A curved fiber metal laminate and its preparation method

Abstract

The present invention discloses a curved fiber metal laminate and a preparation method thereof. The curved fiber metal laminate includes a plurality of metal-fiber composite layers stacked, and the metal-fiber composite layer includes a metal layer and a curved fiber prepreg layer stacked; the curved fiber prepreg layer is processed from resin and curved fibers arranged in a curved path. The present invention utilizes the automatic fiber placement technology to realize the curved fiber laying of the fiber composite layer; compared with the straight fiber laying method of the traditional fiber metal laminate, the preparation method of the curved fiber metal laminate provided by the present invention has higher material utilization rate, wider design space, and more uniform stress distribution; the curved fiber metal laminate prepared by this method has a higher degree of light weight and better mechanical properties, and has broad market application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation, and particularly relates to a curved fiber metal laminate and a preparation method thereof. Background Art

[0002] A fiber metal laminate is a hybrid composite material formed by alternating layers of metal materials and fiber composite materials. It has good specific strength and specific stiffness, excellent impact resistance, fatigue resistance, and high damage tolerance. It can not only overcome the disadvantages of traditional metal materials with poor fatigue resistance and corrosion resistance, but also make up for the shortcomings of traditional fiber composite materials with insufficient impact resistance and material toughness. It is an advanced composite material favored in the aerospace industry equipment. Therefore, it is necessary to continue to explore the application potential of advanced new fiber metal laminates on the basis of traditional fiber metal laminates.

[0003] So far, four generations of fiber metal laminates have been developed, namely aramid fiber aluminum alloy laminates, glass fiber aluminum alloy laminates, carbon fiber aluminum alloy laminates, and graphite fiber titanium alloy laminates. Very systematic research has been carried out at home and abroad on the comprehensive performance of these four generations of fiber metal laminates. With the increasing requirements of the aerospace industry for material performance and lightweight degree, the demand for new fiber metal laminates is also becoming increasingly urgent. Therefore, the design of new laminates and the research on their mechanical properties have become the focus of attention of scholars at home and abroad in recent years. The development of new fiber metal laminates mainly focuses on three aspects: First, changing the fiber-reinforced resin composite layer; second, changing the metal or alloy layer; third, changing the structural configuration.

[0004] In recent years, the research on new fiber metal laminates has mainly focused on straight fiber metal laminates, including their material composition and structural form. The fiber composite layers of straight fiber metal laminates are all laid with straight fibers at a single angle of 0°, 90°, and ±45°. The constant direction angle makes the structure unable to fully develop the directional characteristics of the fibers, restricting the performance of the structure. The automatic fiber placement technology developed in recent years has broken the limitation of straight fiber laying, making it possible to form a composite material structure with curved fiber laying. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a curved fiber metal laminate and a preparation method thereof in view of the above-mentioned deficiencies in the prior art.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is: In the first aspect of the present invention, a curved fiber metal laminate is provided, which includes a plurality of metal-fiber composite layers stacked, and the metal-fiber composite layer includes a metal layer and a curved fiber prepreg layer stacked; the outermost layer of the curved fiber metal laminate is a metal layer;

[0007] The curve fiber prepreg layer is processed from resin and curve fibers arranged in a curved path.

[0008] Preferably, an adhesive film bonding layer is further provided between the metal layer and the curve fiber prepreg layer.

[0009] Preferably, the curve fibers in the curve fiber prepreg layer are carbon fibers and the resin is epoxy resin; the volume ratio of the curve fibers in the curve fiber prepreg layer is 50 - 70%.

[0010] Preferably, the material of the metal layer is elemental metal or alloy material.

[0011] Preferably, the adhesive film bonding layer is a polyethylene film or a polypropylene film.

[0012] Preferably, the curve fiber metal laminate includes two metal - fiber composite layers arranged in a stacked manner. The two curve fiber prepreg layers of the two metal - fiber composite layers are on the inner side and in contact with each other, and the two metal layers are both on the outer side.

[0013] In the second aspect of the present invention, a method for preparing the curve fiber metal laminate as described above is provided, including the following steps:

[0014] S1. Pretreatment of the metal layer;

[0015] S2. Using an automatic fiber placement process and an automatic lamination process, process curve fibers and resin to obtain a curve fiber prepreg layer, and dry it for later use;

[0016] S3. Using a mold to prepare the pretreated metal layer, curve fiber prepreg layer and adhesive film bonding layer into a curve fiber metal laminate.

[0017] Preferably, the mold includes: an upper cover plate, a forming mold and a lower cover plate. The upper cover plate, the forming mold and the lower cover plate are all made of metal or alloy. The upper cover plate and the lower cover plate are flat plates, and the forming mold is a flat plate with a forming hole opened in the center.

[0018] Preferably, the method for preparing the curve fiber metal laminate includes the following steps:

[0019] S1. Pretreatment of the metal layer: Polish the surface of the metal layer with silicon carbide sandpaper, then rinse and degrease it with acetone solution, wash it repeatedly with clean water, and finally dry it for storage and later use;

[0020] S2. Using an automatic fiber placement process and an automatic lamination process, process curve fibers and resin to obtain a curve fiber prepreg layer, dry it and naturally cool it to room temperature for later use;

[0021] S3. Spray a release agent on the surfaces of the upper cover plate, the forming die, and the lower cover plate, and place separator films between the upper cover plate and the forming die and between the forming die and the lower cover plate. Bond the pretreated metal layer and the curved fiber prepreg layer through an adhesive film bonding layer to prepare a metal-fiber composite layer. Stack a plurality of metal-fiber composite layers in the forming holes of the forming die, and then close the forming die through the upper cover plate and the lower cover plate. Seal the closed die with a vacuum bag, evacuate the air, and then put it into a hot press for hot pressing and curing to form, and finally cool it naturally to room temperature and demold to obtain a curved fiber metal laminate;

[0022] S4. Use an ultrasonic C-scan system to detect the internal quality of the curved fiber metal laminate, and select the curved fiber metal laminates that meet the quality standards.

[0023] Preferably, the separator film is a polyimide film.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention provides a curved fiber metal laminate and a preparation method thereof. The present invention utilizes the automatic fiber placement technology to realize the curved fiber laying of the fiber composite layer. Compared with the straight fiber laying method of the traditional fiber metal laminate, the preparation method of the curved fiber metal laminate provided by the present invention has higher material utilization rate, wider design space, and more uniform stress distribution. The curved fiber metal laminate prepared by this method has higher lightweight degree and better mechanical properties, and has broad market application prospects. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the curved fiber metal laminate in Embodiment 1;

[0027] Figure 2 is a schematic front structural diagram of the curved fiber prepreg layer in Embodiment 1;

[0028] Figure 3 is a schematic structural diagram of the die in Embodiment 1;

[0029] Figure 4 is a preparation flow chart of the curved fiber metal laminate in Embodiment 1 of the present invention;

[0030] Figure 5 is a step schematic diagram of the preparation method of the curved fiber metal laminate provided in Embodiment 1 of the present invention;

[0031] Figure 6 is a schematic structural diagram of the straight fiber metal laminate in Comparative Example 1;

[0032] Figure 7a is a stress nephogram of the curved fiber metal laminate in Embodiment 1;

[0033] Figure 7b is the stress nephogram of the straight fiber metal laminate in Comparative Example 1;

[0034] Figure 8a is the displacement nephogram of the curved fiber metal laminate in Example 1;

[0035] Figure 8b is the displacement nephogram of the straight fiber metal laminate in Comparative Example 1.

[0036] Description of reference numerals:

[0037] 1 - metal layer;

[0038] 2 - curved fiber prepreg layer, 21 - curved fiber, 22 - resin;

[0039] 3 - adhesive film bonding layer;

[0040] 4 - upper cover plate;

[0041] 5 - forming die;

[0042] 6 - lower cover plate;

[0043] 7 - release film;

[0044] 8 - straight fiber prepreg layer. Detailed implementation manners

[0045] The following further elaborates on the present invention in conjunction with examples, enabling those skilled in the art to implement it with reference to the text of the specification.

[0046] It should be understood that terms such as "having", "including", and "comprising" as used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0047] Unless otherwise specified, the test methods used in the following examples are all conventional methods. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained through commercial channels. For those not specifying specific conditions in the following examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments not indicating the manufacturer, they are all conventional products that can be purchased commercially.

[0048] The present invention provides a curved fiber metal laminate, including a plurality of metal - fiber composite layers arranged in a stack. The metal - fiber composite layer includes a metal layer 1 and a curved fiber prepreg layer 2 arranged in a stack; the outermost layer of the curved fiber metal laminate is the metal layer 1;

[0049] In a preferred embodiment, the curved fiber metal laminate is designed to have a balanced and symmetrical structure, such as metal layer 1, curved fiber prepreg layer 2, curved fiber prepreg layer 2, and metal layer 1.

[0050] The curved fiber prepreg layer 2 is processed from resin 22 and curved fibers 21 arranged in a curved path. In a preferred embodiment, the volume ratio of the curved fibers 21 in the curved fiber prepreg layer 2 is 50 - 70%.

[0051] The path planning of the curved fibers is the key to realizing the laying of the curved fibers. Usually, a mathematical equation is used to define the laying trajectory of the fibers. Common methods include the linear variable angle method, polynomial interpolation methods (Lobatto - Legendre polynomials, Lagrange polynomials...), variable angle curve methods (Bezier curves, B - spline curves, non - uniform rational B - spline curves...), etc. To prevent the fiber ribbon from having wrinkles and kink defects during the laying process, the fiber path should satisfy the curvature radius constraint.

[0052] In a preferred embodiment, an adhesive film bonding layer 3 is also provided between the metal layer 1 and the curved fiber prepreg layer 2 to achieve a firm connection between the two.

[0053] In a preferred embodiment, the curved fibers 21 in the curved fiber prepreg layer 2 are carbon fibers, and the resin 22 is an epoxy resin, such as E21 type epoxy resin.

[0054] In a preferred embodiment, the material of the metal layer 1 is a single - element metal or an alloy material.

[0055] In a preferred embodiment, the adhesive film bonding layer 3 is a polyethylene film or a polypropylene film.

[0056] In a preferred embodiment, the curved fiber metal laminate includes two metal - fiber composite layers arranged in a laminated manner. The two curved fiber prepreg layers 2 of the two metal - fiber composite layers are on the inner side and in contact with each other, and the two metal layers 1 are both on the outer side.

[0057] The present invention also provides a method for preparing the above - mentioned curved fiber metal laminate, which includes the following steps:

[0058] S1. Pretreatment of the metal layer 1;

[0059] S2. Using the automatic fiber placement process and the automatic lamination process, process the curved fibers 21 and the resin 22 to obtain the curved fiber prepreg layer 2, and dry it for later use;

[0060] S3. Using a mold to prepare the pretreated metal layer 1, the curved fiber prepreg layer 2, and the adhesive film bonding layer 3 into a curved fiber metal laminate.

[0061] In a preferred embodiment, the mold includes: an upper cover plate 4, a forming mold 5 and a lower cover plate 6. The upper cover plate 4, the forming mold 5 and the lower cover plate 6 are all made of metal or alloy. The upper cover plate 4 and the lower cover plate 6 are flat plates, and the forming mold 5 is a flat plate with a forming hole in the center. The size of the forming mold 5 needs to be determined according to the size of the curved fiber metal laminate to be prepared.

[0062] In a preferred embodiment, the method for preparing the curved fiber metal laminate comprises the following steps:

[0063] S1, pretreatment of the metal layer 1: grinding the surface of the metal layer 1 with silicon carbide sandpaper, then washing and degreasing with acetone solution, then repeatedly washing with clean water, and finally drying and storing for later use;

[0064] S2, using an automatic fiber placement process and an automatic lamination process to process the curved fiber 21 and the resin 22 to obtain a curved fiber prepreg layer 2, drying and then naturally cooling to room temperature for standby use;

[0065] S3, spraying a release agent on the surface of the upper cover plate 4, the forming mold 5 and the lower cover plate 6, and placing an isolation film 7 between the upper cover plate 4 and the forming mold 5, and between the forming mold 5 and the lower cover plate 6, bonding the pretreated metal layer 1 and the curved fiber prepreg layer 2 through the adhesive film bonding layer 3 to prepare a metal-fiber composite layer, stacking and laying a plurality of metal-fiber composite layers in the forming hole of the forming mold 5, and then closing the forming mold 5 through the upper cover plate 4 and the lower cover plate 6; sealing the closed mold with a vacuum bag, evacuating the vacuum, and placing it in an autoclave for hot pressing and curing, and finally naturally cooling to room temperature and demoulding to obtain a curved fiber metal laminate;

[0066] S4. Use an ultrasonic C-scan system to detect the internal quality of the curved fiber metal laminates and select the curved fiber metal laminates that meet the quality standards.

[0067] In a preferred embodiment, the isolation film 7 is a polyimide film, which is non-sticky, corrosion-resistant and high-temperature resistant.

[0068] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention. Example

[0069] Reference Figure 1-2 The present embodiment provides a curved fiber metal laminate, comprising two stacked metal-fiber composite layers, each metal-fiber composite layer comprising a stacked metal layer 1 and a curved fiber prepreg layer 2, the two curved fiber prepreg layers 2 of the two metal-fiber composite layers are on the inner side and contact each other, and the two metal layers 1 are on the outer side; a film bonding layer 3 is also arranged between the metal layer 1 and the curved fiber prepreg layer 2.

[0070] In this embodiment, the curved fiber prepreg layer 2 is processed from a resin 22 and curved fibers 21 arranged in a curved path. The curved fibers 21 are made of T700 type carbon fiber material, and the resin 22 is an E21 type epoxy resin. The single-layer size of the curved fiber prepreg layer 2 is 100 mm × 100 mm × 0.25 mm.

[0071] In this embodiment, the material of the metal layer 1 is aluminum alloy material, and a specimen with a size of 100 mm × 100 mm × 0.5 mm is made by laser cutting.

[0072] In this embodiment, the adhesive film bonding layer 3 uses a polyethylene film with a size of 100 mm × 100 mm × 50 mm.

[0073] Refer to Figures 3-5 , and in this embodiment, a method for preparing the above-mentioned curved fiber metal laminate is further provided, including the following steps:

[0074] S1. Pretreatment of the metal layer 1: The surface of the metal layer 1 is polished with 400-mesh silicon carbide sandpaper, then rinsed with acetone solution for degreasing, repeatedly washed with clean water, and finally dried for storage.

[0075] S2. By using the automatic fiber placement process and the automatic lamination process, the curved fibers 21 and the resin 22 are processed to obtain the curved fiber prepreg layer 2, which is placed in a constant-temperature drying oven, dried, and then naturally cooled to room temperature for standby.

[0076] The mold for laying the curved fiber metal laminate is as Figure 3 shown, which includes an upper cover plate 4, a forming mold 5, and a lower cover plate 6, made of laser-cut stainless steel plate. The upper cover plate 4 and the lower cover plate 6 are flat plates with a size of 200 mm × 200 mm × 1 mm; the forming mold 5 is a flat plate with a forming hole in the center. The external size of the forming mold 5 is 150 mm × 150 mm × 1.5 mm, and the internal size of the forming hole is 100 mm × 100 mm × 1.5 mm.

[0077] S3. Release agent is sprayed on the surfaces of the upper cover plate 4, the forming mold 5, and the lower cover plate 6, and isolation films 7 are placed between the upper cover plate 4 and the forming mold 5 and between the forming mold 5 and the lower cover plate 6. The isolation film 7 uses a polyimide film with a size of 200 mm × 200 mm × 50 mm; the pretreated metal layer 1 and the curved fiber prepreg layer 2 are bonded through the adhesive film bonding layer 3 to prepare a metal-fiber composite layer, and two layers of the metal-fiber composite layer are laminated and laid in the forming hole of the forming mold 5 (with the metal layer 1 facing outwards and the curved fiber prepreg layer 2 facing inwards), and then the forming mold 5 is closed by the upper cover plate 4 and the lower cover plate 6.

[0078] Seal the closed mold with a vacuum bag, evacuate the air, and then place it in an autoclave for hot pressing and curing. Set the heating temperature of the autoclave to 120 °C, the curing pressure to 0.6 MPa, and the time to 2 h. Finally, cool it naturally to room temperature and demold it to obtain a curved fiber metal laminate;

[0079] S4. Use an ultrasonic C-scan system to detect the internal quality of the curved fiber metal laminate. According to the scanning results, observe whether there are defects and the type, location, and size information of the defects. Select the curved fiber metal laminates that meet the quality standards. The final size of the fabricated curved fiber metal laminate is 100 mm × 100 mm × 1.5 mm.

[0080] The difference between this example and Example 1 is only that: in this example, a straight fiber prepreg layer 8 is used instead of the curved fiber prepreg layer 2 in Example 1. The structure of the straight fiber metal laminate is as Figure 6 shown.

[0081] Use finite element software to perform simulation tests on the fiber metal laminates prepared in Example 1 and Comparative Example 1. The laminate is subjected to a uniformly distributed lateral load p 0 = 10 N / m 2 , and the boundary condition is fixed at the left end. The material parameters of the metal layer are E = 70 GPa, μ = 0.33. The elastic constants of the fiber prepreg layer are E 1 = 148 GPa, E 2 = E 3 = 10.5 GPa, G 12 = G 23 = G 13 = 5.61 GPa, μ 12 = μ 23 = μ 13 = 0.3. The specific material properties are shown in Table 1:

[0082] Table 1 Material properties of the metal layer and the fiber prepreg layer

[0083]

[0084] The simulation test results are as Figure 7a , Figure 7b , Figure 8a , Figure 8b and Table 2 show:

[0085] Table 2 Maximum stress and maximum displacement of square laminates

[0086]

[0087] It can be seen from the simulation results that both the maximum stress and the maximum displacement of the curved fiber metal laminate structure are much smaller than those of the straight fiber metal laminate. Compared with the straight fiber metal laminate, the stress distribution of the curved fiber metal laminate is more uniform. Through the design of curved fiber layup, the fiber performance can be fully utilized, making the material utilization rate of the structure higher and the mechanical properties better.

[0088] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to specific details.

Claims

1. A curved fiber metal laminate, characterized in that: It comprises two stacked metal-fiber composite layers, wherein the metal-fiber composite layer comprises a stacked metal layer and a curved fiber prepreg layer, wherein the two curved fiber prepreg layers of the two metal-fiber composite layers are located inside and in contact with each other, and the two metal layers are located outside; The curved fiber prepreg layer is made of resin and curved fibers arranged along a curved path. The specific preparation method of the curved fiber prepreg layer is: using an automatic fiber placement process and an automatic lamination process to process the curved fibers and resin to obtain a curved fiber prepreg layer, and drying it for standby use; The curved fibers in the curved fiber prepreg layer are carbon fibers, and the resin is epoxy resin; the volume proportion of the curved fibers in the curved fiber prepreg layer is 50-70%.

2. The curved fiber metal laminate according to claim 1, characterized in that: An adhesive film bonding layer is also arranged between the metal layer and the curved fiber prepreg layer.

3. The curved fiber metal laminate according to claim 1, characterized in that: The material of the metal layer is a single metal or an alloy material.

4. The curved fiber metal laminate according to claim 2, characterized in that: The adhesive film bonding layer is a polyethylene film or a polypropylene film.

5. A method for preparing a curved fiber metal laminate according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, metal layer pretreatment; S2, using an automatic fiber placement process and an automatic lamination process to process the curved fiber and resin to obtain a curved fiber prepreg layer, which is then dried for later use; S3. Using a mold, the pretreated metal layer, the curved fiber prepreg layer and the film bonding layer are prepared into a curved fiber metal laminate.

6. The method for preparing a curved fiber metal laminate according to claim 5, characterized in that: The mold comprises: an upper cover plate, a forming mold and a lower cover plate, wherein the upper cover plate, the forming mold and the lower cover plate are all made of metal or alloy, the upper cover plate and the lower cover plate are flat plates, and the forming mold is a flat plate with a forming hole in the center.

7. The method for preparing a curved fiber metal laminate according to claim 6, characterized in that: The following steps are involved: S1. Pretreatment of the metal layer: Grind the surface of the metal layer with silicon carbide sandpaper, then rinse and degrease with acetone solution, then repeatedly wash with clean water, and finally dry and store for later use; S2, using an automatic fiber placement process and an automatic lamination process to process the curved fiber and resin to obtain a curved fiber prepreg layer, drying it and then naturally cooling it to room temperature for standby use; S3, spraying a release agent on the surface of the upper cover plate, the forming mold and the lower cover plate, and placing an isolation film between the upper cover plate and the forming mold, and between the forming mold and the lower cover plate, bonding the pretreated metal layer and the curved fiber prepreg layer through a film bonding layer to prepare a metal-fiber composite layer, stacking and laying a number of metal-fiber composite layers in the forming hole of the forming mold, and then closing the forming mold through the upper cover plate and the lower cover plate; sealing the closed mold with a vacuum bag, evacuating the vacuum, and placing it in an autoclave for hot pressing and curing molding, and finally naturally cooling to room temperature and demolding to obtain a curved fiber metal laminate; S4. Use an ultrasonic C-scan system to detect the internal quality of the curved fiber metal laminates and select the curved fiber metal laminates that meet the quality standards.

8. The method for preparing a curved fiber metal laminate according to claim 7, characterized in that: The isolation film is a polyimide film.

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