Compressed resin transfer perfusion method

Abstract

The invention discloses a compressed resin transfer infusion method and a method of compressed resin transfer infusion to form cavitation bubbles in a cured composite part. According to the method for transferring and pouring the compressed resin, a dry preform with a thermoplastic covering is placed on a lower mold. The upper mold is placed over the lower mold to create a potting and curing tool having a sealed cavity holding the dry preform, the sealed cavity defining a gap corresponding to a cavity volume corresponding to an amount of resin to potting the dry preform. Resin is injected into the gap of the sealed cavity while maintaining the infusion and curing tool at the infusion temperature. The upper mold is lowered to pour the dried preform, thereby forming a resin-poured preform. The resin infused preform is cured within an infusion and curing tool to form a cured composite part, where the curing occurs at a curing temperature higher than the infusion temperature.

Description

Technical Field

[0001] The present application relates generally to methods for forming composite structures and, more particularly, to high-speed resin infusion techniques. Background Art

[0002] Composite materials and structures (including resin-infused carbon fiber laminates) are often used in applications that require high strength and light weight. For example, in the aerospace industry, composite structures are increasingly used to form fuselages, wings, and other components of aircraft. However, conventional methods and systems for forming composite structures are often time and labor intensive, particularly for composite structures that combine complementary pieces such as fuselage skins and stringers into a single composite structure. In addition, using current aerospace composite manufacturing materials and methods to produce composite structures at high rates would require multiple sets of tools and processing equipment and the factory floor space required to accommodate the equipment. Therefore, it would be difficult and expensive to use current production methods to manufacture high-quality composite structures with aerospace-grade materials at high rates to meet performance characteristics, limiting the speed at which production can be achieved at an affordable cost.

[0003] Therefore, it is desirable to have a method and apparatus that takes into account at least some of the issues discussed above as well as other possible issues. For example, it is desirable to provide a system and method for forming composite structures that provides an increase in productivity, particularly for composite structures of larger size and complexity that are typically associated with the aerospace industry. Summary of the invention

[0004] Embodiments of the present application provide a method for compression resin transfer infusion. A dry preform with a thermoplastic veil is placed on a lower mold. An upper mold is placed above the lower mold to create an infusion and curing tool having a sealed cavity for holding the dry preform, the sealed cavity defining a gap corresponding to the cavity volume equivalent to the amount of resin infused into the dry preform. While maintaining the infusion and curing tool at an infusion temperature, resin is injected into the gap of the sealed cavity. The upper mold is lowered to infuse the dry preform to form a resin-infused preform. The resin-infused preform is cured within the infusion and curing tool to form a cured composite component, wherein curing occurs at a curing temperature higher than the infusion temperature.

[0005] Another embodiment of the present application provides a method for compressed resin transfer infusion. While maintaining the infusion and curing tool at an infusion temperature in the range of 130 degrees Celsius to 160 degrees Celsius, resin is injected into the gap of the sealed cavity of the infusion and curing tool. The upper mold of the infusion and curing tool is lowered to infuse the dry preform in the sealed cavity with the resin, thereby forming a resin-infused preform. The temperature of the infusion and curing tool is increased from the infusion temperature to the curing temperature at a slope of 1 degree Celsius to 3 degrees Celsius. The resin-infused preform is cured in the infusion and curing tool to form a cured composite part, wherein curing occurs at the curing temperature in the range of 165 degrees Celsius to 190 degrees Celsius, wherein the curing temperature is sufficient to expand and melt the thermoplastic covering in the dry preform.

[0006] Another embodiment of the present application provides a method of compressed resin transfer infusion to form cavitation bubbles in the cured composite part. While maintaining the infusion and curing tool at an infusion temperature in the range of 130 degrees Celsius to 160 degrees Celsius, resin is injected into the gap of the sealed cavity of the infusion and curing tool. The upper mold of the infusion and curing tool is lowered at a closing speed of 0.01 inches per minute to 0.2 inches per minute to infuse the dry preform in the sealed cavity with the resin through its thickness to form a resin-infused preform, the dry preform including a thermoplastic cover. The temperature of the infusion and curing tool is increased from the infusion temperature to a curing temperature. The resin-infused preform is cured in the infusion and curing tool to form a cured composite part, wherein curing occurs at the curing temperature of 165 degrees Celsius to 190 degrees Celsius and the curing pressure of 10 PSIG to 100 PSIG. After curing, the temperature of the infusion and curing tool is reduced, thereby generating cavitation bubbles in the thermoplastic covering as the thermoplastic covering cools below the melting temperature of the thermoplastic covering.

[0007] The features and functions may be achieved independently in various embodiments of the present application or may be combined in yet other embodiments, in which more details may be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The novel features believed to be characteristic of the exemplary embodiments are set forth in the appended claims. However, the exemplary embodiments and their preferred modes of use, additional objects and features will be better understood by reference to the following detailed description of exemplary embodiments of the present application when read in conjunction with the accompanying drawings, in which:

[0009] Figure 1 is a diagram of an aircraft according to an exemplary embodiment;

[0010] Figure 2 is an illustration of a block diagram of a manufacturing environment according to an illustrative embodiment;

[0011] Figure 3 is a graphical representation of a temperature graph of an infusion temperature and a curing temperature for a high speed resin infusion method according to an exemplary embodiment;

[0012] Figure 4 is a diagram of a resin infusion and curing tool according to an exemplary embodiment;

[0013] Figure 5 is a diagrammatic representation of the interaction between a thermoplastic cover and a resin prior to curing according to an exemplary embodiment;

[0014] Figure 6 is a diagrammatic representation of the interaction between a thermoplastic cover and a resin during curing according to an exemplary embodiment;

[0015] Figure 7 is a schematic diagram of the interaction between a thermoplastic cover and a resin after curing according to an exemplary embodiment;

[0016] Figure 8 is a flow chart of a compression resin transfer infusion method according to an exemplary embodiment;

[0017] Fig. 9 is a flow chart of a compression resin transfer infusion method according to an exemplary embodiment;

[0018] Fig.10 is a flow chart of a method for forming cavitation bubbles in a cured composite part by compression resin transfer infusion according to an exemplary embodiment;

[0019] Fig.11 is an illustration, in block diagram form, of an aircraft manufacturing and service method according to an illustrative embodiment; and

[0020] Fig.12 is an illustration, in block diagram form, of an aircraft in which an illustrative embodiment may be implemented. DETAILED DESCRIPTION

[0021] Now go to Figure 1 , depicts an illustration of an aircraft, according to an illustrative embodiment. Aircraft 100 has wing 102 and wing 104 attached to body 106. Aircraft 100 includes engine 108 attached to wing 102 and engine 110 attached to wing 104.

[0022] The body 106 has a tail section 112. Attached to the tail section 112 of the body 106 are a horizontal stabilizer 114, a horizontal stabilizer 116, and a vertical stabilizer 118.

[0023] Aircraft 100 is an example of an aircraft that may have a composite structure formed using a compression resin transfer infusion method. In some illustrative examples, body 106, wing 102, or portions of wing 104 may include a composite structure formed using a compression resin transfer infusion method.

[0024] Now go to Figure 2 , depicts an illustration of a block diagram of a manufacturing environment according to an illustrative embodiment. A resin infusion and curing tool 202 in the manufacturing environment is used to infuse resin 204 into a preform 206 and to cure the resin infused preform 208. A compression resin transfer infusion 210 performed using the resin infusion and curing tool 202 utilizes multiple temperatures.

[0025] The resin infusion and curing tool 202 includes an upper mold 218 and a lower mold 216 that are sealed together by a seal 222. A sealed cavity 220 exists between the upper mold 218 and the lower mold 216.

[0026] The compression resin transfer infusion 210 includes placing a dry preform 212 with a thermoplastic cover 214 on a lower mold 216 of the resin infusion and curing tool 202. The raw material of the dry preform 212 can be formed of any desired type of fiber. In some exemplary examples, the dry preform 212 can have a carbon fiber content of up to 70% by weight. In some exemplary examples, the raw material of the dry preform 212 can include carbon fiber with knitted wire, carbon fiber with knitted wire and thermoplastic cover, or carbon fiber with cover. In some exemplary examples, the dry preform 212 material can include a carbon fiber-based fabric, such as a non-crimped fabric (NCF). In some exemplary examples, the dry preform 212 material is a dry multi-axial non-crimped fabric (MA-NCF). In some exemplary examples, the dry preform 212 material is a dry unidirectional non-crimped fabric (UD-NCF).

[0027] An upper mold 218 is placed over the lower mold 216 to create an infusion and curing tool 202 having a sealed cavity 220 that holds the dry preform 212. The sealed cavity 220 defines a gap 224. The gap 224 corresponds to a cavity volume 226 equivalent to the amount of resin 204 that infuses the dry preform 212. While the infusion and curing tool 202 is maintained at an infusion temperature 236, the resin 204 is injected into the gap 224 of the sealed cavity 220.

[0028] In some illustrative examples, resin 204 is an epoxy resin. The resin may have an incubation period 205. In some illustrative examples, resin 204 includes a premixed and degassed epoxy resin having an incubation period 205. In some illustrative examples, resin 204 may include epoxy resins, cyanate esters, benzoxazine, bismaleimide, polyimide, cross-linkable thermoplastics, and in-situ polymerizable thermoplastics, or combinations thereof. In some illustrative examples, resin 204 may include, but is not limited to, epoxy resin / cyanate esters and epoxy resin / benzoxazine.

[0029] As used herein, the incubation period 205 of the resin 204 refers to the time before the viscosity of the resin reaches an unacceptable increase after the components of the resin 204 are mixed. For example, an epoxy resin can be formed by mixing an epoxy component with a hardener (e.g., an amine). Once mixed, the epoxy resin crosslinks, increasing its viscosity. The resin can have an incubation period of about 20 minutes to about 1 hour. For example, the resin can have an incubation period of about 30 minutes or less.

[0030] The upper mold 218 is lowered to infuse the dry preform 212, thereby forming a resin infused preform 208. Lowering the upper mold 218 infuses the resin 204 into the dry preform 212 through a thickness 228 of the dry preform 212.

[0031] Aspects of infusion 232, including closing speed 230, infusion temperature 236, and infusion time 233, are configured to produce cured composite part 252 having desired stiffness and strength values. In some illustrative examples, aspects of infusion 232, including closing speed 230, infusion temperature 236, and infusion time 233, are configured to reduce the processing time of cured composite part 252. In some illustrative examples, upper mold 218 is lowered at closing speed 230 of 0.01 inches / minute-0.2 inches / minute. In some illustrative examples, infusion temperature 236 is in the range of 130 degrees Celsius-160 degrees Celsius.

[0032] Resin-infused preform 208 is cured within infusion and curing tool 202 to form cured composite part 252. Curing 260 occurs at a curing temperature 240 that is greater than infusion temperature 236. Curing temperature 240 is sufficient to expand, and at least one of soften or melt, thermoplastic covering 214. To adequately bond to resin 204, thermoplastic covering 214 is at least softened. In some illustrative examples, curing temperature 240 is at least melting temperature 244 of thermoplastic covering 214.

[0033] After curing 260, temperature 234 of infusion and curing tool 202 is decreased from curing temperature 240 at decreasing slope 249. Curing temperature 240 and decreasing slope 249 are selected to produce a desired bond between thermoplastic covering 254 and resin 204 in cured composite part 252. Curing temperature 240 and decreasing slope 249 are selected to generate cavitation bubbles 256 in thermoplastic covering 254 in cured composite part 252. In some illustrative examples, cavitation bubbles 256 are an indication of a desired level of bonding between thermoplastic covering 254 and resin 204 in cured composite part 252.

[0034] The time, temperature, pressure 242 and other aspects of the curing 260 are controlled to produce a cured composite part 252 having the desired stiffness and strength. In some illustrative examples, the curing 260 requires 45 minutes to 180 minutes. In some illustrative examples, the curing temperature 240 is in the range of 165 degrees Celsius to 190 degrees Celsius. In some illustrative examples, the temperature ramp 238 for curing between the infusion temperature 236 and the curing temperature 240 has a slope 239 of 1 degree Celsius per minute to 3 degrees Celsius per minute. In some illustrative examples, the difference between the infusion temperature 236 and the curing temperature 240 is 40 degrees Celsius or less. In some illustrative examples, after lowering the upper mold 218, the pressure 242 within the sealing cavity 220 is 10 PSIG to 100 PSIG, and during the curing 260, the pressure 242 is maintained at 10 PSIG to 100 PSIG.

[0035] Curing temperature 240 is selected based on resin 204 and thermoplastic covering 214. In some illustrative examples, curing temperature 240 may be a temperature of about 170° C. to about 190° C. Curing temperature 240 is selected to produce a desired bond between resin 204 and thermoplastic covering 214.

[0036] Aspects of infusion 232 and curing 260 may be configured to maximize productivity of resin infusion and curing tool 202 Aspects of infusion 232 and curing 260 may be configured to maximize productivity of cured composite part 252 .

[0037] The curing time 261 is set to fully cure the preform 206 in the resin infusion and curing tool 202. The curing time 261 may be from about 45 minutes to about 180 minutes.

[0038] In some illustrative examples, cured composite part 252 is removed from infusion and curing tool 202 while infusion and curing tool 202 is still warm. In some illustrative examples, cured composite part 252 is removed from infusion and curing tool 202 when infusion and curing tool 202 is at temperature 234 in the range of 130 degrees Celsius-160 degrees Celsius, removal temperature 250.

[0039] The cured composite part 252 has sufficient stiffness and strength so that the cured composite part 252 can be safely removed from the resin infusion and curing tool 202. The cured composite part 252 is sufficiently cured to retain its shape without deformation or damage after being removed from the resin infusion and curing tool 202. Additionally, the cured composite part 252 is not post-cured after being removed from the resin infusion and curing tool 202. The cured composite part 252 has sufficient stiffness and strength to meet the desired objectives without additional post-curing.

[0040] Each of the infusion temperature 236 and the curing temperature 240 is a temperature value that has a variation of less than ±5° C. from a desired value. For example, a temperature of 100° C. refers to a temperature maintained between 95° C. and 105° C.

[0041] The temperature 234 of the resin infusion and curing tool 202 can be maintained / managed by electrical or resistive heating, induction heating, liquid heating, steam heating, etc. In some embodiments, the mass and heat capacity of the lower mold 216 are configured to prevent large temperature fluctuations due to the external environment or any exothermic or endothermic reactions. For example, the lower mold 216 can include a material selected for its higher heat capacity, such as steel, aluminum, invar, etc. Likewise, the large mass can control the exothermic reaction by acting as a heat sink and maintain the temperature during the loss of the environment, thereby helping to maintain a constant temperature.

[0042] Cured composite part 252 includes a desired level of bonding between cured resin 258 and thermoplastic covering 254. Due to temperature ramp 238, resin 204 remains fluid for a longer time and can gel (vitrify) after thermoplastic covering 214 reaches melting temperature 244. In some illustrative examples, thermoplastic covering 214 has a melting temperature 244 of more than 170 degrees Celsius. When thermoplastic covering 214 melts, it expands. After thermoplastic covering 214 melts, resin 204 forms a network around thermoplastic covering 214 while thermoplastic covering 214 expands and resin 204 bonds to the surface of thermoplastic covering 214.

[0043] When the thermoplastic covering 214 cools back below the melting temperature 244, the thermoplastic covering 214 attempts to shrink back to its original size. When the thermoplastic covering 214 is now bonded to the resin 204, the thermoplastic covering 214 has nowhere to shrink, resulting in a cavitation bubble 256 in the center of the thermoplastic covering 254.

[0044] In some illustrative examples, at a temperature below melting temperature 244 (e.g., infusion temperature 236), resin 204 is still liquid and thermoplastic covering 214 has an original value of diameter 246. In some illustrative examples, diameter 246 may have an original value of approximately 35 um. At temperature 234 equal to or above melting temperature 244 of thermoplastic covering 214, thermoplastic covering 214 expands when softening or melting while resin 204 is still in a liquid state. In some illustrative examples, thermoplastic covering 214 may expand to have a diameter 246 of approximately 45-50 um when softening or melting.

[0045] After the resin 204 hardens, the thermoplastic covering 214 is locked into the expanded size diameter 246. When the thermoplastic covering 214 cools below the melting temperature 244 again, the thermoplastic covering 214 attempts to shrink back to the original size diameter 246. With the outer surface of the thermoplastic covering 214 locked in place, a cavitation bubble 256 is formed in the center of the thermoplastic covering 254.

[0046] Figure 2 The illustration of manufacturing environment 200 is not meant to imply physical or architectural limitations on the implementation of the exemplary embodiments. Other components other than the illustrated components or other components replacing the illustrated components may be used. Some components may be unnecessary. In addition, these square blocks are used to illustrate some functional components. When implemented in the exemplary embodiments, one or more of these square blocks may be combined, split, or combined and split into different square blocks.

[0047] For example, in some illustrative examples, resin infusion and curing tool 202 may also include a vacuum system (not shown). The vacuum system may be configured to evacuate gap 224. The vacuum system may create a vacuum in gap 224 before injecting resin 204 into gap 224.

[0048] In some illustrative examples, curing temperature 240 is less than melting temperature 244. In some illustrative examples, curing temperature 240 is sufficient to soften but not melt thermoplastic covering 214 such that thermoplastic covering 214 is desirably bonded to resin 204.

[0049] Now go to Figure 3, depicts a graphical representation of a temperature graph of an infusion temperature and a curing temperature for a high-speed resin infusion method, according to an exemplary embodiment. The temperature cycle 302 may be used to Figure 2 The resin infusion and curing tool 202 is used to form Figure 2 The cured composite part 252 is provided.

[0050] Temperature graph 300 depicts a temperature cycle 302 for infusing and curing a composite material with a thermoplastic cover. Temperature graph 300 has time 304 as an X-axis and temperature 306 as a Y-axis. In temperature cycle 302, infusion 308 is performed at an infusion temperature 310. In some illustrative examples, infusion temperature 310 is in the range of 130 degrees Celsius to 160 degrees Celsius. After infusion 308, a temperature ramp 312 occurs as temperature 306 is increased to a curing temperature 314. In some illustrative examples, temperature ramp 312 for curing between infusion temperature 310 and curing temperature 314 has a slope of 1 degree Celsius / minute to 3 degrees Celsius / minute. In some illustrative examples, curing temperature 314 is in the range of 165 degrees Celsius to 190 degrees Celsius. In some illustrative examples, the difference between infusion temperature 310 and curing temperature 314 is 40 degrees Celsius or less.

[0051] As shown, curing 316 is performed at curing temperature 314. In some illustrative examples, curing 316 takes between 45 minutes and 180 minutes. After curing 316, temperature ramp 318 reduces the temperature of the composite material.

[0052] The cured composite part is removed at removal temperature 320. In some illustrative examples, removal temperature 320 is approximately the same as infusion temperature 310. In some illustrative examples, removal temperature 320 is within a range of 130 degrees Celsius - 160 degrees Celsius.

[0053] Now go to Figure 4 , according to an exemplary embodiment, a diagram of a resin infusion and curing tool is depicted. The resin infusion and curing tool 400 is Figure 2 The temperature cycle 302 may be performed in the resin infusion and curing tool 400 to infuse and cure the composite preform.

[0054] The resin infusion and curing tool 400 includes an upper mold 404 and a lower mold 406 sealed together by a seal 408. A sealed cavity 410 exists between the upper mold 404 and the lower mold 406. A preform 412 exists on the lower mold 406 in the sealed cavity 410. A gap 416 exists between the preform 412 and the upper mold 404 in the sealed cavity 410. The gap 416 corresponds to a cavity volume equivalent to the amount of resin 414 infused into the preform 412. While the infusion and curing tool 400 is maintained at an infusion temperature, the resin 414 is injected into the gap 416 of the sealed cavity 410.

[0055] View 402 is a cross-sectional view through the resin infusion and curing tool 400 after resin 414 has been injected into the sealed cavity 410 formed between the upper mold 404 and the lower mold 406. By lowering the upper mold 404 toward the lower mold 406, the resin 414 is infused into the preform 412.

[0056] During the process of infusing resin 414 into preform 412, resin infusion and curing tool 400 is maintained at the infusion temperature. After infusing resin 414 into preform 412, the infused preform is cured. In order to cure resin 414 in preform 412, resin infusion and curing tool 400 is heated from the infusion temperature to the curing temperature. In some illustrative examples, the difference between the infusion temperature and the curing temperature is up to 40 degrees Celsius.

[0057] Now go to Figure 5 , depicts a diagram of the interaction between a thermoplastic covering and a resin prior to curing, according to an exemplary embodiment. Thermoplastic covering 501 and resin 502 may be Figure 1 Thermoplastic covering 501 and resin 502 are Figure 2 Thermoplastic covering 501 and resin 502 may be subjected to Figure 3 Thermoplastic covering 501 and resin 502 can be Figure 4 The resin infusion and curing tool 400 is processed.

[0058] In view 500, thermoplastic covering 501 and resin 502 are at a temperature below the melting temperature of thermoplastic covering 501. In view 500, thermoplastic covering 501 is at an initial size having a first diameter 504. In some illustrative examples, the diameter of the thermoplastic covering is in a range of about 30 um to about 40 um. In some illustrative examples, the diameter of the thermoplastic covering is about 35 um.

[0059] Now go to Figure 6, according to an exemplary embodiment, depicts a diagram of the interaction between a thermoplastic covering and a resin during a curing process. In view 600, a thermoplastic covering 501 and a resin 502 are at a curing temperature (e.g., Figure 3 600 ). In view 600 , the thermoplastic covering 501 expands due to the curing temperature. In view 600 , the thermoplastic covering 501 has a diameter 602. In some illustrative examples, the thermoplastic covering 501 can expand by 15%-45%. In some illustrative examples, the thermoplastic covering 501 expands to have a diameter 602 between about 45um and about 50um. In some illustrative examples, the thermoplastic covering 501 expands to have a diameter 602 between about 45um and about 55um.

[0060] Now go to Figure 7 , depicts a graphical representation of the interaction between a thermoplastic covering and a resin after curing, according to an exemplary embodiment. In view 700, the thermoplastic covering 501 and the resin 502 have cooled below the melting temperature of the thermoplastic covering 501. As the thermoplastic covering 501 cools back below the melting temperature, the thermoplastic covering 501 attempts to shrink back to its original size. In view 700, the resin 502 has hardened into a network 702, and the thermoplastic covering 501 is now bonded to the resin 502.

[0061] After the resin 502 hardens, the thermoplastic covering 501 is locked into its expanded size. When the thermoplastic covering 501 cools below the melting temperature, the thermoplastic covering 501 attempts to shrink back to its original size. Due to the bonding of the thermoplastic covering 501 to the resin 502, the thermoplastic covering 501 has nowhere to shrink, resulting in cavitation bubbles in the center of the thermoplastic covering. With the outer surface of the thermoplastic covering 501 locked in place, cavitation bubbles 704 are formed in the center of the thermoplastic covering 501.

[0062] Now go to Figure 8 , according to an exemplary embodiment, depicts a flow chart of a compression resin transfer infusion method. The method 800 may be performed to form Figure 1 The method 800 may be performed using the resin infusion and curing tool 202 to form a composite component of the aircraft 100. Figure 2 The method 800 may be performed using the temperature cycle 302. The method 800 may be performed using Figure 4 The method 800 may be performed by the resin infusion and curing tool 400. Figure 5 Thermoplastic covering 501 and resin 502.

[0063] The method 800 places a dry preform with a thermoplastic cover on a lower mold (operation 802). The method 800 places an upper mold over the lower mold to create an infusion and curing tool having a sealed cavity to hold the dry preform, the sealed cavity defining a gap corresponding to a cavity volume equivalent to an amount of resin to infuse the dry preform (operation 804). The method 800 injects resin into the gap of the sealed cavity while maintaining the infusion and curing tool at an infusion temperature (operation 806). The method 800 lowers the upper mold to infuse the dry preform to form a resin-infused preform (operation 808). The method 800 cures the resin-infused preform within the infusion and curing tool to form a cured composite part, wherein curing occurs at a curing temperature that is higher than the infusion temperature (operation 810). The method 800 then terminates.

[0064] In some illustrative examples, the upper mold is lowered at a closing speed of 0.01 inches / minute to 0.2 inches / minute (operation 812). In some illustrative examples, the infusion temperature is in the range of 130 degrees Celsius to 160 degrees Celsius (operation 814). In some illustrative examples, the infusion temperature is selected based on the incubation period of the resin.

[0065] In some illustrative examples, the curing temperature is sufficient to expand and melt the thermoplastic covering (operation 816). In some illustrative examples, the curing temperature is sufficient to expand and soften the thermoplastic covering. In some illustrative examples, the curing temperature is sufficient to expand the thermoplastic covering by 15%-45%. In some illustrative examples, the curing temperature exceeds 170 degrees Celsius.

[0066] In some illustrative examples, method 800 reduces the temperature of the infusion and curing tool from the curing temperature at a decreasing slope after curing, wherein the curing temperature and the decreasing slope are selected to generate cavitation bubbles in the thermoplastic cover in the cured composite part (operation 818). During curing, the resin forms a network. During curing, the thermoplastic cover bonds to the resin. The cavitation bubbles may be caused by the thermoplastic cover trying to shrink to the original size after bonding to the resin network. In some illustrative examples, curing takes 45 minutes to 180 minutes (operation 820).

[0067] In some illustrative examples, the curing temperature is in the range of 165 degrees Celsius to 190 degrees Celsius (operation 822). In some illustrative examples, the temperature ramp for curing between the priming temperature and the curing temperature has a slope of 1 degree Celsius to 3 degrees Celsius per minute (operation 824). In some illustrative examples, the difference between the priming temperature and the curing temperature is 40 degrees Celsius or less (operation 826).

[0068] In some illustrative examples, method 800 removes the cured composite part from the infusion and curing tool while the infusion and curing tool is at a temperature in the range of 130 degrees Celsius to 160 degrees Celsius (operation 828). In some illustrative examples, the cured composite part is removed from the infusion and curing tool at the infusion temperature. In some illustrative examples, the cured composite part is removed from the infusion and curing tool after a ramp down having a slope substantially the same as the curing temperature ramp.

[0069] In some illustrative examples, the cured composite part is removed from the infusion and curing tool at about the infusion temperature. In some illustrative examples, removing the cured composite part while warm reduces the processing time of the cured composite part. Removing the cured composite part while warm increases the throughput of the infusion and curing tool. Removing the cured composite part while warm can reduce downtime between composite part infusions. Removing the cured composite part while warm can reduce the energy used to prepare the infusion and curing tool for infusion of the next dry preform.

[0070] Now go to Fig. 9 , according to an exemplary embodiment, a flow chart of a compression resin transfer infusion method is depicted. The method 900 may be performed to form Figure 1 The method 900 may be performed using the resin infusion and curing tool 202 to form a composite component of the aircraft 100. Figure 2 The method 900 may be performed using the temperature cycle 302. The method 900 may be performed using Figure 4 The method 900 can be performed by the resin infusion and curing tool 400. Figure 5 Thermoplastic covering 501 and resin 502.

[0071] The method 900 injects resin into a gap of a sealed cavity of an infusion and curing tool while maintaining the infusion and curing tool at an infusion temperature in the range of 130 degrees Celsius to 160 degrees Celsius (operation 902). The method 900 lowers an upper mold of the infusion and curing tool to infuse the dry preform in the sealed cavity with resin under a resin latent condition to form a resin-infused preform (operation 904). The method 900 increases the temperature of the infusion and curing tool from the infusion temperature to the curing temperature at a desired ramp rate (operation 906). The method 900 cures the resin-infused preform in the infusion and curing tool to form a cured composite part, wherein curing occurs at a curing temperature that is higher than the infusion temperature, wherein the curing temperature is sufficient to expand and melt a thermoplastic covering in the dry preform, thereby bonding the resin to the thermoplastic covering (operation 908). The method 900 then terminates.

[0072] In some illustrative examples, the infusion temperature is in the range of 130 degrees Celsius to 160 degrees Celsius, the slope is 1 degree Celsius to 3 degrees Celsius, and the curing temperature is in the range of 165 degrees Celsius to 190 degrees Celsius (operation 909). In some illustrative examples, injecting the resin and lowering the upper mold occurs in 30 minutes or less (operation 910). The injection time can be selected based on the incubation period.

[0073] In some illustrative examples, the upper mold is lowered at a closing speed of 0.01 inches / minute to 0.2 inches / minute (operation 912). The upper mold is lowered to infuse the resin into the dry preform through the entire thickness of the dry preform.

[0074] In some illustrative examples, after lowering the upper mold, the pressure in the sealing cavity is 10 PSIG-100 PSIG, and wherein the pressure is maintained at 10 PSIG-100 PSIG during the curing process (operation 914). In some illustrative examples, curing takes 45 minutes-180 minutes (operation 916). In some illustrative examples, the difference between the infusion temperature and the curing temperature is 40 degrees Celsius or less (operation 918).

[0075] In some illustrative examples, process 900 reduces the temperature of the infusion and curing tool from the curing temperature at a decreasing slope after curing, wherein the curing temperature and the decreasing slope are selected to generate cavitation bubbles in the thermoplastic capping in the cured composite part (operation 920). The cavitation bubbles are generated by the thermoplastic capping attempting to shrink to an original diameter after bonding to the cured resin.

[0076] In some illustrative examples, method 900 removes the cured composite part from the infusion and curing tool while the infusion and curing tool is at a temperature in the range of 130 degrees Celsius to 160 degrees Celsius (operation 922). In some illustrative examples, the cured composite part is removed from the infusion and curing tool at about the infusion temperature. In some illustrative examples, removing the cured composite part while warm will reduce the processing time of the cured composite part. Removing the cured composite part while warm will increase the throughput of the infusion and curing tool. Removing the cured composite part while warm can reduce downtime between composite part infusions. Removing the cured composite part while warm can reduce the energy used to prepare the infusion and curing tool to infuse the next dry preform.

[0077] Now go to Fig.10 , a flow chart of a method for compressing resin transfer infusion to form cavitation bubbles in a cured composite part is depicted, according to an exemplary embodiment. The method 1000 may be performed to form Figure 1The method 1000 may be performed using the resin infusion and curing tool 202 to form a composite component of the aircraft 100. Figure 2 The method 1000 may be performed using the temperature cycle 302. The method 1000 may be performed using Figure 4 The method 1000 may be performed by a resin infusion and curing tool 400. Figure 5 Thermoplastic covering 501 and resin 502.

[0078] The method 1000 injects resin into a gap of a sealed cavity of an infusion and curing tool while maintaining the infusion and curing tool at an infusion temperature (operation 1002). The method 1000 lowers an upper mold of the infusion and curing tool to infuse a dry preform in the sealed cavity with resin through its thickness to form a resin-infused preform, the dry preform including a thermoplastic cover (operation 1004). The method 1000 increases the temperature of the infusion and curing tool from the infusion temperature to expand the thermoplastic cover while it melts (operation 1006). The method 1000 cures the resin-infused preform in the infusion and curing tool to form a cured composite part (operation 1008). Process 1000 reduces the temperature of the infusion and curing tool after curing to shrink the thermoplastic covering in the cured composite part when the thermoplastic covering cools below the melting temperature of the thermoplastic covering, thereby generating cavitation bubbles in the thermoplastic covering (operation 1010). Process 1000 then terminates.

[0079] In some illustrative examples, the curing temperature is sufficient to expand and melt the thermoplastic covering in the resin-infused preform (operation 1012). In some illustrative examples, the curing temperature is greater than the melting temperature of the thermoplastic covering. In some illustrative examples, the curing temperature is selected so that after the thermoplastic covering cools, the thermoplastic covering expands sufficiently to generate cavitation bubbles.

[0080] In some illustrative examples, the infusion temperature is in the range of 130 degrees Celsius to 160 degrees Celsius, and wherein curing is performed at a curing temperature in the range of 165 degrees Celsius to 190 degrees Celsius (operation 1014). In some illustrative examples, an upper mold of the infusion and curing tool is lowered at a closing speed of 0.01 inches / minute to 0.2 inches / minute (operation 1016).

[0081] As used herein, when used with a list of items, the phrase "at least one" means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. For example, "at least one of item A, item B, or item C" may include, but is not limited to, item A, item A and item B, or item B. This example may also include item A, item B, and item C, or item B and item C. Of course, any combination of these items may exist. In other examples, "at least one" may be, for example, but not limited to, two of item A; one of item B; and ten of item C; four of item B and seven of item C; or other suitable combinations. The item may be a specific object, thing, or category. In other words, at least one of any combination of items and numbers of items in the list may be used, but not all items in the list are required.

[0082] As used herein, "a number" when used with reference to items means one or more items.

[0083] Additionally, all numerical values ​​are "about" or "approximate" indicative values, and experimental errors and variations expected by a person of ordinary skill in the art are taken into account. It should be understood that all numerical values ​​and ranges disclosed herein are approximate values ​​and ranges. With respect to amounts or measurements, the terms "about" or "roughly" and "substantially" or "approximately" mean that the listed features, parameters or values ​​do not need to be precisely implemented. On the contrary, deviations or variations, such as those including tolerances, measurement errors, measurement accuracy limitations, and other factors known to those skilled in the art, may appear in amounts that do not exclude the effect that the feature is intended to provide. As used herein, "approximately" means within a range of + / -10% of a specified target value, maximum value, or minimum value.

[0084] The flow charts and block diagrams in the different depicted embodiments illustrate some possible architectures, functions and operations of the equipment and methods in the illustrative embodiments. In this regard, each box in the flow chart or block diagram may represent at least one of a module, a segment, a function or a part of an operation or a step.

[0085] In some alternative implementations of the illustrative embodiments, one or more functions described in the blocks may appear in the order shown in the figure. For example, in some cases, two blocks shown in succession may be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functions involved. In addition, in addition to the blocks illustrated in the flow chart or block diagram, other blocks may be added. Some blocks may be optional. For example, operations 812 to 828 may be optional. As another example, operations 910 to 922 may be optional. As yet another example, operation 1012 may be optional.

[0086] The exemplary embodiments of the present application can be Fig.11 Aircraft manufacturing and service method 1100 as shown in Fig.12 The description will be made in the context of the aircraft 1200 shown in FIG. Fig.11 , according to an illustrative embodiment, an illustration of an aircraft manufacturing and service method is depicted in the form of a block diagram. During pre-production, aircraft manufacturing and service method 1100 may include Fig.12 Specification and design 1102 of aircraft 1200 and material procurement 1104 .

[0087] During production, component and subassembly manufacturing 1106 and system integration 1108 of the aircraft 1200 occurs. Thereafter, the aircraft 1200 may be certified and delivered 1110 for entry into service 1112. While in service 1112 with a customer, the aircraft 1200 is scheduled for routine maintenance and service 1114, which may include modification, reconfiguration, refurbishment, or other maintenance and service.

[0088] Each of the processes of aircraft manufacturing and service method 1100 may be performed or carried out by a system integrator, a third party, and / or an operator. In these examples, the operator may be a customer. For purposes of this description, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; and an operator may be an airline, leasing company, military entity, service organization, etc.

[0089] Now refer to Fig.12 , depicts, in block diagram form, an illustration of an aircraft in which an illustrative embodiment may be implemented. In this example, aircraft 1200 is illustrated by Fig.11 1206 and may include airframe 1202 having multiple systems 1204 and interior 1206. Examples of systems 1204 include one or more of propulsion system 1208, electrical system 1210, hydraulic system 1212, and environmental system 1214. Any number of other systems may be included.

[0090] Apparatus and methods described herein may be employed during at least one of the stages of aircraft manufacturing and service method 1100. One or more exemplary embodiments may be employed in Fig.11 The components and subassemblies are manufactured or used during at least one of manufacturing 1106 , system integration 1108 , commissioning 1112 , or maintenance and service 1114 .

[0091] Exemplary embodiments provide for compression resin transfer infusion. The resin latency period refers to the period during which the resin remains liquid and has not begun to cure. In some illustrative examples, the resin latency period is in the range of 20 minutes to 60 minutes. In some illustrative examples, the resin maintains a viscosity of 100 cps or less. In some illustrative examples, the infusion temperature of the resin infusion and curing tool is in the range of 130°C to 160°C. In some illustrative examples, the closing speed of lowering the upper mold toward the lower mold is in the range of 0.01 inches / minute to 0.2 inches / minute. In some illustrative examples, the pressure within the sealed cavity of the resin infusion and curing tool at the end of closing is in the range of 10PSIG to 100PSIG.

[0092] The resin infusion and curing tool increases the temperature from the infusion temperature to the curing temperature. In some illustrative examples, the difference between the infusion temperature and the curing temperature is 40° C. or less. In some illustrative examples, the slope from the infusion temperature to the curing temperature is in the range of 1° C. / min-3° C. / min.

[0093] In some exemplary examples, the curing temperature is in the range of 165° C.-190° C. During curing, the pressure in the sealed cavity of the resin infusion and curing tool is maintained at 10 PSIG-100 PSIG. In some exemplary examples, the curing time is in the range of 45 minutes-180 minutes.

[0094] In some illustrative examples, the pressure is maintained at 10 PSIG-100 PSIG during the temperature drop from the curing temperature to the part removal temperature. In some illustrative examples, the cured composite part is removed from the hot resin infusion and curing tool at a temperature in the range of 130° C.-160° C. After removal from the resin infusion and curing tool, the cured composite part is not subjected to additional post-curing. The cured composite part includes a desired level of bonding between the resin in the preform and the thermoplastic cover.

[0095] Due to the thermal ramp, the resin remains fluid for a longer time and can gel (vitrify) after the thermoplastic covering reaches the melting temperature. In some illustrative examples, the thermoplastic covering melts above 170 degrees Celsius. When the thermoplastic covering melts, it expands. After the thermoplastic covering melts, the resin forms a network around the expanded covering and bonds to the surface of the thermoplastic covering.

[0096] When the thermoplastic covering cools back below the melting temperature, it attempts to shrink back to its original size. Since the thermoplastic covering is now bonded to the resin, it has nowhere to shrink, which results in cavitation bubbles in the center of the thermoplastic covering.

[0097] In some illustrative examples, at temperatures below the melting temperature, the resin is still liquid and the thermoplastic covering is at its original diameter, for example, about 35 um. At temperatures at or above the melting temperature of the thermoplastic covering, the thermoplastic covering expands as it softens or melts while the resin is still in a liquid state. In some illustrative examples, the thermoplastic covering may expand to about 45 um-50 um as it softens or melts.

[0098] After the resin hardens, the thermoplastic covering is locked into its expanded size. When the thermoplastic covering cools below its melting temperature again, it attempts to shrink back to its original size. As the outer surface of the thermoplastic covering locks in place, a cavitation bubble is formed in the center of the thermoplastic covering.

[0099] Furthermore, the present application includes implementations according to the following examples:

[0100] 1. A method (800) for transfer infusion of compressed resin, the method comprising:

[0101] placing (802) the dried preform (212, 412) with the thermoplastic cover (214, 501) onto a lower mold (216, 406);

[0102] placing (804) an upper mold (218, 404) over the lower mold (216, 406) to create an infusion and cure tool (202, 400) having a sealed cavity (220, 410) that holds the dry preform (212, 412), the sealed cavity (220, 410) defining a gap (224, 416) that corresponds to a cavity volume (226) equivalent to the amount of resin (204, 414, 502) that infuses the dry preform (212, 412);

[0103] injecting (806) a resin (204, 414, 502) into the gap (224, 416) of the sealed cavity (220, 410) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310);

[0104] lowering (808) the upper mold (218, 404) to infuse the dried preform (212, 412) to form a resin-infused preform (208); and

[0105] The resin-infused preform (208) is cured (810, 260, 316) within the infusion and cure tool (202, 400) to form a cured composite part (252), wherein curing (260, 316) occurs at a curing temperature (240, 314) that is greater than the infusion temperature (236, 310).

[0106] 2. The method (800) of Example 1, wherein (816) the curing temperature (240, 314) is sufficient to cause the thermoplastic covering (214, 501) to expand and melt.

[0107] 3. The method (800) of Example 1, further comprising:

[0108] After the curing (260, 316), the temperature of the infusion and curing tool (202, 400) is reduced (818) from the curing temperature (240, 314) at a decreasing slope (249), wherein the curing temperature (240, 314) and the decreasing slope (249) are selected to generate cavitation bubbles (256, 704) in the thermoplastic covering (214, 501) in the cured composite part (252).

[0109] 4. The method (800) of Example 1, wherein (812), the upper mold (218, 404) is lowered at a closing speed (230) of 0.01 inches / minute to 0.2 inches / minute.

[0110] 5. The method (800) of Example 1, wherein (820), curing (260, 316) takes 45 minutes to 180 minutes.

[0111] 6. The method (800) of Example 1, wherein (814), the perfusion temperature (236, 310) is in the range of 130 degrees Celsius to 160 degrees Celsius.

[0112] 7. The method (800) of Example 1, wherein (822), the curing temperature (240, 314) is in the range of 165 degrees Celsius to 190 degrees Celsius.

[0113] 8. The method (800) of Example 1, wherein (824) the temperature ramp (238, 312) for curing between the infusion temperature (236, 310) and the curing temperature (240, 314) has a slope (239) of 1 degree Celsius / minute to 3 degrees Celsius / minute.

[0114] 9. The method (800) of Example 1, wherein (826) the difference between the infusion temperature (236, 310) and the curing temperature (240, 314) is 40 degrees Celsius or less.

[0115] 10. The method (800) of example 1, further comprising:

[0116] The cured composite part (252) is removed (828) from the infusion and curing tool (202, 400) while the infusion and curing tool (202, 400) is at a temperature (234) in the range of 130 degrees Celsius to 160 degrees Celsius.

[0117] 11. A method (900) for compressed resin transfer infusion, the method comprising:

[0118] Injecting (902) a resin (204, 414, 502) into a gap (224, 416) of a sealed cavity (220, 410) of an infusion and curing tool (202, 400) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310);

[0119] lowering (904) an upper mold (218, 404) of the infusion and curing tool (202, 400) to infuse the dry preform (212, 412) in the sealed cavity (220, 410) with the resin (204, 414, 502) in a resin latent condition to form a resin-infused preform (208);

[0120] increasing (906) the temperature (234) of the infusion and curing tool (202, 400) from the infusion temperature (236, 310) to the curing temperature (240, 314) at a desired ramp rate; and

[0121] The resin-infused preform (208) is cured (908, 260, 316) in the infusion and curing tool (202, 400) to form a cured composite part (252), wherein curing (260, 316) occurs at the curing temperature (240, 314) that is greater than the infusion temperature (236, 310), wherein the curing temperature (240, 314) is sufficient to expand and melt a thermoplastic covering (214, 501) in the dry preform (212, 412) to bond the resin to the thermoplastic covering (241, 501).

[0122] 12. The method (900) of Example 11, wherein the infusion temperature (236, 310) is in the range of 130 degrees Celsius to 160 degrees Celsius, wherein the slope is 1 degree Celsius to 3 degrees Celsius, and wherein the curing temperature (240, 314) is in the range of 165 degrees Celsius to 190 degrees Celsius.

[0123] 13. The method (900) of example 11, wherein (912), the upper mold (218, 404) is lowered at a closing speed (230) of 0.01 inches / minute to 0.2 inches / minute.

[0124] 14. The method (900) of Example 11, wherein (914), after lowering the upper mold (218, 404), the pressure (242) within the sealed cavity (220, 410) is 10 PSIG-100 PSIG, and wherein, during the curing (260, 316), the pressure (242) is maintained at 10 PSIG-100 PSIG.

[0125] 15. The method (900) of Example 11, wherein (916), curing (260, 316) requires 45 minutes to 180 minutes.

[0126] 16. The method (900) of Example 11, wherein (918) the difference between the infusion temperature (236, 310) and the curing temperature (240, 314) is 40 degrees Celsius or less.

[0127] 17. The method (900) of example 11, further comprising:

[0128] The cured composite part (252) is removed (922) from the infusion and curing tool (202, 400) while the infusion and curing tool (202, 400) is at a temperature (234) in the range of 130 degrees Celsius - 160 degrees Celsius.

[0129] 18. The method (900) of example 11, further comprising:

[0130] After the curing (260, 316), the temperature (234, 302) of the infusion and curing tool (202, 400) is reduced (920) from the curing temperature (240, 314) at a decreasing slope (249), wherein the curing temperature (24314) and the decreasing slope (249) are selected to generate cavitation bubbles (256, 704) in the thermoplastic covering (214, 501) in the cured composite part (252).

[0131] 19. The method (900) of example 11, wherein (910), injecting the resin (204, 414, 502) and lowering the upper mold (218, 404) occur in 30 minutes or less.

[0132] 20. A method (1000) of compressing resin transfer infusion to form cavitation bubbles (256, 704) in a cured composite part (252), the method comprising:

[0133] Injecting (1002) a resin (204, 414, 502) into a gap (224, 416) of a sealed cavity (220, 410) of an infusion and curing tool (202, 400) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310);

[0134] lowering (1004) an upper mold (218, 404) of the infusion and curing tool (202, 400) to infuse the dry preform (212, 412) in the sealed cavity (220, 410) with the resin (204, 414, 502) through its thickness (228) to form a resin-infused preform (208), the dry preform (212, 412) including a thermoplastic cover (214, 501);

[0135] increasing (1006) the temperature (234) of the infusion and curing tool (202, 400) from the infusion temperature (236, 310) to expand the thermoplastic covering while it melts;

[0136] curing (1008, 260, 316) the resin-infused preform (208) in the infusion and curing tool (202, 400) to form a cured composite part (252); and

[0137] After curing (260, 316), the temperature (234) of the infusion and curing tool (202, 400) is reduced (1010) to shrink the thermoplastic covering (214, 501) in the cured composite part (252) when the thermoplastic covering (214, 501) cools below the melting temperature of the thermoplastic covering (214, 501), thereby generating cavitation bubbles (256, 704) in the thermoplastic covering (214, 501).

[0138] 21. A method according to Example 20, wherein the infusion temperature (236, 310) is in the range of 130 degrees Celsius-160 degrees Celsius, and wherein curing is performed at a curing temperature (240, 314) in the range of 165 degrees Celsius-190 degrees Celsius.

[0139] 22. The method of example 20, wherein lowering (1004) the upper mold (218, 404) of the infusion and curing tool (202, 400) is performed at a closing speed (230) of 0.01 inches per minute to 0.2 inches per minute.

[0140] 23. The method of example 21, wherein (1012) the curing temperature (240, 314) is sufficient to expand and melt the thermoplastic covering (214, 501) in the resin-infused preform (208).

[0141] The descriptions of different illustrative embodiments have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the embodiments disclosed in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. In addition, different illustrative embodiments may provide different features compared to other illustrative embodiments. The selected one or more embodiments are selected and described in order to best explain the principles of the embodiment, the practical application, and to enable those of ordinary skill in the art to understand the disclosure of various embodiments with various modifications suitable for the intended specific use.

Claims

1. A method (800) for transfer infusion of compressed resin, the method comprising: placing (802) the dried preform (212, 412) with the thermoplastic cover (214, 501) onto a lower mold (216, 406); placing (804) an upper mold (218, 404) over the lower mold (216, 406) to create an infusion and cure tool (202, 400) having a sealed cavity (220, 410) that holds the dry preform (212, 412), the sealed cavity (220, 410) defining a gap (224, 416) that corresponds to a cavity volume (226) equivalent to the amount of resin (204, 414, 502) that infuses the dry preform (212, 412); injecting (806) a resin (204, 414, 502) into the gap (224, 416) of the sealed cavity (220, 410) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310); lowering (808) the upper mold (218, 404) to infuse the dried preform (212, 412) to form a resin-infused preform (208); and The resin-infused preform (208) is cured (810, 260, 316) within the infusion and cure tool (202, 400) to form a cured composite part (252), wherein curing (260, 316) occurs at a curing temperature (240, 314) that is greater than the infusion temperature (236, 310).

2. The method (800) of claim 1, wherein (816) the curing temperature (240, 314) is sufficient to cause the thermoplastic covering (214, 501) to expand and melt.

3. The method (800) of claim 1, further comprising: After the curing (260, 316), the temperature of the infusion and curing tool (202, 400) is reduced (818) from the curing temperature (240, 314) at a decreasing slope (249), wherein the curing temperature (240, 314) and the decreasing slope (249) are selected to generate cavitation bubbles (256, 704) in the thermoplastic covering (214, 501) in the cured composite part (252).

4. The method (800) of claim 1, further comprising: The cured composite part (252) is removed (828) from the infusion and curing tool (202, 400) while the infusion and curing tool (202, 400) is at a temperature (234) in the range of 130 degrees Celsius to 160 degrees Celsius.

5. A method (900) of compressed resin transfer infusion, the method comprising: Injecting (902) a resin (204, 414, 502) into a gap (224, 416) of a sealed cavity (220, 410) of an infusion and curing tool (202, 400) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310); lowering (904) an upper mold (218, 404) of the infusion and curing tool (202, 400) to infuse the dry preform (212, 412) in the sealed cavity (220, 410) with the resin (204, 414, 502) in a resin latent condition to form a resin-infused preform (208); increasing (906) the temperature (234) of the infusion and curing tool (202, 400) from the infusion temperature (236, 310) to the curing temperature (240, 314) at a desired slope; and The resin-infused preform (208) is cured (908, 260, 316) in the infusion and curing tool (202, 400) to form a cured composite part (252), wherein curing (260, 316) occurs at the curing temperature (240, 314) that is greater than the infusion temperature (236, 310), wherein the curing temperature (240, 314) is sufficient to expand and melt a thermoplastic covering (214, 501) in the dry preform (212, 412) to bond the resin to the thermoplastic covering (241, 501).

6. The method (900) of claim 5, wherein: The infusion temperature (236, 310) is in the range of 130 degrees Celsius to 160 degrees Celsius, wherein the slope is 1 degree Celsius to 3 degrees Celsius, and the curing temperature (240, 314) is in the range of 165 degrees Celsius to 190 degrees Celsius.

7. The method (900) of claim 5, further comprising: After the curing (260, 316), the temperature (234, 302) of the infusion and curing tool (202, 400) is reduced (920) from the curing temperature (240, 314) at a decreasing slope (249), wherein the curing temperature (24314) and the decreasing slope (249) are selected to generate cavitation bubbles (256, 704) in the thermoplastic covering (214, 501) in the cured composite part (252).

8. A method (1000) of compressing resin transfer infusion to form cavitation bubbles (256, 704) in a cured composite part (252), the method comprising: Injecting (1002) a resin (204, 414, 502) into a gap (224, 416) of a sealed cavity (220, 410) of an infusion and curing tool (202, 400) while maintaining the infusion and curing tool (202, 400) at an infusion temperature (236, 310); lowering (1004) an upper mold (218, 404) of the infusion and curing tool (202, 400) to infuse the dry preform (212, 412) in the sealed cavity (220, 410) with the resin (204, 414, 502) through its thickness (228) to form a resin-infused preform (208), the dry preform (212, 412) including a thermoplastic cover (214, 501); increasing (1006) the temperature (234) of the infusion and curing tool (202, 400) from the infusion temperature (236, 310) to expand the thermoplastic covering while it melts; curing (1008, 260, 316) the resin infused preform (208) in the infusion and curing tool (202, 400) to form a cured composite part (252); and After curing (260, 316), the temperature (234) of the infusion and curing tool (202, 400) is reduced (1010) to shrink the thermoplastic covering (214, 501) in the cured composite part (252) when the thermoplastic covering (214, 501) cools below the melting temperature of the thermoplastic covering (214, 501), thereby generating cavitation bubbles (256, 704) in the thermoplastic covering (214, 501).

9. The method according to claim 8, wherein: The infusion temperature (236, 310) is in the range of 130 degrees Celsius-160 degrees Celsius, and wherein curing is performed at a curing temperature (240, 314) in the range of 165 degrees Celsius-190 degrees Celsius.

10. The method of claim 9, wherein (1012) the curing temperature (240, 314) is sufficient to expand and melt the thermoplastic covering (214, 501) in the resin-infused preform (208).

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