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CN-122011676-A - Co-cured fiber reinforced composite material for wing girder joint

CN122011676ACN 122011676 ACN122011676 ACN 122011676ACN-122011676-A

Abstract

The invention belongs to the field of aviation composite materials, and provides a co-cured fiber reinforced composite material for a wing girder joint, which adopts a resin system design of synergistic toughening and flame retarding of a phosphorus-containing epoxy adduct and 1, 4-butanediol diglycidyl ether, a conductive thin felt layer construction of polydopamine coating and silane coupling agent double modification, and a sandwich structure design of gradient zone layering assembly, so that the high Tg and low porosity of a resin matrix under a low viscosity infiltration condition, the combination of low surface sheet resistance and strong interface of a modified conductive thin felt layer, the high lap joint bearing capacity and layering damage tolerance of a gradient sandwich structure are realized, the problems that full infiltration and conductive network continuity are difficult to be compatible in a co-curing molding process, the interlayer weak surface and interface embrittlement risk caused by conductive flame retarding modification, and the residual stress concentration and insufficient dimensional stability caused by high-temperature curing are solved, and the co-cured composite material has a wide aviation structure application value.

Inventors

  • Yan Ziao
  • LI RENFU

Assignees

  • 仁合智航科技(武汉)有限责任公司

Dates

Publication Date
20260512
Application Date
20260123

Claims (10)

  1. 1. A co-cured fiber reinforced composite for a wing spar joint, comprising: a continuous fiber reinforcement comprising a carbon fiber lay-up; a thermosetting resin matrix formed by curing the co-curable epoxy resin composition; Modified conduction Bao Zhanceng located at the wing girder joint region; The co-curing epoxy resin composition comprises an epoxy resin component, a curing agent and an accelerator, wherein the epoxy resin component comprises 5-30 parts by weight of a phosphorus-containing epoxy adduct, 2-15 parts by weight of 1, 4-butanediol diglycidyl ether and bisphenol A diglycidyl ether, the balance of the bisphenol A diglycidyl ether being up to 100 parts by weight, the curing agent is 4,4' -diaminodiphenyl sulfone, the amount of the curing agent is 15-40 parts by weight, the total amount of the epoxy resin component is 100 parts by weight, and the accelerator is 2-methylimidazole, the amount of the accelerator is 0.05-1.00 parts by weight; the surface density of the modified conductive thin felt layer is 5-30g/m < 2 >, the thickness is 10-80 mu m, and the modified conductive thin felt layer is arranged between two adjacent carbon fiber layers; The wing girder joint area comprises a gradient area along the lap joint direction, the length of the gradient area is 10-80mm, the gradient area comprises a first subarea and a second subarea, the first subarea and the second subarea are sequentially arranged along the lap joint direction, the number of layers of the modified conductive felt layer in the first subarea is 1, and the number of layers of the modified conductive felt layer in the second subarea is 2-3.
  2. 2. The co-cured fiber reinforced composite of claim 1, wherein the modified conductive felt layer is prepared by: A1 Preparing a solution by taking deionized water as a solvent, adding dopamine hydrochloride with the addition amount of 0.5-5.0g/L and tris (hydroxymethyl) aminomethane with the addition amount of 1.0-20.0g/L, and regulating the pH value of the solution to 8.5-9.0 by using a hydrochloric acid solution or a sodium hydroxide solution with the concentration of 0.1-1.0 mol/L; a2 Immersing the conductive thin felt substrate into the solution obtained in the step A1), wherein the bath ratio of the conductive thin felt substrate immersed into the solution is 50-500mL of the solution corresponding to 1g of the conductive thin felt substrate, and reacting for 0.5-6.0h under the conditions of 15-35 ℃ and air atmosphere to obtain a coated conductive thin felt, wherein the conductive thin felt substrate is selected from multi-wall carbon nano tube thin felt or carbon fiber thin felt; A3 Washing and drying, namely washing with deionized water for 1-5 times, washing with absolute ethyl alcohol for 1-5 times, wherein the bath ratio of each washing in the step A3) is 20-200mL of washing liquid corresponding to 1g of conductive mat, and then drying for 2-12 hours at the temperature of 40-80 ℃; A4 Immersing the dried product obtained in the step A3) into a coupling solution, wherein the bath ratio of the dried product immersed into the coupling solution is 30-300mL of the coupling solution corresponding to the coupling solution, reacting for 0.5-4.0h at the temperature of 20-60 ℃ to obtain the coupling treated conductive thin felt, wherein the coupling agent in the coupling solution is one or two of 3-aminopropyl triethoxysilane and 3-glycidol ether oxypropyl trimethoxysilane, the total mass fraction of the coupling agent in the coupling solution is 0.1-5.0wt%, the mass fraction is based on the total mass of the coupling solution, the solvent of the coupling solution is a mixture of ethanol and deionized water, and the mass ratio of the ethanol to the deionized water is 90:10-50:50; A5 Drying and quality control, namely drying for 2-12 hours at the temperature of 40-80 ℃ to obtain the modified conductive thin felt layer, wherein the coating weight gain of the modified conductive thin felt layer is 0.5-5.0wt%, the coating weight gain is based on the mass of the conductive thin felt substrate, and the surface sheet resistance of the modified conductive thin felt layer is 1-10 4 ohm/sq.
  3. 3. The co-cured fiber reinforced composite of claim 1, wherein the gradient-assembled conductive interlayer sheet for the gradient zone is prepared by: B1 Providing a modified conductive felt layer and cutting into strip-shaped sheets, wherein the dimension of the strip-shaped sheets along the lap joint direction is 10-80mm; B2 Step-stacking the strip-shaped sheets in a layer number step-by-step manner along the lap joint direction, so that the number of layers of the first subarea is 1 layer, the number of layers of the second subarea is 2-3 layers, and the total length of the gradient area is 10-80mm; B3 Shaping, namely hot-pressing for 1-30min under the condition that the temperature is 60-120 ℃ and the pressure is 0.05-0.50MPa to obtain a gradient assembled conductive interlayer sheet; B4 Quality control, wherein the position tolerance of the gradient region of the gradient assembly conductive interlayer sheet is +/-2 mm.
  4. 4. A co-cured fiber reinforced composite according to claim 1, wherein the phosphorus-containing epoxy adduct is prepared by: c1 Mixing 100 parts by weight of bisphenol A diglycidyl ether with 8-26 parts by weight of 9, 10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide; c2 The addition reaction is carried out for 1 to 6 hours under the condition of 110 to 130 ℃ in the industrial nitrogen atmosphere; c3 End point criterion, stopping the reaction when the mass fraction of the phosphorus element of the obtained adduct is 1.0-3.0wt% and the epoxy equivalent is 250-500 g/equivalent; C4 Cooling to a temperature of 60-90 ℃ to obtain the phosphorus-containing epoxy adduct.
  5. 5. The co-cured fiber reinforced composite of claim 1, wherein the co-cured epoxy resin composition is prepared by: d1 Premixing, namely mixing bisphenol A diglycidyl ether, a phosphorus-containing epoxy adduct and 1, 4-butanediol diglycidyl ether, and keeping the mixture for 0.5 to 2.0 hours at the temperature of 60 to 90 ℃; D2 Adding a curing agent and an accelerator, namely adding 4,4' -diaminodiphenyl sulfone and 2-methylimidazole into the mixture obtained in the step D1), and keeping the temperature at 80-120 ℃ for 0.5-3.0h; D3 Defoaming, namely defoaming for 0.5 to 2.0 hours under the condition of absolute pressure of 0.1 to 10kPa to obtain the co-cured epoxy resin composition; D4 Viscosity control, namely, the apparent viscosity of the co-cured epoxy resin composition is 5-30 Pa.s under the condition that the temperature is 80 ℃ and the shear rate is 1-100/s by adopting a rotational viscometer or a rheometer.
  6. 6. The co-cured fiber reinforced composite according to claim 2, wherein the conductive mat substrate is one selected from the group consisting of a multi-walled carbon nanotube mat and a composite mat, the composite mat being formed by supporting multi-walled carbon nanotubes on a carbon fiber mat, the mass fraction of the multi-walled carbon nanotubes in the composite mat being 10-60wt%, the mass fraction being based on the total mass of the composite mat; The surface density of the carbon fiber layer is 120-300g/m < 2 >.
  7. 7. A method for co-curing a fibre reinforced composite material for a wing spar joint as claimed in claim 1, comprising the steps of: s1, providing modified conduction Bao Zhanceng; S2, providing a gradient assembly conductive interlayer sheet; S3, providing a phosphorus-containing epoxy adduct; s4, mixing bisphenol A diglycidyl ether, the phosphorus-containing epoxy adduct, 1, 4-butanediol diglycidyl ether, 4' -diaminodiphenyl sulfone and 2-methylimidazole and defoaming to obtain a co-cured epoxy resin composition; S5, laminating a carbon fiber layer, the co-cured epoxy resin composition and the gradient assembly conductive interlayer sheet in a wing girder joint area to form a prefabricated body, wherein the gradient assembly conductive interlayer sheet is positioned between two adjacent carbon fiber layers; s6, vacuum packaging the prefabricated body, and then executing a curing program under the condition of the pressure of 0.30-0.70MPa, wherein the temperature is increased from 20-30 ℃ to 90-130 ℃ at the temperature increasing rate of 1-5 ℃ per minute, the temperature is kept for 1.0-3.0h, the temperature is increased from 160-190 ℃ at the temperature increasing rate of 1-5 ℃ per minute, and the temperature is kept for 2.0-4.0h, so that the co-cured fiber reinforced composite material for the wing girder joint is obtained.
  8. 8. The method of claim 7, wherein the absolute pressure of the vacuum package in step S6 is 0.1-10kPa.
  9. 9. The method according to claim 7, wherein the co-cured epoxy resin composition obtained in step S4 has an apparent viscosity of 5 to 30 Pa-S as measured by a rotational viscometer or rheometer at a shear rate of 1 to 100/S at a temperature of 80 ℃.
  10. 10. The method according to claim 7, wherein the modified conductive thin felt layer provided in step S1 has a coating weight gain of 0.5 to 5.0wt% and a surface sheet resistance of 1 to 10 4 Ω/sq.

Description

Co-cured fiber reinforced composite material for wing girder joint Technical Field The invention relates to the field of aviation composite materials, in particular to a co-cured fiber reinforced composite material for a wing girder joint. Background The main wing beam joint is used as a key bearing part for the connection of large civil aircraft wings, bears the long-term effects of complex multidirectional load and fatigue cyclic stress, and has extremely high requirements on the lap joint bearing capacity, delamination damage tolerance resistance, conductive protection performance and heat-resistant dimensional stability of the composite material. In the lightning protection application scene, the joint area needs to construct a continuous and complete conductive network to realize effective current dispersion and dissipation and avoid local arc ablation and layering damage, and meanwhile, the lap joint structure of the joint area needs to bear shearing stress and stripping load of tens of megapascals, so that the material is required to have excellent interlaminar shearing strength, interlaminar fracture toughness of mode I and mode II and long-term bearing stability in a high-temperature high-humidity environment. The method for meeting and developing the comprehensive performances has important significance for improving the safety margin of the aircraft structure, prolonging the service life and reducing the weight of the structure, and is a key technical breakthrough point for promoting the application of the aviation composite material from the secondary bearing structure to the main bearing structure. Aiming at the current development situation of fiber reinforced composite materials for wing girder joints, the current research faces three defects. Firstly, when the traditional epoxy resin pursues low-viscosity infiltration and defoaming, the glass transition temperature after curing is low, the crosslinking density is insufficient, the requirement of high Wen Fuyi is difficult to meet, and resin loss and pore defects are easy to cause, which is caused by the contradiction between the low-molecular-weight epoxy and the formula of the quick curing agent. Second, conductive interlayers such as carbon nanotube mats can build conductive networks, but the surface inertness results in weak bonding with the resin interface, which is prone to interfacial debonding and microcracking during curing, forming interlayer weaknesses, significantly reducing delamination resistance tolerance, due to the lack of active functional groups on the carbonaceous material surface. Thirdly, if the conductive interlayer of the joint overlap region is uniformly laid, stress concentration can be formed, the gradient structure can be relieved, but the assembly precision is difficult to control, and the introduction of the phosphorus-containing flame retardant component can weaken the interface and aggravate residual stress and unstable dimension caused by coupling of curing shrinkage and thermal stress. For example, chinese patent publication No. CN116355357B discloses a long-short carbon nanotube reinforced and toughened fiber composite material and a preparation method thereof, but has the problems of uneven dispersion and insufficient interface bonding, and Chinese patent publication No. CN113896746B discloses a method for preparing flame-retardant epoxy resin by using phosphorus-nitrogen long-chain flame retardant compound, but has the defects of reduced toughness and narrowed curing process window. Disclosure of Invention The invention aims to provide a co-cured fiber reinforced composite material for a wing girder joint, which solves the problems that low-viscosity infiltration and conductive network continuity are difficult to be compatible in the current co-curing forming process, interlayer weakness and interface embrittlement risks are introduced by conductive flame retardant modification, and residual stress concentration and insufficient dimensional stability are caused by high-temperature curing. According to the invention, a synergistic toughening flame-retardant thought of the phosphorus-containing epoxy adduct and the 1, 4-butanediol diglycidyl ether is adopted, the flame retardant property and the crosslinking density are provided by the phosphorus-containing epoxy adduct, and the flexible chain segment and the toughness are contributed by the 1, 4-butanediol diglycidyl ether, so that the comprehensive performance improvement of the resin matrix with high glass transition temperature and excellent toughness under the condition of low viscosity is realized by the synergistic effect of the phosphorus-containing epoxy adduct and the 1, 4-butanediol diglycidyl ether, meanwhile, the strong interface chemical bonding of the conductive thin felt layer and the resin matrix is constructed by the polydopamine coating and the silane coupling agent through double surface modification, the interface bonding defect of a sin