Repair system for a thermoplastic component of an aircraft structure

Abstract

A repair system (S) for a thermoplastic component (C) of an aircraft structure having a repairable area (W), the repair system (S) comprising: a first flexible envelope (1) defining with a first face (C1) of the thermoplastic component (C) a first sealed enclosure (1A); a second flexible envelope (2) defining with a second face (C2) of the thermoplastic component (C) a second sealed enclosure (2A); a third flexible envelope (3) defining with the second envelope (2) a third sealed enclosure (3A); a vacuum system (9) for each enclosure (1A, 2A, 3A);a heating device (5) configured to heat the area to be repaired (W) so as to melt it for repair, a mold (4) being configured to maintain a predefined shape of the thermoplastic component (C) during heating, the heating device (5) being mounted between the second jacket (2) and a thermally insulating element (6), so as to prevent any heat loss to the outside. Figure of the abstract: Figure 2;

Description

Title of the invention: System for repairing a thermoplastic component of an aircraft structure technical field

[0001] The present invention relates to the field of repairing components made of composite materials. The invention is particularly aimed at the field of repairing thermoplastic components of an aircraft structure.

[0002] As is known, an aircraft comprises a primary structure through which mechanical forces are transmitted and a secondary structure mounted on the primary structure. The primary structure includes in particular the fuselage, delimiting the body of the aircraft and defining its structural envelope, the wing assembly, comprising the two wings and enabling the aircraft to generate lift in flight, and the empennage, located at the rear of the aircraft and enabling its stability.

[0003] The components forming the primary structure are generally large panels and may have a curved profile to ensure the aerodynamics of the aircraft.

[0004] In order to reduce the mass of aircraft, the aircraft structure is increasingly being made of composite material.

[0005] In this respect, it is known to manufacture, for example, an aircraft fuselage panel from composite material by impregnating layers of reinforcing fibers in a thermosetting polymer matrix. Such a thermosetting matrix is ​​set by polymerization, that is, by means of a chemical reaction during which it changes from a liquid or viscous state to a solid state under the effect of heat. When the thermosetting matrix is ​​hot, it is molded to obtain the desired shape, for example, a curved shape. Once cooled, the thermosetting matrix solidifies and is irreversibly set.

[0006] During the manufacture of the component, or for example when the aircraft is in operation, defects may appear in its structure. For example, a foreign object may become lodged within the thickness of the component during its manufacture. Debris encountered in flight or during a ground taxiing phase of the aircraft may also cause an impact, for example, on the fuselage.

[0007] To repair such a defect, it is known to apply a patch, known as a "doubler," to the surface of the component to be repaired. The doubler, usually made of metal, is screwed or bolted onto the component. However, such a doubler increases the mass of the aircraft, resulting in an increase in its Fuel consumption. Furthermore, adding the doubler to the fuselage can affect the aircraft's aerodynamics and therefore its performance.

[0008] To overcome this drawback, a bonding repair process is known in which a quantity of thermosetting matrix is ​​added between the doubler and the thermosetting component.

[0009] However, the manufacture and repair of thermosetting composite components require thermocompression molding, generally in an autoclave, which presents numerous drawbacks. An autoclave is extremely energy-intensive, and the manufacturing cycles are time-consuming. Polymerization is achieved by heating for more than eight hours. The manufacturing rate is therefore low.

[0010] Also, there is a desire to replace certain thermosetting matrix composite parts with thermoplastic matrix composite parts which generally have a shorter manufacturing cycle and which have good mechanical resistance.

[0011] A thermoplastic component is formed from reinforcing fibers impregnated in the thermoplastic matrix, which is known to those skilled in the art as a prepreg material or "prepreg". The prepreg material is heated to very high temperatures, generally 450°C, and positioned in a mold for shaping, for example in a press.

[0012] However, in the event of a defect, the processes applied to thermosetting matrix components and described above are not applicable to thermoplastic matrices. Indeed, unlike a thermosetting matrix which solidifies irreversibly once manufactured, the very high temperatures required to melt the thermoplastic matrix lead to softening, or even liquefaction, of the entire component to be repaired, which can alter its geometry.

[0013] In other words, there is currently no method for repairing a thermoplastic component that allows for reliable repair without damaging the component.

[0014] The invention thus aims to eliminate at least some of these drawbacks by providing a reliable and efficient system and method for repairing a thermoplastic component. In particular, the invention aims to repair the thermoplastic component without altering its mechanical properties, while simultaneously ensuring that the aircraft's mass is limited and its aerodynamics remain unchanged. PRESENTATION OF THE INVENTION

[0015] The invention relates to a system for repairing a thermoplastic component of an aircraft structure, the thermoplastic component having a shape predetermined and defining a first face and a second face opposite the first face, the thermoplastic component having an area to be repaired, the repair system comprising: • a first flexible envelope configured to be mounted on the first face of the thermoplastic component at least opposite the area to be repaired, a first sealed enclosure being defined between the thermoplastic component and the first envelope, • a mold having a profile representative of the predetermined shape of the thermoplastic component, the mold being configured to be mounted in the first enclosure, the mold having thermally insulating characteristics, the first enclosure being configured to hold the mold against the first face of the thermoplastic component, • a second flexible envelope configured to be mounted on the second face of the thermoplastic component at least opposite the area to be repaired, a second sealed enclosure being defined between the thermoplastic component and the second envelope, • a third flexible envelope configured to be mounted on the second face of the thermoplastic component, the second envelope being configured to be mounted between the thermoplastic component and the third envelope, a third sealed enclosure being defined between the second envelope and the third envelope, • a vacuum system configured to apply a predetermined pressure in each chamber, lower than the ambient pressure external to the repair system, • at least one heating device mounted in the third enclosure, the heating device being configured to heat, through the second enclosure, at least the area to be repaired of the thermoplastic component so as to melt at least the thermoplastic component and repair the area to be repaired, the mold being configured to maintain the predefined shape of the thermoplastic component during heating, and • at least one thermally insulating element mounted in the third enclosure, the heating device being mounted between the second enclosure and the thermally insulating element, so as to avoid any thermal dispersion to the outside of the repair system.

[0016] The repair system according to the invention makes it possible to repair a thermoplastic component without altering its mechanical properties. Advantageously, it is no longer necessary to discard a damaged thermoplastic component and replace it, as was the case in the prior art. The system The repair unit, installed locally next to the area to be repaired, is also compact and easy to handle. The repair system allows for localized heating for a localized repair, without the need to heat the entire thermoplastic component.

[0017] The second flexible sheath protects the thermoplastic component from the heating device, while allowing heat transmission to soften the thermoplastic material of the thermoplastic component.

[0018] The thermally insulating element, on the one hand, and the mold having thermally insulating characteristics, on the other hand, make it possible to avoid heat loss outside the repair system, which makes it possible to reach inside the repair system, and therefore in the area to be repaired of the thermoplastic component, a temperature high enough to allow the melting of the thermoplastic material.

[0019] The mold allows the initial shape of the thermoplastic component to be maintained even during heating and softening of the thermoplastic material. The reinforcing folds of the thermoplastic component are also held in place, which helps to preserve the mechanical properties of the thermoplastic component.

[0020] Advantageously, only one mold on one side of the thermoplastic component and one heating device on the opposite side, thus sandwiching the thermoplastic component, are required to repair it. The system is therefore compact while ensuring optimal efficiency.

[0021] According to one aspect, the area to be repaired of the thermoplastic component being to be repaired by application of a thermoplastic patch, the thermoplastic patch being configured to be mounted in the second sealed enclosure between the thermoplastic component and the second envelope, the heating device is configured to heat, through the second envelope, at least the area to be repaired of the thermoplastic component and the thermoplastic patch, so as to fuse them to repair the area to be repaired.

[0022] The thermally insulating element and the mold having thermally insulating properties make it possible to reach in the area to be repaired of the thermoplastic component and the thermoplastic patch, a temperature high enough to allow the melting of the thermoplastic material and thus the mixing of the thermoplastic component and the thermoplastic patch in the area to be repaired.

[0023] According to one aspect, the first chamber having a first pressure, the first pressure is between 0 and 900 MPa in absolute pressure, so as to press the mold against the thermoplastic component and ensure that the thermoplastic component retains its shape during heating. Thus, even when the thermoplastic matrix of the thermoplastic component is softened, the pressure ensures that the mold remains in place throughout the heating process.

[0024] In a preferred embodiment, the second chamber has a second pressure, the second pressure being between 0 and 250 MPa in absolute pressure, so as to position the second envelope in intimate contact with the thermoplastic component. Such a near-vacuum pressure allows the second envelope to consolidate the thermoplastic component during heating and then cooling, preventing any risk of altering its geometry. If a thermoplastic patch is applied to repair the area to be repaired, the second pressure allows the second envelope to consolidate the thermoplastic patch onto the thermoplastic component.

[0025] Preferably, the third chamber having a third pressure, the pressure difference between an external pressure on the repair system and the third pressure is between 10 and 100 MPa, so as to avoid pressing the heating device against the thermoplastic component. Thus, the third pressure being close to the external pressure prevents the heating device from leaving an imprint in the thermoplastic matrix of the softened thermoplastic component.

[0026] According to one aspect, the heating device is configured to heat to temperatures of 350°C or higher, so as to reach the melting temperatures of thermoplastic materials. Preferably, the heating device is configured to heat to temperatures of 450°C or higher, thereby accelerating the temperature rise.

[0027] Preferably, at least the second jacket is made of a material configured to withstand temperatures of 350°C or higher. Thus, the second jacket can be mounted between the heating device and the thermoplastic component to protect the latter and eliminate any risk of damage.

[0028] According to one aspect, the second envelope is made of a material chosen from polyimide-type polymers, allowing a material configured to withstand the melting temperatures of thermoplastic materials.

[0029] According to a preferred aspect, the first envelope and / or the third envelope is made of a material chosen from among polyamide, thermoplastic elastomer and polyethylene type polymers, allowing the use of a material whose cost is reduced, since it does not need to withstand temperatures greater than or equal to 350°C.

[0030] Preferably, the thermally insulating element has an insulating value between 0.02 and 0.2 W / mK, which limits the risk of heat flux loss by more than 70%. Thus, a temperature high enough to soften the thermoplastic component is reached inside the repair system.

[0031] The invention also relates to an assembly of a thermoplastic component of an aircraft structure and a repair system as described above, the first layer being mounted opposite the first face and the second and third layers being mounted opposite the second face. Advantageously, the repair system is compact and comprises a single heating device mounted on only one face, which allows for easy assembly and increases accessibility around the thermoplastic component even during the repair operation.

[0032] In one embodiment, the thermoplastic component defines an inner face, intended to be mounted internally relative to the aircraft structure, and an outer face, opposite the inner face. The first layer is mounted opposite the inner face, and the second and third layers are mounted opposite the outer face, so as to mount the heating device and the thermally insulating element externally relative to the aircraft structure. A single heating device mounted on the outer face of the thermoplastic component limits the size of the repair system inside the aircraft structure, thus facilitating its installation. The repair can advantageously be carried out in situ, directly on the aircraft. Furthermore, the heating device is thus easily accessible.

[0033] According to one aspect, the area to be repaired on the thermoplastic component is to be repaired by applying a thermoplastic patch. The thermoplastic patch is mounted in the second sealed enclosure between the thermoplastic component and the second enclosure. The heating device is configured to heat, through the second enclosure, both the area to be repaired on the thermoplastic component and the thermoplastic patch, so as to co-consolidate them to repair the area. Advantageously, the repair system allows the thermoplastic matrices of the thermoplastic patch and the thermoplastic component to fuse in the area to be repaired without risking alteration of the geometry and mechanical properties of the thermoplastic component.

[0034] Finally, the invention relates to a method for repairing a thermoplastic component comprising an area to be repaired, the method being carried out using the repair system as described above and comprising the steps of: • Mount the repair system around the area of ​​the thermoplastic component to be repaired, with each enclosure closed and sealed. • apply, using the vacuum system, a predetermined pressure in each chamber, lower than the external pressure on the repair system, and • heat, using the heating device, at least the thermoplastic component in the area to be repaired to a temperature of at least 350°C, so as to melt it and repair the area to be repaired, the mold maintaining the predefined shape of the thermoplastic component during heating, the mold having thermally insulating characteristics and the thermally insulating element preventing heat loss outside the repair system, so as to reach the temperature of at least 350°C in the thermoplastic component.

[0035] In one embodiment, the thermoplastic component having an area to be repaired by application of a thermoplastic patch, the method comprising a step consisting of: • Apply a thermoplastic patch to the area of ​​the thermoplastic component to be repaired, with the repair system mounted around the thermoplastic component and the thermoplastic patch, each enclosure being closed and sealed. • heating, by means of the heating device, heating the thermoplastic component and the thermoplastic patch to a temperature of at least 350°C, so as to melt the thermoplastic component and the thermoplastic patch at least in the area to be repaired and repair the thermoplastic component, the mold having thermally insulating characteristics and the thermally insulating element preventing heat loss outside the repair system, so as to reach a temperature of at least 350°C in the thermoplastic component and the thermoplastic patch. PRESENTATION OF THE FIGURES

[0036] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0037] Fig. 1 is a schematic representation of a thermoplastic component to be repaired and a thermoplastic patch.

[0038] Fig. 2 is a schematic representation of a system for repairing the thermoplastic component of Fig. 1 according to a first embodiment.

[0039] Fig. 3 is a schematic representation of a repair system for the thermoplastic component of Fig. 1 according to a second embodiment.

[0040] Fig. 4 is a diagram of the steps of a repair process according to one embodiment of the invention.

[0041] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0042] As is known, an aircraft structure comprises a primary structure through which mechanical forces are transmitted and a secondary structure mounted on the primary structure. According to one aspect of the invention, the aircraft structure is made at least in part from a thermoplastic matrix composite material. More specifically, the aircraft structure is made from the assembly of several thermoplastic components. The invention will be described hereafter with respect to one of the thermoplastic components of the aircraft structure.

[0043] The thermoplastic component is made from reinforcing fibers, generally layers of reinforcing fibers, impregnated in a thermoplastic matrix, which is known to those skilled in the art as a prepreg material or "prepreg". The prepreg material is heated to very high temperatures, between 300 and 380 °C, generally around 350 °C, and placed in a mold for shaping, for example in a press.

[0044] In this example, the thermoplastic material of the thermoplastic component is chosen from: PEEK (meaning Polyetheretherketone), PAEK (meaning Polyaryletherketones), PEKK (meaning Polyetherketoneketone), PEI (meaning Polyetherimides) type polymers.

[0045] In this example, with reference to [Fig. 1], the thermoplastic component C is a large panel configured to form an element of the aircraft's primary structure, in this example the fuselage. By large dimension, it is understood that the thermoplastic component C has at least one dimension greater than 5 m. It is understood that the thermoplastic component C could alternatively have smaller dimensions.

[0046] In practice, the thermoplastic component C has a predetermined shape, for example, flat or curved. For the sake of clarity in the figures, the invention will subsequently be described for a thermoplastic component C with a substantially flat shape.

[0047] With reference to [Fig. 1], the thermoplastic component C defines a first face Cl and a second face C2 opposite the first face CL. In this example, the first face Cl corresponds to an inner face CI when the thermoplastic component C is mounted on the aircraft structure, and the second face C2 corresponds to an outer face CE, that is, a face extending outside the aircraft structure when the thermoplastic component C is mounted on the aircraft. In other words, the inner face CI extends inside the aircraft and the The outer face CE extends to the outside of the aircraft. It goes without saying that the inner face CI could alternatively correspond to the second face C2.

[0048] According to one aspect, the thermoplastic component C has a defect. The defect may be due to local delamination of the composite plies. In this example, the defect is due to the introduction of a foreign body (known to those skilled in the art as FOD, meaning "Foreign Object Debris") into the material during its manufacture or due to an impact, for example. To guarantee the integrity of the aircraft structure, such a defect must be repaired.

[0049] In this respect, with reference to [Fig. 1], the thermoplastic component C includes a repair area W encompassing the defect. It is understood that the thermoplastic component C could include several defects and therefore several repair areas W. In this example, the repair area W is to be repaired by applying a thermoplastic patch Q, as will be described in more detail later. In the embodiment in which the defect is a delamination defect, the repair can be carried out without applying a thermoplastic patch Q by heating the repair area W so as to remelt it, as will be described in more detail later.

[0050] Preferably, the thermoplastic patch Q is made of a thermoplastic material similar to the thermoplastic material of the thermoplastic component C to allow the thermoplastic matrices to melt at a similar melting temperature, as will be described in more detail later. In this example, the thermoplastic patch Q is made of a material selected from PEEK, PAEK, PEKK, and PEI polymers. It is understood that the thermoplastic patch Q can alternatively be made of a different polymer than the thermoplastic material of the thermoplastic component C.

[0051] The area to be repaired W is repaired by means of a repair system S according to the invention, which will now be described.

[0052] With reference to [Fig.2], the repair system S comprises a first flexible envelope 1, a second flexible envelope 2 and a third flexible envelope 3, as well as a mold 4, a heating device 5 and a thermally insulating element 6 distributed on either side of the thermoplastic component C to be repaired.

[0053] In this example, the repair system S is mounted opposite the area to be repaired W, onto which a thermoplastic repair patch Q has been previously affixed. It is understood that the repair system S could cover a larger area than the area to be repaired W, for example, the entire thermoplastic component C.

[0054] Each envelope 1, 2, 3 is flexible and preferably takes the form of a flexible membrane, known to those skilled in the art as "bagging".

[0055] Still with reference to [Fig.2], the first envelope 1 is configured to be mounted on the first face Cl of the thermoplastic component C, in this example on the inner face CI.

[0056] A first sealed enclosure IA is defined between the first face Cl of the thermoplastic component C and the first casing 1. In this example, the repair system S comprises one or more first sealing gaskets 81, mounted at the ends of the first casing 1 (for example, around its entire periphery), between the first casing 1 and the thermoplastic component C. The first enclosure IA is thus sealed. The first enclosure IA has a first pressure PL

[0057] According to one aspect, a mold 4 is mounted in the first enclosure IA, that is to say between the first envelope 1 and the first face Cl of the thermoplastic component C.

[0058] The mold 4 is configured to maintain the predefined shape of the thermoplastic component C during heating, as will be described in more detail later.

[0059] For this purpose, the mold 4 has a profile representative of the predetermined shape of the thermoplastic component C. For example, if the shape of the thermoplastic component C is curved, as is the case for example of an aircraft fuselage panel, the profile of the mold 4 is curved with a similar radius of curvature.

[0060] According to one aspect of the invention, the mold 4 has thermally insulating characteristics. By the term "thermally insulating," it is understood that the mold 4 is configured to prevent heat loss between the first enclosure IA and the outside of the repair system S of more than 70%. Preferably, the mold 4 has an insulating value of between 0.02 and 0.2 W / mK

[0061] In a first embodiment, the mold 4 is made of a thermally insulating material. In practice, in this example, the mold 4 is made of calcium silicate / alumina. It goes without saying that the material of the mold 4 could be different, for example, any material configured to withstand a temperature greater than or equal to 350°C and to prevent excessive heat loss, as defined above.

[0062] In a second embodiment, the mold 4 includes a layer of an insulating material, for example, calcium or alumina powder. In this example, the mold 4 is made of a material resistant to temperatures of 350°C or higher, without necessarily possessing thermal insulation properties, thus allowing the use of a less expensive material. For example, the mold 4 can be made of a metallic material. The layer of thermally insulating material enables it to perform its thermal insulation functions.

[0063] As shown in [Fig. 3], the repair system S includes a vacuum system 9 connected to the first chamber IA. The vacuum system 9 is configured to remove at least some of the air contained in the first chamber IA, so as to lower the first pressure PI relative to an external pressure Pext to the repair system S. In this example, the external pressure Pext corresponds to the ambient pressure outside the aircraft.

[0064] Preferably, the first pressure PI is, in absolute pressure value, between 0 and 900 MPa, so as to keep the mold 4 pressed against the thermoplastic component C and ensure that the latter retains its shape during heating. In this example, the first pressure PI is, in absolute pressure, on the order of 250 MPa.

[0065] As described previously, the repair system S comprises a second flexible envelope 2 and a third flexible envelope 3.

[0066] With reference to [Fig. 2], the second envelope 2 and the third envelope 3 are configured to be mounted on the second face C2 of the thermoplastic component C, in this example on the outer face CE. In other words, the second envelope 2 and the third envelope 3 are mounted on a face opposite to the first envelope 1. In practice, the second envelope 2 is mounted between the thermoplastic component C and the third envelope 3.

[0067] A second sealed enclosure 2A is defined between the second face C2 of the thermoplastic component C and the second casing 2. In this example, the repair system S includes one or more second sealing gaskets 82, mounted at the ends of the second casing 2, between the second casing 2 and the thermoplastic component C. The second enclosure 2A is thus sealed. The second enclosure 2A has a second pressure P2.

[0068] Similarly, a third sealed enclosure 3A is defined between the second enclosure 2 and the third enclosure 3. In other words, the third enclosure 3A extends externally from the second enclosure 2A and completely covers the second enclosure 2 at least up to the second sealing joints 82. In this example, the repair system S includes one or more third sealing joints 83, mounted at the ends of the third enclosure 3, between the third enclosure 3 and the thermoplastic component C. The third enclosure 3A is thus hermetically sealed. The third enclosure 3A has a third pressure P3.

[0069] According to a preferred aspect, the vacuum system 9 described above is also connected to the second chamber 2A and the third chamber 3A, as shown in [Fig. 3]. In this example, the vacuum system 9 comprises one or more drainage duct(s) 90 mounted through the sealing joints. 81, 82, 83 to aspirate at least part of the air contained in each chamber IA, 2A, 3A. The vacuum system 9 is configured to apply in each sealed chamber IA, 2A, 3A a pressure lower than the external pressure Pext.

[0070] Preferably, the second pressure P2 is between 0 and 250 MPa in absolute pressure, so as to position the second envelope 2 in intimate contact with the thermoplastic patch Q and the thermoplastic component C. In this example, the second pressure P2 is between 30 and 50 MPa in absolute pressure. Such a pressure, close to a vacuum, makes it possible to hold the thermoplastic patch Q in place within the area to be repaired on the thermoplastic component C in order to consolidate it, particularly during heating.

[0071] Preferably, the difference between the external pressure on the repair system S and the third pressure P3 is between 10 and 100 MPa. In this example, the difference between the external pressure on the repair system S and the third pressure P3 is between 30 and 40 MPa. Such a pressure, close to the external pressure and well above the second pressure P2 in the second chamber 2A, prevents any element present in the third chamber 3A from being pressed against the thermoplastic component C.

[0072] As described previously, the repair system S comprises a heating device 5 and a thermally insulating element 6. A single heating device 5 is described, however it is understood that the repair system S could alternatively comprise several of them, for example to repair several areas to be repaired W on the same thermoplastic component C.

[0073] With reference to [Fig. 2], the heating device 5 and the thermally insulating element 6 are mounted, in this example, in the third enclosure 3A, between the second shell 2 and the third shell 3. In practice, in this example where the second face C2 corresponds to an external face CE of the aircraft structure, the heating device 5 and the thermally insulating element 6 are mounted externally to the aircraft structure. Thus, the bulky components of the repair system S are mounted only outside the aircraft structure, which facilitates their accessibility and limits the volume of the repair system S inside the aircraft structure, where space is already limited and accessibility is restricted.It goes without saying that the assembly could be reversed and that the heating device 5 and the thermally insulating element 6 could alternatively be mounted internally relative to the aircraft structure.

[0074] More specifically, the thermally insulating element 6 is mounted between the heating device 5 and the third envelope 3. The thermally insulating element 6 thus forms a thermal barrier for the third envelope 3, which allows the use of a third layer 3 made of a material that does not need to withstand high temperatures and therefore a less expensive material.

[0075] By "thermally insulating," it is understood that the thermally insulating element 6 is configured to prevent heat loss between the third enclosure 3A and the environment external to the repair system S by more than 70%. In particular, in this example, the thermally insulating element 6 is made of a material with an insulating value between 0.02 and 0.2 W / mK. In this example, the thermally insulating element 6 is made of calcium or alumina silicate or needle-punched glass. It is understood that the material of the thermally insulating element 6 could be different.

[0076] The heating device 5 is configured to heat, through the second casing 2, the thermoplastic component C and the thermoplastic patch Q. According to a preferred aspect, the heating device 5 is configured to heat to temperatures greater than or equal to 350°C. Even more preferably, the heating device 5 is configured to heat to temperatures greater than or equal to 450°C, so as to reach the melting temperatures of thermoplastic materials. Furthermore, the heating device 5 is electrically connected, in this example, to a power source, as shown in [Fig. 3]. It is understood that the heating device 5 could alternatively include an integrated power supply, for example, a battery.

[0077] The heating device 5 melts the thermoplastic matrix of the thermoplastic component C and the thermoplastic patch Q, thereby co-consolidating them and repairing the area to be repaired W. The term "co-consolidate" means that the thermoplastic matrices of the thermoplastic component C and the thermoplastic patch Q are fused and consolidated together. In other words, the thermoplastic component C and the thermoplastic patch Q are bonded to each other by mixing their thermoplastic matrices. As described previously, when the heating device 5 is heated, the mold 4, which is pressed against the thermoplastic component C on a face opposite the heating device 5, preserves the initial shape of the thermoplastic component C, which is thus not altered even after the thermoplastic matrix has been remelted for the repair.

[0078] The insulating characteristics of the mold 4 on one side (first face side Cl) and of the thermally insulating element 6 on the other (second face side C2), as described above, make it possible to limit heat dissipation outside the first envelope 1 and the third envelope 3, and therefore outside the repair system S. This allows all the heat emitted by the heating device 5 to be kept inside the repair system S, that is, between the first envelope 1 and the third envelope 3, to reach the inside of the repair system S the temperature levels required for the thermoplastic component C and the thermoplastic patch Q to transition to a viscous state. The first envelope 1 and the third envelope 3 are also advantageously protected from high temperatures and can be made of a less thermally resistant material.

[0079] In practice, preferably, the second jacket 2, mounted between the thermoplastic component C and the heating device 5, is made of a material configured to withstand temperatures greater than or equal to 350°C, preferably greater than 420°C. In this example, the second jacket 2 is made of a material selected from polyimide-type polymers.

[0080] Furthermore, due to the thermally insulating mold 4, on the one hand, and the thermally insulating element 6, on the other hand, the first envelope 1 and the third envelope 3 are made of a material that does not need to withstand such temperatures. This allows the use of less expensive flexible envelopes.

[0081] In this example, the first envelope 1 is made of a material chosen from polyamide-type polymers, thermoplastic elastomers and polyethylenes.

[0082] Similarly, the third sheath 3 is preferably made of a material selected from polyamide-type polymers, thermoplastic elastomers, and polyethylenes. More specifically, in this example, the first sheath 1 and the third sheath 3 are made of a similar material, which facilitates the assembly of the repair system S and limits the risk of reversing the flexible sheaths. It goes without saying that each sheath 1, 3 can alternatively be made of a different material.

[0083] In one embodiment, with reference to [Fig. 3], the repair system S comprises a first release film 71, mounted between the first face Cl of the thermoplastic component C and the first envelope 1, and a second release film 71, mounted between the second face Cl of the thermoplastic component C and the second envelope 2. Preferably, each release film 71 is configured to be positioned directly in contact with one of the faces Cl, C2 of the thermoplastic component C. Such release films 71 preferably include a non-stick surface layer and facilitate the removal of the repair system S after the repair has been carried out. In this example, each release film 71 is a polyimide film. It is understood that the material of the release film 71 could be different.Similarly, the repair system S could alternatively comprise a single release film 71 configured to be affixed to either of the faces Cl, C2 of the thermoplastic component C.

[0084] In one embodiment, the repair system S comprises a first drainage element 72 mounted in the first enclosure 1A and a second element of Drainage element 72 is mounted in the second chamber 2A to optimize the vacuum. In this example, each drainage element 72 is made of glass fabric. It is understood that the drainage element 72 could have a different shape and / or be made of a different material. Similarly, it is understood that the repair system S could alternatively consist of a single drainage element 72 mounted in either chamber IA or 2A.

[0085] The use of release films 71 and drainage elements 72 is advantageously independent.

[0086] A method for repairing a thermoplastic component C of an aircraft structure, with reference to [Fig. 4], will now be described. In this example, the thermoplastic component C is a fuselage panel of the aircraft. The thermoplastic component C has an area to be repaired W, due, for example, to an impact. In this example, the thermoplastic component C is mounted on the aircraft structure. On the aircraft structure, the first face Cl corresponds to the inner face CI and the second face C2 corresponds to the outer face CE. In this example, the area to be repaired W is to be repaired by means of a thermoplastic patch Q. It is understood that the method works analogously for a repair without the application of a thermoplastic patch Q.

[0087] In a preliminary step (not shown), the repair area W containing the defect was hollowed out to remove the damaged material. Preferably, since the thermoplastic component C has a stack of reinforcing plies impregnated in the thermoplastic matrix, a stepped cut was made to obtain a series of steps formed by the different plies. Such cleaning of the repair area is known to those skilled in the art and will not be described in further detail in this document. The thermoplastic patch Q is positioned over the repair area W so as to cover it. In the case of a delamination defect, for example, it is not necessary to hollow out the repair area W, and the application of a thermoplastic patch Q is unnecessary.

[0088] The process includes a first step El of positioning the mold 4 opposite the first face Cl (here the inner face CI) of the thermoplastic component C. The first shell 1 is also mounted on this same first face CL. In this example, a first sealing element 81 is mounted at the periphery of the first shell 1, between the first shell 1 and the thermoplastic component C, and forms the first sealed enclosure IA. The mold 4 is then sandwiched between the thermoplastic component C and the first shell 1. In this example, a release film 71 (shown in [Fig. 3]) is also mounted in the first enclosure IA between the mold 4 and the thermoplastic component C before the first sealing element 81 is attached.

[0089] In this same step, an operator positions the second envelope 2 opposite the second face C2 (here the outer face CE) of the thermoplastic component C. The second envelope 2 is positioned substantially opposite the first envelope 1. Preferably, a second sealing element 82 is mounted on the periphery of the second envelope 2, between the second envelope 2 and the thermoplastic component C, thus forming the second sealed enclosure 2A. In this example, a release film 71 is also mounted in the second enclosure 2A between the second envelope 2 and the thermoplastic component C before the second sealing element 82 is attached.

[0090] In practice, the positioning of the first envelope 1 and the second envelope 2 can be carried out successively or simultaneously since they are mounted on either side of the thermoplastic component C.

[0091] In a second step E2, the operator positions the heating device 5 opposite the second enclosure 2, and then the thermally insulating element 6 opposite the heating device 5. The third enclosure 3 is also positioned so as to cover the thermally insulating element 6, the heating device 5, and the second enclosure 2. Preferably, a third sealing element 83 is mounted around the periphery of the third enclosure 3, between the third enclosure 3 and the thermoplastic component C, thus forming the third sealed enclosure 3A. In practice, the third sealing element 83 is mounted on the second face C2 substantially adjacent to the second sealing element 82, with the third enclosure 3 preferably covering the second enclosure 2 and the second sealing element 82.

[0092] An external positioning of the heating device 5 relative to the aircraft structure is advantageously practical, since it is not necessary to move within a limited and constrained space inside the aircraft structure.

[0093] When the three enclosures 1, 2, 3 are hermetically sealed, in a third step E3, the vacuum system 9 is activated and the air in each sealed enclosure IA, 2A, 3A is evacuated. Three different pressure levels are preferably applied in the sealed enclosures IA, 2A, 3A. In this example, the first pressure PI of the first enclosure (IA) is, in absolute pressure, between 0 and 900 MPa, the second pressure P2 of the second enclosure (2A) is, in absolute pressure, between 0 and 250 MPa, and the difference between the pressure outside the repair system S and the third pressure P3 of the third enclosure (3A) is between 10 and 100 MPa. Such pressures PI, P2, P3 allow the mold 4 to be pressed against the first face Cl of the thermoplastic component C and to protect the second face C2 of the thermoplastic component C thanks to the second envelope 2 which holds the thermoplastic patch in position Q in the area to be repaired W. The third envelope 3 advantageously maintains the heating device 5 substantially in contact with the second envelope 2. The third pressure P3 makes it possible not to compress the heating device 5 against the thermoplastic component C so as not to alter its shape and not to impregnate the softened material.

[0094] The process then includes a fourth step E4 of activating the heating device 5. In this example, the heating device heats to a temperature of 450°C, which allows the thermoplastic matrix of the thermoplastic component C and the thermoplastic patch Q to transition to a viscous state with respect to the heating device 5. The softened thermoplastic matrices of the thermoplastic component C and the thermoplastic patch Q mix, and the mold 4 allows the thermoplastic component C to retain its initial shape. The thermally insulating material of the mold 4 on the first face C1 and of the thermally insulating element 6 on the second face C2 limit heat dissipation outside the repair system S. The high temperatures necessary to achieve the viscous state of the thermoplastic matrices are thus reached.Advantageously, this unilateral heating allows the heat to be concentrated on the side of the second face C2 and promotes melting of the thermoplastic patch Q while promoting a mixing of thermoplastic materials to achieve a robust repair.

[0095] When the thermoplastic matrices of the thermoplastic component C and the thermoplastic patch Q have mixed, the heating device 5 is stopped and the repaired thermoplastic component C is cooled. The pressures P1, P2, P3 in the three chambers IA, 2A, 3A are maintained so as to preserve the shape of the thermoplastic component C until it has completely cooled.

[0096] When the repaired thermoplastic component C is cooled, the vacuum system 9 is stopped and the pressure PI, P2, P3 in each chamber IA, 2A, 3A returns to approximately equal to the external pressure. The repair system S can then be removed in step E5. The thermoplastic component C is repaired and its mechanical properties are preserved.

[0097] Thanks to the repair system according to the invention, a local repair of a thermoplastic matrix component can be carried out and any risk of alteration of the thermoplastic component is eliminated.

Claims

Claims

1. A repair system (S) for a thermoplastic component (C) of an aircraft structure, the thermoplastic component (C) having a predetermined shape and defining a first face (C1) and a second face (C2) opposite the first face (C1), the thermoplastic component (C) comprising a repair zone (W), the repair system (S) comprising: A first flexible envelope (1) configured to be mounted on the first face (C1) of the thermoplastic component (C) at least opposite the repair zone (W), a first sealed enclosure (1A) being defined between the thermoplastic component (C) and the first envelope (1), a mold (4) having a profile representative of the predetermined shape of the thermoplastic component (C), the mold (4) being configured to be mounted in the first enclosure (1A), the mold (4) having thermally insulating characteristics, the first envelope (1) being configured to hold the mold (4) against the first face (C1) of the thermoplastic component (C), a second flexible envelope (2) configured to be mounted on the second face (C2) of the thermoplastic component (C) at least opposite the repair zone (W), a second sealed enclosure (2A) being defined between the thermoplastic component (C) and the second envelope (2), a third flexible envelope (3) configured to be mounted on the second face (C2) of the thermoplastic component (C), the second envelope (2) being configured to be mounted between the thermoplastic component (C) and the third envelope (3), a third sealed enclosure (3A) being defined between the second envelope (2) and the third envelope (3), a vacuum system (9) configured to apply respectively in each enclosure (IA, 2A, 3A) a predetermined pressure (PI, P2, P3) lower than an ambient pressure, outside the repair system (S), • at least one heating device (5) mounted in the third enclosure (3A), the heating device (5) being configured to heat, through the second envelope (2), at least the repair area (W) of the thermoplastic component (C) so as to at least melt the thermoplastic component (C) and repair the repair area (W), the mold (4) being configured to maintain the predefined shape of the thermoplastic component (C) during heating, and • at least one thermal insulation member (6) mounted in the third enclosure (3A), the heating device (5) being mounted between the second envelope (2) and the thermal insulation member (6), so as to prevent any thermal dissipation to the outside of the repair system (S).

2. Repair system (S) according to claim 1, wherein the first chamber (IA) having a first pressure (PI), the first pressure (PI) is, in absolute pressure, between 0 and 900 MPa, so as to press the mold (4) against the thermoplastic component (C) and ensure that the thermoplastic component (C) retains its shape during heating.

3. Repair system (S) according to one of claims 1 to 2, wherein the second chamber (2A) having a second pressure (P2), the second pressure (P2) is, in absolute pressure, between 0 and 250 MPa, so as to position the second envelope (2) in intimate contact with the thermoplastic component (C).

4. Repair system (S) according to one of claims 1 to 3, wherein the third chamber (3A) having a third pressure (P3), the pressure difference between an external pressure of the repair system (S) and the third pressure (P3) is between 10 and 100 MPa, so as to prevent the heating device (5) from being pressed against the thermoplastic component (C).

5. Repair system (S) according to one of claims 1 to 4, wherein the heating device (5) is configured to heat to temperatures higher than or equal to 350 °C.

6. Repair system (S) according to one of claims 1 to 5, wherein at least the second envelope (2) is made of a material configured to withstand temperatures higher than or equal to 350 °C.

7. Repair system (S) according to one of claims 1 to 6, wherein the second envelope (2) is made of a material chosen from polymers of the polyimide type.

8. Repair system (S) according to one of claims 1 to 7, wherein the first envelope (1) and / or the third envelope (3) is made of a material chosen from polymers of the polyamide type, thermoplastic elastomers and polyethylenes.

9. Repair system (S) according to one of claims 1 to 8, wherein the thermal insulation member (6) has an insulation power between 0.02 and 0.2 W / m.K.

10. An assembly consisting of a thermoplastic component (C) of an aircraft structure and a repair system (S) according to one of claims 1 to 9, the first envelope (1) being mounted opposite the first face (C1) and the second envelope (2) and the third envelope (3) being mounted opposite the second face (C2).

11. An assembly according to claim 10, in which the area to be repaired (W) of the thermoplastic component (C) is to be repaired by applying a thermoplastic patch (Q), the thermoplastic patch (Q) being mounted in the second sealed enclosure (2A) between the thermoplastic component (C) and the second envelope (2), the heating device (5) is configured to heat, through the second envelope (2), the area to be repaired (W) of the thermoplastic component (C) and the thermoplastic patch (Q), so as to co-consolidate them to repair the area to be repaired (W).

12. A method for repairing a thermoplastic component (C) having a repair zone (W), the method being carried out by means of the repair system (S) according to one of claims 1 to 9 and comprising the steps of:

13. • mounting the repair system (S) around the repair zone (W) of the thermoplastic component (C), each enclosure (IA, 2A, 3A) being closed and sealed, • applying, by means of the vacuum system (9), in each enclosure (IA, 2A, 3A) respectively a predetermined pressure (PI, P2, P3) lower than an external pressure (Pext) on the repair system (S), and • Using the heating device (5), heat at least the thermoplastic component (C) in the repair area (W) to a temperature of at least 350°C so as to melt it and repair the repair area (W), the mold (4) maintaining the predefined shape of the thermoplastic component (C) during heating, the mold (4) having thermally insulating characteristics and the thermal insulation member (6) preventing heat loss outside the repair system (S), so as to reach a temperature of at least 350°C in the thermoplastic component (C). A repair method according to claim 12, wherein the repair area (W) of the thermoplastic component (C) is to be repaired by applying a thermoplastic patch (Q), the method comprising the step of: Apply a thermoplastic patch (Q) to the repair zone (W) of the thermoplastic component (C), the repair system (S) being mounted around the thermoplastic component (C) and the thermoplastic patch (Q), each enclosure (IA, 2A, 3A) being closed and sealed, the heating, by means of the heating device (5), heating the thermoplastic component (C) and the thermoplastic patch (Q) up to a temperature at least equal to 350°C, so as to melt the thermoplastic component (C) and the thermoplastic patch (Q) at least in the repair zone (W) and repair the thermoplastic component (C), the mold (4) having thermally insulating characteristics and the thermal insulation member (6) preventing heat loss outside the repair system (S), so as to reach a temperature at least equal to 350°C in the thermoplastic component (C) and the thermoplastic patch (Q).