Intelligent shape-preserving clamping plate for aircraft panel based on magnetorheological elastomer and regulation and control method of intelligent shape-preserving clamping plate

Abstract

According to the intelligent shape-preserving clamping plate for the aircraft panel based on the magneto-rheological elastomer and the regulation and control method of the intelligent shape-preserving clamping plate, self-adaptive attachment and rigid supporting of the aircraft panel are achieved through the magneto-induced deformation and magneto-induced hardening characteristics of the intelligent shape-preserving clamping plate for the aircraft panel based on the magneto-rheological elastomer. The clamping plate is composed of a supporting layer, a functional layer and an interface layer, and the supporting layer is detachable and convenient to replace and adapt to different machine types. The interface layer is integrated with a flexible sensor, fitting pressure distribution is fed back in real time, on this basis, the tool is switched from flexible deformation fitting of the actual appearance of the wallboard to rigid locking through the magnetic field domain-dividing regulation and control technology, the appearance deviation of the wallboard can be compensated, the problem that a traditional rigid tool cannot adapt to the appearance deviation is solved, and the production efficiency is improved. The requirement for high precision of aircraft panel assembly is met, and particularly the assembly quality of the composite material panel can be remarkably improved. In addition, as the functional layer and the interface layer have certain softness in the absence of a magnetic field, the clamping plate can directly adapt to a new model after the supporting layer is replaced, and the universality of the tool is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of aircraft manufacturing process equipment technology, specifically relating to an intelligent, shape-retaining fixture for aircraft panels based on magnetorheological elastomers (MREs) and its control method. The fixture is suitable for maintaining the shape of aircraft panels, particularly composite panels, during the lifting and assembly process. Through domain-specific magnetic field control and flexible sensor feedback, the fixture achieves high-precision, adaptive shape retention, addressing the inability of traditional rigid tooling to adapt to actual panel shape deviations and accommodate multiple aircraft models. Background Art

[0002] The wall panel is the core component of the aircraft's aerodynamic shape and an important load-bearing component in the fuselage structure. It is composed of skin, long stringers and frame edges, with the skin as the core. The skin of large aircraft is usually a typical thin-walled curved surface structure with a complex three-dimensional curved surface shape and a large span-wise scale. After installation, the geometric accuracy of such components directly affects the aerodynamic characteristics of the aircraft, so the requirements for their manufacturing and assembly accuracy are extremely stringent. Due to the large size, lightweight characteristics and thin wall thickness of the skin, even with the support of components such as long stringers, the inherent rigidity of the wall panel is still low, and deformation during processing, lifting and assembly is unavoidable. This shape maintenance problem has always been a key control point and difficulty in the assembly process of large aircraft, and is directly related to the overall assembly quality and flight performance of the aircraft.

[0003] Traditional aircraft panel retaining fixtures rely on aluminum alloy or rigid pallets, whose shapes are designed based on the theoretical panel's shape. Due to their high rigidity, they cannot effectively conform to the panel's actual shape, potentially causing damage during forced assembly when connecting the panel and pallet, especially for composite materials, which can lead to delamination or fiber breakage. Furthermore, rigid pallets lack universality, requiring custom fixtures for each aircraft type, which is costly. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides an intelligent shape-preserving card plate based on magnetorheological elastomer and its control method to solve the problem that traditional rigid tooling cannot adapt to the actual shape deviation of the wall panel and the adaptation of multiple models.

[0005] A first aspect of the present invention provides an aircraft wall panel intelligent shape-keeping cardboard based on magnetorheological elastomer, which is arranged between a rigid frame and an aircraft wall panel, and the intelligent shape-keeping cardboard includes: a support layer, a functional layer and an interface layer;

[0006] The interface layer is an integrated piezoresistive microstructure array, which is bonded to the aircraft wall panel. The functional layer is a silicone rubber-based magnetorheological elastomer. The support layer's profile matches the aircraft wall panel's profile and is equipped with a groove array with built-in micro-electromagnetic coils for magnetic field domain control.

[0007] The electromagnetic control system composed of the pressure sensing of the interface layer and the electromagnetic coils nested in the support layer adjusts the shape of the card to adapt to the actual shape of the aircraft wall panel.

[0008] Optionally, the support layer adopts an aluminum alloy frame;

[0009] A wire groove is provided at the bottom of the groove for electrically connecting the electromagnetic control system with each electromagnetic coil;

[0010] The groove is 30mm long, 30mm wide and 25-30mm deep, and the grooves are arranged at a spacing of 25-30mm;

[0011] The supporting layer is fixedly connected to the functional layer by bolts, and is also fixedly connected to the wall panel by bolts.

[0012] Optionally, the functional layer has a thickness of 15 mm.

[0013] Optionally, the interface layer is a flexible sensing coating covering the surface of the functional layer, with a thickness of 1 mm. The flexible sensing coating is a composite material of silver nanowires and PDMS, and the contact pressure distribution is inverted by the resistance change;

[0014] The functional layer and the interface layer are connected by bonding using a modified epoxy resin film.

[0015] Optionally, each solenoid coil consists of a 25mm diameter coil and a soft magnetic core, and is independently controlled to a current of 5A.

[0016] Optionally, the electromagnetic coil is made of copper alloy material.

[0017] Optionally, the electromagnetic control system is used to monitor the contact situation between the card plate and the wall panel in real time based on the pressure distribution data of the interface layer, and to adjust the intensity and direction of the magnetic field in different regions to achieve precise control of the deformation of the card plate.

[0018] Optionally, a liquid cooling channel is designed inside the support layer to remove the heat generated by the electromagnetic coil during operation through the circulation of coolant, thereby ensuring a stable working temperature of the tooling.

[0019] A second aspect further provides a method for controlling an intelligent shape-maintaining card for aircraft wall panels based on a magnetorheological elastomer, using the intelligent shape-maintaining card as described in any one of the first aspects, the method comprising the following steps:

[0020] Deformation stage: According to the preset control cycle, a 50-100mT magnetic field is applied based on the pressure distribution data of the interface layer to make the functional layer flexibly fit the actual shape of the wall panel;

[0021] Locking stage: Increase the magnetic field to 200-300mT and maintain it for 30 seconds to increase the shear modulus of the functional layer from 0.8MPa to 10MPa, so that the smart shape-preserving card is locked in the target shape.

[0022] In the field of aircraft manufacturing process equipment technology, in order to improve the shape retention of wall panel products during the hoisting and assembly process and reduce wall panel damage, the present invention proposes an intelligent shape-retaining card for aircraft wall panels based on magnetorheological elastomers and its control method. This method uses a flexible sensing coating to monitor the fitting pressure between the wall panel product and the card in real time to dynamically adjust the magnetic field strength. By utilizing its magnetostrictive deformation characteristics, the card shape is adaptively deformed according to the actual shape of the wall panel to fit the wall panel surface. The magnetostrictive hardening characteristics are then used to rapidly increase the card stiffness to achieve real-time locking, solving the problem that traditional rigid tooling cannot adapt to shape deviations. Moreover, based on the characteristics of the card support layer that can be quickly disassembled and the high softness of the interface layer and functional layer, the card can be flexibly adapted to different models. It is a design method based on the high-quality, high-precision and universal shape retention requirements of wall panel products. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of an intelligent shape-preserving card for aircraft wall panels based on magnetorheological elastomers and its control method;

[0024] Figure 2 This is a schematic diagram of the structure of an intelligent shape-preserving card based on magnetorheological elastomer;

[0025] Figure 3 It is a schematic diagram of the structure of large-sized, irregular and complex surface retaining tooling. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0027] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0028] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" are based on the directions or positional relationships described in the accompanying drawings and are intended only to facilitate and simplify the description of the present invention and should not be construed as limiting the present invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is intended to distinguish between objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly, and may refer to direct connection or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0032] The specific invention content of the present invention includes the following contents:

[0033] 1. Use MRE to make pallets and achieve dynamic shape control

[0034] The core of this invention lies in the use of magnetorheological elastomers to create intelligent, shape-retaining pallets. Leveraging their magneto-deformable properties, the pallet's shape can be dynamically adjusted to the actual shape of the aircraft's panels. Magneto-hardening rapidly increases the pallet's rigidity, achieving real-time locking. By precisely controlling the intensity and distribution of the magnetic field, the pallet adaptively conforms to the panel surface during assembly, resolving the problem of traditional rigid tooling's inability to adapt to shape deviations.

[0035] 2. Magnetic domain grid partitioning control technology

[0036] The card board is divided into independently controlled magnetic domain units (30mm square grid), each unit is equipped with a micro electromagnetic coil (25mm diameter, soft magnetic core).

[0037] Through magnetic field gradient design (the edge magnetic field strength is 1.2-1.5 times that of the central area), the boundary deformation resistance is compensated to ensure the overall deformation consistency.

[0038] The introduction of a liquid cooling system effectively controls the heat generated by the electromagnetic coil during operation, ensuring the stability and reliability of the tooling under complex working conditions.

[0039] 3. Sensor feedback system

[0040] The contact pressure distribution is inverted by the resistance change. This function requires direct contact with the wall plate to be realized. Its specific functions include:

[0041] Resistance change monitoring: The interface layer uses conductive materials (silver nanowires and PDMS composite conductive coating) to monitor contact pressure through resistance changes.

[0042] Pressure distribution inversion: Utilizing the relationship between resistance change and contact pressure, the contact pressure distribution between the wall panel and the card plate is inverted in real time through a sensor network and data processing algorithm.

[0043] Optimize contact performance: By real-time monitoring of contact pressure distribution, the magnetic field distribution can be dynamically adjusted to optimize the contact performance between the card and the wall panel.

[0044] 4. Quickly adapt to new models

[0045] The supporting layer and the functional layer are connected by bolts and snap-on structures, which enable quick and damage-free disassembly and replacement, making it easy to adapt to different models.

[0046] After replacing the supporting layer, the functional layer and the sensing layer have a certain degree of softness when there is no magnetic field, so they can be directly connected to the new supporting layer and quickly adapted to the new model.

[0047] For example, the preparation process and structure of the intelligent shape-preserving card board are described. Figure 2As shown, the intelligent shape-preserving card board consists of three layers: a support layer, a functional layer, and an interface layer. The support layer is made of 6061-T6 aluminum alloy. CNC machining technology is used to machine a groove array inside the aluminum alloy base layer. M8 and M10 bolt holes are set on the side of the groove. The M8 bolt hole is used to connect to the functional layer, and the M10 bolt hole is used to connect to the aircraft wall panel to fix the wall panel. A single groove is 30mm long, 30mm wide, and 25-30mm deep. The groove spacing is 25-30mm. The electromagnetic coil is built into the groove. The electromagnetic coil consists of a 25mm diameter coil and a soft magnetic core. A wire groove is set in the groove to connect each electromagnetic coil. The wire groove is 5-8mm wide and 3-5mm deep. It is arranged at the bottom of the groove and avoids the bolt hole area. A liquid cooling channel is designed inside the groove for heat dissipation.

[0048] The functional layer is primarily made of silicone rubber (Shore A25 / 40), mixed with carbonyl iron powder (30%-40% by volume), and has a thickness of 15mm. The two components are mixed in an internal mixer and then vulcanized by high-temperature compression molding. The mold is then cooled to room temperature in a high-intensity magnetic field to enhance the magnetorheological effect. Prior to vulcanization, a metal-carbon fiber composite bushing with an embedded stainless steel threaded sleeve is embedded within the functional layer to address compatibility issues between the flexible material and the rigid connection, preventing damage to the functional layer caused by bolt preload. The functional layer is bolted to the support layer using M8 titanium alloy bolts for easy disassembly and replacement.

[0049] The interface layer is a flexible sensing coating with an integrated piezoresistive microstructure array. It's made of silver nanowires and PDMS (polydimethylsiloxane). The material is screen-printed onto the functional layer and then cured at high temperature. The thickness is 1mm. The interface layer is in direct contact with the wall panel, inverting the contact pressure distribution through resistance changes. This is used to monitor the contact pressure distribution in real time, dynamically adjust the magnetic field distribution, and optimize the contact performance between the card and the wall panel. A modified epoxy resin film is used to bond the functional layer and interface layer, followed by heat-pressing and curing.

[0050] The electromagnetic control system includes a multi-stage coil drive system, a power supply and control module, and a cooling system. The multi-stage coil drive system utilizes a multi-stage coil-driven magnetic field control system, with each electromagnetic coil unit independently controlled, enabling a finer magnetic field distribution. The coils are made of a highly conductive copper alloy to reduce resistance loss and increase magnetic field response speed. The power supply and control module is equipped with a high-precision programmable DC power supply capable of outputting stable current, ensuring precise control of magnetic field strength. The power module integrates a feedback control system for real-time monitoring of magnetic field strength and dynamic adjustment. The 48-channel programmable DC power supply independently controls four electromagnetic units per channel. The cooling system utilizes microchannel liquid cooling technology, with coolant circulating through the channels to remove excess heat, maintain coil temperatures within a safe range, and prevent overheating under high current.

[0051] Figure 1A flowchart of an intelligent, shape-retaining card for aircraft sidings based on magnetorheological elastomers and its control method is provided in accordance with an embodiment of the present disclosure. As shown in the flowchart, after the aircraft siding is mounted, the intelligent shape-retaining card is locked and connected to the frame. When the card's interface layer contacts the siding, the contact pressure causes a change in resistance. A sensor network and data processing algorithm then invert the contact pressure distribution between the siding and card in real time to determine the contact status between the siding and card. Based on the card's fit test data, areas without pressure are identified as gaps, requiring the card to extend toward the siding; areas with pressure greater than 5 kPa are identified as over-limit areas, requiring the card to retract in the opposite direction. The card's deformation direction is determined by the direction of the magnetic field. According to Ampere's right-hand rule, the direction of the current determines the direction of the magnetic field. This means that changing the current direction can control the direction of the magnetic field, and thus the deformation direction of the card. When the magnetic field generated by the electromagnetic coil is directed downward, the magnetic particles in the card are subjected to a downward force, resulting in a magnetostrictive effect, causing the card to deform downward. When the magnetic field is directed upward, the magnetic particles are subjected to an upward force, causing the card to deform upward. By adjusting the current in the electromagnetic coil, the magnetic field strength is controlled within a range of 50-100 mT, enabling precise control of the cardboard's deformation. This deformation process achieves flexible contact between the cardboard and the wall panel. After the deformation and contact are complete and stabilized, the contact is tested. Pressure must be present in all areas and less than 5 kPa. If this is not achieved, further adjustments are made based on the data. Once the contact is achieved, the magnetic field is rapidly increased to 200-300 mT and maintained for 30 seconds, increasing the shear modulus of the functional layer from 0.8 MPa to 10 MPa, locking the cardboard into the target shape. After the assembly task is completed, the magnetic field is turned off, returning the cardboard to its flexible state and releasing the cardboard lock. This illustrates the workflow and deformation mechanism of the intelligent shape-preserving cardboard. Furthermore, the cardboard can be quickly adapted to new machine models by replacing the support layer.

[0052] The support layer and functional layer are connected via bolts and snap-fit mechanisms, allowing for quick and non-destructive removal of the support layer to accommodate new models. The support layer can then be customized or replaced based on the theoretical shape of the panel for different models or different parts of the same model. A laser scanner is used to determine whether the internal shape of the support layer conforms to the theoretical panel shape. Once this conformity is met, the electromagnetic control system, including the electromagnetic coil, is installed within the new support layer. Because the functional and sensor layers exhibit a certain degree of flexibility in the absence of a magnetic field, they can be directly connected to the new support layer to accommodate the new model.

[0053] For example, the application of intelligent shape-keeping pallets in actual shape-keeping tooling is further demonstrated by taking the large-sized special-shaped fuselage wall panel shape-keeping tooling as an example. Figure 3 shown. Figure 3The large-sized special-shaped fuselage wall panel shape-preserving fixture includes a frame, a card plate, a lifting point and a support point. In order to provide as much support surface as possible for the wall panel shape and avoid the problem of large local deformation of the wall panel product caused by the large span of the positioner, the corresponding intelligent deformable shape card plates (about 15 places) are set according to the position of the wall panel connection frame. According to the rigid deformation trend of the card plate itself, the frame circumferential direction is divided into 3 sections, and each section of the card plate is provided with 3 joints with wall panel shape to connect with the aircraft wall panel. The connection holes are wall panel and long stringer or sheet metal frame connection holes. The wall panel connection holes can effectively control deformation, that is, according to the principle of uniform distribution in the frame circumferential plane, 9 wall panel and frame or long stringer connection holes are selected for wall panel clamping, forming a dot matrix distribution method to ensure that the wall panel shape does not deform.

[0054] The main frame, lifting points and support points form a rigid reinforcement frame, which is used to enhance the rigidity of the shape-retaining tooling itself, ensure that the wall panel shape-retaining tooling can position and support the wall panel products, and have strong deformation resistance when subjected to external loads. Through the combined shape-retaining structure attached to the wall panel shape, the main frame adopts a large-section plate-welded square interface as the main beam and a plate-welded I-beam section as the auxiliary beam, which is screwed together. The connection process joints ensure that the wall panel products are tightened during the lifting and transfer process. Support ball heads are designed around the shape-retaining tooling as support points, which are used to position and support large-sized wall panels during the overall assembly of the upper components and the rear body. After the wall panel is connected to the long girder and frame, it is connected and assembled with the shape-retaining tooling. During the lifting and assembly process, the shape-retaining tooling always keeps the wall panel shape in line with the assembly requirements, thereby improving the assembly accuracy and quality.

[0055] The foregoing description shows and describes preferred embodiments of the present invention. As previously mentioned, it should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the inventive concept described herein by the teachings above or by techniques or knowledge in the relevant art. Modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the appended claims.

Claims

1. An intelligent shape-preserving cardboard for aircraft wall panels based on magnetorheological elastomer, characterized in that: Set between the rigid frame and the aircraft wall panel, the intelligent shape-preserving card board includes: a support layer, a functional layer and an interface layer; The interface layer is an integrated piezoresistive microstructure array, which is bonded to the aircraft wall panel. The functional layer is a silicone rubber-based magnetorheological elastomer. The support layer's profile matches the aircraft wall panel's profile and is equipped with a groove array with built-in micro-electromagnetic coils for magnetic field domain control. The electromagnetic control system composed of the pressure sensing of the interface layer and the electromagnetic coils nested in the support layer adjusts the shape of the card to adapt to the actual shape of the aircraft wall panel.

2. The intelligent shape-preserving card board according to claim 1, characterized in that: The supporting layer adopts aluminum alloy frame; A wire groove is provided at the bottom of the groove for electrically connecting the electromagnetic control system with each electromagnetic coil; The groove is 30mm long, 30mm wide and 25-30mm deep, and the grooves are arranged at a spacing of 25-30mm; The supporting layer is fixedly connected to the functional layer by bolts, and is also fixedly connected to the wall panel by bolts.

3. The intelligent shape-preserving card board according to claim 1, characterized in that: The thickness of the functional layer is 15 mm.

4. The intelligent shape-preserving card board according to claim 1, characterized in that: The interface layer is a flexible sensing coating covering the surface of the functional layer with a thickness of 1mm. The flexible sensing coating is a composite material of silver nanowires and PDMS, and the contact pressure distribution is inverted by the change in resistance. The functional layer and the interface layer are connected by bonding using a modified epoxy resin film.

5. The intelligent shape-preserving card board according to claim 1, characterized in that: Each electromagnetic coil consists of a 25mm diameter coil and a soft magnetic core, and is independently controlled with a current of 5A.

6. The intelligent shape-maintaining card board according to claim 1, characterized in that: The electromagnetic coil is made of copper alloy material.

7. The intelligent shape-maintaining card board according to claim 1, characterized in that: The electromagnetic control system is used to monitor the contact between the card plate and the wall panel in real time according to the pressure distribution data of the interface layer, and to adjust the magnetic field strength and direction in different areas to achieve precise control of the deformation of the card plate.

8. The intelligent shape-preserving card board according to claim 1, characterized in that: Liquid cooling channels are designed inside the support layer to remove the heat generated by the electromagnetic coil during operation through coolant circulation, ensuring a stable working temperature of the tooling.

9. A method for controlling an intelligent shape-preserving plate for aircraft wall panels based on magnetorheological elastomers, characterized in that: Using the intelligent shape-maintaining card board according to any one of claims 1 to 8, the control method includes the following steps: Deformation stage: According to the preset control cycle, a 50-100mT magnetic field is applied based on the pressure distribution data of the interface layer to make the functional layer flexibly fit the actual shape of the wall panel; Locking stage: Increase the magnetic field to 200-300mT and maintain it for 30 seconds to increase the shear modulus of the functional layer from 0.8MPa to 10MPa, so that the smart shape-preserving card is locked in the target shape.

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