Multi-point flexible gas-assisted hot pressing pressure control method and system for curved surface of fiber composite material

Abstract

The invention relates to the technical field of curved surface forming of fiber composite materials, in particular to a fiber composite material curved surface multi-point flexible gas-assisted hot pressing pressure control method and system.The method comprises the steps that the fiber direction is obtained by obtaining a design mold, and a deformation mismatching area is determined according to the fiber direction and the obtained airbag deformation direction; according to the method, a deformation mismatch area is obtained, a mismatch dynamic control network is constructed to carry out adaptive adjustment on the deformation mismatch area, local pressure compensation is carried out according to obtained adaptive adjustment feedback, and finally, the mismatch dynamic network is controlled by collecting a mold gap and a gap fitting standard. The problem of deformation mismatch caused by elasticity modulus difference in the primary and secondary directions of the fibers is effectively solved, and the direction and position accuracy of the fibers in the forming process is ensured through dynamic adaptive adjustment of a deformation mismatch area, so that the structural integrity and the mechanical property of a formed object are improved, the pressure can be more accurately controlled, and the production efficiency is improved. The requirements of complex mold curved surfaces and fiber layout are met, and the forming precision is improved.

Description

Technical Field

[0001] This invention relates to the field of curved surface forming technology of fiber composite materials, and in particular to a method and system for controlling the pressure of multi-point flexible gas-assisted hot pressing of curved fiber composite materials. Background Technology

[0002] With the widespread application of fiber-reinforced composite materials in aerospace, automotive manufacturing and high-end equipment, the high-precision forming of curved components has placed stringent requirements on manufacturing processes. Gas-assisted hot pressing technology has gradually become the core process for the preparation of complex curved composite components due to its advantages such as high mold adaptability and controllable pressure distribution. In particular, with the support of a multi-point flexible air pressure control system, the forming accuracy and mechanical properties of irregular curved components have been significantly improved by dynamically adjusting the matching degree between airbag deformation and fiber layup direction.

[0003] However, existing gas-assisted hot pressing pressure control methods still have significant shortcomings in fiber orientation adaptation and local pressure compensation. Traditional solutions mostly adopt static pressure mapping strategies, which fail to effectively solve the deformation mismatch problem caused by the difference in elastic modulus between the primary and secondary fiber directions. In particular, in the region of abrupt curvature change of the surface, it is easy to cause dynamic offset between the deformation direction of the air bladder and the fiber layup direction, resulting in stress concentration and interface delamination defects in the composite material, which seriously restricts the molding efficiency and quality consistency of high-performance fiber composite components.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a method and system for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composite materials, the method comprising: Determine the design mold, collect the mold surface based on the design mold, and obtain the fiber direction based on the mold surface; The deformation direction of the airbag is collected, the angle between the fiber direction and the deformation direction of the airbag is compared, and the deformation mismatch area is marked. The deformation mismatch area represents the area where the deformation direction of the airbag does not match the fiber direction. A mismatch dynamic control network is constructed to dynamically adapt and adjust the deformation mismatch region and obtain mismatch adjustment feedback. Local pressure gradient compensation is performed on the adjacent regions of the deformation mismatch area based on the mismatch adjustment feedback; The mold gap is collected in real time, and the gap fitting standard is obtained. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

[0007] Furthermore, the deformation mismatch region is dynamically adapted and adjusted to obtain mismatch adjustment feedback, including: The fiber orientation is extracted based on the deformation mismatch region, and the angle comparison result is obtained. The fiber orientation includes the main fiber orientation and several secondary fiber orientations. Collect historical pressure regulation information, and determine the air pressure regulation demand based on the angle comparison results and historical pressure regulation information; Weighting factors are assigned to the main fiber direction and the secondary fiber direction, and vibration correction is performed according to the weighting factors to obtain the airbag deformation state. Based on the airbag deformation state and the air pressure regulation requirements, the airbag air pressure is adaptively adjusted to obtain mismatch regulation feedback.

[0008] Further, assigning weighting factors to the fiber principal direction and the fiber secondary direction includes: Collect fiber composite information, which includes the volume fraction of fiber and matrix material, the elastic modulus of fiber and matrix material in the principal direction, and the elastic modulus of fiber and matrix material in the perpendicular direction; The principal elastic modulus of the fiber composite and the vertical elastic modulus of the fiber composite, based on the elastic modulus of the fiber and matrix materials in the principal direction and respectively, are calculated according to the volume fraction of the fiber and matrix materials, respectively. The angles between the vertical direction of the fiber and several secondary directions of the fiber are collected respectively. Based on the angles and the vertical elastic modulus of the fiber composite, the secondary elastic modulus of the fiber composite in several secondary directions is calculated respectively. Weighting factors are assigned based on the principal elastic modulus, vertical elastic modulus, and several secondary elastic moduli of the fiber composite.

[0009] Furthermore, based on the mismatch adjustment feedback, local pressure gradient compensation is performed on the adjacent regions of the deformation mismatch area, including: Real-time monitoring is performed on the deformation mismatch area and adjacent areas to obtain real-time deformation data and real-time pressure data. The deformation gradient is calculated based on the mismatch adjustment feedback and the real-time deformation data, and the pressure gradient is obtained based on the real-time pressure data. The compensation requirement is determined based on the deformation gradient and pressure gradient, and local pressure gradient compensation is performed on the adjacent area based on the compensation requirement.

[0010] Further, obtaining the fiber orientation based on the mold surface includes: The arrangement direction of the fiber composite is obtained according to the mold surface, and an electrode array is set on the fiber composite according to the arrangement direction. The electrode array includes the parallel direction and the perpendicular direction of the fiber composite. An electric current is applied to the fiber composite material, and the conductivity of several fibers is obtained; A fiber discrimination database is constructed, and the mapping relationship between the fiber conductivity and the fiber direction is obtained based on the fiber discrimination database, and the fiber direction is obtained based on the mapping relationship.

[0011] Furthermore, a fiber discrimination database is constructed, including: Collect historical fiber conductivity information, and extract historical fiber conductivity in several directions based on the historical fiber conductivity information; A one-to-one correspondence is established between the fiber orientation and the historical fiber conductivity to construct a fiber orientation mapping relationship; An index relationship is established for fiber conductivity based on the fiber orientation mapping relationship. A fiber discrimination database is constructed based on the index relationship, and the fiber discrimination database is dynamically updated according to the real-time fiber conductivity.

[0012] Furthermore, the mold gap is collected in real time, and a gap fitting standard is obtained. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated, including: The mold gap is collected in real time using scanning technology to obtain a three-dimensional gap cloud map; Key gap features are extracted based on the three-dimensional gap cloud map, and the key gap features are judged according to the gap fitting requirements. If the gap fitting requirements are met, the mismatch dynamic network control is terminated.

[0013] Furthermore, the fiber discrimination database is dynamically updated based on the real-time fiber conductivity, including: Set the conductivity deviation tolerance based on the fiber composite material information; The real-time fiber conductivity is extracted and compared with the fiber discrimination database to determine whether the real-time fiber conductivity meets the conductivity deviation tolerance. If it does not meet the tolerance, the fiber discrimination database is updated.

[0014] A multi-point flexible gas-assisted hot-pressing pressure control system for curved fiber composite materials, the system comprising: The mold surface fiber orientation module determines the mold design, acquires the mold surface based on the mold design, and obtains the fiber direction based on the mold surface. The deformation mismatch area marking module collects the airbag deformation direction, compares the angle between the fiber direction and the airbag deformation direction, and marks the deformation mismatch area, which represents the area where the airbag deformation direction does not match the fiber direction; The mismatch dynamic control network module constructs a mismatch dynamic control network to dynamically adapt and adjust the deformation mismatch region and obtain mismatch adjustment feedback. The local pressure gradient compensation module performs local pressure gradient compensation on the adjacent areas of the deformation mismatch zone based on the mismatch adjustment feedback. The gap control termination network module collects the mold gap in real time and obtains the gap fitting standard. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

[0015] Furthermore, the mismatch dynamic control network module includes: The fiber orientation angle extraction unit extracts the fiber orientation based on the deformation mismatch region and obtains the angle comparison result. The fiber orientation includes the main fiber orientation and several secondary fiber orientations. The air pressure regulation demand determination unit collects historical pressure regulation information and determines the air pressure regulation demand based on the angle comparison results and the historical pressure regulation information. The airbag deformation state acquisition unit assigns weight factors to the main fiber direction and the secondary fiber direction, and performs vibration correction according to the weight factors to acquire the airbag deformation state. The adaptive air pressure regulation feedback unit adaptively adjusts the air pressure of the airbag according to the airbag deformation state and the air pressure regulation requirements, and obtains mismatch regulation feedback.

[0016] The technical solution of this invention can achieve the following technical effects: It effectively solves the deformation mismatch problem caused by the difference in elastic modulus between the primary and secondary directions of fibers. By dynamically adapting and adjusting the deformation mismatch area, it ensures the accuracy of the fiber direction and position during the molding process, thereby improving the structural integrity and mechanical properties of the molded product. By collecting mold surface and fiber direction data in real time and dynamically adjusting the airbag pressure, it can control the pressure more precisely to adapt to the needs of complex mold surfaces and fiber layouts, which helps to improve material consistency during the molding process and reduce defects in the finished product.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the process for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites; Figure 2 This is a schematic diagram of the process for obtaining feedback on mismatch adjustment; Figure 3 A schematic diagram of the weight factor allocation process; Figure 4 This is a structural diagram of a multi-point flexible gas-assisted hot-pressing pressure control system for curved surfaces of fiber composite materials. Detailed Implementation

[0020] 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.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1; like Figure 1 As shown, this application provides a method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites. The method includes: S100: Determine the mold design, collect the mold surface based on the mold design, and obtain the fiber direction based on the mold surface; S200: Collects the airbag deformation direction, compares the angle between the fiber direction and the airbag deformation direction, and marks the deformation mismatch area. The deformation mismatch area represents the area where the airbag deformation direction does not match the fiber direction. S300: Construct a mismatch dynamic control network to dynamically adapt and adjust the deformation mismatch area and obtain mismatch adjustment feedback; S400: Local pressure gradient compensation is performed on adjacent areas of the deformation mismatch zone based on the mismatch adjustment feedback; S500: Real-time acquisition of mold gap and acquisition of gap fitting standard. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

[0023] Specifically, in this invention, the required mold is first designed using computer-aided design (e.g., CAD) software. When designing the mold, preferably, the mold design should consider the specific application requirements of the final product and the characteristics of the fiber composite material, such as the curvature and dimensional accuracy of the mold. As a method for acquiring the mold surface, a 3D laser scanner or optical measuring equipment can be used to perform high-precision scanning of the mold surface based on the 3D geometric data. During the scanning process, the equipment must be kept stable to avoid vibration or movement. After each scan, the equipment automatically generates point cloud data. Using the point cloud data, reverse engineering software (such as Geomagic Design) is employed. Surface reconstruction is performed using X or SolidWorks, converting point cloud data into NURBS surfaces or triangular mesh models. The accuracy of the data is then verified by comparing the reconstructed surface model with the original mold. During the hot pressing process, in some embodiments, high-precision pressure sensors (such as piezoresistive sensors) and deformation sensors (such as strain gauges or fiber optic sensors) are used to monitor the deformation state of the airbag in real time and provide high-precision data. Sensors are placed at key locations on the airbag, such as the central region, edge region, and areas with significant curvature changes. At least one pressure sensor and one deformation sensor are placed at each key location to ensure comprehensive data. The sensors then collect the deformation direction and amount of the airbag in real time. Based on the data from the deformation sensors, the deformation amount of the airbag in each direction is calculated. For example, the deformation amount of the airbag in the X, Y, and Z directions is calculated using strain gauge data, and the deformation direction of the airbag is determined based on the magnitude and direction of the deformation amount. For example, if the airbag's deformation is greatest in the X direction, then the X direction is the deformation direction. Subsequently, the angle between the obtained fiber direction and the airbag's deformation direction is calculated. Based on the process requirements of the fiber composite, an angle threshold (e.g., 5°) is set. If the calculated angle exceeds the threshold, the area is marked as a deformation mismatch zone. Then, a mismatch control network can be constructed using a neural network or fuzzy control algorithm. The network input includes parameters such as the deformation of the deformation mismatch zone, the fiber direction, and the airbag's deformation direction. The output is an airbag pressure adjustment command. Based on the characteristics of the deformation mismatch zone, the airbag pressure distribution is dynamically adjusted. For example, for the deformation mismatch zone... In the mismatch zone, the air pressure is increased to enhance local pressure. In the non-mismatch zone, the air pressure is maintained or decreased to balance the overall pressure distribution. The deformation state of the mismatch zone is monitored in real time by sensors to obtain mismatch adjustment feedback. The mismatch zone and its adjacent areas are monitored in real time to collect deformation and pressure data. The deformation gradient is calculated based on the mismatch adjustment feedback and real-time deformation data. The pressure gradient is calculated based on the real-time pressure data. Based on the deformation gradient and pressure gradient, the compensation requirement is determined. Finally, the mismatch dynamic control network is controlled by comparing the obtained mold gap with the collected gap fitting standard.

[0024] The technical solution of this invention effectively solves the deformation mismatch problem caused by the difference in elastic modulus between the primary and secondary directions of fibers. By dynamically adapting and adjusting the deformation mismatch area, the direction and position of the fibers during the molding process are ensured to be accurate, thereby improving the structural integrity and mechanical properties of the molded product. By collecting mold surface and fiber direction data in real time and dynamically adjusting the airbag pressure, the pressure is controlled more precisely to adapt to the needs of complex mold surfaces and fiber layouts, which helps to improve material consistency during the molding process and reduce defects in the finished product.

[0025] Furthermore, such as Figure 2 As shown, dynamic adaptation and adjustment are performed on the deformation mismatch region to obtain mismatch adjustment feedback, including: S310: Extract fiber orientation based on deformation mismatch region and obtain angle comparison results. Fiber orientation includes main fiber orientation and several secondary fiber orientations. S320: Collect historical pressure regulation information, and determine the air pressure regulation requirements based on the angle comparison results and historical pressure regulation information; S330: Assign weight factors to the main fiber direction and the secondary fiber direction, and perform vibration correction according to the weight factors to obtain the airbag deformation state; S340: Based on the airbag deformation state and air pressure regulation requirements, the airbag pressure is adaptively adjusted to obtain mismatch adjustment feedback.

[0026] As a preferred embodiment of the above, firstly, the main direction and several secondary directions of the fiber orientation are obtained through the deformation mismatch region, and historical pressure adjustment information and angle comparison results are extracted, including historical air pressure values, adjustment time, adjustment effect, etc. Based on the angle comparison results and historical pressure adjustment information, the air pressure adjustment requirement is determined. For example, if the angle comparison result is 6° and the deformation decreased by 20% when the historical air pressure value is 0.5MPa, then the current air pressure adjustment requirement is determined to increase the air pressure to 0.6MPa. Subsequently, according to the importance of the main and secondary fiber orientations, weight factors are assigned, and vibration correction is performed on the main and secondary fiber orientations using a vibrator according to the weight factors. During the hot pressing process, the fiber composite may experience stress concentration due to the mismatch between the airbag deformation direction and the fiber orientation. Applying vibration can promote the redistribution of the fiber composite and alleviate stress. Force concentration improves molding quality; for example, a 70% vibration correction is applied to the main fiber direction and a 30% vibration correction is applied to the secondary fiber direction. The vibration correction includes adjusting the vibration frequency and amplitude of the airbag to optimize the deformation state. Then, the deformation state of the airbag after vibration correction is monitored in real time by sensors to obtain data on deformation amount and deformation direction. Finally, the deformation state of the airbag is monitored in real time by sensors, and the air pressure adjustment requirement is calculated based on the airbag deformation state. The rationality of the air pressure adjustment requirement is verified by simulation or experiment. Then, the airbag air pressure is adaptively adjusted according to the air pressure adjustment requirement. The adjustment method can be as follows: the airbag air pressure is precisely controlled by the air pressure control system (such as a proportional valve or servo valve), and the mismatch adjustment feedback is obtained by monitoring the adjusted airbag deformation state in real time by sensors. The feedback data includes deformation amount, pressure distribution, fiber stress, etc.

[0027] Furthermore, such as Figure 3 As shown, weighting factors are assigned to the primary and secondary fiber directions, including: S331: Collect fiber composite information, which includes the volume fraction of fiber and matrix materials, the principal elastic modulus of fiber and matrix materials, and the perpendicular elastic modulus of fiber and matrix materials. S332: Calculate the principal elastic modulus of the fiber composite based on the principal elastic modulus of the fiber and matrix materials and the vertical elastic modulus of the fiber composite based on the vertical elastic modulus of the fiber and matrix materials, respectively, according to the volume fraction of the fiber and matrix materials. S333: Collect the angles between the vertical direction of the fiber and several secondary directions of the fiber, and calculate the secondary elastic modulus of the fiber composite based on the angles and the vertical elastic modulus of the fiber composite. S334: Assign weighting factors based on the principal elastic modulus of the fiber composite, the vertical elastic modulus of the fiber composite, and the secondary elastic modulus of several fiber composites.

[0028] In this embodiment, as a method for acquiring information on fiber composites, high-precision material testing equipment (such as scanning electron microscopes (SEM) and X-ray diffractometers) can be used to conduct in-depth analysis of the fiber and matrix materials. These devices can provide microstructure images and chemical composition data of the materials, thereby determining the volume fraction of the fibers and the matrix, as well as their principal and perpendicular elastic moduli. Based on the obtained volume fractions and their principal and perpendicular elastic moduli, mathematical modeling methods are used to calculate the weighting factors of the fiber's principal and secondary directions. The calculation can be performed as follows: Elastic modulus of the principal direction (parallel direction): Elastic modulus in the vertical direction: ,in Elastic modulus in other directions (angle directions): , and These represent the volume fractions of the fiber and the matrix, respectively. and These are the elastic moduli of the fiber and the matrix, respectively. This is an empirical parameter, usually taken as 2. It is the elastic modulus along the included angle θ; weighting factors are assigned according to the calculated elastic modulus in each direction.

[0029] Furthermore, based on the mismatch adjustment feedback, local pressure gradient compensation is performed on the adjacent regions of the deformation mismatch area, including: Real-time monitoring of the deformation mismatch area and adjacent areas is performed to obtain real-time deformation data and real-time pressure data. The deformation gradient is calculated based on the mismatch adjustment feedback and real-time deformation data, and the pressure gradient is obtained based on the real-time pressure data. The compensation requirement is determined based on the deformation gradient and pressure gradient, and local pressure gradient compensation is performed on adjacent areas according to the compensation requirement.

[0030] Specifically, a high-precision deformation sensor array and pressure sensor matrix can be used for real-time monitoring. The deformation sensor array is used to detect the deformation of the fiber composite during hot pressing, including deformation, direction, and strain distribution. The pressure sensor matrix is ​​used to collect air-assisted pressure distribution data, including local pressure and overall pressure gradient. During hot pressing, the fiber composite may experience stress concentration and mismatch due to differences in the elastic modulus of local areas or uneven deformation of the air bladder. For accurate compensation, the deformation gradient and pressure gradient need to be calculated separately. The deformation gradient reflects the rate of deformation change between adjacent regions and can be calculated using the finite difference method: the deformation gradient is calculated by obtaining the deformation difference and spatial interval between adjacent regions. In actual calculations, the deformation gradient is represented by a gradient vector field to identify areas of concentrated deformation and determine the direction requiring compensation. The pressure gradient reflects the change in air-assisted pressure and can also be calculated using the same method as the deformation gradient: it is obtained by calculating the pressure difference and spatial interval between adjacent regions. Typically, the Laplace operator is used to calculate the local pressure gradient, which can be used to identify areas with excessively low or high pressure for pressure compensation. Subsequently, the area requiring compensation is obtained based on the deformation gradient and pressure gradient, and the required compensation pressure is calculated. In some embodiments, the required local compensation pressure is calculated using the deformation gradient and pressure gradient, and finally, the compensation pressure is applied by the airbag control system to complete the local pressure compensation.

[0031] Furthermore, obtaining the fiber orientation based on the mold surface includes: The arrangement direction of the fiber composite is obtained from the mold surface, and an electrode array is set on the fiber composite according to the arrangement direction. The electrode array includes the parallel direction and the perpendicular direction of the fiber composite. An electric current is applied to the fiber composite material, and the conductivity of several fibers is obtained; Construct a fiber discrimination database, obtain the mapping relationship between fiber conductivity and fiber orientation based on the fiber discrimination database, and obtain the fiber orientation based on the mapping relationship.

[0032] As a preferred embodiment of the above, the arrangement direction of the fiber composite is obtained by acquiring the mold surface. To accurately detect the fiber orientation, an electrode array needs to be set on the surface of the fiber composite. The electrode arrangement is as follows: a parallel electrode array, with electrodes arranged along the main direction of the fiber composite layup to ensure current transmission along the fiber; and a perpendicular electrode array, with electrodes perpendicular to the parallel direction to monitor the secondary conductivity of the fiber. The electrode spacing should be small enough to provide high-resolution measurement results; in at least one embodiment, 0.5 mm is used. A 2mm spacing range can be used, and flexible conductive electrodes (such as graphene films or silver nanowire coatings) can be employed to ensure that current measurement is not affected when the fiber composite is bent. The fiber conductivity is then obtained by applying current: low-voltage DC (1-10V) or AC (1kHz-100kHz) can be used, applying current to electrodes in the parallel and perpendicular directions respectively, and measuring their resistance or conductivity. Since the fiber has high conductivity along the main direction and low conductivity along the perpendicular direction, the measurement results conform to the following trend: if the conductivity in the main direction is significantly higher than that in the secondary direction, the main direction is correct; if the conductivity changes abnormally, it indicates that the fiber may have local misalignment or defects. Subsequently, by constructing a fiber discrimination database, the mapping relationship between fiber conductivity and direction can be obtained. Through database matching, the actual fiber laying direction can be determined.

[0033] Furthermore, constructing a fiber discrimination database includes: Collect historical fiber conductivity information and extract historical fiber conductivity in several directions based on the historical fiber conductivity information; A one-to-one correspondence between fiber orientation and historical fiber conductivity is established to construct a fiber orientation mapping relationship; An index relationship is established for fiber conductivity based on the fiber orientation mapping relationship. A fiber discrimination database is built based on the index relationship and dynamically updated according to the real-time fiber conductivity.

[0034] In this embodiment, historical fiber conductivity information under different experimental conditions is first collected, including fiber conductivity in different directions. The conductivity value in each direction is recorded. By analyzing the historically collected fiber conductivity data, a mapping relationship between fiber direction and conductivity is established using mathematical models (such as linear regression, multinomial regression, or machine learning methods). The specific steps for establishing the mapping relationship are as follows: First, all collected conductivity data are preprocessed to remove noise and outliers to ensure data accuracy. A suitable algorithm is selected to fit the relationship between conductivity and fiber direction. In some embodiments, the support vector machine method is preferred, as it can handle complex multidimensional data mapping problems. The model is trained using historical data and validated using cross-validation to ensure that the model's prediction accuracy meets the requirements. After establishing the mapping relationship between fiber orientation and conductivity, the next step is to create an index based on the fiber orientation characteristics to facilitate fast querying and matching. This involves extracting the maximum, minimum, and average conductivity values ​​for all directions, and building an index database based on these features. Data structures such as hash tables, B-trees, and Kd-trees can be used to optimize query speed. All directions and their corresponding conductivity values ​​and index information are stored in the database for real-time querying and updating. During production, the system collects new conductivity data and immediately adds it to the database. The existing mapping model is then retrained using the new data to optimize the accuracy of the fiber orientation and conductivity matching. Incremental learning or online learning algorithms are used to update the index relationship and model in real time, thereby improving processing speed and efficiency.

[0035] Furthermore, the mold gap is collected in real time, and a gap fitting standard is obtained. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated, including: The mold gap is collected in real time using scanning technology to obtain a three-dimensional gap cloud map; Key gap features are extracted from the 3D gap cloud map, and the key gap features are judged according to the gap fitting requirements. If the gap fitting requirements are met, the mismatch dynamic network control is terminated.

[0036] Specifically, this implementation uses 3D laser scanning technology to monitor mold gaps in real time: a high-precision and high-resolution 3D laser scanner, such as the FARO Focus 3D laser scanner, is selected to perform a full-coverage scan of the mold, acquiring raw point cloud data. After point cloud registration, noise reduction, and precise matching, a 3D gap cloud map is generated. From the 3D gap cloud map, key gap features are extracted using image processing algorithms and geometric analysis tools. The following method can be used as an example for extraction: First, the scanned image or 3D point cloud data needs to be preprocessed. The goal of this step is to remove noise and enhance image quality. The minimum, maximum, and average gap values ​​are calculated on the preprocessed 3D point cloud data. For the minimum gap value, the minimum gap value is obtained by detecting the minimum distance between the gap region in the image and the mold surface. Distance transformation algorithms (such as Euclidean distance transformation) can be used to calculate the distance from each pixel or point in the point cloud to the nearest point on the mold surface, thereby obtaining the minimum gap value. The maximum gap value is calculated using a similar method. By traversing the entire image or point cloud data, the average value of all gaps is calculated to obtain the average gap size. Then, the standard deviation of the gap data is calculated to understand the uniformity of the gap distribution. Geometric analysis tools such as convex hull algorithms and edge detection are used to determine the shape of the gap. Then, morphological processing methods such as dilation and erosion can be used to extract specific gap region features. Finally, the extracted key features (such as minimum gap value, maximum gap value, gap standard deviation, etc.) are compared with the preset gap standard. If all key features meet the fitting standard, the mold gap is considered to meet the requirements, and the adjustment of the mismatch dynamic control network can be terminated.

[0037] Furthermore, the fiber discrimination database is dynamically updated based on real-time fiber conductivity, including: Set the conductivity deviation tolerance based on the fiber composite material information; Extract the real-time fiber conductivity and compare it with the fiber discrimination database to determine whether the real-time fiber conductivity meets the conductivity deviation tolerance. If it does not meet the tolerance, update the fiber discrimination database.

[0038] As a preferred embodiment of the above, the conductivity deviation tolerance refers to the maximum allowable deviation range between the conductivity measured in real time and the conductivity recorded in the historical database for different fiber materials and orientations. The setting of the tolerance depends on the type of composite material, the manufacturing process, and its accuracy requirements. First, based on the acquired fiber composite material information and historical data, the conductivity tolerance is set through statistical analysis: after calculating the mean and standard deviation of the historical data, in some embodiments, the tolerance is usually set to a multiple of the mean plus or minus the standard deviation (such as 2 times the standard deviation). This ensures that most data falls within the set tolerance range, and the tolerance can be dynamically adjusted as the data changes during the production process. For example, an online learning algorithm (such as incremental learning) can be used to analyze and adjust the conductivity data in real time, automatically adapting the tolerance setting according to the changes in the current data. Subsequently, a conductivity measuring instrument (such as the four-probe method or Hall effect sensor) is used to monitor the conductivity of the fiber composite material in real time. The measurement process should be carried out before, during, and after molding to ensure that the change in conductivity is tracked throughout the process. The real-time measured fiber conductivity data is compared with the historical conductivity data stored in the fiber discrimination database to determine whether it meets the conductivity deviation tolerance. If the difference between the real-time measured conductivity data and the historical data exceeds the set tolerance (for example, the deviation exceeds 10%), the database is dynamically updated. The update method can be as follows: the current conductivity data is comprehensively analyzed with conductivity data of other known directions to calculate more accurate fiber orientation data and update the relevant mapping relationship in the database.

[0039] Example 2; Based on the same inventive concept as the multi-point flexible gas-assisted hot pressing pressure control method for curved fiber composite surfaces described in the foregoing embodiments, this invention also provides a multi-point flexible gas-assisted hot pressing pressure control system for curved fiber composite surfaces, such as... Figure 4 As shown, the system includes: The mold surface fiber orientation module determines the mold design, acquires the mold surface based on the mold design, and obtains the fiber orientation based on the mold surface. The deformation mismatch area marking module collects the airbag deformation direction, compares the angle between the fiber direction and the airbag deformation direction, and marks the deformation mismatch area. The deformation mismatch area represents the area where the airbag deformation direction does not match the fiber direction. The mismatch dynamic control network module constructs a mismatch dynamic control network to dynamically adapt and adjust the deformation mismatch region and obtain mismatch adjustment feedback. The local pressure gradient compensation module performs local pressure gradient compensation on adjacent areas of the deformation mismatch zone based on the mismatch adjustment feedback. The gap control termination network module collects the mold gap in real time and obtains the gap fitting standard. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

[0040] The adjustment system described above in this invention can effectively realize the multi-point flexible gas-assisted hot pressing pressure control method for curved surfaces of fiber composites, and the technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0041] Furthermore, the mismatch dynamic control network module includes: The fiber orientation angle extraction unit extracts the fiber orientation based on the deformation mismatch area and obtains the angle comparison results. The fiber orientation includes the main fiber orientation and several secondary fiber orientations. The air pressure regulation demand determination unit collects historical pressure regulation information and determines the air pressure regulation demand based on the angle comparison results and the historical pressure regulation information. The airbag deformation state acquisition unit assigns weight factors to the main fiber direction and the secondary fiber direction, and performs vibration correction according to the weight factors to acquire the airbag deformation state. The adaptive air pressure regulation feedback unit adaptively adjusts the air pressure of the airbag according to the airbag deformation state and air pressure regulation requirements, and obtains mismatch regulation feedback.

[0042] Similarly, the above-mentioned optimization schemes for the system can also achieve the optimization effects corresponding to the methods in Embodiment 1, which will not be repeated here.

[0043] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites, characterized in that, The method includes: Determine the design mold, collect the mold surface based on the design mold, and obtain the fiber direction based on the mold surface; The deformation direction of the airbag is collected, the angle between the fiber direction and the deformation direction of the airbag is compared, and the deformation mismatch area is marked. The deformation mismatch area represents the area where the deformation direction of the airbag does not match the fiber direction. A mismatch dynamic control network is constructed to dynamically adapt and adjust the deformation mismatch region and obtain mismatch adjustment feedback. Local pressure gradient compensation is performed on the adjacent regions of the deformation mismatch area based on the mismatch adjustment feedback; The mold gap is collected in real time, and the gap fitting standard is obtained. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

2. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 1, characterized in that, Dynamically adapting and adjusting the deformation mismatch region to obtain mismatch adjustment feedback includes: The fiber orientation is extracted based on the deformation mismatch region, and the angle comparison result is obtained. The fiber orientation includes the main fiber orientation and several secondary fiber orientations. Collect historical pressure regulation information, and determine the air pressure regulation demand based on the angle comparison results and historical pressure regulation information; Weighting factors are assigned to the main fiber direction and the secondary fiber direction, and vibration correction is performed according to the weighting factors to obtain the airbag deformation state. Based on the airbag deformation state and the air pressure regulation requirements, the airbag air pressure is adaptively adjusted to obtain mismatch regulation feedback.

3. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 2, characterized in that, Assigning weighting factors to the fiber principal direction and the fiber secondary direction includes: Collect fiber composite information, which includes the volume fraction of fiber and matrix material, the elastic modulus of fiber and matrix material in the principal direction, and the elastic modulus of fiber and matrix material in the perpendicular direction; The principal elastic modulus of the fiber composite and the vertical elastic modulus of the fiber composite, based on the elastic modulus of the fiber and matrix materials in the principal direction and respectively, are calculated according to the volume fraction of the fiber and matrix materials, respectively. The angles between the vertical direction of the fiber and several secondary directions of the fiber are collected respectively. Based on the angles and the vertical elastic modulus of the fiber composite, the secondary elastic modulus of the fiber composite in several secondary directions is calculated respectively. Weighting factors are assigned based on the principal elastic modulus, vertical elastic modulus, and several secondary elastic moduli of the fiber composite.

4. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 3, characterized in that, Based on the mismatch adjustment feedback, local pressure gradient compensation is performed on the adjacent regions of the deformation mismatch area, including: Real-time monitoring is performed on the deformation mismatch area and adjacent areas to obtain real-time deformation data and real-time pressure data. The deformation gradient is calculated based on the mismatch adjustment feedback and the real-time deformation data, and the pressure gradient is obtained based on the real-time pressure data. The compensation requirement is determined based on the deformation gradient and pressure gradient, and local pressure gradient compensation is performed on the adjacent area based on the compensation requirement.

5. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 1, characterized in that, Obtaining the fiber orientation based on the mold surface includes: The arrangement direction of the fiber composite is obtained according to the mold surface, and an electrode array is set on the fiber composite according to the arrangement direction. The electrode array includes the parallel direction and the perpendicular direction of the fiber composite. An electric current is applied to the fiber composite material, and the conductivity of several fibers is obtained; A fiber discrimination database is constructed, and the mapping relationship between the fiber conductivity and the fiber direction is obtained based on the fiber discrimination database, and the fiber direction is obtained based on the mapping relationship.

6. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 5, characterized in that, Construct a fiber discrimination database, including: Collect historical fiber conductivity information, and extract historical fiber conductivity in several directions based on the historical fiber conductivity information; A one-to-one correspondence is established between the fiber orientation and the historical fiber conductivity to construct a fiber orientation mapping relationship; An index relationship is established for fiber conductivity based on the fiber orientation mapping relationship. A fiber discrimination database is constructed based on the index relationship, and the fiber discrimination database is dynamically updated according to the real-time fiber conductivity.

7. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 1, characterized in that, Real-time acquisition of mold gap and obtaining gap fitting standard; when the mold gap meets the gap fitting standard, termination of the mismatch dynamic control network control, including: The mold gap is collected in real time using scanning technology to obtain a three-dimensional gap cloud map; Key gap features are extracted based on the three-dimensional gap cloud map, and the key gap features are judged according to the gap fitting requirements. If the gap fitting requirements are met, the mismatch dynamic network control is terminated.

8. The method for controlling the pressure of multi-point flexible gas-assisted hot pressing on curved surfaces of fiber composites according to claim 6, characterized in that, The fiber discrimination database is dynamically updated based on real-time fiber conductivity, including: Set the conductivity deviation tolerance based on the fiber composite material information; The real-time fiber conductivity is extracted and compared with the fiber discrimination database to determine whether the real-time fiber conductivity meets the conductivity deviation tolerance. If it does not meet the tolerance, the fiber discrimination database is updated.

9. A multi-point flexible gas-assisted hot-pressing control system for curved surfaces of fiber composite materials, characterized in that, The system includes: The mold surface fiber orientation module determines the mold design, acquires the mold surface based on the mold design, and obtains the fiber direction based on the mold surface. The deformation mismatch area marking module collects the airbag deformation direction, compares the angle between the fiber direction and the airbag deformation direction, and marks the deformation mismatch area, which represents the area where the airbag deformation direction does not match the fiber direction; The mismatch dynamic control network module constructs a mismatch dynamic control network to dynamically adapt and adjust the deformation mismatch region and obtain mismatch adjustment feedback. The local pressure gradient compensation module performs local pressure gradient compensation on the adjacent areas of the deformation mismatch zone based on the mismatch adjustment feedback. The gap control termination network module collects the mold gap in real time and obtains the gap fitting standard. When the mold gap meets the gap fitting standard, the mismatch dynamic control network control is terminated.

10. The fiber composite curved surface multi-point flexible gas-assisted hot press pressure control system according to claim 9, characterized in that, The mismatch dynamic control network module includes: The fiber orientation angle extraction unit extracts the fiber orientation based on the deformation mismatch region and obtains the angle comparison result. The fiber orientation includes the main fiber orientation and several secondary fiber orientations. The air pressure regulation demand determination unit collects historical pressure regulation information and determines the air pressure regulation demand based on the angle comparison results and the historical pressure regulation information. The airbag deformation state acquisition unit assigns weighting factors to the main fiber direction and the secondary fiber direction, and performs vibration correction according to the weighting factors to acquire the airbag deformation state. The adaptive air pressure regulation feedback unit adaptively adjusts the air pressure of the airbag according to the airbag deformation state and the air pressure regulation requirements, and obtains mismatch regulation feedback.

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