RU2641744C1 - Layer hybrid composite material and the product made of it - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: composite material contains external and internal layers of Al-Li alloys and layers of fiberglass based on adhesive prepregs with reinforcing filler. As outer layers, Al-Li sheets of 1-2 mm. As internal layers, Al-Li sheets with a thickness of 0.3-0.5 mm in an amount not less than three. Layers of fiberglass, located under external Al-Li layers are made on the basis of glutinous prepreg on satin weave fiberglass reinforcing fillers content not more than 40 per cent of the bulk.

EFFECT: increasing the resource, the bearing capacity for compression and the weight efficiency of products.

7 cl, 1 dwg, 3 tbl, 1 ex

Description

The invention relates to the field of layered hybrid composite materials containing external and internal sheets of aluminum-lithium alloys and fiberglass layers based on adhesive prepregs with different content of reinforcing filler, used as a structural material for power skins of an aircraft wing, as well as for use in other transport means.

For many years, wing sheathing has been made by machining plates (sheets, pressed panels): upper ones from high-strength alloys of type B95ochT2 (7475-T76 abroad), differing mainly in high static compressive strength, lower ones from resource medium-strength alloys of type 1163T (2524- T351 abroad), characterized by increased characteristics of ductility and fracture toughness, and are used as monolithic stringer structures with a processed web thickness of ~ 5-10 mm (A.A. Tupolev, VV Sulimenkov, VK Zeltin. lutational characteristics and design efficiency of passenger aircraft.Metal science of aluminum alloys M., Nauka, 1985, pp. 22-40; OG Senatorova, VV Antipov, AV Bronz, AV Somov, N. Yu. Serebrennikova, High-strength and heavy-duty alloys of the traditional Al-Zn-Mg-Cu system, their role in technology and development possibilities // TLS, 2016, No. 2, pp. 43-49).

A known class of laminated hybrid aluminum-glass-reinforced plastics under the brand GLARE (Glass + Aluminum + Reinforced), which are proposed and implemented in the fuselage skin by AKZO (Netherlands) (EP 0312151 A1, publ. 1989), consisting of thin, uniform thicknesses (0.2-0, 5 mm) of sheets of traditional alloys of alloying systems Al-Cu-Mg (2024-T3 - type D16chT) and Al-Zn-Mg-Cu (7475-T76 - type B95ochT2) and intermediate layers of fiberglass, usually on an adhesive binder, reinforced continuous glass fibers of type S glass (VMP series in Russia).

Known Russian layered composite hybrid aluminum-glass plastic SIAL (Glass And Aluminum) low density and high elastic modulus based on thin sheets of Al-Li alloys of the resource type 1441 (RU No. 2185964, publ. 07.27.2002; RU No. 2565215, publ. 20.10. 2015), marked with the SIAL-1-1P brand.

Materials (GLARE and SIAL) are used in the form of relatively thin fuselage skins up to 2.5 mm thick (maximum structure 6/5, where 6 is the number of aluminum sheets and 5 is the number of fiberglass layers). The main disadvantages of the known laminated aluminum-glass-reinforced plastics (GLARE and SIAL) as applied to wing panels are as follows: when used in wing skins, a large multilayer is required, which dramatically increases the complexity of manufacturing the composite - the preparation of the surface of thin Al-Li sheets is complicated (anodic oxidation and soil coating) and manual laying out of more layers of adhesive prepregs; at the same time, the problems of defectiveness and difficulties in their determination are growing.

For these main reasons, the developed multilayer materials of the SIAL and GLARE class are difficult to use in massive wing skins of increased thickness.

Gradient metal-fiberglass plastic is known from the prior art, consisting of external sheets of the same thickness of a high-modulus Al-Li alloy with a yield strength in the range of 300-400 MPa and fiberglass layers based on a thermosetting adhesive binder with fiberglass reinforcing in the form of fabrics or roving. It contains inner sheets of high-strength Al-Li alloy with a yield strength of more than 500 MPa, with each fiberglass layer located between the said inner sheet and the outer sheets, the thickness of the inner sheet is 25-40% of the total thickness of the gradient metal-plastic (RU 2565215, publ. 20.10 .2015, B32B 15/08).

The closest analogue of the claimed invention is a layered composite material consisting of alternating aluminum sheets and layers of fiberglass with a thermosetting binder and reinforcing filler. The material contains at least two layers of aluminum sheets, one of which is made of a high-modulus Al-Li alloy of reduced density with a Li content of more than 1.5%, and the other is made of an alloy of the Al-Mg-Si system with a ratio of layer thicknesses (70 -12): 1 (RU 2270098, publ. 02.20.2006, B32B 15/08).

The disadvantages of these materials are small thickness, reduced bearing capacity and compression resistance, insufficient rigidity.

An object of the present invention is to provide a layered hybrid composite material based on sheets of different thicknesses from two Al-Li alloys and fiberglass layers, which has an increased resource and compressive strength, high resistance to fatigue failure, low density, high strength, high elastic modulus, for structural use in the main power elements of an airplane glider (such as wing skins) and other transport equipment.

The technical result of the claimed invention is to create a layered hybrid composite material based on Al-Li sheets with an increased resource and compressive strength, while maintaining high resistance to fatigue fracture and strength, low density, increased elastic modulus.

To solve this problem, a layered hybrid composite material is proposed containing external and internal layers of Al-Li alloys and fiberglass layers based on adhesive prepregs with reinforcing filler. As external layers, Al-Li sheets with a thickness of 1-2 mm are used. The inner layers are Al-Li sheets with a thickness of 0.3-0.5 mm in an amount of at least three, while the fiberglass layers located under the outer Al-Li layers are made on the basis of an adhesive prepreg in the form of a satin weave fiberglass with a reinforcing content filler no more than 40 volume percent (vol.%).

As metal layers, sheets of Al-Li alloys with a reduced density and a high tensile modulus are used. For example, for the outer layers - sheets of Al-Li alloy with a density of not more than 2690 kg / m ³ and tensile modulus of at least 76 GPa, for the inner metal layers - sheets of Al-Li alloy with a density of not more than 2620 kg / m ³ and a tensile modulus of at least 78 GPa.

Between the inner sheets of the Al-Li alloy, fiberglass reinforced with fiberglass of at least 60 volume percent can be used.

The reinforcing filler between the inner sheets of the Al-Li alloy can be made in the form of unidirectional fiberglass (with a base of high-strength glass fibers and with a weft of fibers of low-melting polymer material) or in the form of glass roving. The base of the reinforcing filler between the inner sheets of the Al-Li alloy can be made of glass fibers with a diameter of 5-20 μm, a density of 2500-2580 kg / m ³ , with a tensile strength of 4000-5000 MPa, a tensile modulus of 85-100 GPa.

The adhesive binder can be made on the basis of a mixture of epoxy resins, modified with a thermoplastic material with an increased curing temperature of 170-180 ° C and provides a monolithic layer of fiberglass and reliable bonding between the layers of the composite material.

Also proposed is a product made from the claimed layered hybrid composite material.

A layered hybrid aluminopolymer composite material (Fig. 1) consists of alternating sheets of different thicknesses from Al-Li alloys and fiberglass layers. External (external) sheets 1 have a thickness of 1-2 mm and are made of high-modulus Al-Li alloy with a density of not more than 2690 kg / m ³ , internal 3 sheets have a thickness of 0.3-0.5 mm and are made of high-modulus Al-Li alloy with a density of not more than 2620 kg / m ³ . The number of internal (thin) sheets 0.3-0.5 mm thick in the structure is at least three, between which fiberglass 4 with a reinforcing filler of at least 60 volume percent of unidirectional glass fibers in the form of glass roving or unidirectional fiberglass is used. Between the outer sheets, 1-2 mm thick, fiberglass 2 based on an adhesive prepreg in the form of a satin weave fiberglass with a reinforcing filler content of not more than 40 volume percent was used.

The proposed regulation of the number of internal thin sheets with a thickness of 0.3-0.5 mm in a structure of at least three, between which a fiberglass based on an adhesive prepreg with a reinforcing filler of unidirectional glass fibers of at least 60 volume percent is applied, provides an increase of 5-10 times the resistance the growth of crack resistance of the layered hybrid material, which leads to an increase in resource.

The use of sheets of low density Al-Li alloys as a part of the layered hybrid material can further increase weight efficiency, while the use of 1-2 mm thick high-modulus Al-Li alloy with a density of not more than 2690 kg / m ³ as outer layers of sheets also to increase the bearing capacity and structural rigidity.

The use of fiberglass layers based on adhesive prepregs with different contents of reinforcing filler in the layered hybrid material can increase the tensile and compression strength, while the fiberglass located between the outer sheets of increased thickness is reinforced with satin fiberglass, which increases the static strength of the material in the transverse direction. Between the inner thin sheets, fiberglass reinforced with unidirectional glass fibers is used.

The use of fiberglass reinforced with satin weave fabric, instead of fiberglass reinforced with roving from traditional high-strength fibers (VMP, S, etc.), increases the static strength properties of the material in width, because the wing covering of the aircraft experiences the action of workloads in the fractional and transverse directions.

A reduced content of up to 40 volume percent of the reinforcing filler ensures sufficient quality of the connection of the outer sheets, as evidenced by direct shear tests (table 1) and the absence of delamination in the samples for other types of tests.

An additional factor is the compatibility of alloys of external and internal Al-Li sheets according to the temperature-time parameters of hardening heat treatment. These parameters, in turn, are compatible with the increased curing temperature (170-180 ° C) of the used adhesive modified binder to create a reliable bond between metal sheets and polymer layers and increase the operating temperature of the composite material.

Figure 1 shows a diagram of a layered hybrid material, where:

1 - outer (outer) layer with a thickness of 1.0-2.0 mm from an Al-Li alloy;

2 - fiberglass based on adhesive prepreg on fiberglass with a content of reinforcing filler not more than 40 vol. %;

3 - inner layer 0.3-0.5 mm thick of Al-Li alloy;

4 - fiberglass based on an adhesive prepreg on a roving or unidirectional fiberglass with a content of reinforcing filler of at least 60 vol. %

Table 3 shows the mechanical and physical properties of sheet blanks from the claimed (examples 2, 3), experimental (examples 1, 4), known (examples 5, 6) laminated composite materials and known monolithic material (example 7). Example 1 - with the content in the structure of two inner sheets with a thickness of 0.3-0.5 mm; example 2 - with the content in the structure of three inner sheets with a thickness of 0.3-0.5 mm; example 3 - with the content in the structure of the four inner sheets with a thickness of 0.3-0.5 mm; example 4 - with the content in the structure of three inner sheets with a thickness of 0.3-0.5 mm and layers of fiberglass reinforced with fabric (up to 40 vol.%); Example 5 - SIAL-1-1P with the same thickness sheets of Al-Li alloy and fiberglass layers on the roving; Example 6 - GLARE with the same thickness mid-strength sheets of alloy 2024 of the Al-Cu system and interlayers of fiberglass on the roving; Example 7 - a monolithic sheet with a thickness of 5-10 mm from an Al-Li alloy.

Examples of implementation

In the pilot industrial production, layered hybrid sheet blanks of the proposed composite material with dimensions of 5 × 500 × 500 mm were formed, consisting of: two external (external) sheets of Al-Li alloy (thickness from 1.0 to 2.0 mm, tensile strength σ _B ~ 560 MPa, reduced density d ~ 2680 kg / m ³ and increased elastic modulus E ~ 78 GPa) and layers of internal unidirectional aluminum-glass plastic structures 2/1, 3/2 and 4/3 based on thin sheets of Al-Li alloy ( 0.35 mm thick (in the amount of two, three, four), tensile strength σ _B ~ 460 MPa, reduced densely with d ~ 2590 kg / m ³ and increased elastic modulus E ~ 79 GPa) and fiberglass layers with fabric reinforcing filler of not more than 40 vol. %, located between the outer Al-Li layers, and fiberglass layers with roving reinforced with at least 60 vol. % by continuous high-strength fibers between the inner thin sheets in unidirectional aluminum-glass-reinforced plastics of structure 2/1, 3/2 and 4/3.

Aluminum-lithium sheets were subjected to preliminary surface preparation: degreasing, etching, anodic oxidation and coating with adhesive primer. The calculation of the material was carried out manually. The sheet blanks of the layered hybrid material were molded by the autoclave method at an increased curing temperature of the modified binder (170-180 ° C).

The microstructure and the regulated ratios of sheets and fiberglass layers, the volumetric content of components in a layered hybrid material was evaluated on thin sections cut from different zones using quantitative microstructural analysis in an optical microscope.

Thus, the proposed crack-resistant, lightweight, high-strength, high-modulus layered hybrid composite material extends the production capabilities of parts, provides increased resource, reliability, weight efficiency, rigidity, compressive strength, temperature range of operation of the products.

The material is recommended for the manufacture of skins (panels) of an airplane wing, as well as for ground transportation products and other transport equipment instead of monolithic plates (sheets, extruded panels) of aluminum and Al-Li alloys and layered materials of the SIAL / GLARE series.

Claims (7)

1. A layered hybrid composite material containing outer and inner layers of Al-Li alloys and fiberglass layers based on an adhesive prepreg with reinforcing filler, characterized in that 1-2 mm thick Al-Li sheets are used as outer layers layers, Al-Li sheets with a thickness of 0.3-0.5 mm in an amount of at least three are used, while the fiberglass layers located under the outer Al-Li layers are made on the basis of an adhesive prepreg in the form of a satin-woven fiberglass with no reinforcing filler content its 40 volume percent. 2. The material according to claim 1, characterized in that, as the outer layers, Al-Li alloy sheets with a density of not more than 2690 kg / m ³ and a tensile modulus of at least 76 GPa are used, Al-Li sheets are used as inner layers alloy with a density of not more than 2620 kg / m ³ and a tensile modulus of at least 78 GPa. 3. The material according to p. 1, characterized in that between the inner layers of the Al-Li alloy, fiberglass reinforced with fiberglass at least 60 percent by volume is used. 4. The material according to claim 1, characterized in that the reinforcing filler between the inner sheets of the Al-Li alloy is made in the form of glass roving or in the form of a unidirectional fiberglass. 5. The material according to claim 1, characterized in that the base of the reinforcing filler between the inner layers of the Al-Li alloy is made of glass fibers with a diameter of 5-20 μm, a density of 2500-2580 kg / m ³ , with a tensile strength of 4000-5000 MPa, a module tensile elasticity 85-100 GPa. 6. The material according to claim 1, characterized in that it contains an adhesive binder modified with a thermoplastic material with an increased curing temperature of 170-180 ° C. 7. A product of a layered hybrid composite material, characterized in that it is made of a material according to any one of paragraphs. 1-6.

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