Composite material rudder sheet for aircraft and forming method of composite material rudder sheet

Abstract

The invention relates to a composite rudder sheet for an aircraft and a forming method of the composite rudder sheet, and belongs to the technical field of composites.The composite rudder sheet comprises a base layer, an upper structural layer, a lower structural layer and a metal piece; the matrix layer is made of chopped carbon fiber prepreg; the upper structural layer and the lower structural layer are both made of carbon fiber unidirectional belt prepreg; the metal piece is made of 7075 aluminum alloy or 7050 aluminum alloy; according to the technical scheme, the reinforcing material is obtained by combining the organic compound with the silanized composite material; combining the reinforcing material with diethanol amine to obtain a hyperbranched polymer; mixing the hyperbranched polymer with the composite epoxy resin, and then adding a curing agent to obtain modified epoxy resin; impregnating the short carbon fibers with the modified epoxy resin to obtain a short carbon fiber prepreg; impregnating the carbon fiber unidirectional belt with the modified epoxy resin to obtain a carbon fiber unidirectional belt prepreg; the specific strength and the specific modulus of the composite material ostrich section are improved on the whole, the overall weight of the composite material ostrich section is reduced, and the comprehensive performance of the composite material ostrich section is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly to a composite rudder for an aircraft and a forming method thereof. Background Art

[0002] Among missile components, the rudder plays an important role in the flight and steering of the missile. Its control system uses the aerodynamic force generated by the deflection of the rudder as the control force, so as to effectively control the missile to maintain a good attitude flight in the atmosphere. Therefore, the rudder needs to have sufficient strength and stiffness. At present, the rudder mainly has structural forms such as titanium alloy, alloy steel, aluminum alloy, metal, and composite material mixture. These structures have problems such as large weight and small load-bearing capacity. The lightweight of the rudder has an obvious effect on improving the flight speed of the missile, its range, and maneuverability.

[0003] At present, lightweight rudders are mainly formed by carbon fiber composite materials. Compared with other traditional materials, carbon fiber composite materials have the advantages of light weight and large load-bearing capacity. Using composite materials is one of the important ways to lighten the weight of missiles, but it is still necessary to further improve the strength and stiffness of carbon fiber composite materials. Therefore, there is an urgent need to prepare a composite rudder that can not only meet the load-bearing requirements, but also be simple in forming, light in weight, and low in cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite rudder for an aircraft and a forming method thereof. By combining an organic compound with a silanized composite material, then combining with diethanolamine, and then mixing with a composite epoxy resin, a modified epoxy resin is obtained; not only can the thermal stability, heat resistance, etc. of the epoxy resin be improved, but also the toughness and impact resistance of the epoxy resin can be better enhanced; at the same time, the modified epoxy resin can increase its adhesion performance with chopped carbon fibers and carbon fiber unidirectional tapes, and reduce the overall weight of the composite rudder; impregnate the chopped carbon fibers and carbon fiber unidirectional tapes with the modified epoxy resin to obtain a matrix layer, an upper structure layer, and a lower structure layer respectively, and then lay them with metal parts to form a composite body, and finally obtain a composite rudder for an aircraft through hot pressing. The mechanical properties and thermal stability of the composite rudder are improved as a whole, making it have good specific strength and specific modulus, and the overall weight is light, which improves the comprehensive performance of the composite rudder.

[0005] The technical problem to be solved by the present invention: At present, lightweight rudders are mainly formed by carbon fiber composite materials. Compared with other traditional materials, carbon fiber composite materials have the advantages of light weight and large load-bearing capacity. Using composite materials is one of the important ways to lighten the weight of missiles, but it is still necessary to further improve the strength and stiffness of carbon fiber composite materials. Therefore, there is an urgent need to prepare a composite rudder that can not only meet the load-bearing requirements, but also be simple in forming, light in weight, and low in cost.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A composite rudder blade for an aircraft, comprising a matrix layer, an upper structural layer, a lower structural layer and a metal part;

[0008] The matrix layer is a chopped carbon fiber prepreg;

[0009] The chopped carbon fiber prepreg is obtained by impregnating chopped carbon fibers with a modified epoxy resin;

[0010] Both the upper structural layer and the lower structural layer are carbon fiber unidirectional tape prepregs;

[0011] The carbon fiber unidirectional tape prepreg is obtained by impregnating carbon fiber unidirectional tapes with a modified epoxy resin;

[0012] The preparation method of the modified epoxy resin comprises the following steps:

[0013] S1: Combining an organic compound with a silanized composite material to obtain a reinforcing material;

[0014] S2: Combining the reinforcing material with diethanolamine to obtain a hyperbranched polymer;

[0015] S3: Mixing the hyperbranched polymer with a composite epoxy resin, and then adding a curing agent to obtain a modified epoxy resin.

[0016] Further, the metal part is made of 7075 aluminum alloy or 7050 aluminum alloy.

[0017] Further, step S1 is specifically:

[0018] Adding the silanized composite material to N,N-dimethylformamide, stirring evenly, then adding the organic compound, and then stirring in a water bath at 70 - 80 °C for 3 - 4 h, filtering, washing with a mixed solution of methanol and acetone, and finally drying in vacuo at 50 - 60 °C to obtain the reinforcing material.

[0019] During the above reaction process, the silanized composite material has amino groups, the organic compound has epoxy groups, and the epoxy groups in the organic compound can be combined with the amino groups in the silanized composite material through ring-opening reaction to combine the silanized composite material with the organic compound, and finally obtain the reinforcing material.

[0020] Further, the mass ratio of the silanized composite material, N,N-dimethylformamide, and the organic compound is 0.8 - 1.2: 35 - 45: 1 - 1.4.

[0021] Further, the organic compound is at least one of 4-epoxyisoeugenol, methyl methacrylate, and glycidyl methacrylate.

[0022] Further, the preparation method of the silylated composite material comprises the following steps:

[0023] Add the composite material into absolute ethanol, and ultrasonically disperse for 25 - 35 min, then add a silane coupling agent, stir in a water bath at 55 - 65 °C for 1 - 2 h, filter, wash with absolute ethanol, and finally vacuum dry at 40 - 50 °C to obtain the silylated composite material.

[0024] During the above reaction process, the composite material has hydroxyl groups, and the silane coupling agent generates silanol groups after hydrolysis. The hydroxyl groups in the composite material can combine with the silanol groups in the silane coupling agent to graft the silane coupling agent onto the composite material, and finally obtain the silylated composite material.

[0025] Further, the mass ratio of the composite material to absolute ethanol is 0.9 - 1.1:90 - 110.

[0026] Further, the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed in a mass ratio of 0.5 - 0.6:0.2 - 0.3.

[0027] Further, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0028] Further, step S2 is specifically as follows:

[0029] Add the reinforcing material and diethanolamine in step S1 into methanol, and stir for 22 - 24 h, then add a catalyst and carry out a step-by-step reaction, cool to room temperature, filter, wash with methanol, and finally vacuum dry at 40 - 50 °C to obtain the hyperbranched polymer.

[0030] During the above reaction process, the reinforcing material has a carbon-carbon double bond on 4-epoxyisoeugenol, and diethanolamine has a secondary amine group. The carbon-carbon double bond in the reinforcing material can undergo a Michael addition reaction with the secondary amine in diethanolamine to combine the reinforcing material and diethanolamine together to obtain the hyperbranched polymer.

[0031] Further, the mass ratio of the reinforcing material, diethanolamine, and methanol is 4.5 - 5.5:2.5 - 3.5:10 - 20.

[0032] Further, the catalyst is zinc acetate.

[0033] Further, the stepwise reaction is specifically as follows: reacting at 55 - 65 °C for 0.5 - 1.5 h, reacting at 95 - 105 °C for 1.5 - 2.5 h, reacting at 115 - 125 °C for 1.5 - 2.5 h, and finally reacting at 145 - 155 °C for 1.5 - 2.5 h.

[0034] Further, step S3 is specifically as follows:

[0035] Adding the hyperbranched polymer obtained in step S2 into the composite epoxy resin, then stirring at 25 - 35 °C for 10 - 15 min, adding a curing agent, and standing at room temperature to obtain a modified epoxy resin.

[0036] Further, the mass ratio of the hyperbranched polymer to the composite epoxy resin is 8 - 12:90 - 110.

[0037] Further, the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol glycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed in a mass ratio of 1 - 1.2:0.5 - 0.6:0.2 - 0.3.

[0038] Further, the curing agent is 4,4'-diaminodiphenylmethane.

[0039] Further, the preparation method of the chopped carbon fiber prepreg includes the following steps:

[0040] Adding chopped carbon fibers into the modified epoxy resin and impregnating for 20 - 30 min, then curing at 75 - 85 °C for 4 - 5 h to obtain a chopped carbon fiber prepreg.

[0041] Further, the impregnation ratio of the chopped carbon fibers to the modified epoxy resin is 5 - 6:4 - 5.

[0042] Further, the preparation method of the carbon fiber unidirectional tape prepreg includes the following steps:

[0043] Adding a carbon fiber unidirectional tape into the modified epoxy resin and impregnating for 30 - 40 min, then curing at 85 - 95 °C for 2 - 3 h to obtain a carbon fiber unidirectional tape prepreg.

[0044] Further, the impregnation ratio of the carbon fiber unidirectional tape to the modified epoxy resin is 6 - 7:3 - 4.

[0045] A forming method for a composite rudder sheet for an aircraft includes the following steps:

[0046] Weigh the matrix laminate, then pre-cut the upper structural laminate and the lower structural laminate and mix them according to the laying sequence. Then, combine and lay the lower structural layer, the matrix layer, the upper structural layer and the metal parts in sequence to form an assembly. Exclude the air bubbles between the layers by vacuum pumping, place the assembly in the lower die body of the mold, and position it with the metal part positioning block. Operate the hot press to close the upper die body and the lower die body through the guide pillars and guide sleeves, release the pressure, and demold to obtain the composite rudder for the aircraft.

[0047] Furthermore, the die closing clearance is 0.01 - 0.03 mm.

[0048] Furthermore, the pressure of the hot press is 8 - 20 Mpa, the temperature is 140 - 150 °C, and the heat preservation time is 5 - 10 min.

[0049] The beneficial effects of the present invention:

[0050] (1) In the technical solution of the present invention, an enhanced material is obtained by combining an organic compound with a silanized composite material; the organic compound is at least one of 4-epoxyisoeugenol, methyl methacrylate, and glycidyl methacrylate. Among them, 4-epoxyisoeugenol not only has a good binding force with the silanized composite material, enhances the compatibility between the silanized composite material and epoxy resin, but also can provide reaction sites for subsequent reactions. At the same time, 4-epoxyisoeugenol contains an aromatic ring, which can further improve the thermal stability, heat resistance, etc. of epoxy resin, and preferably enhances the toughness and impact resistance of epoxy resin; the silanized composite material is prepared by grafting a silane coupling agent onto the surface of the composite material. Among them, the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers. Carboxymethyl-β-cyclodextrin has a unique rigid ring structure, which can preferably improve the toughness and impact resistance of epoxy resin. Cellulose nanofibers have a small particle size, which can effectively improve the toughness of epoxy resin. Carboxymethyl-β-cyclodextrin and cellulose nanofibers play a synergistic effect, preferably enhancing the mechanical properties of epoxy resin. The silane coupling agent can increase the dispersibility of the composite material, improve its compatibility with epoxy resin, and enhance the binding force with 4-epoxyisoeugenol; combine the enhanced material with diethanolamine to obtain a hyperbranched polymer; the enhanced material and diethanolamine are chemically combined with a strong binding force. The formed hyperbranched polymer can effectively improve the toughness and impact resistance of epoxy resin, and can also be used as an adhesive to increase the bonding performance between epoxy resin and chopped carbon fiber and carbon fiber unidirectional tape, further improving the specific strength and specific modulus of the composite rudder.

[0051] (2) In the technical solution of the present invention, a hyperbranched polymer is mixed with a composite epoxy resin, and then a curing agent is added to obtain a modified epoxy resin; the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol glycidyl ether, and poly(dimethylsiloxane) diglycidyl ether. The three have a synergistic effect. Bisphenol F diglycidyl ether has a low viscosity, which helps it better penetrate into the chopped carbon fibers and carbon fiber unidirectional tapes, enhancing their mechanical properties. Sorbitol glycidyl ether can further improve the toughness of the epoxy resin, and poly(dimethylsiloxane) diglycidyl ether can better improve the impact strength of the epoxy resin. Moreover, the mixture of the three has a good effect on reducing the overall weight of the composite rudder blade, and can effectively improve the specific strength and specific modulus of the rudder blade. Mixing the hyperbranched polymer with the composite epoxy resin can better improve the overall performance of the composite rudder blade; impregnating the modified epoxy resin into the chopped carbon fibers and carbon fiber unidirectional tapes respectively to obtain a matrix layer, an upper structure layer, and a lower structure layer, and then laminating them with metal parts to form a composite body, and finally hot pressing to obtain a composite rudder blade for an aircraft.

[0052] (3) In the technical solution of the present invention, an organic compound is combined with a silanized composite material, then combined with diethanolamine, and then mixed with a composite epoxy resin to obtain a modified epoxy resin; impregnating the modified epoxy resin into the chopped carbon fibers and carbon fiber unidirectional tapes respectively, and then laminating them with metal parts to form a composite body, and finally hot pressing to obtain a composite rudder blade for an aircraft; overall improving the mechanical properties and thermal stability of the composite rudder blade, making it have good specific strength and specific modulus, and having a light overall weight, simple molding, and low production cost, with good overall comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0054] Figure 1 It is a schematic diagram of the external shape of a composite rudder blade in a composite rudder blade for an aircraft and its molding method of the present invention.

[0055] Figure 2 It is a cross-sectional view of a composite rudder blade in a composite rudder blade for an aircraft and its molding method of the present invention.

[0056] Figure 3 It is a schematic diagram of the lower die body of a mold for a composite rudder blade in a composite rudder blade for an aircraft and its molding method of the present invention.

[0057] Figure 4 In a composite rudder blade for an aircraft and its molding method according to the present invention, it is a schematic diagram of the upper die body of the composite rudder blade mold.

[0058] Reference numerals in the drawings: upper structural layer 1; lower structural layer 2; matrix layer 3; metal part 4; lower die body 5; upper die body 6; metal part positioning block 7; guide pillar 8; guide sleeve 9. Specific embodiments

[0059] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0060] The specific parameters of the raw materials used in the present invention are as follows:

[0061] 4-Epoxyisoeugenol, CAS No.: 36115-41-0, provided by Pand (Shanghai) International Trading Co., Ltd.; Methyl methacrylate, CAS No.: 80-62-6, provided by Shanghai Macklin Biochemical Co., Ltd.; Carboxymethyl-β-cyclodextrin, CAS No.: 218269-34-2, purity: 98%, provided by Shanghai Yuanye Bio-Technology Co., Ltd.; Cellulose nanofibers, product number: YXL0026, particle size 4-10 nm, length 200 nm, provided by Shanghai Yingxin Laboratory Equipment Co., Ltd.; Diethanolamine, CAS No.: 111-42-2, provided by Shanghai Macklin Biochemical Co., Ltd.; Bisphenol F diglycidyl ether, CAS No.: 2095-03-6, provided by Shanghai Titan Technology Co., Ltd.; Sorbitol glycidyl ether, CAS No.: 68412-01-1, provided by Shanghai Macklin Biochemical Co., Ltd.; Poly(dimethylsiloxane) diglycidyl ether, CAS No.: 130167-23-6, provided by Shanghai Macklin Biochemical Co., Ltd.

[0062] In the following examples and comparative examples, the fiber model of the chopped carbon fiber used is T700; the fiber model of the carbon fiber unidirectional tape used is M40J.

[0063] Example 1

[0064] Prepare modified epoxy resin, the specific steps are as follows:

[0065] S1: According to the mass ratio of silanized composite material, N,N-dimethylformamide, and 4-epoxyisoeugenol being 0.8:35:1, add the silanized composite material into N,N-dimethylformamide. After stirring evenly, add 4-epoxyisoeugenol, and then stir in a water bath at 70 °C at a rotation speed of 500 rpm for 4 h. After filtration, wash with a mixed solution of methanol and acetone (the volume ratio of methanol to acetone is 1:9) 3 times (each time the mass of the mixed solution of methanol and acetone is 40% of the mass of N,N-dimethylformamide), and finally vacuum dry at 50 °C for 24 h to obtain the reinforcing material;

[0066] Among them, the preparation method of the silanized composite material includes the following steps:

[0067] According to the mass ratio of the composite material and absolute ethanol being 0.9:90, add the composite material into absolute ethanol and ultrasonically disperse for 25 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 10% of the mass of absolute ethanol), and stir in a water bath at 55 °C at a rotation speed of 500 rpm for 2 h. After the reaction is completed, filter, wash with absolute ethanol 3 times (each time the mass of absolute ethanol is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 40 °C for 24 h to obtain the silanized composite material, where the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed according to the mass ratio of 0.5:0.2;

[0068] S2: According to the mass ratio of the reinforcing material, diethanolamine, and methanol being 4.5:2.5:10, add the reinforcing material and diethanolamine in step S1 into methanol, and stir at room temperature for 22 h, then add zinc acetate (the mass of zinc acetate is 8% of the mass of diethanolamine), and react at 55 °C for 1.5 h, react at 95 °C for 2.5 h, react at 115 °C for 2.5 h, and finally react at 145 °C for 2.5 h. After the reaction is completed, cool to room temperature, filter, wash with methanol 3 times (each time the mass of methanol is equal to the above methanol), and finally vacuum dry at 40 °C for 12 h to obtain the hyperbranched polymer;

[0069] S3: According to the mass ratio of the hyperbranched polymer and the composite epoxy resin being 8:90, add the hyperbranched polymer in step S2 into the composite epoxy resin, then stir at 25 °C for 10 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let it stand at room temperature for 24 h to obtain the modified epoxy resin, where the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed according to the mass ratio of 1:0.5:0.2;

[0070] The preparation method of the chopped carbon fiber prepreg comprises the following steps:

[0071] According to the impregnation ratio of chopped carbon fiber to modified epoxy resin being 5:5, add the chopped carbon fiber into the modified epoxy resin, and impregnate for 20 min, then cure at 75 °C for 4 h to obtain the chopped carbon fiber prepreg;

[0072] The preparation method of the carbon fiber unidirectional tape prepreg comprises the following steps:

[0073] According to the impregnation ratio of carbon fiber unidirectional tape to modified epoxy resin being 6:4, add the carbon fiber unidirectional tape into the modified epoxy resin, and impregnate for 30 min, then cure at 85 °C for 2 h to obtain the carbon fiber unidirectional tape prepreg;

[0074] A composite rudder for an aircraft comprises a matrix layer 3, an upper structure layer 1, a lower structure layer 2 and a metal part 4;

[0075] The matrix layer is a chopped carbon fiber prepreg;

[0076] The chopped carbon fiber prepreg is obtained by impregnating chopped carbon fiber with modified epoxy resin;

[0077] Both the upper structure layer and the lower structure layer are carbon fiber unidirectional tape prepregs;

[0078] The carbon fiber unidirectional tape prepreg is obtained by impregnating carbon fiber unidirectional tape with modified epoxy resin;

[0079] The material of the metal part is 7050 aluminum alloy;

[0080] The forming method of the composite rudder for an aircraft comprises the following steps:

[0081] Weigh the matrix layer sheet material, then use an automatic cutting machine to pre-cut 7 layers of the upper structure layer sheet material and the lower structure layer sheet material respectively and combine the materials according to the laying sequence. Then, combine and lay the lower structure layer 2, the matrix layer 3, the upper structure layer 1 and the metal part 4 in sequence to form a combined body. Exclude the air bubbles between the laying layers by vacuum pumping. Place the combined body in the lower die body 5 of the mold, and position it with the metal part positioning block 7. Operate the hot press to close the upper die body 6 with the lower die body 5 through the guide pillars 8 and the guide sleeves 9. The closing gap is 0.01 mm. The pressure of the hot press is 8 Mpa, the temperature is 140 °C, and the heat preservation time is 10 min. Release the pressure and demold to obtain the composite rudder for an aircraft.

[0082] Example 2

[0083] Prepare the modified epoxy resin, and the specific steps are as follows:

[0084] S1: According to the mass ratio of the silanized composite material, N,N-dimethylformamide, and 4-epoxyisoeugenol being 1:40:1.2, add the silanized composite material to N,N-dimethylformamide. After stirring evenly, add 4-epoxyisoeugenol, and then stir at a speed of 600 rpm in a water bath at 75 °C for 3.5 h. After filtration, wash with a mixed solution of methanol and acetone (the volume ratio of methanol to acetone is 1:9) 3 times (each time the mass of the mixed solution of methanol and acetone is 40% of the mass of N,N-dimethylformamide), and finally vacuum dry at 55 °C for 24 h to obtain the reinforcing material;

[0085] Among them, the preparation method of the silanized composite material includes the following steps:

[0086] According to the mass ratio of the composite material to absolute ethanol being 1:100, add the composite material to absolute ethanol and ultrasonically disperse for 30 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 10% of the mass of absolute ethanol), and stir at a speed of 600 rpm in a water bath at 60 °C for 1.5 h. After the reaction is completed, filter, wash with absolute ethanol 3 times (each time the mass of absolute ethanol is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 45 °C for 24 h to obtain the silanized composite material, where the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed in a mass ratio of 0.55:0.25;

[0087] S2: According to the mass ratio of the reinforcing material, diethanolamine, and methanol being 5:3:15, add the reinforcing material and diethanolamine in step S1 to methanol, and stir at room temperature for 23 h, then add zinc acetate (the mass of zinc acetate is 8% of the mass of diethanolamine), and react at 60 °C for 1 h, react at 100 °C for 2 h, react at 120 °C for 2 h, and finally react at 150 °C for 2 h. After the reaction is completed, cool to room temperature, filter, wash with methanol 3 times (each time the mass of methanol is equal to the mass of the above methanol), and finally vacuum dry at 45 °C for 12 h to obtain the hyperbranched polymer;

[0088] S3: According to the mass ratio of the hyperbranched polymer to the composite epoxy resin being 10:100, add the hyperbranched polymer in step S2 to the composite epoxy resin, then stir at 30 °C for 12 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let stand at room temperature for 24 h to obtain the modified epoxy resin, where the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed in a mass ratio of 1.1:0.55:0.25;

[0089] The preparation method of the chopped carbon fiber prepreg comprises the following steps:

[0090] According to the impregnation ratio of chopped carbon fiber to modified epoxy resin being 5.5:4.5, add the chopped carbon fiber into the modified epoxy resin, and impregnate for 25 min, then cure at 80 °C for 4.5 h to obtain the chopped carbon fiber prepreg;

[0091] The preparation method of the carbon fiber unidirectional tape prepreg comprises the following steps:

[0092] According to the impregnation ratio of carbon fiber unidirectional tape to modified epoxy resin being 6.6:3.4, add the carbon fiber unidirectional tape into the modified epoxy resin, and impregnate for 35 min, then cure at 90 °C for 2.5 h to obtain the carbon fiber unidirectional tape prepreg;

[0093] A composite rudder for an aircraft comprises a matrix layer 3, an upper structural layer 1, a lower structural layer 2 and a metal part 4;

[0094] The matrix layer is a chopped carbon fiber prepreg;

[0095] The chopped carbon fiber prepreg is obtained by impregnating chopped carbon fiber with modified epoxy resin;

[0096] Both the upper structural layer and the lower structural layer are carbon fiber unidirectional tape prepregs;

[0097] The carbon fiber unidirectional tape prepreg is obtained by impregnating carbon fiber unidirectional tape with modified epoxy resin;

[0098] The metal part is made of 7075 aluminum alloy;

[0099] The forming method of the composite rudder for an aircraft comprises the following steps:

[0100] Weigh the matrix layer sheet material, then pre-cut 7 layers of the upper structural layer sheet material and the lower structural layer sheet material respectively by an automatic cutting machine and combine the materials according to the laying sequence. Then, combine and lay the lower structural layer 2, the matrix layer 3, the upper structural layer 1 and the metal part 4 in sequence to form a combined body. Exclude the air bubbles between the laying layers by vacuum pumping, place the combined body in the lower die body 5 of the mold, position it with the metal part positioning block 7, operate the hot press to close the upper die body 6 and the lower die body 5 through the guide posts 8 and the guide sleeves 9. The closing gap is 0.02 mm, the pressure of the hot press is 15 Mpa, the temperature is 145 °C, and the heat preservation time is 8 min. Remove the pressure and demold to obtain the composite rudder for an aircraft.

[0101] Example 3

[0102] Prepare the modified epoxy resin, and the specific steps are as follows:

[0103] S1: According to the mass ratio of the silanized composite material, N,N-dimethylformamide, and 4-epoxyisoeugenol being 1.2:45:1.4, add the silanized composite material to N,N-dimethylformamide. After stirring evenly, add 4-epoxyisoeugenol, and then stir at a speed of 700 rpm in a water bath at 80 °C for 3 h. After filtration, wash 3 times with a mixed solution of methanol and acetone (the volume ratio of methanol to acetone is 1:9) (the mass of the methanol and acetone mixed solution each time is 40% of the mass of N,N-dimethylformamide), and finally vacuum dry at 60 °C for 24 h to obtain the reinforcing material;

[0104] Among them, the preparation method of the silanized composite material includes the following steps:

[0105] According to the mass ratio of the composite material and absolute ethanol being 1.1:110, add the composite material to absolute ethanol and ultrasonically disperse for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 10% of the mass of absolute ethanol), and stir at a speed of 700 rpm in a water bath at 65 °C for 1 h. After the reaction is completed, after filtration, wash 3 times with absolute ethanol (the mass of absolute ethanol each time is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 50 °C for 24 h to obtain the silanized composite material, where the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed according to a mass ratio of 0.6:0.3;

[0106] S2: According to the mass ratio of the reinforcing material, diethanolamine, and methanol being 5.5:3.5:20, add the reinforcing material and diethanolamine in step S1 to methanol and stir at room temperature for 24 h, then add zinc acetate (the mass of zinc acetate is 8% of the mass of diethanolamine), and react at 65 °C for 0.5 h, react at 105 °C for 1.5 h, react at 125 °C for 1.5 h, and finally react at 155 °C for 1.5 h. After the reaction is completed, cool to room temperature, after filtration, wash 3 times with methanol (the mass of methanol each time is equal to the mass of the above methanol), and finally vacuum dry at 50 °C for 12 h to obtain the hyperbranched polymer;

[0107] S3: According to the mass ratio of the hyperbranched polymer and the composite epoxy resin being 12:110, add the hyperbranched polymer in step S2 to the composite epoxy resin, then stir at 35 °C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let stand at room temperature for 24 h to obtain the modified epoxy resin, where the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed according to a mass ratio of 1.2:0.6:0.3;

[0108] The preparation method of the chopped carbon fiber prepreg includes the following steps:

[0109] According to the impregnation ratio of chopped carbon fiber to modified epoxy resin being 6:4, add the chopped carbon fiber to the modified epoxy resin, impregnate for 30 min, and then cure at 85 °C for 5 h to obtain the chopped carbon fiber prepreg;

[0110] The preparation method of the carbon fiber unidirectional tape prepreg includes the following steps:

[0111] According to the impregnation ratio of carbon fiber unidirectional tape to modified epoxy resin being 7:3, add the carbon fiber unidirectional tape to the modified epoxy resin, impregnate for 40 min, and then cure at 95 °C for 3 h to obtain the carbon fiber unidirectional tape prepreg;

[0112] A composite rudder for an aircraft includes a matrix layer 3, an upper structure layer 1, a lower structure layer 2, and a metal part 4;

[0113] The matrix layer is a chopped carbon fiber prepreg;

[0114] The chopped carbon fiber prepreg is obtained by impregnating chopped carbon fiber with modified epoxy resin;

[0115] Both the upper structure layer and the lower structure layer are carbon fiber unidirectional tape prepregs;

[0116] The carbon fiber unidirectional tape prepreg is obtained by impregnating carbon fiber unidirectional tape with modified epoxy resin;

[0117] The metal part is made of 7050 aluminum alloy;

[0118] The forming method of the composite rudder for an aircraft includes the following steps:

[0119] Weigh the matrix layer sheet material, then use an automatic cutting machine to pre-cut 7 layers of the upper structure layer sheet material and the lower structure layer sheet material respectively and combine the materials according to the laying sequence. Then, combine and lay the lower structure layer 2, the matrix layer 3, the upper structure layer 1, and the metal part 4 in sequence to form a combined body. Exclude the air bubbles between the layers by vacuum pumping, place the combined body in the lower die body 5 of the mold, and position it with the metal part positioning block 7. Operate the hot press to close the upper die body 6 and the lower die body 5 through the guide pillars 8 and the guide sleeves 9. The closing gap is 0.01 mm, the pressure of the hot press is 20 Mpa, the temperature is 150 °C, and the heat preservation time is 5 min. Release the pressure and demold to obtain the composite rudder for an aircraft.

[0120] Example 4

[0121] Prepare the modified epoxy resin, and the specific steps are as follows:

[0122] S1: According to the mass ratio of the silanized composite material, N,N-dimethylformamide, and methyl methacrylate being 1.2:45:1.4, add the silanized composite material to N,N-dimethylformamide. After stirring evenly, add methyl methacrylate, and then stir at a speed of 700 rpm in a water bath at 80 °C for 3 h. After filtration, wash with a mixed solution of methanol and acetone (the volume ratio of methanol to acetone is 1:9) 3 times (the mass of the mixed solution of methanol and acetone each time is 40% of the mass of N,N-dimethylformamide), and finally vacuum dry at 60 °C for 24 h to obtain the reinforcing material;

[0123] Among them, the preparation method of the silanized composite material includes the following steps:

[0124] According to the mass ratio of the composite material and absolute ethanol being 1.1:110, add the composite material to absolute ethanol and ultrasonically disperse for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 10% of the mass of absolute ethanol), and stir at a speed of 700 rpm in a water bath at 65 °C for 1 h. After the reaction is completed, filter, wash with absolute ethanol 3 times (the mass of absolute ethanol each time is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 50 °C for 24 h to obtain the silanized composite material, where the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed according to a mass ratio of 0.6:0.3;

[0125] S2: According to the mass ratio of the reinforcing material, diethanolamine, and methanol being 5.5:3.5:20, add the reinforcing material and diethanolamine in step S1 to methanol, and stir at room temperature for 24 h, then add zinc acetate (the mass of zinc acetate is 8% of the mass of diethanolamine), and react at 65 °C for 0.5 h, react at 105 °C for 1.5 h, react at 125 °C for 1.5 h, and finally react at 155 °C for 1.5 h. After the reaction is completed, cool to room temperature, filter, wash with methanol 3 times (the mass of methanol each time is equal to the mass of the above methanol), and finally vacuum dry at 50 °C for 12 h to obtain the hyperbranched polymer;

[0126] S3: According to the mass ratio of the hyperbranched polymer and the composite epoxy resin being 12:110, add the hyperbranched polymer in step S2 to the composite epoxy resin, then stir at 35 °C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let stand at room temperature for 24 h to obtain the modified epoxy resin, where the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed according to a mass ratio of 1.2:0.6:0.3;

[0127] The preparation method of the chopped carbon fiber prepreg comprises the following steps:

[0128] According to the impregnation ratio of chopped carbon fiber to modified epoxy resin being 6:4, add the chopped carbon fiber into the modified epoxy resin, and impregnate for 30 min, then cure at 85 °C for 5 h to obtain the chopped carbon fiber prepreg;

[0129] The preparation method of the carbon fiber unidirectional tape prepreg comprises the following steps:

[0130] According to the impregnation ratio of carbon fiber unidirectional tape to modified epoxy resin being 7:3, add the carbon fiber unidirectional tape into the modified epoxy resin, and impregnate for 40 min, then cure at 95 °C for 3 h to obtain the carbon fiber unidirectional tape prepreg;

[0131] A composite rudder for an aircraft comprises a matrix layer 3, an upper structure layer 1, a lower structure layer 2 and a metal part 4;

[0132] The matrix layer is a chopped carbon fiber prepreg;

[0133] The chopped carbon fiber prepreg is obtained by impregnating chopped carbon fiber with modified epoxy resin;

[0134] Both the upper structure layer and the lower structure layer are carbon fiber unidirectional tape prepregs;

[0135] The carbon fiber unidirectional tape prepreg is obtained by impregnating carbon fiber unidirectional tape with modified epoxy resin;

[0136] The material of the metal part is 7050 aluminum alloy;

[0137] The forming method of the composite rudder for an aircraft comprises the following steps:

[0138] Weigh the matrix layer sheet material, then use an automatic cutting machine to pre-cut 7 layers of the upper structure layer sheet material and the lower structure layer sheet material respectively and combine the materials according to the laying sequence. Then, combine and lay the lower structure layer 2, the matrix layer 3, the upper structure layer 1 and the metal part 4 in sequence to form a combined body. Exclude the air bubbles between the layers by vacuum pumping, place the combined body in the lower die body 5 of the mold, and position it with the metal part positioning block 7. Operate the hot press to close the upper die body 6 and the lower die body 5 through the guide columns 8 and the guide sleeves 9. The closing gap is 0.01 mm, the pressure of the hot press is 20 Mpa, the temperature is 150 °C, and the heat preservation time is 5 min. Remove the pressure and demold to obtain the composite rudder for an aircraft.

[0139] Comparative Example 1

[0140] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the composite material in step S1 is replaced with carboxymethyl-β-cyclodextrin in equal mass, and the remaining steps and raw materials are the same as those in Example 3;

[0141] The preparation method of silanized carboxymethyl-β-cyclodextrin comprises the following steps:

[0142] According to the mass ratio of carboxymethyl-β-cyclodextrin to absolute ethanol being 1.1:110, add carboxymethyl-β-cyclodextrin into absolute ethanol, and ultrasonically disperse for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminoethylaminopropyltrimethoxysilane (the mass of γ-aminoethylaminopropyltrimethoxysilane is 10% of the mass of absolute ethanol), stir at a rotation speed of 700 rpm in a water bath at 65 °C for 1 h. After the reaction is completed, filter, wash with absolute ethanol three times (the mass of absolute ethanol each time is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 50 °C for 24 h to obtain silanized carboxymethyl-β-cyclodextrin.

[0143] Comparative Example 2

[0144] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the composite material in step S1 is replaced with cellulose nanofibers in equal mass, and the remaining steps and raw materials are the same as those in Example 3;

[0145] The preparation method of silanized cellulose nanofibers comprises the following steps:

[0146] According to the mass ratio of cellulose nanofibers to absolute ethanol being 1.1:110, add cellulose nanofibers into absolute ethanol, and ultrasonically disperse for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminoethylaminopropyltrimethoxysilane (the mass of γ-aminoethylaminopropyltrimethoxysilane is 10% of the mass of absolute ethanol), stir at a rotation speed of 700 rpm in a water bath at 65 °C for 1 h. After the reaction is completed, filter, wash with absolute ethanol three times (the mass of absolute ethanol each time is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 50 °C for 24 h to obtain silanized cellulose nanofibers.

[0147] Comparative Example 3

[0148] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the reinforcing material in step S1 is directly added into the composite epoxy resin, and the original step S2 is deleted, and the remaining steps and raw materials are the same as those in Example 3;

[0149] To prepare the modified epoxy resin, the specific steps are as follows:

[0150] S1: According to the mass ratio of the silanized composite material, N,N-dimethylformamide, and 4-epoxyisoeugenol being 1.2:45:1.4, add the silanized composite material to N,N-dimethylformamide. After stirring evenly, add 4-epoxyisoeugenol, and then stir in a water bath at 80 °C at a rotation speed of 700 rpm for 3 h. After filtration, wash 3 times with a mixed solution of methanol and acetone (the volume ratio of methanol to acetone is 1:9) (the mass of the mixed solution of methanol and acetone each time is 40% of the mass of N,N-dimethylformamide), and finally vacuum dry at 60 °C for 24 h to obtain the reinforcing material;

[0151] Among them, the preparation method of the silanized composite material includes the following steps:

[0152] According to the mass ratio of the composite material and absolute ethanol being 1.1:110, add the composite material to absolute ethanol and ultrasonically disperse for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then add γ-aminopropyltriethoxysilane (the mass of γ-aminopropyltriethoxysilane is 10% of the mass of absolute ethanol), and stir in a water bath at 65 °C at a rotation speed of 700 rpm for 1 h. After the reaction is completed, filter, wash 3 times with absolute ethanol (the mass of absolute ethanol each time is 15% of the mass of the above absolute ethanol), and finally vacuum dry at 50 °C for 24 h to obtain the silanized composite material, where the composite material is composed of carboxymethyl-β-cyclodextrin and cellulose nanofibers mixed in a mass ratio of 0.6:0.3;

[0153] S2: According to the mass ratio of the reinforcing material and the composite epoxy resin being 12:110, add the reinforcing material in step S1 to the composite epoxy resin, then stir at 35 °C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the reinforcing material), and let stand at room temperature for 24 h to obtain the modified epoxy resin, where the composite epoxy resin is composed of bisphenol F diglycidyl ether, sorbitol glycidyl ether, and poly(dimethylsiloxane) diglycidyl ether mixed in a mass ratio of 1.2:0.6:0.3.

[0154] Comparative Example 4

[0155] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the composite epoxy resin in step S3 is composed of bisphenol F diglycidyl ether and sorbitol glycidyl ether, and the remaining steps and raw materials are the same as those in Example 3;

[0156] S3: Add the hyperbranched polymer obtained in step S2 to the composite epoxy resin according to the mass ratio of the hyperbranched polymer to the composite epoxy resin being 12:110, then stir at 35°C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let it stand at room temperature for 24 h to obtain the modified epoxy resin. Among them, the composite epoxy resin is composed of bisphenol F diglycidyl ether and sorbitol glycidyl ether mixed according to the mass ratio of 1.2:0.9.

[0157] Comparative Example 5

[0158] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the composite epoxy resin in step S3 is composed of bisphenol F diglycidyl ether and poly(dimethylsiloxane) diglycidyl ether, and the remaining steps and raw materials are the same as those in Example 3;

[0159] S3: Add the hyperbranched polymer obtained in step S2 to the composite epoxy resin according to the mass ratio of the hyperbranched polymer to the composite epoxy resin being 12:110, then stir at 35°C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let it stand at room temperature for 24 h to obtain the modified epoxy resin. Among them, the composite epoxy resin is composed of bisphenol F diglycidyl ether and poly(dimethylsiloxane) diglycidyl ether mixed according to the mass ratio of 1.2:0.9.

[0160] Comparative Example 6

[0161] The difference between this comparative example and Example 3 is that when preparing the modified epoxy resin, the composite epoxy resin in step S3 is composed of sorbitol glycidyl ether and poly(dimethylsiloxane) diglycidyl ether, and the remaining steps and raw materials are the same as those in Example 3;

[0162] S3: Add the hyperbranched polymer obtained in step S2 to the composite epoxy resin according to the mass ratio of the hyperbranched polymer to the composite epoxy resin being 12:110, then stir at 35°C for 15 min, and then add 4,4'-diaminodiphenylmethane (the mass of 4,4'-diaminodiphenylmethane is 50% of the mass of the hyperbranched polymer), and let it stand at room temperature for 24 h to obtain the modified epoxy resin. Among them, the composite epoxy resin is composed of sorbitol glycidyl ether and poly(dimethylsiloxane) diglycidyl ether mixed according to the mass ratio of 1.2:0.9.

[0163] Perform performance tests on the composite material rudder blades for aircraft prepared in Examples 1-3 and Comparative Examples 1-6, including density, specific strength, and specific modulus. According to GB 1463-2005, test the density of the chopped carbon fiber prepreg and carbon fiber unidirectional tape prepreg in the composite material rudder blades for aircraft prepared in Examples 1-3 and Comparative Examples 1-6; according to GB / T 1447-2005, test the specific strength and specific modulus of the chopped carbon fiber prepreg and carbon fiber unidirectional tape prepreg in the composite material rudder blades for aircraft prepared in Examples 1-3 and Comparative Examples 1-6. The test results are shown in Table 1 below:

[0164] Table 1 Performance parameters of the composite material rudder blades for aircraft prepared in Examples 1-3 and Comparative Examples 1-6

[0165] Project <![CDATA[Density (g / cm 3 )]]> <![CDATA[Specific strength (MPa·cm 3 / g)]]> <![CDATA[Specific modulus (GPa·cm 3 / g)]]> Example 1 1.704 2043 192 Example 2 1.695 2058 197 Example 3 1.711 2032 188 Example 4 1.709 2024 184 Comparative Example 1 1.710 2015 173 Comparative Example 2 1.709 2011 170 Comparative Example 3 1.704 2001 164 Comparative Example 4 1.706 2004 167 Comparative Example 5 1.707 2002 165 Comparative Example 6 1.708 2000 163

[0166] As can be seen from the data in Table 1 above, by comparing Examples 4, Comparative Examples 1-2 with Example 3, it can be seen that when methyl methacrylate is combined with the silanized composite material, or the composite material in step S1 is replaced with carboxymethyl-β-cyclodextrin or cellulose nanofibers in equal mass to prepare the composite material rudder blade for aircraft, the test results are worse than those of Example 3. This shows that the combination of 4-epoxyisoeugenol and the silanized composite material not only has good bonding strength, but also 4-epoxyisoeugenol can enhance the thermal stability and heat resistance of epoxy resin, further improve the toughness and impact resistance of epoxy resin, and enhance the specific strength and specific modulus of the composite material rudder blade; the composite material composed of a mixture of carboxymethyl-β-cyclodextrin and cellulose nanofibers can play a synergistic effect, can better improve the toughness and impact resistance of epoxy resin, and further improve the specific strength and specific modulus of the composite material rudder blade;

[0167] By comparing Comparative Example 3 with Example 3, it can be seen that when the reinforcing material is directly added to the composite epoxy resin and finally the composite material rudder blade for aircraft is prepared, the test results are worse than those of Example 3. This shows that chemically combining the reinforcing material with diethanolamine first can effectively enhance the bonding strength between the two, and the hyperbranched polymer formed by the combination of the reinforcing material and diethanolamine can better improve the toughness and impact resistance of epoxy resin, while increasing the adhesion between epoxy resin and chopped carbon fiber and carbon fiber unidirectional tape, and further improving the specific strength and specific modulus of the composite material rudder blade;

[0168] It can be seen from the comparison between Comparative Examples 4-6 and Example 3 that when the composite epoxy resin in Step S3 is prepared by mixing bisphenol F diglycidyl ether and sorbitol glycidyl ether, or the composite epoxy resin is prepared by mixing bisphenol F diglycidyl ether and poly(dimethylsiloxane) diglycidyl ether, or the composite epoxy resin is prepared by mixing sorbitol glycidyl ether and poly(dimethylsiloxane) diglycidyl ether to prepare the composite material rudder for aircraft, the test results are worse than those of Example 3. This shows that the composite epoxy resin composed of bisphenol F diglycidyl ether, sorbitol glycidyl ether and poly(dimethylsiloxane) diglycidyl ether has a synergistic effect among the three. It can not only penetrate into the chopped carbon fiber and carbon fiber unidirectional tape well, but also further improve the toughness and impact strength of the epoxy resin, while reducing the overall weight of the composite material rudder, effectively improving the specific strength and specific modulus of the rudder.

[0169] As can be seen from Table 1 above, for the composite material rudder for aircraft prepared in Examples 1-3 compared with the composite material rudder for aircraft prepared in Comparative Examples 1-6, by combining an organic compound with a silylated composite material, then combining with diethanolamine, and then mixing with a composite epoxy resin, a modified epoxy resin is obtained; the modified epoxy resin is impregnated into the chopped carbon fiber and carbon fiber unidirectional tape respectively, and then laid with metal parts to form a combined body, and finally hot-pressed to obtain the composite material rudder for aircraft, meeting the requirements of the test performance. However, the composite material rudder for aircraft prepared in Comparative Examples 1-6 does not meet the performance requirements standard, indicating that the composite material rudder for aircraft prepared by the present invention not only has better specific strength and specific modulus, but also has a lighter overall weight, simple molding, lower production cost, and better overall comprehensive performance.

[0170] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0171] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by the claims of this patent, they should belong to the protection scope of the present invention.

Claims

1. A composite rudder blade for an aircraft, characterized in that: It includes a base layer, an upper structural layer, a lower structural layer and metal parts; The matrix layer is chopped carbon fiber prepreg; The chopped carbon fiber prepreg is prepared by impregnating chopped carbon fibers with modified epoxy resin; The upper structural layer and the lower structural layer are both carbon fiber unidirectional tape prepreg; The carbon fiber unidirectional tape prepreg is prepared by impregnating the carbon fiber unidirectional tape with a modified epoxy resin; The preparation method of the modified epoxy resin comprises the following steps: S1: Reinforced material is obtained by combining organic compounds with silanized composite materials; S2: combining the reinforcing material with diethanolamine to obtain a hyperbranched polymer; S3: Mixing the hyperbranched polymer with the composite epoxy resin, and then adding a curing agent to obtain a modified epoxy resin.

2. The composite rudder blade for aircraft according to claim 1, characterized in that: Step S1 is specifically as follows: The silanized composite material is added to N,N-dimethylformamide, stirred evenly, and then the organic compound is added, followed by stirring in a water bath at 70-80°C for 3-4 hours, filtered, washed with a mixed solution of methanol and acetone, and finally vacuum dried at 50-60°C to obtain a reinforced material.

3. The composite rudder blade for aircraft according to claim 2, characterized in that: The organic compound is at least one of 4-epoxyisoeugenol, methyl methacrylate and glycidyl methacrylate.

4. The composite rudder blade for aircraft according to claim 2, characterized in that: The preparation method of the silanized composite material comprises the following steps: The composite material is added to anhydrous ethanol and ultrasonically dispersed for 25-35 minutes, then a silane coupling agent is added, stirred in a water bath at 55-65° C. for 1-2 hours, filtered, washed with anhydrous ethanol, and finally vacuum dried at 40-50° C. to obtain a silanized composite material.

5. The composite rudder blade for aircraft according to claim 4, characterized in that: The composite material is formed by mixing carboxymethyl-β-cyclodextrin and cellulose nanofibers in a mass ratio of 0.5-0.6:0.2-0.

3.

6. The composite rudder blade for aircraft according to claim 1, characterized in that: Step S2 is specifically as follows: The reinforcing material and diethanolamine in step S1 are added to methanol and stirred for 22-24 hours, and then a catalyst is added and a stepwise reaction is performed, the mixture is cooled to room temperature, filtered, washed with methanol, and finally vacuum dried at 40-50° C. to obtain a hyperbranched polymer.

7. The composite rudder blade for aircraft according to claim 1, characterized in that: Step S3 is specifically as follows: The hyperbranched polymer in step S2 is added to the composite epoxy resin, and then stirred at 25-35° C. for 10-15 minutes, and then a curing agent is added, and the mixture is allowed to stand at room temperature to obtain a modified epoxy resin.

8. The composite rudder blade for aircraft according to claim 7, characterized in that: The composite epoxy resin is prepared by mixing bisphenol F diglycidyl ether, sorbitol glycidyl ether and poly(dimethylsiloxane) diglycidyl ether in a mass ratio of 1-1.2:0.5-0.6:0.2-0.

3.

9. A method for forming a composite material rudder blade for an aircraft according to any one of claims 1 to 8, characterized in that: The following steps are involved: Weigh the substrate layer sheet, then pre-cut the upper structure layer sheet and the lower structure layer sheet and combine them in the order of laying, then combine and lay the lower structure layer, substrate layer, upper structure layer and metal parts in order to form an assembly, remove the bubbles between the layers by vacuuming, place the assembly in the lower mold body of the mold, position it with a metal positioning block, operate the hot press to press and close the upper mold body with the lower mold body through guide pillars and guide sleeves, release the pressure, demould, and obtain the composite material rudder blade for aircraft.

10. The method for forming a composite material rudder blade for an aircraft according to claim 9, characterized in that: The pressure of the hot press is 8-20 MPa, the temperature is 140-150° C., and the insulation time is 5-10 min.

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