Processing technology of medium-temperature 120 DEG C curing prepreg applied to undercarriage

Abstract

The invention provides a processing technology of a medium-temperature 120 DEG C cured prepreg applied to an undercarriage, which adopts a one-way prepreg composed of ER468 glass fiber and 7901DNK epoxy resin, the resin content is 32% + / -3%, and the unfreezing time is controlled through a specific unfreezing regulation: the unfreezing time of the prepreg with the length of less than or equal to 30 meters is more than or equal to 6 hours, and the unfreezing time of the prepreg with the length of more than 30 meters is more than or equal to 12 hours. A multi-layer vacuum packaging structure is adopted and comprises a demolding layer, an edge breathable felt, a non-porous isolating membrane and a vacuum bag membrane, and a curing curve is selected according to the thickness of a prepreg laminated body: when the thickness is smaller than 5mm, the temperature is directly increased to 120 DEG C, and heat preservation is performed for 90 minutes; when the thickness is greater than or equal to 5mm, the temperature is gradually increased to 80 DEG C and kept for 60 minutes, and then is increased to 120 DEG C and kept for 90 minutes. And after curing, naturally cooling and demolding, and standing a product with the thickness of more than or equal to 5mm for 7 days. The invention relates to the field of aerospace composite material manufacturing.

Description

Technical Field

[0001] The present invention relates to the field of aerospace composite material manufacturing, and particularly to a processing technology for medium-temperature 120°C curing prepreg applied to landing gears. Background Art

[0002] Advanced resin matrix composites play an important role in the aerospace field. Their lightweight and high-strength characteristics make them an ideal choice for key components such as aircraft landing gears. As the core raw material of composite materials, the curing process of epoxy prepregs directly affects the mechanical properties and dimensional stability of products. Traditional prepregs mostly adopt high-temperature curing processes (such as above 180°C). Although they can ensure material properties, they have problems such as high energy consumption, large internal stress, and strict requirements for molds. Moreover, high-temperature curing easily leads to premature gelation of the resin, restricting the forming efficiency of large-sized or complex-structured products.

[0003] To reduce the curing temperature, existing technologies have proposed medium-temperature curing epoxy prepreg solutions. For example, CN102746622A discloses a prepreg with medium-temperature curing epoxy resin as the matrix material and its preparation method, which relates to a prepreg and its preparation method. The present invention solves the problems that the energy consumption is high when preparing products with a curing temperature above 120°C for prepregs, and it is not conducive to controlling the dimensional accuracy of products. A prepreg with medium-temperature curing epoxy resin as the matrix material is made by impregnating a reinforcing material with medium-temperature curing epoxy resin prepared from an epoxy resin mixture, a curing agent system mixture, and a toughening agent. The epoxy resin mixture is composed of solid or semi-solid epoxy resin and liquid epoxy resin, and the curing agent system mixture is composed of a curing agent and an accelerator. Preparation method: First, prepare the epoxy resin mixture; second, prepare the curing agent system mixture; third, prepare the medium-temperature curing epoxy resin; fourth, prepare the prepreg. The products prepared by the present invention can be used to prepare aircraft, spacecraft, yachts, golf clubs, etc., and have important commercial value.

[0004] However, such solutions still have significant defects: First, the curing process is single, and no adaptive temperature curve is designed for products with different thicknesses, resulting in incomplete curing of the core of thick products and poor interlayer bonding force; second, the prepreg encapsulation process lacks optimization, and the resin is easily lost or unevenly distributed during the curing process, affecting the denseness of products; third, the heat resistance of the general epoxy resin system is insufficient, and the maximum service temperature of the cured composite material is difficult to meet the high-temperature working conditions requirements of aircraft landing gears (such as ≤120°C). In addition, the existing prepregs have a short storage period, and the mechanical properties are not specifically improved for high-load structural components, restricting their application in the aviation field.

[0005] In view of the above problems, there is an urgent need to develop a processing technology for medium-temperature 120°C curing prepreg applied to landing gears. Summary of the Invention

[0006] In view of the deficiencies of the above-mentioned existing technologies, the present invention provides a processing technology for a medium-temperature 120°C curing prepreg applied to landing gears, aiming to solve the problems of incomplete curing of the core of thick products, difficult control of resin loss, short storage period, and insufficient heat resistance and mechanical properties of composites caused by a single curing process of existing medium-temperature curing prepregs.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a processing technology for a medium-temperature 120°C curing prepreg applied to landing gears, comprising the following steps:

[0008] S1: Preparation of prepreg;

[0009] Select a unidirectional glass fiber prepreg, which is composed of ER468 glass fiber and 7901DNK epoxy resin. The content of the 7901DNK epoxy resin is 32% ± 3%, and the unit area mass of the ER468 glass fiber is 1600 g / m 2 ±5%;

[0010] S2: Thawing of prepreg;

[0011] Thaw the refrigerated stored unidirectional glass fiber prepreg at room temperature. The thawing time of the unidirectional glass fiber prepreg with a length ≤ 30 meters is ≥ 6 hours, and the thawing time of the unidirectional glass fiber prepreg with a length > 30 meters is ≥ 12 hours. Keep the sealed packaging during the thawing process;

[0012] S3: Laying and encapsulation of prepreg;

[0013] Vacuum encapsulate the thawed unidirectional glass fiber prepreg to form a prepreg laminate, and complete the vacuum encapsulation on the mold through auxiliary materials in the following order:

[0014] a. Lay a release layer on the mold surface;

[0015] b. Place the unidirectional glass fiber prepreg;

[0016] c. Lay an edge breather felt outside the unidirectional glass fiber prepreg by ≥ 20 mm;

[0017] d. Completely wrap and cover the unidirectional glass fiber prepreg and the edge breather felt with a second non-porous separator film;

[0018] e. Lay a surface breather felt;

[0019] f. Seal the outer edge of the edge breather felt with a sealing tape;

[0020] g. Cover the vacuum bag film and evacuate to a pressure ≥ 0.8 bar;

[0021] S4: Curing process;

[0022] Select the curing curve according to the thickness of the prepreg laminate:

[0023] h. When the thickness of the prepreg laminate < 5 mm: Heat from room temperature to 120 °C at 1 - 2 °C / min and hold for 90 min;

[0024] i. When the thickness of the prepreg laminate ≥ 5 mm: Heat from room temperature to 80 °C at 0.5 - 1 °C / min and hold for 60 min, then heat to 120 °C at 0.5 - 1 °C / min and hold for 90 min;

[0025] S5: Post-treatment;

[0026] Naturally cool to below 60 °C and demold. Among them, the prepreg laminate with a thickness ≥ 5 mm is allowed to stand for 7 days, and the composite landing gear component is obtained after removing the auxiliary materials.

[0027] Based on the above, the beneficial effects of a medium-temperature 120 °C curing prepreg processing technology applied to landing gears are as follows: It solves the problems of incomplete curing of the core of thick products, difficult control of resin loss, short storage period, and insufficient heat resistance and mechanical properties of composites caused by a single curing process in existing medium-temperature curing prepregs; mainly reflected in:

[0028] 1. In step S4 of the present invention, for the prepreg laminate with a thickness ≥ 5 mm, a staged curing process of heating from room temperature to 80 °C at 0.5 - 1 °C / min and holding for 60 min, and then heating to 120 °C at 0.5 - 1 °C / min and holding for 90 min is adopted to ensure synchronous curing of the core and surface layer of thick products, thus solving the problems of incomplete curing of the core of thick products and poor interlayer bonding force caused by a single curing curve in existing medium-temperature curing prepregs;

[0029] 2. In step S3 of the present invention, the prepreg laminate is composed of a demolding layer, a first peel ply, a rubber dam, an edge breather felt, a second non-porous separator film, a surface breather felt, a sealing tape, and a vacuum bag film. Among them, the setting of the rubber dam restricts the flow of resin to the outside of the prepreg laminate. The synergistic effect of the edge breather felt and the surface breather felt guides the volatiles (including residual solvents, moisture, low molecular by-products, etc.) to discharge and evenly distribute the vacuum pressure. The complete wrapping of the prepreg laminate by the second non-porous separator film prevents local enrichment of resin. The sealing of the sealing tape and the vacuum bag film ensures that the vacuum pressure is stably maintained above 0.8 bar. In summary, it not only ensures the stability of the basic process but also provides adaptability for diverse product requirements, thus systematically solving the problems of difficult control of resin loss and insufficient density of products;

[0030] 3. In the present invention, by using a unidirectional glass fiber prepreg formula composed of ER468 glass fiber and 7901DNK epoxy resin with a resin content of 32% ± 3% in step S1, the crosslinking density of the resin system and the interfacial bonding strength are improved, thereby solving the problems of insufficient heat resistance and mechanical properties of the composite material.

[0031] 4. In the present invention, by strictly controlling the thawing time in step S2, that is, the thawing time of the unidirectional glass fiber prepreg with a length ≤ 30 m is ≥ 6 hours, and the thawing time of the unidirectional glass fiber prepreg with a length > 30 m is ≥ 12 hours, and the grading storage conditions include storing at 18 - 26 °C for 30 days, storing at - 5 - 0 °C for 6 months, and storing at - 18 °C for 12 months, the volatiles are inhibited from escaping and the resin precuring is delayed, thereby solving the problems of short storage period of the existing prepreg and limited process applicability.

[0032] Further, the demolding layer is one of a first non - porous isolation film, a demolding cloth, or a demolding agent.

[0033] Based on the above, the beneficial effect of the flexible selection of the first non - porous isolation film, the demolding cloth, or the demolding agent is to adapt to different mold surface characteristics and demolding requirements, thereby solving the problem of surface damage of the product caused by difficult demolding in the traditional process.

[0034] Further, in step S3 - e, the length of the edge breather felt ≥ 25 mm.

[0035] Further, in step S3 - f, glass limiting yarns are pasted on the outside of the unidirectional glass fiber prepreg, the upper end of the rubber - blocking strip, and the inside of the edge breather felt, and the second non - porous isolation film completely wraps and covers the unidirectional glass fiber prepreg, the glass limiting yarns, and the edge breather felt.

[0036] Based on the above, the beneficial effect of pasting the glass limiting yarns on the outside of the prepreg, the upper end of the rubber - blocking strip, and the inside of the edge breather felt is to form a physical constraint barrier to prevent the unidirectional glass fiber from shifting during resin flow or vacuum pumping, ensuring the fiber orientation accuracy; the beneficial effect of the second non - porous isolation film completely wrapping the prepreg, the limiting yarns, and the breather felt is to both limit the excessive loss of resin in the unidirectional glass fiber prepreg and promote the infiltration of resin and fiber through uniform pressure distribution, improving the interlaminar shear strength.

[0037] Further, step S3 further includes at least one of the following steps:

[0038] Laying a first peelable cloth on the upper surface of the demolding layer;

[0039] Setting a rubber - blocking strip at the outer edge of the unidirectional glass fiber prepreg;

[0040] Laying a second peelable cloth on the upper surface of the unidirectional glass fiber prepreg;

[0041] Place a pressure equalizing plate on the upper end of the second non-porous separator membrane.

[0042] Based on the above, the beneficial effect of optionally laying a second peel ply on the upper surface of the unidirectional glass fiber prepreg is that after curing the unidirectional glass fiber prepreg, the second non-porous separator membrane is peeled off, effectively reducing resin enrichment, ensuring the surface finish of the product, and meeting the high appearance requirements of aviation components; the beneficial effect of optionally placing a pressure equalizing plate on the upper end of the second non-porous separator membrane is to evenly disperse the vacuum pressure and avoid thickness deviation or fiber distortion caused by uneven local pressure, especially suitable for complex curved surface structures.

[0043] Furthermore, the volatile content of the unidirectional glass fiber prepreg is ≤1%, and the gel time is 15 ± 3 minutes at 120°C.

[0044] Based on the above, the beneficial effect of strictly limiting the volatile content to ≤1% is to effectively reduce the formation of defects such as bubbles and pores during the curing process, ensure the denseness of the product, and make the interlaminar shear strength of the composite material stable ≥65 MPa; the beneficial effect of controlling the gel time to be 15 ± 3 minutes at 120°C is to provide a reasonable time window for resin flow and fiber infiltration, ensuring sufficient exhaust while avoiding uneven resin distribution caused by excessive flow.

[0045] Furthermore, the storage conditions of the unidirectional glass fiber prepreg are as follows:

[0046] Storage period of 30 days at 18 - 26°C;

[0047] Storage period of 6 months at -5 - 0°C;

[0048] Storage period of 12 months at -18°C.

[0049] Furthermore, the operating temperature of the cured composite landing gear component is ≤120°C.

[0050] Furthermore, the mechanical properties of the unidirectional glass fiber prepreg meet the following requirements:

[0051] Tensile strength at 0° ≥1000 MPa, tensile modulus at 0° ≥36 GPa;

[0052] Tensile strength at 90° ≥35 MPa, tensile modulus at 90° ≥8 GPa;

[0053] Compressive strength at 0° ≥900 MPa, compressive strength at 90° ≥115 MPa;

[0054] Interlaminar shear strength ≥65 MPa.

[0055] To more clearly illustrate the above features of the present invention and the objectives to be achieved, the following further describes the present invention in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0056] Figure 1 : Process flow chart of the present invention;

[0057] Figure 2 : Process flow chart of the prepreg layup and encapsulation of the present invention;

[0058] Figure 3 : Curing curve diagram when the thickness of the prepreg laminate of the present invention is < 5 mm;

[0059] Figure 4 : Curing curve diagram when the thickness of the prepreg laminate of the present invention is ≥ 5 mm;

[0060] Figure 5 : Schematic diagram of the vacuum encapsulation of the present invention.

[0061] Description of the reference numerals in the drawings: 1 - unidirectional glass fiber prepreg, 2 - release layer, 3 - first peel ply, 4 - rubber strip, 5 - edge breather felt, 6 - second non-porous separator film, 7 - surface breather felt, 8 - sealing tape, 9 - vacuum bag film, 10 - glass limit yarn, 11 - second peel ply, 12 - equalizing plate, 100 - prepreg laminate. Detailed Description of the Invention

[0062] As Figures 1-5 shown, a medium-temperature 120°C curing prepreg processing technology applied to landing gears includes the following steps:

[0063] S1: Preparation of prepreg;

[0064] Select unidirectional glass fiber prepreg 1, which is composed of ER468 glass fiber and 7901DNK epoxy resin, the content of the 7901DNK epoxy resin is 32% ± 3%, and the unit area mass of the ER468 glass fiber is 1600 g / m 2 ± 5%;

[0065] S2: Thawing of prepreg;

[0066] Thaw the refrigerated stored unidirectional glass fiber prepreg 1 at room temperature. The thawing time of the unidirectional glass fiber prepreg 1 with a length ≤ 30 m is ≥ 6 hours, and the thawing time of the unidirectional glass fiber prepreg 1 with a length > 30 m is ≥ 12 hours. Keep the sealed packaging during the thawing process;

[0067] S3: Prepreg layup and encapsulation;

[0068] Vacuum package the thawed unidirectional glass fiber prepreg 1 to form a prepreg laminate 100, and complete the vacuum packaging on the mold with auxiliary materials in the following order:

[0069] a. Lay a release layer 2 on the mold surface;

[0070] b. Place the unidirectional glass fiber prepreg 1;

[0071] c. Lay an edge breather felt 5 at a position ≥20 mm outside the unidirectional glass fiber prepreg 1;

[0072] d. Completely wrap and cover the unidirectional glass fiber prepreg 1 and the edge breather felt 5 with a second non-porous separator film 6;

[0073] e. Lay a surface breather felt 7;

[0074] f. Seal the outer edge of the edge breather felt 5 with a sealing tape 8;

[0075] g. Cover the vacuum bag film 9 and evacuate to a pressure ≥0.8 bar;

[0076] S4: Curing process;

[0077] Select a curing curve according to the thickness of the prepreg laminate 100:

[0078] h. When the thickness of the prepreg laminate 100 < 5 mm: Heat from room temperature to 120 °C at a rate of 1 - 2 °C / min and hold for 90 min;

[0079] i. When the thickness of the prepreg laminate 100 ≥ 5 mm: Heat from room temperature to 80 °C at a rate of 0.5 - 1 °C / min, hold for 60 min, then heat to 120 °C at a rate of 0.5 - 1 °C / min and hold for 90 min;

[0080] S5: Post-treatment;

[0081] Naturally cool to below 60 °C and demold. Among them, the prepreg laminate 100 with a thickness ≥ 5 mm is left standing for 7 days, and the composite landing gear component is obtained after removing the auxiliary materials.

[0082] In this embodiment, the release layer 2 is one of a first non-porous separator film, a release cloth, or a release agent.

[0083] In this embodiment, in step S3 e, the length of the edge breather felt 5 ≥ 25 mm.

[0084] In this embodiment, in step S3 f, a glass limiting yarn 10 is pasted on the outside of the unidirectional glass fiber prepreg 1, the upper end of the rubber dam 4, and the inside of the edge breather felt 5, and the second non-porous separator film 6 completely wraps and covers the unidirectional glass fiber prepreg 1, the glass limiting yarn 10, and the edge breather felt 5.

[0085] In this embodiment, step S3 further includes at least one of the following steps:

[0086] Lay a first peel ply 3 on the upper surface of the demolding layer 2;

[0087] Set a rubber dam 4 at the outer edge of the unidirectional glass fiber prepreg 1;

[0088] Lay a second peel ply 11 on the upper surface of the unidirectional glass fiber prepreg 1;

[0089] Place a pressure equalizing plate 12 on the upper end of the second non-porous separator 6.

[0090] In this embodiment, the volatile content of the unidirectional glass fiber prepreg 1 is ≤1%, and the gel time is 15±3 minutes at 120°C.

[0091] In this embodiment, the storage conditions of the unidirectional glass fiber prepreg 1 are as follows:

[0092] The storage period is 30 days at 18 - 26°C;

[0093] The storage period is 6 months at -5 - 0°C;

[0094] The storage period is 12 months at -18°C.

[0095] In this embodiment, the service temperature of the cured composite landing gear component is ≤120°C.

[0096] In this embodiment, the mechanical properties of the unidirectional glass fiber prepreg 1 meet the following requirements:

[0097] Tensile strength at 0°≥1000MPa, tensile modulus at 0°≥36GPa;

[0098] Tensile strength at 90°≥35MPa, tensile modulus at 90°≥8GPa;

[0099] Compressive strength at 0°≥900MPa, compressive strength at 90°≥115MPa;

[0100] Interlaminar shear strength≥65MPa.

[0101] Comparative document CN102746622A (Test 1) uses carbon fiber T700 and single-stage curing, with an interlaminar shear strength of 72MPa, but does not solve the problem of uniform curing of thick products; the present invention shortens the process of thick products to 2.5 hours through staged curing, and the tensile strength at 0° of glass fiber ER468≥1000MPa, meeting aviation standards while reducing costs; in addition, the prior art does not disclose low-temperature storage data, while the present invention has a storage period of 12 months at -18°C, significantly extending the available cycle of the prepreg.

[0102] Based on the data of the embodiments disclosed in the comparative document and combined with the test results of the embodiments of the present invention, the comparative analysis is as follows:

[0103]

[0104]

[0105]

[0106] Process comparison experiment:

[0107]

[0108] Although the 0° compression strength (950 MPa) of the present invention is slightly lower than 1033 MPa of the comparative document, through the following comprehensive design, it is more suitable for the compression load scenario of the landing gear:

[0109] High fiber content design: The mass per unit area of the fiber reaches 1600 g / m 2 ±5% (not clearly stated in the comparative document, presumably with a lower fiber content), significantly improving the material stiffness and anti-deformation ability;

[0110] Optimization of process compactness: Through the staged curing process and vacuum pressure control (≥0.8 bar), the porosity is reduced to 0.28% (0.32% in the comparative document), reducing the influence of defects on the compression performance;

[0111] High temperature adaptability: The specified use temperature ≤ 120 °C, meeting the long-term stability requirements of the landing gear in high temperature environments (the comparative document does not mention heat resistance).

[0112] As a high-load structural component, the landing gear needs to meet the following performance simultaneously:

[0113] Compressive strength: Withstand the impact load in the vertical direction;

[0114] Interlayer shear resistance: Prevent delamination failure (the interlayer shear strength of the present invention ≥ 65 MPa, 72 MPa in the comparative document, with similar performance);

[0115] Fatigue resistance and heat resistance: Stable performance under long-term cyclic loads and no softening under high temperature conditions.

[0116] Therefore, through the design of high fiber content and low porosity, the present invention can still reduce local stress concentration and improve the fatigue resistance through higher stiffness and more uniform fiber distribution even when the compression strength is slightly lower.

[0117] In summary, the specific implementation manner of the present invention is:

[0118] In the prepreg preparation stage, a unidirectional glass fiber prepreg 1 composed of ER468 glass fiber and 7901DNK epoxy resin is selected. Its resin content of 32% ± 3% and fiber unit area mass of 1600 g / m2 ± 5% ensure the mechanical property basis of the material system. During the thawing process of the prepreg, by strictly controlling the thawing time (≥ 6 hours when the length ≤ 30 meters, ≥ 12 hours when the length > 30 meters) and keeping the sealed packaging, the volatiles escape and resin pre-curing are effectively inhibited, and the prepreg process stability is maintained;

[0119] In the prepreg layup and encapsulation stage, a multi-layer structure design is adopted to achieve resin flow control and uniform pressure distribution. The demolding layer 2 (the first non-porous isolation film, release cloth or release agent) laid on the mold surface ensures smooth demolding after molding. The optional first peel ply 3 further protects the surface quality of the product. The rubber stop strip 4 set at the outer edge of the unidirectional glass fiber prepreg 1 and the edge breather felt 5 (length ≥ 25 mm) laid at a position ≥ 20 mm outside form a resin flow barrier and a volatiles discharge channel. The prepreg and the edge breather felt 5 are completely wrapped by the second non-porous isolation film 6. With the evacuation (pressure ≥ 0.8 bar) of the surface breather felt 7 and the vacuum bag film 9, a stable pressure environment is established. The glass limiting yarn 10 is pasted on the outside of the prepreg, the upper end of the rubber stop strip 4 and the inside of the edge breather felt 5 to prevent fiber deviation and maintain the orientation accuracy. The optional second peel ply 11 and the equalizing plate 12 respectively improve the surface finish and the pressure distribution uniformity;

[0120] The curing process implements a differential temperature curve according to the thickness of the prepreg laminate 100. For products with a thickness < 5 mm, a rapid curing scheme of directly heating to 120 °C at 1 - 2 °C / min and holding for 90 min is adopted; when the thickness ≥ 5 mm, it is heated in segments at 0.5 - 1 °C / min (holding at 80 °C for 60 min → holding at 120 °C for 90 min) to achieve synchronous curing of the core and surface. In the post-treatment stage, it is demolded by natural cooling to below 60 °C, and products with a thickness ≥ 5 mm are left standing for 7 days to eliminate residual stress, and finally the composite landing gear components are obtained.

[0121] The above is only the optimal solution embodiment of the present invention and is not used to limit the present invention. Modifications or substitutions made by those skilled in the art to the present invention without departing from the essence and protection scope of the present invention should also be within the protection scope of the present invention.

Claims

1. A processing technology for medium-temperature 120°C curing prepreg applied to landing gears, characterized in that, It includes the following steps: S1: Prepreg preparation; Select a unidirectional glass fiber prepreg (1), which is composed of ER468 glass fiber and 7901DNK epoxy resin. The content of the 7901DNK epoxy resin is 32% ± 3%, and the unit area mass of the ER468 glass fiber is 1600 g / m 2 ± 5%; S2: Prepreg thawing; Thaw the unidirectional glass fiber prepreg (1) stored in refrigeration at room temperature. For the unidirectional glass fiber prepreg (1) with a length ≤ 30 m, the thawing time ≥ 6 hours; for the unidirectional glass fiber prepreg (1) with a length > 30 m, the thawing time ≥ 12 hours. Keep the sealed packaging during the thawing process; S3: Prepreg layup and encapsulation; Vacuum encapsulate the thawed unidirectional glass fiber prepreg (1) to form a prepreg laminate (100), and complete the vacuum encapsulation on the mold with auxiliary materials in the following order: a. Lay a release layer (2) on the mold surface; b. Place the unidirectional glass fiber prepreg (1); c. Lay an edge breather felt (5) ≥ 20 mm outside the unidirectional glass fiber prepreg (1); d. Completely wrap and cover the unidirectional glass fiber prepreg (1) and the edge breather felt (5) with a second non-porous separator film (6); e. Lay a surface breather felt (7); f. Seal the outer edge of the edge breather felt (5) with a sealing tape (8); g. Cover with a vacuum bag film (9) and evacuate to a pressure ≥ 0.8 bar; S4: Curing process; Select a curing curve according to the thickness of the prepreg laminate (100): h. When the thickness of the prepreg laminate (100) < 5 mm: Heat from room temperature to 120 °C at 1 - 2 °C / min and hold for 90 min; i. When the thickness of the prepreg laminate (100) ≥ 5 mm: Heat from room temperature to 80 °C at 0.5 - 1 °C / min and hold for 60 min, then heat to 120 °C at 0.5 - 1 °C / min and hold for 90 min; S5: Post-treatment; Naturally cool to below 60 °C for demolding. Among them, for the prepreg laminate (100) with a thickness ≥ 5 mm, let it stand for 7 days, and a composite landing gear component is obtained after removing the auxiliary materials.

2. The processing technology of a medium-temperature 120°C curing prepreg applied to the landing gear according to claim 1, wherein: The release layer (2) is one of a first non-porous separator film, a release cloth, or a release agent.

3. A processing technology of medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: In step S3 e, the length of the edge breather felt (5) ≥ 25 mm.

4. A processing technology of medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: In step S3 d, glass limiting yarns (10) are pasted on the outside of the unidirectional glass fiber prepreg (1), the upper end of the rubber dam strip (4), and the inner side of the edge breather felt (5), and the second non-porous separator film (6) completely wraps and covers the unidirectional glass fiber prepreg (1), the glass limiting yarns (10), and the edge breather felt (5).

5. A processing process of a medium-temperature 120°C curing prepreg applied to a landing gear according to claim 1, characterized in that, Step S3 further includes at least one of the following steps: Lay a first peel ply (3) on the upper surface of the release layer (2); Set a rubber dam strip (4) on the outer edge of the unidirectional glass fiber prepreg (1); Lay a second peel ply (11) on the upper surface of the unidirectional glass fiber prepreg (1); Place a pressure equalizing plate (12) on the upper end of the second non-porous separator film (6).

6. A processing technology of medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: The volatile content of the unidirectional glass fiber prepreg (1) ≤ 1%, and the gel time is 15 ± 3 minutes at 120 °C.

7. A processing technology of medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: The storage conditions of the unidirectional glass fiber prepreg (1) are: The storage period is 30 days at 18 - 26 °C; The storage period is 6 months at -5 - 0 °C; The storage period is 12 months at -18 °C.

8. A processing technology for medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: The service temperature of the cured composite landing gear component ≤ 120 °C.

9. A processing technology of medium-temperature 120°C curing prepreg applied to landing gear according to claim 1, characterized in that: The mechanical properties of the unidirectional glass fiber prepreg (1) meet the following requirements: Tensile strength at 0° ≥ 1000 MPa, tensile modulus at 0° ≥ 36 GPa; Tensile strength at 90° ≥ 35 MPa, tensile modulus at 90° ≥ 8 GPa; Compressive strength at 0° ≥ 900 MPa, compressive strength at 90° ≥ 115 MPa; Interlaminar shear strength ≥ 65 MPa.

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