The present invention relates to a fiber-metal laminate producing method with low weight and high strength.

As a result of the search for stronger materials with the developing technology, more durable structures have been achieved by combining metal materials and fiber materials. Fiber metal laminates (FML) are composite materials that can be used as an alternative to conventional aluminum used in aviation due to their high fatigue resistance and low density. Fiber metal materials made of aluminum-glass fiber are called GLARE. Its tensile strength is quite high compared to an aluminum material of the same weight, and its compressive and shear strength is lower. In addition, fatigue and crack propagation strength values are higher than conventional materials. Moreover, by further development of fiber metal laminate materials, lighter and stronger structures can be obtained.

Article titled “Reinforcement effects of aluminum lithium alloy on the mechanical” properties of novel fiber metal laminate”, which is included in the known-state of the art, discloses investigation of new fiber laminates based on aluminum-lithium alloy to improve the stiffness and damage tolerance of the material. The aluminum-lithium sheets were rolled from 2 mm to 0.3 mm by cold forming, and compared with glare materials.

Article titled “Effects of surface pre-treatment and void content on GLARE laminate process characteristics”, which is included in the known-state of the art, discloses comparison of GLARE materials in terms of differences on surface texture by sanding, abrasion and chemical abrasion, surface roughness levels and surface morphologies.

Thanks to the fiber-metal laminate producing method according to the present invention, more effective, efficient, practical and economical fiber-metal laminate materials can be obtained.

Another object of the present invention is to provide a lighter and more durable fiber-metal laminated material for air vehicles. A further object of the present invention is to obtain a fiber-metal laminate material more quickly.

The fiber-metal laminate producing method realized to achieve the object of the invention, which is defined in the first claim and other claims dependent thereon, comprises a body made of composite material with a layered structure; at least one sheet made of an aluminum material and forming the body; a first thickness corresponding to a wall thickness of the sheet; at least one fabric produced by impregnating glass fiber reinforced resin and located in contact with the sheet forming the body; the sheet of which the surface is roughened by melting the material from the surface thanks to the chemical etching process.

The fiber-metal laminate producing method according to the invention comprises a second thickness, wherein the sheet pre-produced by a user is getting thinner, after the production, to a rough surface by removing material from the sheet surface of the first thickness only by chemical etching without a physical treatment; the body produced by curing the sheets and fabrics that have been combined in a number and configuration predetermined by the user by directly joining after chemical treatment to the sheet of the second thickness.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the sheet of which the thickness is reduced by at least half from the first thickness to the second thickness with only the chemical etching process, wherein the first thickness is the wall thickness before the chemical etching process, and the second thickness predetermined by the user is less than the first thickness.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the sheet of the second thickness with a higher amount of roughness after chemical etching, which has a higher adhesion surface to the fabric due to a greater surface area than the surface area of the first thickness as a result of forming the rough structure on the surface when it is at the second thickness. In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the body which is obtained by: cleaning the surface of the sheet of the first thickness with any kind of liquid cleaner; immersing the sheet of the first thickness into a chemical bath, keeping said sheet in the chemical bath for a period predetermined by the user, thereby reducing the thickness and increasing the roughness by means of chemical machining; cleaning the surface of the sheet, which has been removed from the chemical bath and has a second thickness and a large amount of roughness on the surface after the process, with a cleaner; combining and curing the sheet of the second thickness with fabrics in an amount and configuration predetermined by the user.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the body obtained by combining fabrics and sheets of almost exactly the same thickness.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the sheet having a first thickness preferably between 1.7 mm and 1.8 mm; and the sheet having a second thickness preferably between 0.4 mm and 0.5 mm.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the sheet which is created by heating and mixing NaOH/ NaHS/ NaAIO ₂ chemicals in a container at a temperature between 90°C and 110°C, and which is positioned in the chemical bath for chemical etching with the machining method, thereby reducing the first thickness thereof to the second thickness.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the body used in air and/or space vehicle structures by curing the body in an autoclave at a temperature predetermined by the user so as to make it monolithic. In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the body in a GLARE type fiber-metal laminate structure.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises the sheet made of 2024 or 2198 grade Aluminum Lithium alloy.

In an embodiment of the invention, the fiber-metal laminate producing method according to the invention comprises at least one hanging apparatus which enables the sheet to be held firm in the chemical bath and to be rotated from one end to the other in the chemical bath at time intervals predetermined by the user, thereby enabling the chemical reaction to be equal on the entire surface of the sheet; at least one mixer which enables the chemicals in the chemical bath to be equally distributed over all areas.

The fiber-metal laminate producing method realized to achieve the object of the present invention is illustrated in the attached drawings, in which:

Figure 1 is a sectional view of the body.

Figure 2 is a sectional view of the sheet in the first thickness (x) and the second thickness (y).

Figure 3 is a schematic view of the fiber-metal laminate producing method.

All the parts illustrated in figures are individually assigned a reference numeral and the corresponding terms of these numbers are listed below:

1. Fiber-metal laminate producing method

2. Body

3. Sheet

4. Fabric

5. Hanging Apparatus

6. Mixer x. First Thickness y. Second Thickness The fiber-metal laminate producing method (1) comprises a body (2) in a layered structure; at least one sheet (3) in the body (2), which is made of aluminum; a first thickness (x) which corresponds to the cross-sectional area of the sheet (3); at least one resin-impregnated fabric (4) reinforced with glass fiber, which is located in contact with the sheet (3) provided the body (2); the sheet (3) with roughness on the surface as a result of a chemical treatment.

The fiber-metal laminate producing method (1) according to the invention comprises a second thickness (y), wherein the sheet (3) pre-produced by a user is subjected to a chemical etching process without a physical treatment, so as to be brought from the first thickness (x) to the second thickness (y) by forming a rough surface on the sheet (3) surface by the machining method; the body (2) produced by curing the sheets (3) and fabrics (4) that have been combined in a number and configuration predetermined by the user by directly joining after chemical treatment to the sheet (3) of the second thickness (y).

A body (2) with a layered structure comprises at least one sheet (3) made of an aluminum material. The sheet (3) has a first thickness (x) that corresponds to the wall thickness immediately after the production. There is at least one resin-impregnated fabric (4) reinforced with glass fiber, which is located in contact with the sheet (3) inside the body

(2). Thanks to the chemical treatment, a roughness is formed on the surface of the sheet

(3), thereby adhering to the fabric (4) more tightly (Figure 1).

After the sheet (3) is produced by the user, it is subjected to a chemical etching process without any physical treatment, so that it is brought from the first thickness (x) to a second thickness (y) by obtaining a rough surface by chemical machining. The body (2) is obtained by combining and curing the sheet (3) of the second thickness (y) and the fabrics

(4) in a number and configuration determined directly by the user immediately after the chemical treatment. Therefore, thinner sheets (3) provided in the body (2) results in a lighter and more durable body (2) (Figure 2).

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the sheet (3) of which the thickness is reduced by at least half from the first thickness (x) to the second thickness (y) with only the chemical etching process, wherein the first thickness (x) is the wall thickness before the chemical etching process, and the second thickness (y) predetermined by the user is less than the first thickness (x). By using the chemical etching process only, a chemical reaction is created on the surface of the sheet (3) and materials are removed from the surface. In this way, thickness of the sheet (3), which had the first thickness (x) before the chemical etching process, is reduced to the second thickness (y) to obtain a thinner sheet (3).

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the sheet (3) of the second thickness (y) with a higher amount of roughness after chemical etching, which has a higher adhesion surface to the fabric (4) since the surface area of the second thickness (y) is greater than the surface area of the first thickness (x). After the chemical etching process, a rougher structure is obtained on the surface of the sheet (3) than before the process. Therefore, the sheet (3) with an increased surface area can adhere better to the fabric (4). Thus, a more durable structure is obtained.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the body (2) which is obtained by: cleaning the surface of the sheet (3) of the first thickness (x) with a cleaner; placing the sheet (3) of the first thickness (x) into a chemical bath, keeping said sheet (3) in the chemical bath for a period predetermined by the user, thereby reducing the thickness of the sheet (3); cleaning the surface of the sheet (3), which has been removed from the chemical bath so as to have a second thickness (y) and roughness on its surface, with a cleaner; combining and curing the sheet (3) of the second thickness (y) with fabrics (4) in an amount and configuration predetermined by the user. Sheet (3) of the first thickness (x) is prepared for the chemical etching process and placed in the chemical bath prepared by the user beforehand, so that the chemical etching process is initiated. In the chemical bath, the sheet (3) is kept in the bath for a period predetermined by the user. During this process, chemicals remove material from the sheet (3) surface. After the process is completed, the sheet (3), the surface of which is cleaned again, is immediately combined with the fabrics (4). Afterwards, the curing process is performed to obtain the body (2). In this way, an effective, fast and efficient production method is provided.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the body (2) made of fabrics (4) and sheets (3) that have almost exactly the same thickness. Thus, a lighter structure and a durable body (2) is obtained.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the sheet (3) having the first thickness (x) between 1.6 mm and 1.9 mm; and the sheet (3) having the second thickness (Y) between 0.3 mm and 0.6 mm. Sheet (3) of the first thickness (x) is preferably between 1.7 mm and 1.8 mm. Sheet (3) of the second thickness (y) is preferably between 0.4 mm and 0.5 mm. In this way, a more resistant body (2) is obtained.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the sheet (3) which is placed in a chemical bath formed by heating NaOH/NaHS/NaAIO ₂ acids at a temperature predetermined by the user, so that thickness of the sheet (3) is reduced from the first thickness (x) to the second thickness (y) by chemical etching with the machining process. According to the chemical etching process, acids are used for the chemical bath. Therefore, a more efficient production method is provided by effectively and efficiently removing chips from the sheet (3) surface.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the body (2) used in air and/or space vehicle structures by curing the body (2) in an autoclave at a temperature predetermined by the user so as to make it monolithic. Thus, lighter and more durable structural part materials are obtained for air vehicles.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the body (2) in a GLARE fiber-metal laminated structure.

In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises the sheet (3) made of 2024 or 2198 Aluminum Lithium alloy. In this way, a stronger and lighter body (2) is obtained. In an embodiment of the invention, the fiber-metal laminate producing method (1) comprises at least one hanging apparatus (5) which enables the sheet (3) to be held in the chemical bath and to be rotated from one end to the other in the chemical bath at a period predetermined by the user, thereby enabling the chemical reaction to be equal on the entire surface of the sheet (3); at least one mixer (6) which enables the chemicals in the chemical bath to be equally distributed over all areas. During the chemical etching process, the sheet (3) is kept in the chemical bath by means of the hanging apparatus (5), such that it is rotated in the chemical bath in the directions predetermined by the user for the certain periods, allowing it to be thinned effectively. A mixer (6) is also used to provide homogenous distribution in the bath during the process (Figure 3).