A method of autoclave molding

Abstract

This invention discloses a method for autoclave molding, comprising: based on the geometric features of the three-dimensional model of the component to be molded, dividing the component into stress-sensitive regions and conventional regions through finite element simulation analysis, establishing a thermo-mechanical coupled finite element analysis model for each region, and pre-setting differentiated temperature-pressure-time process curves; secondly, installing distributed fiber optic sensors inside the composite material preform and installing a micro pressure sensor array at key positions on the mold surface, wherein both the distributed fiber optic sensors and the micro pressure sensors are connected to a central control system; next, sequentially using closed-loop control to perform differentiated pressure and temperature control on each region; finally, the central control system collects sensor data in real time, determines whether the molding process is abnormal through a defect identification algorithm, automatically activates a graded early warning mechanism when an abnormality is detected, and executes an adaptive adjustment strategy, including inter-regional collaborative pressure compensation, to eliminate molding defects.

Description

Technical Field

[0001] This invention relates to the field of autoclave molding technology, and more specifically to an autoclave molding method. Background Technology

[0002] Autoclave molding technology is one of the key processes for manufacturing high-performance composite material components, and it is widely used in high-end equipment fields such as aerospace, wind power generation, and transportation. This technology applies a uniform high-temperature and high-pressure environment within a sealed autoclave to laminate and cure prepregs or preforms, ultimately forming composite material components with excellent mechanical properties.

[0003] Traditional autoclave molding processes typically employ experience-based fixed temperature-pressure-time curves and implement a uniform control strategy across the entire component. However, actual components often possess complex geometries (such as areas of varying thickness, abrupt curvature changes, and reinforcing ribs), leading to significant differences in resin flow behavior, curing reaction rates, and internal stress distribution across different regions during molding. These differences are particularly pronounced in stress concentration areas, easily causing defects such as uneven resin distribution, porosity, dry spots, and even delamination, severely impacting the final quality and service performance of the component.

[0004] While some existing technologies attempt to monitor local temperatures by placing thermocouples or other sensors outside the mold, or employ zoned heating techniques within the mold, they still fall short in terms of real-time sensing and dynamic control of the internal stress state of complex components. Firstly, traditional external temperature measurement struggles to accurately reflect the internal temperature field and curing process of components, especially in the thickness direction. Secondly, the lack of monitoring of internal stress and strain states during molding fails to provide precise data support for process adjustments. Thirdly, existing control strategies are mostly open-loop or simple single-point feedback closed-loop systems, making it difficult to achieve differentiated, adaptive, and precise control tailored to the characteristics of different regions.

[0005] Therefore, it is necessary to provide a hot autoclave molding method to solve the problems mentioned in the background art above. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for forming an autoclave, comprising: Step 1: Based on the geometric features of the three-dimensional model of the component to be formed, stress concentration parameters are analyzed through finite element simulation, and the component is divided into several stress-sensitive regions and normal regions. At the same time, a thermo-mechanical coupled finite element analysis model is established for each region, and different temperature-pressure-time process curves are preset based on the characteristics of each region to adapt to the forming requirements of different regions. Step 2: Distributed fiber optic sensors are installed inside the composite material preform, and a micro pressure sensor array is installed on the mold surface at key locations corresponding to the component; both the distributed fiber optic sensors and the micro pressure sensors are connected to the central control system through a data transmission module. Step 3: Following the sequence of preheating, heating and curing, pressure holding and curing, and cooling, a closed-loop control system is used to differentiate the pressure and temperature control for each zone. Step 4: The central control system collects data from the distributed fiber optic sensors and miniature pressure sensors in real time, and uses a built-in defect identification algorithm to determine whether there are any abnormalities in the component forming process. When an abnormality is detected, the central control system automatically activates a graded early warning mechanism and executes an adaptive adjustment strategy, including an inter-regional collaborative pressure compensation mechanism, to eliminate forming defects.

[0007] Preferably, the interval collaborative pressure compensation mechanism includes: When the actual pressure of a stress-sensitive area is detected to be lower than the preset target pressure threshold, and this state continues for a preset duration, the central control system first adjusts the pressure parameter of the stress-sensitive area at a preset rate, and at the same time increases the pressure setting value of at least one adjacent normal area; wherein the total pressure of the normal area after the increase does not exceed the pressure setting value of that area.

[0008] Preferably, in step three, the control methods for each process stage include: Preheating stage: The component is heated as a whole through the control terminal of the autoclave. During the heating process, the temperature of the stress-sensitive area is always higher than that of the normal area. When the temperature of the normal area reaches the preheating target temperature, the current temperature is maintained, and the molding environment is controlled simultaneously to carry out heat preservation and pressure preservation operations. The vacuum module is used to perform differentiated vacuuming of each area, and the air in each stress-sensitive area is removed first. Pressure curing stage: The pressure control module first brings the stress-sensitive area to the preset proportion of the target pressure for this stage and maintains it for the first holding time; then the pressure of each normal area is controlled to increase at the same rate to be consistent with that of the stress-sensitive area and is maintained for the second holding time, and then each area is controlled to increase at the same rate to the final target pressure for this stage; at the same time, the temperature control module raises the overall temperature of the component to within the temperature range of the pressure curing stage. Pressure holding and curing stage: The central control system dynamically adjusts the temperature difference between the two areas within a limited range based on feedback data from distributed fiber optic sensors and miniature pressure sensors, prioritizing the temperature of the stress-sensitive area; at the same time, the pressure control module ensures the stability of the molding environment pressure until the preform reaches the curing standard. Cooling stage: The temperature control module cools the stress-sensitive area and the normal area at a preset cooling rate, and the difference in cooling rate between the two areas remains constant; the central control system adjusts the molding environment pressure according to the component temperature drop ratio. After the component drops to the end temperature of the cooling stage, it switches to natural cooling. After the temperature stabilizes, the pressure control module reduces the pressure below the threshold to perform a pressure relief operation.

[0009] Preferably, the abnormal judgment criteria in the graded early warning mechanism are: if the strain value of any region exceeds the set proportion of the strain preset threshold, or if the deviation between the actual temperature of any region and the target temperature of the corresponding process stage exceeds the temperature deviation range, and the abnormal state continues for a preset duration, it is judged as a component forming abnormality.

[0010] Preferably, the deployment rule of the distributed optical fiber sensors is that the deployment density of distributed optical fiber sensors in the stress-sensitive area is greater than that in the conventional area; Within the stress-sensitive zone, the sensor spacing does not exceed the maximum spacing of sensors in the sensitive zone, and the sensors are densely deployed at locations with special geometric features of the components; within the normal zone, the spacing of the distributed fiber optic sensors is within the range of the sensor spacing in the normal zone.

[0011] Preferably, each of the distributed optical fiber sensors has a sensor protection structure at its end. The sensor protection structure is made of a high-temperature resistant material and is compatible with the pressure curing temperature range of each process stage. The coating of each of the distributed optical fiber sensors is made of a material that is compatible with the composite matrix and has high-temperature resistance.

[0012] Preferably, during the execution of the inter-regional collaborative pressure compensation mechanism, the duration of pressure increase in adjacent conventional areas does not exceed the upper limit of the compensation duration ratio of the total duration of the current process stage, and the pressure increase value of a single compensation does not exceed the upper limit of the single compensation pressure; if the pressure in the stress-sensitive area still does not reach the target pressure threshold after compensation, the central control system automatically switches to local pressure compensation mode, while extending the compensation duration to the extended compensation duration ratio of the total duration of the current process stage, and triggering a graded early warning mechanism for early warning.

[0013] Preferably, the adaptive adjustment strategy includes: Level 1 Response: When abnormal parameters exceed the Level 1 abnormal threshold range, the central control system automatically fine-tunes the process parameters of the corresponding area. The adjustment range of temperature and pressure is controlled within the Level 1 parameter adjustment range. After adjustment, the Level 1 monitoring duration is continuously monitored. If the parameters return to normal, the parameter change data is recorded. Level 2 Response: When abnormal parameters exceed the Level 2 abnormality threshold range, the central control system activates the inter-regional coordinated pressure compensation mechanism, while expanding the temperature and pressure adjustment range to within the Level 2 parameter adjustment range, and evaluates the adjustment effect according to the Level 2 evaluation cycle until the abnormality is completely eliminated; Level 3 Response: When abnormal parameters exceed the Level 3 abnormal threshold range, the central control system simultaneously triggers local pressure replenishment and inter-regional coordinated pressure compensation mechanisms, suspends the automatic increase of process parameters, and issues an alarm through multi-channel alarm methods.

[0014] Preferably, in step three, after the component is solidified, the distributed optical fiber sensors inside the preform are retained to form a permanent embedded sensor network that matches the molding method, used for real-time monitoring of the structural health of the component during its service life; the distributed optical fiber sensors of the permanent embedded sensor network are adapted to the service environment of the component.

[0015] Compared with the prior art, the present invention provides a method for forming an autoclave, which has the following advantages: 1. This invention analyzes the geometric features of the three-dimensional model of the component to be molded using finite element simulation, dividing the component into stress-sensitive and normal regions. Different temperature-pressure-time process curves are preset for each region. Specifically, during the preheating stage, the temperature of the sensitive region is always higher than that of the normal region, and differentiated vacuuming is used to prioritize the removal of air from the sensitive region. During the pressure curing stage, the pressure in the sensitive region first reaches 70% of the target pressure and is maintained, while the pressure in the normal region is simultaneously increased to ensure uniform resin penetration. During the pressure holding and curing stage, the temperature difference between regions is dynamically adjusted to prioritize temperature stability in the sensitive region. During the cooling stage, the temperature rate difference between regions is kept constant to avoid internal stress accumulation. This solves the problem of localized defects caused by overall uniform control in traditional autoclave molding.

[0016] 2. Distributed fiber optic sensors are deployed inside the composite material preform, and a miniature pressure sensor array is set at key locations on the mold surface. Both are connected to the central control system through a data transmission module, forming a full-dimensional real-time monitoring network, which avoids the problem that external monitoring cannot reflect the internal state in traditional autoclave molding.

[0017] 3. A closed-loop control system is employed to differentiate pressure and temperature control across different zones. Combined with a tiered early warning mechanism and adaptive adjustment strategy, dynamic optimization of the molding process is achieved, avoiding the limitations of traditional open-loop or simple feedback control and significantly improving process flexibility and defect response capabilities. Specifically, the central control system compares sensor data with preset process curves in real time. When an anomaly is detected, a tiered early warning system is automatically activated. When the pressure in a stress-sensitive zone falls below a threshold, the system adjusts the pressure in that zone at a preset rate while simultaneously increasing the pressure in adjacent normal zones. This pressure synergy suppresses abnormal resin flow, ensuring uniform curing across different areas of the component.

[0018] 4. After the component is cured and molded, the distributed fiber optic sensors inside the prefabricated body are retained to form a permanent embedded sensor network for real-time structural health monitoring during the component's service life, realizing the transformation from "planned maintenance" to "predictive maintenance". Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process structure of a hot autoclave molding method. Detailed Implementation

[0020] In aerospace, high-end equipment manufacturing, and other fields, composite material components (such as aircraft wing skin and engine nacelle components) have extremely high requirements for molding precision, internal defect control, and long-term service safety. Traditional autoclave molding technology uses a uniform process curve, which is difficult to adapt to the stress differences in different areas of the component (such as corners and areas with abrupt changes in thickness). This can easily lead to defects such as bubbles, delamination, and cracking in stress-sensitive areas, and it is impossible to achieve real-time intervention for abnormalities in the molding process and health monitoring during service life.

[0021] The autoclave molding method of this invention takes regional differentiated control as its core. It identifies stress-sensitive areas and normal areas of the component in advance through finite element simulation and presets process parameters accordingly. It uses distributed fiber optic sensors and miniature pressure sensors to build a full-dimensional data acquisition network to capture temperature, pressure and strain changes in real time during the molding process. It realizes closed-loop control of process execution, data feedback, anomaly judgment and adaptive adjustment through a central control system. While eliminating molding defects, it retains the embedded sensor network to realize the health monitoring of the component throughout its entire life cycle.

[0022] For details, please refer to Figure 1 The present invention provides a method for forming an autoclave, comprising: Step 1: Simulation Modeling and Process Curve Preset: High-precision 3D models of the components to be manufactured (such as epoxy-based composite wing reinforcing ribs for aerospace) are obtained using 3D design software (such as CATIA V5 and SolidWorks), with a model dimensional error of less than 0.05 mm. The 3D model of the component is then imported into finite element simulation software (such as ANSYS), and composite material parameters, such as the material's elastic modulus, Poisson's ratio, and coefficient of thermal expansion, are set. Subsequently, a thermo-mechanical coupled stress analysis is performed. Areas where the stress concentration factor of the component is greater than a preset value (such as 1.5) are designated as stress-sensitive areas (such as corners of the component and areas with abrupt changes in thickness), while other flat areas are designated as normal areas.

[0023] Thermo-mechanical coupled finite element analysis models were established for the two types of regions. A fine mesh (2mm mesh size) was used for stress-sensitive regions, while a coarse mesh (5mm mesh size) was used for conventional regions to balance computational accuracy and efficiency. Different temperature-pressure-time process curves were preset based on the characteristics of each region to adapt to the molding requirements of different regions. See the table below:

[0024] In the stress-sensitive areas, higher pressure is used to eliminate residual air, and slightly higher temperature is used to ensure sufficient resin flow; in the conventional areas, milder parameters are used to avoid increased brittleness due to over-curing.

[0025] Step 2: Sensor Deployment and System Connection: Distributed fiber optic sensors are installed inside the composite material preform, and a miniature pressure sensor array is installed on the mold surface at key locations corresponding to the component; both the distributed fiber optic sensors and the miniature pressure sensors are connected to the central control system through a data transmission module, thereby realizing real-time interaction between sensor data and the central control system; Specifically, the distributed fiber optic sensors are high-temperature resistant (long-term resistance to 250℃) single-mode quartz fiber optic sensors (such as FBG fiber grating sensors, which also have temperature and strain detection functions), and the miniature pressure sensor array uses MEMS miniature pressure sensors (range 0-5MPa, accuracy ±0.02MPa, temperature resistance 200℃). These sensors are deployed one-to-one with the stress-sensitive areas and key nodes in the normal areas of the mold surface, at intervals of 100cm. 2 At least one sensor should be deployed.

[0026] Furthermore, the deployment rule for the distributed optical fiber sensors is that the deployment density of distributed optical fiber sensors in the stress-sensitive area is greater than that in the conventional area. Within stress-sensitive areas, the sensor spacing does not exceed the maximum spacing for sensors in the sensitive area to ensure full-area coverage monitoring. Furthermore, the sensors are densely deployed at locations with specific geometric features on the components. In conventional areas, the spacing between distributed fiber optic sensors follows the range specified for conventional areas. Specifically, in stress-sensitive areas, the sensor spacing is set to 5mm, while at corners, holes, and other locations with specific geometric features, the sensor spacing is set to 3mm. In conventional areas, the sensor spacing is set to 15mm and is evenly distributed along the length of the component.

[0027] The maximum spacing of the sensors is determined based on the stress concentration and distribution of the components. The greater the stress gradient (such as corners, abrupt changes in thickness, or curved surfaces with drastic curvature changes), the more significant the stress fluctuations within a short distance. To avoid missing local stress peaks, the maximum spacing needs to be smaller. In sensitive areas with relatively gentle stress gradients, the maximum spacing can be appropriately increased, but it must be smaller than the sensor spacing in conventional areas.

[0028] Furthermore, each of the distributed optical fiber sensors has a sensor protection structure at its end. This protection structure is made of a high-temperature resistant material and is compatible with the pressure curing temperature range of each process stage. The coating of each distributed optical fiber sensor is made of a material that is highly compatible with the composite matrix and possesses high-temperature resistance. Specifically, the end of the optical fiber sensor is encapsulated in a quartz sleeve (temperature resistant to 300℃), and the coating is made of polyimide material, which has good compatibility with the epoxy matrix and a peel strength ≥50N / m.

[0029] Step 3: Phased closed-loop process control: Following the preheating stage, heating and curing stage, pressure holding and curing stage, and cooling stage, closed-loop control is used to differentiate the pressure and temperature control of each zone to ensure the molding quality of each zone. Furthermore, the control methods for each stage of the process include: Preheating stage (60 min): Start the autoclave heating system and heat the component as a whole through the autoclave control terminal. During the heating process, the temperature control module ensures that the temperature of the stress-sensitive area is always higher than that of the normal area (e.g., the normal area is heated to 80℃, and the stress-sensitive area is heated to 90℃). When the temperature of the normal area reaches the preheating target temperature (85℃), maintain the current temperature, start the pressure control system to introduce compressed air to 0.2 MPa, control the molding environment to perform heat preservation and pressure preservation operations, and use the vacuum module to perform differentiated vacuuming of each area, giving priority to removing air from the stress-sensitive areas, and then vacuuming the normal areas to avoid residual air in the sensitive areas forming bubbles. Specifically, based on the stress-sensitive area and the normal area defined in step one, a physical separation sealing structure is set between the mold and the component preform to isolate the vacuum environment of the two areas from each other.

[0030] The sealing structure can use high-temperature resistant silicone strips, fluororubber sealing rings, or metal sealing frames, which are embedded along the boundary of the area on the surface of the mold or the edge of the preform to form independent vacuum chambers (i.e., stress-sensitive area chambers and conventional area chambers) to avoid air cross-flow between areas.

[0031] For components with complex geometric features (such as corners, curved surfaces, and stress-sensitive areas with abrupt changes in thickness), the sealing structure must be designed to fit the shape of the component to ensure the airtightness of the chamber in the sensitive area, laying the foundation for subsequent differentiated vacuuming.

[0032] Specifically, the vacuum module includes a multi-channel vacuum control unit (each channel corresponds to a zone), which includes independent vacuum valves, pressure sensors, and pumps (or branch pipelines connected to the main pumping system) to realize independent start / stop, rate adjustment, and vacuum setting for each zone.

[0033] Specifically, for stress-sensitive areas, higher-powered extraction branches are configured (or the extraction volume in the area is increased by adjusting the valve opening in the main pipeline) to enable faster air discharge rates; for conventional areas, the extraction branches have lower power or valve openings, resulting in relatively slower extraction rates.

[0034] Pressure curing stage (duration 90min): The pressure control module first brings the stress-sensitive area to the preset proportion of the target pressure for this stage and maintains the pressure for the first holding time; then the pressure of each normal area is controlled to increase at the same rate to match that of the stress-sensitive area and is maintained for the second holding time; then each area is controlled to increase at the same rate to the final target pressure for this stage; at the same time, the temperature control module raises the overall temperature of the component to within the temperature range of the pressure curing stage. Specifically, the pressure in the sensitive area is first increased to 1.54 MPa (70% of the target pressure of 2.2 MPa) at a rate of 0.03 MPa / min using a proportional valve, and held for 10 minutes. Then, the pressure in the normal area is increased to 1.4 MPa (70% of the target pressure of 2.0 MPa) at the same rate and held for 5 minutes. Finally, both areas are simultaneously increased to the target pressure at a rate of 0.02 MPa / min. Simultaneously with the pressure increase, the heating system is activated to raise the overall temperature of the component to 180-185℃ (185℃ for the stress-sensitive area and 180℃ for the normal area) at a rate of 2℃ / min to prevent uneven resin flow caused by a sudden temperature rise.

[0035] Pressure holding and curing stage (duration 120min): The central control system dynamically adjusts the temperature difference between the two areas within a limited range based on feedback data from distributed fiber optic sensors and miniature pressure sensors, prioritizing the temperature of stress-sensitive areas; at the same time, the pressure control module ensures the stability of the molding environment pressure until the curing degree of the preform reaches the curing standard; differential scanning calorimetry (DSC) is used to monitor the curing degree of the component in real time, and when the curing degree reaches 95% or more, the next stage begins.

[0036] Cooling phase (duration 80min): The temperature control module cools the stress-sensitive area and the normal area at a preset cooling rate, and the difference in cooling rate between the two areas remains constant to avoid excessive temperature difference and internal stress. The central control system adjusts the molding environment pressure according to the component temperature drop ratio. After the component drops to the end temperature of the cooling phase, it switches to natural cooling. After the temperature stabilizes, the pressure control module reduces the pressure below the threshold to perform a pressure relief operation.

[0037] Step 4: Anomaly Detection and Adaptive Adjustment The central control system collects data from the distributed fiber optic sensors and miniature pressure sensors in real time. It uses a built-in defect identification algorithm based on support vector machines to determine whether there are any abnormalities in the component forming process. The model is trained using historical defect-free forming data to extract normal feature ranges (such as temperature deviation, pressure fluctuation, strain change, etc.).

[0038] When an anomaly is detected, the central control system automatically activates a tiered early warning mechanism and executes an adaptive adjustment strategy, including an inter-regional collaborative pressure compensation mechanism, to eliminate molding defects.

[0039] The abnormal judgment criteria in the graded early warning mechanism are as follows: if the strain value of any region exceeds the preset strain threshold (500με) by a set proportion (80%), or if the actual temperature of any region deviates from the target temperature of the corresponding process stage by more than the temperature deviation range (±5℃), and the abnormal state continues for a preset duration (≥3min), it is judged as an abnormal component forming.

[0040] Furthermore, during the execution of the inter-regional collaborative pressure compensation mechanism, the duration of pressure increase in adjacent conventional areas does not exceed the upper limit of the compensation duration ratio of the total duration of the current process stage, and the pressure increase value of a single compensation does not exceed the upper limit of the single compensation pressure. If the pressure in the stress-sensitive area still does not reach the target pressure threshold after compensation, the central control system automatically switches to the local pressure compensation mode, while extending the compensation duration to the extended compensation duration ratio of the total duration of the current process stage, and triggering a graded early warning mechanism for early warning.

[0041] Furthermore, the adaptive adjustment strategy includes: Level 1 Response: When abnormal parameters exceed the Level 1 abnormal threshold range, the central control system automatically fine-tunes the process parameters of the corresponding area. The adjustment range of temperature and pressure is controlled within the Level 1 parameter adjustment range. After adjustment, the system continuously monitors for the Level 1 monitoring duration. Specifically, when the temperature deviation is 3℃ (not exceeding ±5℃) and the strain is 350με, the central control system automatically fine-tunes the process parameters of the corresponding area. The temperature adjustment range is ±0.5℃, and the pressure adjustment range is ±0.05Mpa. After adjustment, the system continuously monitors for 5 minutes. If the parameters return to normal, the parameter change data is recorded to facilitate subsequent process optimization.

[0042] Level 2 Response: When abnormal parameters exceed the Level 2 abnormality threshold range, the central control system activates the inter-regional collaborative pressure compensation mechanism. At the same time, the temperature and pressure adjustment range is expanded to within the Level 2 parameter adjustment range, and the adjustment effect is evaluated according to the Level 2 evaluation cycle until the abnormality is completely eliminated. Specifically, when the temperature deviation is 6℃ (exceeding ±5℃) and the pressure in the stress-sensitive area is lower than the target value of 0.2MPa for 2 minutes, the inter-regional collaborative pressure compensation mechanism is activated; at the same time, the temperature adjustment range is expanded to ±2℃, and the adjustment effect is evaluated every 2 minutes until the abnormality disappears.

[0043] The interval collaborative pressure compensation mechanism includes: When the actual pressure in a stress-sensitive area is detected to be lower than a preset target pressure threshold, and this condition persists for a preset duration, the central control system first adjusts the pressure parameters of the stress-sensitive area at a preset rate, while simultaneously increasing the pressure setpoint of at least one adjacent normal area; wherein the total pressure of the normal area after the increase does not exceed the pressure setpoint of that area. Specifically, the pressure in the stress-sensitive area is increased from 2.0 MPa to 2.2 MPa at a rate of 0.04 MPa / min; at the same time, the pressure in the adjacent normal area is increased from 2.0 MPa to 2.2 MPa, thereby suppressing abnormal resin flow in the sensitive area through the coordinated pressure of adjacent areas.

[0044] Level 3 Response: When abnormal parameters exceed the Level 3 abnormality threshold, the central control system simultaneously triggers local pressure replenishment and regional component collaborative pressure compensation mechanisms, suspends the automatic increase of process parameters, and issues alarms through multi-channel alarms. Specifically, when the strain exceeds the threshold (exceeding 500με) and the temperature deviation is 10℃, the central control system simultaneously triggers local pressure replenishment (using a built-in micro pressure valve in the mold to locally replenish the abnormal area, with a pressure replenishment amplitude of 0.3Mpa) and inter-regional collaborative pressure compensation mechanisms, and suspends the automatic increase of temperature / pressure to prevent defect expansion; at the same time, it triggers multi-channel alarms, including local audible and visual alarms on the autoclave (flashing red light and buzzer), remote push of alarm information to the operator for collection (such as an industrial IoT platform), and recording of abnormal data for subsequent analysis.

[0045] Furthermore, after the component is solidified, the distributed optical fiber sensors inside the preform are retained to form a permanent embedded sensor network that matches the molding method, used for real-time structural health monitoring of the component during its service life; the distributed optical fiber sensors of the permanent embedded sensor network are adapted to the service environment of the component.

[0046] It should be explained that by setting the sensor size (0.125mm diameter fiber optic sensor), material compatibility (using a polyimide coating), and embedding location (intermediate layer of the component), the impact of sensor embedding on the component's mechanical properties is comprehensively reduced, facilitating the formation of a permanent sensing network integrated with the component. By selecting sensors with suitable temperature resistance values ​​that cover the curing process temperature limits, the requirements of the service application environment are met. During service, this network monitors component strain and temperature in real time, and the monitoring data is fed back to the health management system via a wireless transmission module, achieving structural health monitoring throughout the entire lifecycle from molding to service.

[0047] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An autoclave molding method characterized by, include: Step 1: Based on the geometric features of the three-dimensional model of the component to be formed, stress concentration parameters are analyzed through finite element simulation, and the component is divided into several stress-sensitive regions and normal regions. At the same time, a thermo-mechanical coupled finite element analysis model is established for each region, and different temperature-pressure-time process curves are preset based on the characteristics of each region to adapt to the forming requirements of different regions. Step 2: Distributed fiber optic sensors are installed inside the composite material preform, and a micro pressure sensor array is installed on the mold surface at key locations corresponding to the component; both the distributed fiber optic sensors and the micro pressure sensors are connected to the central control system through a data transmission module. Step 3: Following the sequence of preheating, heating and curing, pressure holding and curing, and cooling, a closed-loop control system is used to differentiate the pressure and temperature control for each zone. The control methods for each stage of the process include: Preheating stage: The component is heated as a whole through the control terminal of the autoclave. During the heating process, the temperature of the stress-sensitive area is always higher than that of the normal area. When the temperature of the normal area reaches the preheating target temperature, the current temperature is maintained, and the molding environment is controlled simultaneously to carry out heat preservation and pressure preservation operations. The vacuum module is used to perform differentiated vacuuming of each area, and the air in each stress-sensitive area is removed first. Pressure curing stage: The pressure control module first brings the stress-sensitive area to the preset proportion of the target pressure for this stage and maintains it for the first holding time; then the pressure of each normal area is controlled to increase at the same rate to be consistent with that of the stress-sensitive area and is maintained for the second holding time, and then each area is controlled to increase at the same rate to the final target pressure for this stage; at the same time, the temperature control module raises the overall temperature of the component to within the temperature range of the pressure curing stage. Pressure holding and curing stage: The central control system dynamically adjusts the temperature difference between the two areas within a limited range based on feedback data from distributed fiber optic sensors and miniature pressure sensors, prioritizing the temperature of the stress-sensitive area; at the same time, the pressure control module ensures the stability of the molding environment pressure until the preform reaches the curing standard. Cooling stage: The temperature control module cools the stress-sensitive area and the normal area at a preset cooling rate, and the difference in cooling rate between the two areas remains constant; the central control system adjusts the molding environment pressure according to the component temperature drop ratio. After the component drops to the end temperature of the cooling stage, it switches to natural cooling. After the temperature stabilizes, the pressure control module reduces the pressure below the threshold to perform a pressure relief operation. Step 4: The central control system collects data from the distributed fiber optic sensors and miniature pressure sensors in real time, and uses the built-in defect identification algorithm to determine whether there are any abnormalities in the component forming process. When an abnormality is detected, the central control system automatically activates the hierarchical early warning mechanism and executes an adaptive adjustment strategy, including an inter-regional collaborative pressure compensation mechanism, to eliminate forming defects. The inter-regional collaborative pressure compensation mechanism includes: When the actual pressure of a stress-sensitive area is detected to be lower than the preset target pressure threshold, and this state continues for a preset duration, the central control system first adjusts the pressure parameter of the stress-sensitive area at a preset rate, and at the same time increases the pressure setting value of at least one adjacent normal area; wherein the total pressure of the normal area after the increase does not exceed the pressure setting value of that area.

2. A method of autoclave molding according to claim 1, wherein The abnormal judgment criteria in the graded early warning mechanism are as follows: if the strain value of any region exceeds the set proportion of the preset strain threshold, or if the deviation between the actual temperature of any region and the target temperature of the corresponding process stage exceeds the temperature deviation range, and the abnormal state continues for a preset duration, it is judged as a component forming abnormality.

3. The autoclave forming method according to claim 1, characterized in that, The deployment rule for the distributed optical fiber sensors is that the deployment density of distributed optical fiber sensors in the stress-sensitive area is greater than that in the conventional area. Within the stress-sensitive zone, the sensor spacing does not exceed the maximum spacing of sensors in the sensitive zone, and the sensors are densely deployed at locations with special geometric features of the components; within the normal zone, the spacing of the distributed fiber optic sensors is within the range of the sensor spacing in the normal zone.

4. The autoclave forming method according to claim 1, characterized in that, Each of the distributed optical fiber sensors has a sensor protection structure at its end. The sensor protection structure is made of high-temperature resistant material and is compatible with the pressure curing temperature range of each process stage. The coating layer of each of the distributed optical fiber sensors is made of a material that is compatible with the composite matrix and has high-temperature resistant properties.

5. The autoclave forming method according to claim 1, characterized in that, During the execution of the inter-regional collaborative pressure compensation mechanism, the duration of pressure increase in adjacent conventional regions does not exceed the upper limit of the compensation duration ratio of the total duration of the current process stage, and the pressure increase value of a single compensation does not exceed the upper limit of the single compensation pressure. If the pressure in the stress-sensitive area still does not reach the target pressure threshold after compensation, the central control system automatically switches to local pressure compensation mode, while extending the compensation duration to the proportion of the total duration of the current process stage, and triggering a graded early warning mechanism to issue an early warning.

6. The autoclave forming method according to claim 1, characterized in that, The adaptive adjustment strategy includes: Level 1 Response: When abnormal parameters exceed the Level 1 abnormal threshold range, the central control system automatically fine-tunes the process parameters of the corresponding area. The adjustment range of temperature and pressure is controlled within the Level 1 parameter adjustment range. After adjustment, the Level 1 monitoring duration is continuously monitored. If the parameters return to normal, the parameter change data is recorded. Level 2 Response: When abnormal parameters exceed the Level 2 abnormality threshold range, the central control system activates the inter-regional coordinated pressure compensation mechanism, while expanding the temperature and pressure adjustment range to within the Level 2 parameter adjustment range, and evaluates the adjustment effect according to the Level 2 evaluation cycle until the abnormality is completely eliminated; Level 3 Response: When abnormal parameters exceed the Level 3 abnormal threshold range, the central control system simultaneously triggers local pressure replenishment and inter-regional coordinated pressure compensation mechanisms, suspends the automatic increase of process parameters, and issues an alarm through multi-channel alarm methods.

7. The autoclave forming method according to claim 1, characterized in that, In step three, after the component is solidified and molded, the distributed optical fiber sensors inside the preform are retained to form a permanent embedded sensor network that matches the molding method, which is used to monitor the structural health of the component in real time during its service life. The distributed fiber optic sensors of the permanent embedded sensor network are adapted to the service environment of the component.

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