitrogen flow rate, cool and stabilize the detection environment temperature at 90 K (-183 ℃, simulating liquid oxygen service conditions), and monitor the temperature in real time with the temperature sensor to ensure temperature stability.

[0092] 4. Start the helium mass spectrometry detection unit. If the readings of the detection devices for both samples show a significant increase, it indicates that there is leakage in both samples. Proceed to the localization step.

[0093] 5. Leakage Location: For sample 1 (leakage due to high-pressure penetration damage on the main load-bearing surface), closing the valve in the first detection zone caused the reading to drop rapidly. For sample 2 (leakage due to interlaminar performance degradation damage on the side), closing the valve in the first detection zone caused the reading to continue to rise. Closing the valve in the second detection zone caused the reading to drop, and the location results were consistent with those obtained at room temperature. This is highly consistent with the pattern of resin matrix shrinkage, further reduction in interlaminar bond strength, and accelerated interlaminar performance degradation under low-temperature conditions, further verifying the invention's ability to distinguish different damage forms and its low-temperature adaptability.

[0094] 6. Test Results: This invention can accurately detect leakage of samples even in extreme low-temperature environments, and precisely locate the leakage area through valve control. At the same time, it can capture the differences in leakage characteristics in different areas at low temperatures, verifying the wide temperature range adaptability and positioning reliability. It fills the gap in the existing technology that cannot accurately locate the leakage area at low temperatures, and can provide direct experimental data for the sealing reliability assessment of low-temperature service composite materials.

[0095] In summary:

[0096] This invention achieves accurate detection, location, and differentiation of damage patterns of leakage behavior in different areas of carbon fiber / composite materials by designing a simple structure of "integrated vacuum detection chamber + dual independent detection zones + independent valve control".

[0097] The core of the detection device of this invention is an integrated sealed vacuum chamber, internally divided into two independent detection zones, corresponding to the main bearing surface and side surface of the circular sample, respectively, to detect its leakage behavior. Both detection zones are equipped with independent vacuum pumping units, pressure regulating units, and control valves, sharing a high-sensitivity helium mass spectrometry detection unit. The connection / disconnection between the detection zone and the helium mass spectrometry unit is controlled via branch pipelines and valves. A temperature control module and temperature sensor are also included, enabling simulation of a wide temperature range from 90K (-183℃) to room temperature. The sealing structure is adapted to the wide temperature range requirements; fluororubber or silicone rubber sealing rings are used at room temperature, while indium rings are used at low temperatures, ensuring reliable sealing of each zone and preventing gas exchange from interfering with the detection results. During detection, the sample is installed and double-sealed. Both detection zones are simultaneously evacuated to a stable high vacuum (preferably around -0.01MPa), then simultaneously filled with helium and adjusted to the target pressure (0.001MPa to 1.5MPa). The detection temperature is adjusted as needed (room temperature or extreme low temperatures down to 90K). The helium mass spectrometer detection unit is activated to monitor the reading changes. If the reading does not rise significantly, it is determined that there is no leakage. If the reading rises, the leakage area is accurately located by closing the control valves of the corresponding detection areas and observing the reading changes: if the reading drops after closing the valve of the first detection area, it indicates high-pressure penetration damage leakage on the main bearing surface; if the reading continues to rise, it indicates leakage caused by interlayer performance degradation on the side, thus clearly distinguishing between the two types of damage.

[0098] This invention effectively solves the problems of existing technologies, such as the inability to accurately locate leakage areas, distinguish different damage forms, and adapt to low-temperature service conditions. Focusing on the core scientific issue of interlaminar damage in composite materials, it provides targeted data support for improving composite material performance. The detection method and device are simple in structure, easy to operate, highly accurate (helium mass spectrometry detection accuracy can reach 10^-9 Pa·m³ / s), and cost-effective. Requiring no complex signal processing, it can be widely applied to leakage screening, performance evaluation, and damage localization of carbon fiber / composite material structural components in aerospace, new energy equipment, and rail transportation fields. It is particularly suitable for engineering-scale batch testing scenarios, ensuring the service reliability of composite material structures in harsh environments.

[0099] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A zoned carbon fiber composite material leakage behavior detection device, characterized in that: It includes an integrated sealed vacuum chamber, clamping assembly, vacuum pumping unit, pressure regulating unit, control valve, helium mass spectrometry detection unit, temperature control module, and temperature sensor; The integrated sealed vacuum chamber has a sealed structure and is internally divided into two independent detection zones that are independent of each other and do not communicate with each other, with no gas exchange and eliminating detection interference. The inner side of the integrated sealed vacuum cavity is provided with a clamping assembly, which is used to clamp and seal the disc-shaped sample to be tested, so as to realize the partitioned sealing isolation between the sample and the two detection areas and ensure the reliability of the seal. The two independent detection zones are each equipped with an independent vacuuming unit and a pressure regulating unit; The vacuum pumping unit and the pressure regulating unit respectively provide and maintain a stable high vacuum and target test pressure for the corresponding detection area; The control valves are installed on the branch pipelines and control the connection and disconnection between the two independent detection zones and the helium mass spectrometry detection unit, respectively. The control valves can be manually controlled or automatically controlled. The helium mass spectrometry detection unit is a high-precision helium mass spectrometer. Two independent detection zones share one unit, which is used to capture weak leakage signals and continuously monitor and record changes in readings. The temperature control module and temperature sensor are used in two independent detection zones.

2. The partitioned carbon fiber composite material leakage behavior detection device according to claim 1, characterized in that: The two independent detection zones are the first detection zone and the second detection zone; The first testing area corresponds to the main bearing surface of the circular composite material sample. It adopts an upper-lower double-clamping sealing structure to ensure that the main bearing surface of the sample is only connected to the first testing area. The second detection zone corresponds to the side of the sample and adopts an annular sealing structure to ensure that the side of the sample is only connected to the second detection zone.

3. The partitioned carbon fiber composite material leakage behavior detection device according to claim 1, characterized in that: The temperature control module regulates the low-temperature environment by introducing liquid nitrogen, with temperature fluctuations not exceeding ±2K, thus achieving wide-temperature-range environment simulation.

4. The partitioned carbon fiber composite material leakage behavior detection device according to claim 1, characterized in that: The detection device is used to detect dry helium. The two independent detection zones are in the test pressure range of 0.001 MPa to 1.5 MPa, which can be flexibly adjusted according to the actual service pressure of the sample.

5. The partitioned carbon fiber composite material leakage behavior detection device according to claim 1, characterized in that: The helium mass spectrometry detection unit is a high-precision helium mass spectrometer with a detection accuracy of up to 10^-9 Pa·m³ / s, which can capture weak leakage signals.

6. The partitioned carbon fiber composite material leakage behavior detection device according to claim 1, characterized in that: The detection device also includes a sealing ring for sealing. The sealing ring material is adapted to a wide temperature range. At room temperature, the sealing ring material is selected as fluororubber or silicone rubber, and at low temperature, the sealing ring is an indium ring, to ensure the sealing reliability at different temperatures.

7. A method for detecting the leakage behavior of a partitioned carbon fiber composite material, used in the partitioned carbon fiber composite material leakage behavior detection device according to any one of claims 1-6, characterized in that: Includes the following steps: S1: Installation and sealing: The circular carbon fiber / composite material sample to be tested is sealed and clamped in the preset position, so that the main bearing surface of the sample is sealed and isolated from the first detection area through the "upper-lower double clamping seal" structure, and the side of the sample is sealed and isolated from the second detection area through the "ring seal" structure, ensuring that the two detection areas are independent of each other, do not communicate with each other, and that there is no leakage between the detection area and the outside world. S2: Establish the initial state, close the control valves of the two detection zones, and perform preliminary vacuuming on the two detection zones to verify the sealing reliability; after the sealing is qualified, open the control valves to connect both detection zones to the helium mass spectrometry detection unit, and simultaneously vacuum the two detection zones to achieve and maintain a stable high vacuum; simultaneously fill the two detection zones with detection gas, and maintain the target test pressure through the pressure regulating unit, thereby forming a driving pressure difference between the sample and the detection zone; S3: Wide temperature range monitoring. According to the test requirements, the temperature control module is activated to cool and stabilize the test environment at the target temperature between -183℃ and room temperature, and the helium mass spectrometry detection unit is activated to continuously monitor and record the changes in readings over time. S4: Locating and Differentiating. If the reading of the helium mass spectrometer detection unit does not increase significantly, it is determined that the sample has no leakage. If the reading continues to rise, the leakage area is located and the damage type is differentiated by closing the control valves of the corresponding detection areas respectively and observing the changes in the readings. If the reading decreases after closing the valve of the first detection area, it is leakage caused by high-pressure penetration damage on the main bearing surface. If the reading still rises after closing the valve of the first detection area, it is leakage caused by the degradation of the interlayer performance on the side.

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