Method using heat transfer blanket system

Abstract

This disclosure relates to a method for repairing an aircraft. The method includes energizing a heat transfer blanket comprising a heat energy storage medium with thermal energy from a heat source. The method further includes positioning a heat-curable patch on an outer surface of the aircraft. The heat-curable patch comprises an uncured polymer having a first temperature. The heat transfer blanket is applied to the heat-curable patch. Thermal energy is transferred between the heat transfer blanket and the heat-curable patch to raise the first temperature of the uncured polymer to a curing temperature, sustaining this temperature for a sufficient time to cure the polymer.

Description

Technical Field

[0001] This disclosure relates to a method for repairing the exterior of an aircraft using a heat transfer blanket. Background Technology

[0002] Laminated coatings, sealants, and composite structures are increasingly used in the aircraft industry. Sometimes, these coatings, sealants, and composite structures become damaged, requiring on-site repair rather than replacement of the entire panel or subassembly. Repair typically involves removing the damaged material and then forming a patch over the damaged area. Patch formation involves covering the repaired area with an organic resin or prepreg ply (e.g., a layer of woven material impregnated with an organic matrix resin (such as epoxy), such as graphite or carbon fiber). The repaired area is then cured, in some cases under pressure and at high temperatures. When done correctly, this curing involves a controlled heating profile at a predetermined temperature, held for sufficient time to allow the resin to cure, followed by a slow cooling profile.

[0003] The advantages of using composite materials in design include the ability to tailor the amount of material used to obtain effective structural components. Many composite designs with non-uniform cross-sections have been developed (e.g., laminate drop, wood panels, reinforcing elements, etc.). Heat sinks from these non-uniform cross-sections require increased thermal control to maintain uniform curing. The curing of resins used in composite materials (including those in thermocurable repair patches) is an exothermic reaction that requires heating to initiate. Without adequate control over heating or cooling, hot or cold spots can form during repair. Traditional heat blankets and control techniques aimed at reducing cold spots often exacerbate problems associated with hot spots, and vice versa. Existing portable repair equipment lacks both the required high pressure and the inherent temperature control capabilities of autoclaves. Therefore, repairs of complex structures are often inadequate due to poor temperature control and non-uniform temperature in the repair area, thus reducing the quality or structural capability of the repair.

[0004] Controlling the applied pressure and the temperature profile used for the repair is essential, as these affect the strength of the repair. Improper temperature control can significantly impact repair strength. Heating too quickly can vibrate and weaken the composite structure. Temperatures below the required curing temperature lead to poor adhesion, while temperatures above the required temperature can cause the heat-curable repair patch and surrounding material to burn. Fluctuating temperatures, especially during the curing process, can create a combination of these effects.

[0005] Curing of organic resin repairs is typically accomplished using electric heating blankets, IR lamps, or electric convection heaters. Electric heating blankets are the most common method. However, heating blankets can suffer from uneven heating, which can be compounded by underlying repair sites with variations in thickness and spars position. Monitoring the temperature of the repair site and controlling the heater power supply in response to follow a curve or maintain a relatively constant temperature to cure the resin without localized hot and cold spots can be challenging. This is especially true in cold environments where the electric heating blanket controller may constantly attempt to maintain the temperature and drive heat into the surrounding structure, unintentionally overheating and potentially causing thermal damage to the underlying layers.

[0006] In addition, sometimes heating and curing of resin coatings is required for on-site repairs of the aircraft exterior in the absence of power, for example. While open flame heaters can work, their use near the aircraft is generally not permitted, and / or they may be dangerous, bulky, and provide uneven heating. Summary of the Invention

[0007] This disclosure relates to a method for repairing an aircraft. The method includes energizing a heat transfer blanket comprising a heat energy storage medium with thermal energy from a heat source. The method further includes positioning a heat-curable patch on the outer surface of the aircraft. The heat-curable patch comprises an uncured polymer having a first temperature. The heat transfer blanket is applied to the heat-curable patch. Thermal energy is transferred between the heat transfer blanket and the heat-curable patch to raise the first temperature of the uncured polymer to a curing temperature, sustaining this temperature for a sufficient time to cure the polymer.

[0008] This disclosure also relates to a method for repairing an aircraft. The method includes energizing a heat transfer blanket comprising (i) a flexible container including an insulating material and (ii) a thermal energy storage medium disposed within the flexible container. Energizing the heat transfer blanket includes positioning the thermal energy storage medium in thermal communication with an aircraft engine, wherein thermal energy is transferred from the aircraft engine to the thermal energy storage medium. The method further includes positioning a thermocurable patch on an outer surface of the aircraft. The thermocurable patch comprises an uncured polymer having a first temperature. The heat transfer blanket is applied to the patch. Thermal energy is transferred between the heat transfer blanket and the thermocurable patch to raise the first temperature of the uncured polymer to a curing temperature for a sufficient time to cure the polymer.

[0009] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and not a limitation on the claimed teachings. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various aspects of this teaching and, together with the description, serve to explain the principles of this teaching.

[0011] Figure 1 A flowchart is shown of a method for using a heat transfer blanket according to an example of this disclosure.

[0012] Figure 2 A schematic cross-sectional side view of a heat transfer blanket according to an example of this disclosure is shown.

[0013] Figure 3 A schematic side view of a heat transfer blanket applied to the surface of an aircraft for the purpose of curing a patch, according to an example of this disclosure.

[0014] Figure 4 A schematic cross-sectional side view of a tile layer bonded together by an elastomeric polymer according to an example of the present disclosure is shown, which can be used as a thermal energy storage medium.

[0015] Figure 5 A schematic, angled top view of a slab layer bonded together by an elastomeric polymer according to an example of this disclosure is shown, which can be used as a thermal energy storage medium.

[0016] Figure 6 A schematic cross-sectional side view of a heat transfer blanket according to an example of this disclosure is shown.

[0017] Figure 7 A schematic cross-sectional side view of two thermal resistance pads optionally used during the curing of a thermosetting patch on an aircraft, according to an example of this disclosure, is shown.

[0018] Figure 8 A schematic cross-sectional side view of a thermal resistance pad according to an example of this disclosure is shown.

[0019] Figure 9 A schematic cross-sectional side view of a thermal resistance pad according to an example of this disclosure is shown.

[0020] Figure 10 A schematic cross-sectional side view of a thermal resistance pad according to an example of this disclosure is shown.

[0021] It should be noted that some details in the accompanying drawings have been simplified and drawn to facilitate understanding rather than to maintain strict structural accuracy, detail, and scale. Detailed Implementation

[0022] This teaching will now be referred to in detail, examples of which are shown in the accompanying drawings. Throughout the drawings, the same reference numerals are used to denote the same elements. In the following description, reference is made to the accompanying drawings, which form a part of it, and specific examples of practicing this teaching are shown therein by way of illustration. Therefore, the following description is merely exemplary.

[0023] The methods disclosed herein provide the ability to repair coatings, sealants, and / or thermosetting composites, for example, on the exterior of aircraft. For example, the method can be used to heat adhesives, sealants, prepregs, or other repair materials containing organic resins to a reasonable temperature to cure the organic resin at a high temperature, such as, for example, 120℉ or higher. The apparatus employed is portable and can be used for on-site coating repair (e.g., outdoors or in remote areas without available power) and when the resin is initially at a low temperature (e.g., 20℉ or lower).

[0024] Figure 1 A flowchart of a method for repairing an aircraft according to this disclosure is shown. (Reference) Figure 1 10. The method includes energizing the heat transfer blanket with heat energy from the surface of the aircraft engine. Figure 2 An example of a heat transfer blanket 100 is shown. The heat transfer blanket 100 includes a heat storage medium 104 that stores heat transferred from the surface of an aircraft engine. (As shown...) Figure 1 As described in section 20, the method further includes positioning the thermosetting patch on the outer surface of the aircraft. Reference will be made below. Figure 7 An example of the thermosetting patch 200 is described in more detail. The thermosetting patch 200 comprises an uncured polymer, as is known in the art. The heat transfer blanket can be energized before, after, and / or simultaneously with positioning the thermosetting patch on the aircraft. After energization, the heat transfer blanket 100 is applied to the thermosetting patch, as... Figure 1 As stated in the 30 places. Figure 1 As shown in section 40, heat is transferred between the heat transfer blanket 100 and the heat-curable patch 200 to raise the temperature of the uncured polymer in the heat-curable patch 200 to the curing temperature and maintain the curing time for a sufficient period of time. In this way, aircraft repair is achieved using the heat transfer blanket 100, which is not powered to generate heat.

[0025] Figure 2 It shows that it can be used Figure 1 The method involves a heat transfer blanket 100. The heat transfer blanket 100 includes a flexible container 102 containing insulating material 152. A heat storage medium 104 is disposed within the flexible container 102. One or more thermocouples are optionally in thermal communication with the heat storage medium 104.

[0026] The flexible container 102 may include any suitable insulation material 152. The insulation material 152 retains heat energy within the heat storage medium 104 to reduce unwanted heat loss and protects the user from burns that may occur from contact with the heat storage medium 104. Examples of suitable insulation materials 152 include ceramic insulation 152A, such as alumina insulation boards, capable of withstanding process temperatures up to 1700℉ or higher, and a fabric layer 152B, including glass (such as fiberglass), surrounding the ceramic insulation 152A. Other examples of insulation materials include foam insulation materials capable of withstanding the process temperatures to which the heat transfer blanket will be exposed, for example, ranging from about 300℉ or higher, such as from about 300℉ to about 600℉, or from about 300℉ to about 450℉. Examples of such foam insulation materials include foams containing silicone resin.

[0027] The thermal energy storage medium 104 includes a material used as a heat sink for storing and releasing thermal energy. Suitable materials may include, for example, at least one material selected from metal oxides or non-oxide ceramics, such as AlN, BeO, BN (cubic BN or hexagonal BN), diamond, and Al2O3, and combinations thereof. The thermal conductivity and specific heat capacity of some of these materials are shown in Table 1 below. Materials with relatively high thermal conductivity and specific heat capacity, such as AlN and BeO, can store a relatively large amount of thermal energy per unit mass, while also being able to rapidly transfer thermal energy for the purpose of storing or releasing thermal energy. An example of a commercially available material is the SHAPAL HI-M SOFT manufactured by Tokuyama Corporation of Tokyo, Japan. TM It is a hybrid combination of AlN and BN, which is easy to process into complex shapes, and therefore may have advantages for certain designs.

[0028] Table 1

[0029] thermal properties AIN BeO Al2O3 Thermal conductivity (W / mK) 170-200 209-330 35 Specific heat capacity (J / kg.K) 740 750-1020 880 Dielectric constant 9.7 6.1-7.5

[0030] Figure 1 The heat storage medium 104 used in the heat transfer blanket 100 comprises at least one layer 110 blank 112. The blanks 112 in each layer 110 are spaced apart and bonded together by an elastic polymer 114, which allows the heat transfer blanket to be flexible. (Reference) Figure 4 The spacing S between slabs 112 in the same layer can be, for example, in the range of about 0.02 inches to about 0.1 inches, such as about 0.04 inches to about 0.08 inches. Figure 5An angled top view of an example of layer 110 is shown. Spacing the slabs relatively close together increases the packing density of the slabs, thereby increasing the amount of heat energy that can be stored by each layer 110. On the other hand, spacing the slabs too close together may reduce the flexibility of layer 110, which in turn reduces the flexibility of heat transfer blanket 100.

[0031] The elastomeric polymer 114 can be any flexible polymer and can withstand a relatively high temperature of at least 120℉. In one example, the elastomeric polymer can withstand temperatures of 300℉ or higher, such as 400℉ to 650℉, or 550℉ to 610℉. An example of such an elastomeric polymer is silicone. A commercially available example of silicone is 3145RTV, which is available from Dow Corning of Midland, Michigan. In one example, the elastomeric polymer 114 is a crosslinked silicone. The preform 112 can be primed with a primer (such as DOWSIL) before applying the silicone. TM PR-1200 silicone primer (commercially available from Dow Chemical) is used to treat the substrate so that the silicone resin can adhere to it.

[0032] One or more layers 110 of the blank 112 can be attached to the flexible container 102 using any suitable attachment technique. Examples of suitable attachment techniques include using, for example, glass or other suitable thread to stitch an adhesive to the flexible container 102.

[0033] Another example of a suitable attachment technique involves using an adhesive, such as silicone resin, to attach layer 110. For example, any silicone resin taught herein can be used as an adhesive. In one example, layer 110 may be attached to the flexible container 102 only at the ends of each layer 110, which can provide flexibility to the heat transfer blanket 100. In another example, the blanks 112 of two or more layers 110 are not directly attached to each other, thus providing increased flexibility to the heat transfer blanket 100.

[0034] In an alternative embodiment, layer 110 may be allowed to float freely within the flexible container 102. In this embodiment, heat-permeable layer 118 may function to enclose and retain layer 110 within the flexible container 102. Heat-permeable layer 118 may be in direct thermal communication with the thermal energy storage medium 104. Heat-permeable layer 118 is made of a material that allows the thermal energy stored in the thermal energy storage medium 104 to be released through heat-permeable layer 118. For example, heat-permeable layer 118 may be thin enough (e.g., 0.001 inch to 0.01 inch thick, such as about 0.005 inches thick) to allow heat to be transferred rapidly through it. If desired, heat-permeable layer 118 may also be non-stick to avoid sticking to the heated object. A commercial example of such non-stick material is... It is a non-porous TEFLON (polytetrafluoroethylene) coated glass fiber fabric, known for its use in the manufacture of composite materials.

[0035] The heat transfer blanket 100 may include any desired number of layers 110 of thermal energy storage medium 104. For example, the heat transfer blanket 100 may include about 1 to about 10 layers 110, such as about 2 to about 6 layers 110. The number of layers can be selected to provide the desired amount of thermal energy storage capacity for the thickness of the heat transfer blanket 100 and the layers 110. The thickness of each layer 110 can be any suitable thickness, such as about 0.1 inches to about 1 inch, or about 0.15 inches to about 0.25 inches, or about 0.0157 inches. The thicker the layers 110, the fewer layers are available to achieve the desired thermal energy storage capacity. However, using more thin layers can provide a more flexible heat transfer blanket compared to using fewer, thicker layers to achieve the same thermal energy storage capacity. Although the thermal energy storage medium 104 used in the heat transfer blanket 100 has been described as comprising layers 110 of a blank 112, other thermal energy storage media may optionally be used. For example, instead of the slab layer described herein or otherwise, conductive granules or conductive plates, such as granules or plates comprising aluminum, may be used.

[0036] In one example, the heat transfer blanket described herein includes at least one thermocouple. For example, thermocouples 106 and 108 can be as follows: Figure 2 The arrangement is shown. One or more thermocouples 106 are positioned near the outer surface of the thermal energy storage medium 104 to measure the temperature near the outer surface; for example, this can provide data on the temperature near the surface of the thermocurable repair patch. One or more thermocouples 108 are positioned away from the outer surface within the thermal energy storage medium 104 to measure the temperature within the internal volume of the thermal energy storage medium 104. The data provided by the thermocouples can be used to monitor the surface temperature of the heated object and to provide feedback on when the thermal energy storage medium 104 is fully charged with thermal energy, or alternatively, when the thermal energy stored within the thermal energy storage medium 104 is fully released. For example, temperature difference data collected over time between thermocouples 106 and 108 can be used to calculate the heating rate, predict thermal energy charging time, and monitor the temperature at the interface and within the device to obtain the remaining heat or cold storage. Thermocouple plug 116 can be used to connect the thermocouples to a device (not shown), such as, for example, a handheld, battery-powered computer, for calculating output based on the data and displaying the output to the user.

[0037] Figure 2A heat storage flap 119 is further shown, which can optionally be attached to the flexible container 102 of the heat transfer blanket 100. The heat storage flap 119 may include an insulation material 152, such as any insulation material taught herein with respect to the flexible container 102. The heat storage flap can be opened when the heat transfer blanket 100 is charged with thermal energy and / or used to heat an object, such as... Figure 2 As shown. Figure 6 As shown, the heat storage flap 119 can be closed to cover the heat permeation layer 118 and / or the heat storage medium 104, thereby completely enclosing the heat storage medium 104 within the insulating shell of the flexible container 102 and the heat storage flap 119, so as to more effectively retain the heat energy within the heat storage medium 104.

[0038] In one instance, any method of this disclosure further includes applying a thermal resistance pad 150 to the surface of a thermosetting patch 200, the thermal resistance pad 150 being positioned between the heat transfer blanket 100 and the thermosetting patch. Reference will now be made to... Figure 2 and Figure 7 The method of using the heat transfer blanket 100 and the optional thermal resistance pad 150 is described in detail below. Figure 2 A heat transfer blanket 100 is shown for heating to repair a thermocurable patch 200 comprising a composite material aircraft 210.

[0039] The method may include positioning the heat storage medium 104 of the heat transfer blanket 100 in relation to a heat source 101 having a suitable high temperature. Figure 2 Thermal connectivity, for example, temperatures ranging from about 120℉ to about 1700℉, or from about 120℉ to about 600℉. An example heat source is an engine, such as, for example, an aircraft engine. As heat energy is transferred from the aircraft engine 101 to the heat storage medium 104, the heat storage medium 104 is then energized until it reaches a desired temperature. For example, the heat storage medium 104 may be heated to a temperature ranging from about 120℉ to about 600℉ during energization. These temperatures provide a reasonable temperature at which organic resins used in many repair materials can be cured without being too high to damage the materials used to manufacture the heat transfer blanket. Instead of the aircraft engine or other sources, any other heat source on the aircraft may be used. For example, the heat source may include heated exhaust parts, such as engine exhaust nozzles, engine exhaust decks, or bleed air exhaust systems. Other heat sources separate from the aircraft may also be used.

[0040] The amount of energy stored in the heat transfer blanket is a function of the specific heat capacity of the heat storage medium, as well as the mass and temperature of the heat storage medium after charging. Examples of specific heat capacities for heat storage media can range from approximately 120 J / kgK to approximately 1500 J / kgK, such as from approximately 700 J / kgK to approximately 1200 J / kgK. A higher specific heat capacity means a greater amount of heat energy can be stored for a given mass of heat storage medium. The actual amount of heat energy stored can vary considerably. A higher thermal conductivity of the heat storage medium results in faster heat transfer to and from the heat transfer blanket. For example, thermal conductivity can be 30 W / MK or higher, such as from approximately 150 W / MK to approximately 400 W / MK.

[0041] Figure 7 An example of patch 200 is shown, comprising a fibrous material (referred herein to as prepreg laminate 202) of one or more laminates prepreg-impregnated with resin. One or more filler laminates 204 may optionally be used together with prepreg laminate 202 as part of patch 200, as is known in the art. An adhesive film 214 may be applied to the surface of aircraft 210 between aircraft 210 and patch 200. The damaged composite surface may be scraped or tapered prior to patch application, as is known in the art, to provide sufficient load transfer between the patch and the composite when the repair patch is bonded to the composite.

[0042] The heat transfer blanket 100 is energized with thermal energy and then positioned on the patch 200 for a duration sufficient to provide heat to the patch for curing. If it is necessary to reduce the temperature at the surface of the patch 200 (compared to the temperature of the heat storage medium 104), one or more thermal resistance pads 150 may optionally be applied between the heat transfer blanket 100 and the patch 200. As the heat storage medium 104 of the heat transfer blanket cools, the thermal resistance pads 150 may be gradually removed over time to maintain the desired temperature at the surface of the patch 200. Figure 3 Examples of heat transfer blankets 100 with and without thermal resistance pads 150, applied to the surface of an aircraft for the purpose of curing a patch (not shown), are shown. After curing, the heat transfer blanket 100 and optional thermal resistance pads can be removed from the patch 200. The heat transfer blanket 100 can be flexible enough to allow the same heat transfer blanket to be used on both flat and corrugated surfaces, such as... Figure 3 As shown.

[0043] Figures 8 to 10A thermal barrier pad 150 is shown that can be used in conjunction with a heat transfer blanket as described herein. The thermal barrier pad 150 includes an insulating material 152 and an outer shell layer 154 surrounding the insulating material 152. As an example, the insulating material 152 includes a selection from glass-containing fabrics, ceramic wadding, foam, and combinations thereof. The specific insulating material 152 or combination of materials used will depend on the desired level of insulation and the temperature to which the thermal barrier pad 150 will be exposed, etc. For example, when a relatively small amount of insulation is required, a glass-containing fabric can be used to provide increased heat transfer, while when a relatively large amount of insulation is required, a ceramic wadding can be used to provide reduced heat transfer compared to that achieved when using a glass-containing fabric. If desired, one or more layers of glass-containing fabric can be combined with foam or ceramic wadding to achieve still a larger amount of insulation, thereby providing reduced heat transfer compared to that achieved when using foam or ceramic wadding without additional glass-containing fabric layers. Figure 8 An example of a thermal resistance pad 150 is shown, wherein the insulation material 152 is a fabric containing glass, such as glass fiber. Figure 8 The outer shell layer 154 comprises a glass-containing fabric, such as fiberglass, optionally coated with a non-stick coating. The non-stick coating may be a fluoropolymer, such as polytetrafluoroethylene (PTFE). Examples of commercially available fabrics used for the outer shell layer 154 are: It is a non-porous PTFE-coated glass fiber. The outer shell layer 154 can withstand temperatures of at least 120℉, for example, from about 300℉ to about 650℉ or higher. In applications where the processing temperature exceeds 650℉, PTFE is typically not used in the fabric. For example, the fabric can be made of S-glass (a type of woven glass fiber) or ceramic fiber, such as Nextel 312, 720, or 610 manufactured by 3M in Saint Paul, Minnesota. If desired, the thermocouple 106 can optionally be arranged in the pad, as shown in the figure. Figures 8 to 10 As shown. For example, one or more thermocouples 106 may be positioned close to the outer surface of the thermal resistance pad 150.

[0044] Figure 9 An example of a thermal resistance pad 150 is shown, wherein the insulation material 152 comprises a ceramic cotton wadding 152A, such as alumina cotton, and a fabric layer 152B containing glass (such as glass fiber) surrounding the ceramic cotton wadding 152A. The fabric layer 152B is a separate layer from the outer shell layer 154 and can be used to contain the ceramic cotton wadding 152A independently of the outer shell layer 154 (e.g., in the case where the outer shell layer 154 is removed), and to provide additional insulation. The fabric layer 152B can be the same as or different from the outer shell layer 154. In one example, the outer shell layer 154 can be used with the material described above for... Figure 8 The description is the same.

[0045] Figure 10 An example of a thermal resistance pad 150 is shown, wherein the insulation material 152 comprises foam, such as silicone foam. The outer shell layer 154 can be coupled with the above-mentioned... Figure 8 The description is the same.

[0046] The thermal resistance pad 150 can be used as a separate pad, independent of the heat transfer blanket described herein. Optionally, at least one thermal resistance pad 150 can be attached to the heat transfer blanket 100. For example, one or more thermal resistance pads 150 can be attached to the flexible container 102 of any heat transfer blanket 100, in place of or other than the heat storage flap 119. In an example, the heat storage flap 119 includes at least one thermal resistance pad 150, for example... Figure 8 , 9 Two to four of any of the 10 thermal resistance pads 150, or any combination thereof. The thermal resistance pads 150 can be made of any number of flexible insulating materials and can be stacked between the heat transfer blanket and the heat-curable repair patch to reduce the rate of heat transfer. When the heat storage device is fully charged, it may be too hot (or too cold) and may require a specific rate of heat transfer. One or more thermal resistance pads can be placed between the heat transfer blanket and the heat-curable repair patch to reduce the rate of heat transfer. During heating or cooling, thermal resistance pads can be added or removed to maintain the heating rate as the heat transfer blanket depletes, or to accelerate the heating rate or limit the repair site to a maximum temperature. Thermocouples on the thermal resistance pads and the heat transfer blanket can be monitored and / or data recorded using a battery-powered handheld device to facilitate proper curing repair. The method disclosed herein is described as repairing the exterior of an aircraft using a heat transfer blanket. However, the method can also be used to repair other vehicles by energizing the heat transfer blanket using any desired heat source.

[0047] Example

[0048] Example 1 – Curing Prepreg via Heat Transfer from Aluminum Plate

[0049] An aluminum sheet approximately 1 / 2” thick was placed in a 350℉ oven to absorb heat. The aluminum sheet was used in the experiment to approximate the heat storage medium used in the heat transfer blanket disclosed herein. A hot plate was placed on top of a frozen prepreg (whose specified curing temperature was greater than approximately 250℉ for at least approximately 90 minutes for curing). A layer of ARMALON and woven glass fabric (acting as a thermal resistance pad) was placed between the prepreg and the heated aluminum. The heat from the aluminum cured the prepreg.

[0050] Example 2 – Calculation of Heating Blanket Thickness

[0051] The thickness of the blanket disclosed herein will depend on the specific heat capacity and heat capacity of the materials used to manufacture the blanket, as well as the amount of energy required to raise the temperature of the material to be repaired. Specific heat capacity (C pHeat capacity (Q) is the amount of heat required to raise the temperature of a unit mass of a substance by 1°C. It is the ability of a material to absorb or release heat. Q = m × C p (T1-T2), where m is the mass (Kg) and T is the temperature (°K).

[0052] For example, if the PMC area to be repaired is 10” × 10” × 0.5” thick, and assuming the PMC density is 1.6 g / cc, then the PMC to be repaired will have a mass of approximately 1.311 kg. Assuming the PMC is at a temperature of 20℉ (266°K) and will be heated to 150℉ (339°K), and the C of the PMC... p If the value is 1110 J / Kg-K, then the heat energy (Q) required to raise the PMC to the required temperature is 1.311Kg×1110J / Kg-K(339K-266K)=106,230J.

[0053] Assuming the heating blanket is made of AlN, with a temperature of 300℉ (422°K), a specific heat of 740 J / kg⁻¹K, and the blanket needs to dissipate heat to 150℉, then the mass of AlN required to achieve a heat capacity of 106,230 J is 106,230 J / (740(422-339)) = 1.72 kg of AlN. Assuming the density of AlN is 3.26 g / cc, and the AlN is a 10” square panel, then the thickness of the AlN is approximately 0.32” or 8.128 mm. With a fill density of 85.9%, the thickness is 0.38” or 9.7 mm.

[0054] Taking heat transfer losses into account, the AlN storage blanket can be larger than the calculated size (e.g., twice the size), which would be approximately 0.6” or 16mm. For example, if there were a 0.6” thick AlN storage medium blanket, it would be a 10” square and broken down with a fill factor of 85.9%. It would be 51.5 cubic inches or 844.6 cc. Its weight would be 2.75 kg (6 lbs).

[0055] If the mass of the heat blanket on the engine is heated to 400℉ and then cooled to 120℉ (the lowest instance temperature for curing composite materials), it will be able to release 228,051 joules, as calculated by the following heat capacity equation: Q=m×C p (T1-T2)=2.75Kg×740×(477.6K-339K)=228,051 Joules.

[0056] While this teaching has been described with respect to one or more embodiments, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. Furthermore, while a particular feature of this teaching may be relevant only to one disclosure of several embodiments, such a feature may be combined with one or more other features of other embodiments, as may be desirable and advantageous for any given or particular function. Moreover, with regard to the terms “including,” “includes,” “having,” “has,” “with,” or variations thereof used in the detailed description and claims, these terms are intended to include in a manner similar to the term “comprising.” Furthermore, in the discussion and claims herein, the term “about” indicates that the listed values ​​may be varied, provided that such variation does not result in a process or structure inconsistent with the intended purpose described herein. Finally, “exemplary” indicates that the description is used only as an example and not implying that it is ideal. Furthermore, this disclosure includes examples pursuant to the following terms:

[0057] Clause 1. A method for repairing an aircraft, the method comprising: energizing a heat transfer blanket containing a heat storage medium with thermal energy from a heat source; positioning a heat-curable patch on an outer surface of the aircraft, the heat-curable patch comprising an uncured polymer having a first temperature; applying the heat transfer blanket to the heat-curable patch; and transferring thermal energy between the heat transfer blanket and the heat-curable patch to raise the first temperature of the uncured polymer to a curing temperature for a sufficient time to cure the polymer.

[0058] Clause 2. The method according to Clause 1, wherein the thermal energy storage medium comprises a material selected from AlN, BeO, BN, diamond, Al2O3 and combinations thereof.

[0059] Clause 3. The method according to Clause 1 or 2, wherein the thermal energy storage medium comprises AlN.

[0060] Clause 4. The method according to any one of Clauses 1-3, wherein the heat source is an aircraft engine and energizing the heat transfer blanket comprises: positioning the heat storage medium in thermal communication with the aircraft engine; and energizing the heat storage medium by transferring heat energy from the aircraft engine to the heat storage medium.

[0061] Clause 5. The method according to Clause 4, wherein the thermal energy storage medium is heated to a temperature ranging from about 120℉ to about 600℉ during the charging period.

[0062] Clause 6. The method according to any one of Clauses 1-5, wherein the heat transfer blanket comprises: a flexible container containing insulating material; and

[0063] The thermal energy storage medium disposed within the flexible container.

[0064] Clause 7. The method according to Clause 6, wherein the insulation material comprises a glass fiber fabric shell filled with ceramic cotton board.

[0065] Clause 8. The method according to Clause 6 or 7, wherein the insulation material comprises a foam containing silicone resin.

[0066] Clause 9. The method according to any one of Clauses 6-8, wherein the thermal energy storage medium comprises one or more layers of slabs, each layer of slabs being bonded together by an elastomeric polymer.

[0067] Clause 10. The method according to Clause 9, wherein the slab comprises at least one material selected from AlN, BeO, BN, diamond and Al2O3 and combinations thereof.

[0068] Clause 11. The method according to Clause 9 or 10, wherein the elastomeric polymer comprises a silicone resin.

[0069] Clause 12. The method according to any one of Clauses 1-11, further comprising determining a temperature near the surface of the thermosetting patch.

[0070] Clause 13. The method according to any one of Clauses 1-12, wherein the heat transfer blanket further comprises a heat-permeable layer in direct thermal communication with the heat storage medium.

[0071] Clause 14. The method according to Clause 13, wherein the heat-transmitting layer comprises glass fibers coated with a fluoropolymer.

[0072] Clause 15. The method according to any one of Clauses 1-14, further comprising applying a thermal resistance pad to the surface of the thermocurable patch, the thermal resistance pad being positioned between the heat transfer blanket and the thermocurable patch.

[0073] Clause 16. A method for repairing an aircraft, the method comprising: energizing a heat transfer blanket, the heat transfer blanket comprising (i) a flexible container containing an insulating material and (ii) a thermal energy storage medium disposed within the flexible container, wherein energizing the heat transfer blanket comprises positioning the thermal energy storage medium in thermal communication with an aircraft engine, thermal energy being transferred from the aircraft engine to the thermal energy storage medium; positioning a thermocurable patch on an outer surface of the aircraft, the thermocurable patch comprising an uncured polymer having a first temperature; applying the heat transfer blanket to the patch; and transferring thermal energy between the heat transfer blanket and the thermocurable patch to raise the first temperature of the uncured polymer to a curing temperature for a sufficient duration to cure the polymer.

[0074] Clause 17. The method according to Clause 16, wherein the thermal energy storage medium comprises one or more layers of slabs, each layer of the slabs being bonded together by an elastomeric polymer.

[0075] Clause 18. The method according to Clause 17, wherein the slab comprises at least one material selected from AlN, BeO, BN, diamond and Al2O3 and combinations thereof.

[0076] Clause 19. The method according to Clause 18, wherein the heat transfer blanket further comprises a heat-permeable layer in direct thermal communication with the heat storage medium.

[0077] Clause 20. The method according to any one of Clauses 16-19 further comprises applying a thermal resistance pad to the surface of the thermosetting patch, the thermal resistance pad being positioned between the heat transfer blanket and the thermosetting patch.

[0078] It should be understood that variations or alternatives to the above-disclosed features and functions, and other features and functions, can be combined into many other different systems or applications. Various substitutions, modifications, changes, or improvements that are not currently foreseeable or anticipated by those skilled in the art can then be made to them, and these are also intended to be covered by the claims.

Claims

1. A method for repairing an aircraft (210), the method comprising: The heat transfer blanket, which includes a heat storage medium (104), is energized by heat energy from the heat source (101); A thermosetting patch (200) is positioned on the outer surface of the aircraft (210), the thermosetting patch (200) comprising an uncured polymer having a first temperature; The heat transfer blanket (100) is applied to the heat-curable patch (200); and Heat is transferred between the heat transfer blanket (100) and the heat-curable patch (200) to raise the first temperature of the uncured polymer to the curing temperature for a sufficient period of time to cure the polymer. The thermal energy storage medium (104) comprises materials selected from AlN, BeO, BN, diamond, Al2O3, and combinations thereof. The heat transfer blanket (100) includes: a flexible container (102) comprising an insulating material, and a heat storage medium (104) disposed within the flexible container (102). The thermal energy storage medium (104) comprises one or more layers (110) of blanks (112), wherein the blanks (112) in each layer (110) are bonded together by an elastomeric polymer (114), and The elastomeric polymer (114) mentioned above includes silicone resin.

2. The method according to claim 1, wherein the heat source (101) is an aircraft engine and charging the heat transfer blanket (100) comprises: The thermal energy storage medium (104) is positioned to be in thermal communication with the engine of the aircraft (210); and The thermal energy storage medium (104) is energized by transferring thermal energy from the engine of the aircraft (210) to the thermal energy storage medium (104).

3. The method according to claim 2, wherein the thermal energy storage medium (104) is heated to a temperature in the range of 120℉ to 600℉ during charging.

4. The method according to claim 1, wherein the insulation material comprises a glass fiber fabric (152B) shell filled with ceramic cotton batting (152A).

5. The method according to claim 1, wherein the insulating material comprises a foam containing silicone resin.

6. The method according to claim 1, wherein the slab (112) comprises at least one material selected from AlN, BeO, BN, diamond and Al2O3 and combinations thereof.

7. The method of claim 1, further comprising determining the temperature of the surface near the thermocurable patch (200).

8. The method according to claim 1, wherein the heat transfer blanket (100) further comprises a heat-permeable layer in direct thermal communication with the heat storage medium (104).

9. The method of claim 8, wherein the heat-transmitting layer comprises glass fiber coated with a fluoropolymer.

10. The method of claim 1, further comprising applying a thermal resistance pad to the surface of the thermocurable patch, the thermal resistance pad being positioned between the heat transfer blanket and the thermocurable patch.

11. A method for repairing an aircraft (210), the method comprising: The heat transfer blanket (100) is charged, the heat transfer blanket (100) comprising (i) a flexible container (102) containing insulating material and (ii) a thermal energy storage medium (104) disposed within the flexible container (102), wherein charging the heat transfer blanket (100) comprises positioning the thermal energy storage medium (104) in thermal communication with the engine of the aircraft (210), and thermal energy is transferred from the engine of the aircraft (210) to the thermal energy storage medium (104); A thermosetting patch is positioned on the outer surface of the aircraft, the thermosetting patch comprising an uncured polymer having a first temperature; The heat transfer blanket (100) is applied to the patch (200); and Heat is transferred between the heat transfer blanket (100) and the heat-curable patch (200) to raise the first temperature of the uncured polymer to the curing temperature for a sufficient period of time to cure the polymer.

12. The method of claim 11, wherein the thermal energy storage medium (104) comprises a blank (112) of one or more layers (110), wherein the blank (112) in each layer (110) is bonded together by an elastomeric polymer (114).

13. The method according to claim 12, wherein the slab (112) comprises at least one material selected from AlN, BeO, BN, diamond and Al2O3 and combinations thereof.

14. The method according to claim 13, wherein the heat transfer blanket (100) further comprises a heat-permeable layer in direct thermal communication with the heat storage medium (104).

15. The method of claim 11, further comprising applying a thermal resistance pad (150) to the surface of the thermocurable patch, the thermal resistance pad being positioned between the heat transfer blanket (100) and the thermocurable patch (200).

Images