System for repairing a thermoplastic component of an aircraft structure

Abstract

The invention relates to a repair system (S) for repairing a thermoplastic component (C) of an aircraft structure comprising a region to be repaired (W), the repair system (S) comprising: a first shell (1), a second shell (2), a third shell (3), a system (9) for placing each chamber (1A, 2A, 3A) of the shells under vacuum; a heating device (5) configured to heat the region to be repaired (W) so as to melt it in order to repair it, 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 shell (2) and a thermally insulating member (6) so as to avoid any heat dissipation to the outside.

Description

Repair system for a thermoplastic component of an aircraft structure

[0001] The present invention relates to the field of repairing composite material components. The invention is particularly relevant to the repair of thermoplastic components of an aircraft structure.

[0002] An aircraft is known to consist of 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, which delimits the body of the aircraft and defines its structural envelope; the wing assembly, comprising the two wings and providing lift to the aircraft in flight; and the tail assembly, located at the rear of the aircraft and providing stability.

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

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

[0005] For example, it is known to manufacture an aircraft fuselage panel from composite material by impregnating layers of reinforcing fibers into 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 influence of heat. When the thermosetting matrix is ​​hot, it is molded to obtain the desired shape, for example, a curved one. Once cooled, the thermosetting matrix solidifies and is irreversibly set.

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

[0007] To repair such a defect, a patch, known as a "doubler," is applied to the surface of the component being repaired. The doubler, usually made of metal, is screwed or bolted onto the component. However, such a doubler increases the aircraft's mass, leading to increased 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 repair process by bonding is known in which a quantity of thermosetting matrix is ​​added between the doubler and the thermosetting component.

[0009] However, the manufacturing and repair of thermosetting composite components requires thermocompression molding, usually in an autoclave, which presents several drawbacks. An autoclave is extremely energy-intensive, and the manufacturing cycles are time-consuming. Polymerization is achieved by heating for more than eight hours. Consequently, the production rate is low.

[0010] There is also a desire to replace certain thermosetting matrix composite parts with thermoplastic matrix composite parts, which generally have a shorter manufacturing cycle and 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, typically 450°C, and placed 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 previously 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 process for repairing a thermoplastic component that allows for reliable repair without damaging the component.

[0014] The invention 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 reduced 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 predetermined shape 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 envelope 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 and third envelopes, a vacuum system configured to apply in each enclosure respectively a predetermined pressure lower than an 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 envelope,at least the area to be repaired on the thermoplastic component in such a way 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 prevent any heat dissipation to the outside of the repair system.

[0016] The repair system according to the invention allows a thermoplastic component to be repaired without altering its mechanical properties. Advantageously, it is no longer necessary to discard and replace a damaged thermoplastic component, as was the case in the prior art. The repair system, 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 envelope 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 component, on the one hand, and the mold with thermally insulating characteristics, on the other hand, prevent heat loss outside the repair system, which allows a sufficiently high temperature to be reached inside the repair system, and therefore in the area to be repaired of the thermoplastic component, to allow the thermoplastic material to melt.

[0019] The mold preserves the original shape of the thermoplastic component even during heating and softening of the thermoplastic material. The reinforcing plies of the thermoplastic component are also held in place, thus maintaining its mechanical properties.

[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 for repair. 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 possessing 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] In one aspect, the first chamber, which has an initial pressure, is between 0 and 900 MPa in absolute pressure, in order 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, with the absolute pressure ranging from 0 to 250 MPa, so as to position the second chamber in close contact with the thermoplastic component. This near-vacuum pressure allows the second chamber to consolidate the thermoplastic component during heating and subsequent cooling, preventing any risk of altering its geometry. If a thermoplastic patch is applied to repair the area, the second pressure allows the second chamber to consolidate the thermoplastic patch onto the thermoplastic component.

[0025] Preferably, the third chamber, which has a third pressure, has a pressure difference between an external pressure and the third pressure, ranging from 10 to 100 MPa, to avoid pressing the heating device against the thermoplastic component. This third pressure, close to the external pressure, prevents the heating device from leaving an imprint in the thermoplastic matrix of the softened component.

[0026] In one aspect, the heating device is configured to heat to temperatures of 350°C or higher, in order to reach the melting points of thermoplastic materials. Preferably, the heating device is configured to heat to temperatures of 450°C or higher, allowing for a faster temperature rise.

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

[0028] According to one aspect, the second layer 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%. This ensures that a sufficiently high temperature is reached within the repair system to soften the thermoplastic component.

[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] In 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 a second sealed chamber between the thermoplastic component and the second chamber. The heating device is configured to heat, through the second chamber, both the area to be repaired on the thermoplastic component and the thermoplastic patch, thereby co-consolidating them to repair the area. Advantageously, the repair system allows the thermoplastic matrices of the thermoplastic patch and the thermoplastic component to fuse together 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: mounting the repair system around the area to be repaired of the thermoplastic component, each enclosure being closed and sealed, applying, by means of the vacuum system, in each enclosure respectively a predetermined pressure lower than an external pressure on the repair system, and heating, by means of 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 predetermined shape of the thermoplastic component during heating,The mold possesses thermally insulating characteristics, and the thermally insulating element prevents heat loss outside the repair system, so as to reach a 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 process comprising a step of: applying a thermoplastic patch to the area to be repaired of the thermoplastic component, the repair system being 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,in order 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] This is a schematic representation of a thermoplastic component to be repaired and a thermoplastic patch.

[0038] This is a schematic representation of a thermoplastic component repair system according to a first embodiment.

[0039] This is a schematic representation of a thermoplastic component repair system according to a second embodiment.

[0040] This is a diagram of the steps of a repair process according to an implementation method of the invention.

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

[0042] An aircraft structure, as is known, 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 partially of 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, usually 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 the diagram, the thermoplastic component C is a large panel configured to form part of the aircraft's primary structure, in this case, the fuselage. By large dimension, we mean that the thermoplastic component C has at least one dimension greater than 5 m. It goes without saying 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 the diagram, the thermoplastic component C defines a first face C1 and a second face C2 opposite the first face C1. In this example, the first face C1 corresponds to an internal face CI when the thermoplastic component C is mounted on the aircraft structure, and the second face C2 corresponds to an external 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 internal face CI extends inside the aircraft, and the external face CE extends outside the aircraft. It is understood that the internal face CI could alternatively correspond to the second face C2.

[0048] In 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 object (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 the thermoplastic component C, the component includes a repairable area W encompassing the defect. It is understood that the thermoplastic component C could include several defects and therefore several repairable areas W. In this example, the repairable area W is to be repaired by applying a thermoplastic patch Q, as will be described in more detail later. In the embodiment where the defect is a delamination defect, the repair can be carried out without applying a thermoplastic patch Q by heating the repairable area W 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 that 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 the following polymer types: PEEK, PAEK, PEKK, and PEI. 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 the, 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 applied. It goes without saying that the repair system S could cover a larger area than the repaired area 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] With further reference to the first envelope 1, it is configured to be mounted on the first face C1 of the thermoplastic component C, in this example on the inner face CI.

[0056] A first sealed enclosure 1A is defined between the first face C1 of the thermoplastic component C and the first casing 1. In this example, the repair system S includes 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 1A is thus sealed. The first enclosure 1A has a first pressure P1.

[0057] According to one aspect, a mold 4 is mounted in the first enclosure 1A, that is, between the first envelope 1 and the first face C1 of the thermoplastic component C.

[0058] 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. As an 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. The term "thermally insulating" means that the mold 4 is configured to prevent heat loss between the first enclosure 1A 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 one embodiment, mold 4 is made of a thermally insulating material. In practice, in this example, mold 4 is made of calcium silicate / alumina. It goes without saying that the material of mold 4 could be different; for example, any material configured to withstand a temperature of 350°C or higher and to prevent excessive heat loss, as defined previously.

[0062] In a second embodiment, the mold 4 includes a layer of 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 could be made of a metallic material. The layer of thermally insulating material enables it to perform its thermal insulation functions.

[0063] As shown in the figure, the repair system S includes a vacuum system 9 connected to the first enclosure 1A. The vacuum system 9 is configured to remove at least some of the air contained in the first enclosure 1A, so as to lower the first pressure P1 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 P1 is between 0 and 900 MPa in absolute pressure, 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 P1 is approximately 250 MPa in absolute pressure.

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

[0066] With reference to the diagram, 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 enclosure 2. In this example, the repair system S includes one or more second sealing gaskets 82, mounted at the ends of the second enclosure 2, between the second enclosure 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 the figure. In this example, the vacuum system 9 includes one or more drain tubes 90 mounted through the seals 81, 82, 83 to remove at least some of the air contained in each chamber 1A, 2A, 3A. The vacuum system 9 is configured to apply a pressure in each sealed chamber 1A, 2A, 3A that is 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 close 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, allows the thermoplastic patch Q to be held in place within the area of ​​the thermoplastic component C to be repaired, thus consolidating 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 include several, for example to repair several areas to be repaired W on the same thermoplastic component C.

[0073] With reference to the diagram, the heating device 5 and the thermally insulating element 6 are mounted, in this example, in the third enclosure 3A, between the second envelope 2 and the third envelope 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 envelope 3 made of a material that does not need to withstand high temperatures and therefore a less expensive material.

[0075] By "thermally insulating," we mean that the thermally insulating element 6 is configured to prevent heat loss between the third enclosure 3A and the environment outside the repair system S by more than 70%. Specifically, 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 silicate or alumina, or needle-punched glass. It goes without saying that the material of the thermally insulating element 6 could be different.

[0076] The heating device 5 is configured to heat, through the second envelope 2, the thermoplastic component C and the thermoplastic patch Q. In a preferred configuration, the heating device 5 is configured to heat to temperatures of 350°C or higher. Even more preferably, the heating device 5 is configured to heat to temperatures of 450°C or higher, so as to reach the melting temperatures of the thermoplastic materials. In this example, the heating device 5 is electrically connected to a power source, as shown in the figure. 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 blending their thermoplastic matrices. As described previously, during the heating of the heating device 5, 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 is ​​remelted for the repair.

[0078] The insulating characteristics of the mold 4 on one side (first face side C1) and of the thermally insulating element 6 on the other (second face side C2), described previously, limit heat dissipation outside the first layer 1 and the third layer 3, and therefore outside the repair system S. This allows all the heat emitted by the heating device 5 to be retained within the repair system S, i.e., between the first layer 1 and the third layer 3, thus reaching the temperature levels within the repair system S necessary for the thermoplastic component C and the thermoplastic patch Q to transition to a viscous state. The first layer 1 and the third layer 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 chosen from polyimide-type polymers.

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

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

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

[0083] In one embodiment, the repair system S comprises a first release film 71, mounted between the first face C1 of the thermoplastic component C and the first envelope 1, and a second release film 71, mounted between the second face C1 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 C1, 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 include a single release film 71 configured to be affixed to either face C1, C2 of the thermoplastic component C.

[0084] In one embodiment, the repair system S comprises a first drainage element 72 mounted in the first chamber 1A and a second drainage element 72 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 comprise a single drainage element 72 mounted in either chamber 1A or 2A.

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

[0086] A repair procedure for a thermoplastic component C of an aircraft structure will now be described, with reference to [reference to relevant document]. In this example, the thermoplastic component C is an aircraft fuselage panel. The thermoplastic component C has an area requiring repair W, resulting from an impact, for example. In this example, the thermoplastic component C is mounted on the aircraft structure. On the aircraft structure, the first face C1 corresponds to the inner face CI and the second face C2 corresponds to the outer face CE. In this example, the area requiring repair W is to be repaired using a thermoplastic patch Q. It is understood that the procedure works similarly 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 create 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 E1 of positioning the mold 4 opposite the first face C1 (here the inner face CI) of the thermoplastic component C. The first casing 1 is also mounted on this same first face C1. In this example, a first sealing element 81 is mounted on the periphery of the first casing 1, between the first casing 1 and the thermoplastic component C, thus forming the first sealed enclosure 1A. The mold 4 is then sandwiched between the thermoplastic component C and the first casing 1. In this example, a release film 71 (shown in the figure) is also mounted in the first enclosure 1A 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 around 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 element 5 opposite the second envelope 2, and then the thermally insulating element 6 opposite the heating element 5. The third envelope 3 is also positioned so as to cover the thermally insulating element 6, the heating element 5, and the second envelope 2. Preferably, a third sealing element 83 is mounted around the periphery of the third envelope 3, between the third envelope 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 envelope 3 preferably covering the second envelope 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 operate in 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 1A, 2A, 3A is evacuated. Three different pressure levels are preferably applied in the sealed enclosures 1A, 2A, 3A. In this example, the first pressure P1 of the first enclosure (1A) 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 external pressure to the repair system S and the third pressure P3 of the third enclosure (3A) is between 10 and 100 MPa.Such pressures P1, P2, P3 allow the mold 4 to be pressed against the first face C1 of the thermoplastic component C and the second face C2 of the thermoplastic component C to be protected by the second layer 2, which holds the thermoplastic patch Q in position within the area to be repaired W. The third layer 3 advantageously maintains the heating device 5 in substantial contact with the second layer 2. The third pressure P3 prevents the heating device 5 from being compressed against the thermoplastic component C, thus avoiding altering its shape and impregnating the softened material.

[0094] The process then includes a fourth step E4, which activates the heating device 5. In this example, the heating device heats to a temperature of 450°C, causing the thermoplastic matrix of the thermoplastic component C and the thermoplastic patch Q to transition to a viscous state in relation 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 required 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 mixture 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 switched off and the repaired thermoplastic component C is cooled. The pressures P1, P2, P3 in the three chambers 1A, 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 has cooled, the vacuum system 9 is switched off and the pressure P1, P2, P3 in each chamber 1A, 2A, 3A returns to approximately the same level as 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

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) having a repairable area (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 repairable area (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 area to be repaired (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 in each enclosure (1A, 2A, 3A) respectively a predetermined pressure (P1, P2, P3) lower than ambient pressure,external to 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 enclosure (2), at least the area to be repaired (W) of the thermoplastic component (C) so as to melt at least the thermoplastic component (C) and repair the area to be repaired (W), the mold (4) being configured to maintain the predefined shape of the thermoplastic component (C) during heating, and at least one thermally insulating element (6) mounted in the third enclosure (3A), the heating device (5) being mounted between the second enclosure (2) and the thermally insulating element (6), so as to prevent any heat dissipation to the outside of the repair system (S). Repair system (S) according to claim 1, wherein the first enclosure (1A) having a first pressure (P1), the first pressure (P1) 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. Repair system (S) according to any one of claims 1 to 2, wherein the second enclosure (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 enclosure (2) in intimate contact with the thermoplastic component (C). Repair system (S) according to any one of claims 1 to 3, wherein the third chamber (3A) having a third pressure (P3), the pressure difference between an external pressure to the repair system (S) and the third pressure (P3) is between 10 and 100 MPa, so as to avoid pressing the heating device (5) against the thermoplastic component (C). Repair system (S) according to any one of claims 1 to 4, wherein the heating device (5) is configured to heat to temperatures greater than or equal to 350°C. Repair system (S) according to any one of claims 1 to 5, wherein at least the second envelope (2) is made of a material configured to withstand temperatures greater than or equal to 350°C. Repair system (S) according to any one of claims 1 to 6, wherein the second envelope (2) is made of a material selected from polyimide-type polymers. Repair system (S) according to any one of claims 1 to 7, wherein the first layer (1) and / or the third layer (3) is made of a material selected from polyamide, thermoplastic elastomer and polyethylene type polymers. Repair system (S) according to any one of claims 1 to 8, wherein the thermally insulating element (6) has an insulating power of between 0.02 and 0.2 W / mK Assembly of a thermoplastic component (C) of an aircraft structure and a repair system (S) according to any 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). Assembly according to claim 10, wherein the repair area (W) of the thermoplastic component (C) is to be repaired by application of 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 repair area (W) of the thermoplastic component (C) and the thermoplastic patch (Q), so as to co-consolidate them to repair the repair area (W). A method for repairing a thermoplastic component (C) having a repairable area (W), the method being carried out using the repair system (S) according to any one of claims 1 to 9 and comprising the steps of: mounting the repair system (S) around the repairable area (W) of the thermoplastic component (C), each enclosure (1A, 2A, 3A) being closed and sealed; applying, using the vacuum system (9), in each enclosure (1A, 2A, 3A) respectively a predetermined pressure (P1, P2, P3) lower than an external pressure (Pext) on the repair system (S); and heating, using the heating device (5), at least the thermoplastic component (C) in the repairable area (W) to a temperature of at least 350°C, so as to melt it and repair the repairable area (W), the mold (4) maintaining the predetermined shape of the thermoplastic component (C) during heating.the mold (4) having thermally insulating characteristics and the thermally insulating element (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, the area to be repaired (W) of the thermoplastic component (C) being repaired by application of a thermoplastic patch (Q), the method comprising a step of: applying a thermoplastic patch (Q) to the area to be repaired (W) of the thermoplastic component (C), the repair system (S) being mounted around the thermoplastic component (C) and the thermoplastic patch (Q), each enclosure (1A, 2A, 3A) being closed and sealed, heating, by means of the heating device (5), heating the thermoplastic component (C) and the thermoplastic patch (Q) to a temperature of at least 350°C, so as to melt the thermoplastic component (C) and the thermoplastic patch (Q) at least in the area to be repaired (W) and repair the thermoplastic component (C),the mold (4) having thermally insulating characteristics and the thermally insulating element (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) and the thermoplastic patch (Q).

Images