JP2006297928A - Structure for aeroplane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for an aeroplane enhanced in the adhesiveness of a metal layer and a fiber reinforced resin layer in a case that the structure of the aeroplane is constituted of a metal/fiber reinforced resin composite material and capable of keeping excellent characteristics as a whole. <P>SOLUTION: In the structure for the aeroplane constituted of the metal/fiber reinforced resin composite material obtained by integrally bonding the metal layer and the fiber reinforced resin layer through an intermediate resin layer, the intermediate resin layer contains particles with an average particle size of 3-10 μm comprising a thermoplastic resin and an imidazolesilane compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an aircraft structure made of a metal / fiber reinforced resin composite material, and in particular, a secondary structure member such as an aircraft primary structure member or panel member having improved adhesion between a metal layer and a fiber reinforced resin layer. The present invention relates to an aircraft structure suitable for use.

  A composite material in which metal and fiber reinforced resin are laminated and bonded together is a material that can exhibit both the excellent impact resistance, conductivity, etc. possessed by the metal, and the excellent lightness and high mechanical properties possessed by the fiber reinforced resin. Known as.

  Especially in aircraft structures that require lightweight, corrosion resistance, and high strength properties, composite materials in which titanium alloys and fiber reinforced resins, especially carbon fiber reinforced resins, are laminated and integrated can be used. Are known. Moreover, the panel material which consists of a composite material to which favorable electroconductivity was provided with the titanium alloy is known as a panel material excellent in lightning resistance.

  However, in an aircraft structure made of a metal / fiber reinforced resin composite material simply formed by laminating and bonding a metal layer and a fiber reinforced resin layer, delamination occurs between the metal layer and the fiber reinforced resin layer. There exists a problem that there exists a possibility that the predetermined characteristic which makes it a target may not be expressed. In particular, when the metal layer is made of a titanium alloy, the titanium alloy is a difficult-to-adhere metal. Therefore, delamination is likely to occur, and surface treatment such as chemical etching is necessary to improve adhesion. The problem of deteriorating sex and high cost remains.

In order to improve the adhesion of the metal layer, surface treatments such as forming an anodized film have been proposed (for example, Patent Document 1 and Patent Document 2), but the adhesion between the metal and the adhesive is improved. However, the adhesiveness between the adhesive and the fiber reinforced resin is not necessarily improved. In addition, although a technique for increasing the toughness of the adhesive itself has been proposed (for example, Patent Document 3 and Patent Document 4), the adhesive layer and the fiber reinforced resin layer are suppressed although destruction in the adhesive layer is suppressed. The peel strength at the interface with the film is not necessarily improved.
JP 2002-129387 A JP-A-7-252687 JP 58-189277 A JP 2004-263104 A

  Accordingly, the object of the present invention is to improve the adhesion between the metal layer and the fiber reinforced resin layer, particularly when the aircraft structure is composed of a metal / fiber reinforced resin composite material, thereby improving the excellent characteristics of each layer. An object of the present invention is to provide an aircraft structure that can solve problems such as delamination between both layers while exhibiting the same, and can maintain excellent characteristics as a whole.

  In order to solve the above problems, an aircraft structure according to the present invention is an aircraft structure comprising a metal / fiber reinforced resin composite material in which a metal layer and a fiber reinforced resin layer are bonded and integrated through an intermediate resin layer. It is a structure, wherein the intermediate resin layer contains thermoplastic resin particles having an average particle diameter of 3 to 10 μm and an imidazolesilane compound.

  In this aircraft structure, a boundary portion (interface vicinity portion) between the intermediate resin layer and the fiber reinforced resin layer is a mixture of the thermoplastic resin constituting the particles and the reinforced fibers of the fiber reinforced resin layer. It is preferable to form a mixed layer.

  The thermoplastic resin particles are preferably present in the intermediate resin layer at least partially in the form of a continuous phase due to fusion of particles or the like.

  The matrix resin of the fiber reinforced resin layer and the base resin of the intermediate resin layer are preferably made of the same kind of resin (preferably, the same resin). For example, the matrix resin of the fiber reinforced resin layer and the base resin of the intermediate resin layer are preferably made of the same type or the same thermosetting resin (for example, epoxy resin).

  Various metals can be adopted as the metal layer, but the effect of the present invention is particularly great when the metal layer is composed of a layer containing titanium, which is a difficult-to-adhere metal. Of these, titanium alloys are excellent in corrosion resistance, have high specific strength and high specific modulus, and are excellent in mechanical properties. Therefore, titanium alloys are originally used as desirable materials for aircraft structures.

  Various reinforcing fibers can be used as the reinforcing fiber of the fiber-reinforced resin layer. In particular, the carbon fiber has a high specific strength and a high specific modulus, and has excellent mechanical properties. If it comprises, it will become easy to obtain the more excellent mechanical characteristic as the whole aircraft structure, and it will become easy to control the characteristic.

  The aircraft structure according to the present invention is not particularly limited as long as it is used for an aircraft, and covers a wide range from a primary structure member serving as an aircraft skeleton to a secondary structure member such as a panel member. Applicable. In particular, the present invention is applicable to skin panels, spars, etc. constituting the fuselage, main wing or tail wing.

  In such an aircraft structure according to the present invention, since the intermediate resin layer contains thermoplastic resin particles having a particle diameter in a predetermined range, the thermoplastic resin particles ensure a predetermined thickness of the intermediate resin layer. The intermediate resin layer having a predetermined thickness is reliably interposed between the metal layer and the fiber reinforced resin layer. In addition, since the thermoplastic resin particles are blended in the intermediate resin layer, the toughness of the intermediate resin layer itself can be increased.

  The metal layer and the fiber reinforced resin layer are bonded and integrated through this intermediate resin layer. However, the intermediate resin layer contains an imidazole silane compound, so that the adhesion to the metal is improved, and it is difficult to adhere to the metal. Even for a certain titanium alloy or the like, good adhesiveness can be expressed, and the adhesiveness between the intermediate resin layer and the metal layer is greatly improved.

  Further, since the intermediate resin layer contains thermoplastic resin particles having a fine particle diameter within a predetermined range, in the vicinity of the interface with the fiber reinforced resin layer, more or less thermoplastic particles are present between the reinforced fibers of the fiber reinforced resin layer. An invading form can be easily formed. That is, the boundary portion between the intermediate resin layer and the fiber reinforced resin layer can be formed in a mixed layer in which the thermoplastic resin particles and the reinforced fibers of the fiber reinforced resin layer are mixed. In such a form, for example, if the intermediate resin layer and the fiber reinforced resin layer are simultaneously formed at a temperature equal to or higher than the melting point of the thermoplastic resin particles, the particles are easily at least partially in a continuous phase form by fusion or the like. It is a series. If such a form appears, the thermoplastic resin that is at least partially in the form of a continuous phase by fusion or the like is formed at the interface between the intermediate resin layer and the fiber reinforced resin layer. It exists across both layers, and the anchor effect will be exhibited from any layer. Due to this anchor effect, the adhesion between the intermediate resin layer and the fiber reinforced resin layer is also reliably and significantly improved.

  The metal layer and the fiber reinforced resin layer are bonded and integrated with a strong adhesive force that does not cause peeling through the intermediate resin layer, thereby providing excellent impact resistance of the metal layer such as titanium alloy. In addition, it is possible to stably exhibit both the electrical conductivity and lightning resistance and the excellent light weight and mechanical characteristics of the fiber reinforced resin layer, and an aircraft structure having desirable characteristics can be obtained. Furthermore, when the outermost layer is a fiber reinforced resin layer, it is preferable that the outermost layer of the fiber reinforced resin layer is subjected to water repellent treatment to form a water repellent layer. When the aircraft structure of the present invention is exposed to high humidity or warm water, there is a concern that the adhesion between the metal and the fiber reinforced resin may deteriorate due to moisture absorption or water absorption of the fiber reinforced resin layer. This is because by forming the layer, moisture absorption or water absorption can be suppressed, and deterioration of adhesiveness can be prevented.

  Thus, according to the aircraft structure according to the present invention, the metal layer and the fiber reinforced resin layer are bonded and integrated through the intermediate resin layer containing the thermoplastic resin particles having a predetermined particle diameter and the imidazole silane compound. As a result, it is possible to realize an aircraft structure made of a metal / fiber reinforced resin composite material that can greatly improve adhesion and can exhibit excellent characteristics without causing delamination.

  In particular, by using a titanium alloy for the metal layer, it is possible to achieve both excellent impact resistance, electrical conductivity, and lightning resistance due to the titanium alloy, as well as weight reduction and high strength due to the fiber reinforced resin, and to achieve the desired desirable characteristics. Can be made.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross section of an aircraft structure according to an embodiment of the present invention, and particularly shows an example of the case where the present invention is applied to an aircraft panel member. In FIG. 1, 1 shows the whole panel member as an aircraft structure. The panel member 1 includes a single layer or a plurality of layers (a total of three layers in the illustrated example), a single layer or a plurality of layers (a total of two layers in the illustrated example) fiber reinforced resin layer 3, and a metal layer. 2 and a fiber reinforced resin layer 3, and has a single layer or a plurality of (in the illustrated example, a total of 4 layers) intermediate resin layer 4 that bonds and integrates the metal layer 2 and the fiber reinforced resin layer 3. is doing. However, the metal layer 2 may be in the outermost layer as illustrated, or may be in either the innermost layer or the fiber reinforced resin layer. Moreover, it is preferable that the thickness of the metal layer 2 exists in the range of 0.1-0.3 mm, for example. If the thickness is less than 0.1 mm, the manufacturing cost becomes close to that of a metal foil. If the thickness exceeds 0.3 mm, the weight reduction of the entire panel member 1 may be impaired.

  The intermediate resin layer 4 contains thermoplastic resin particles having a predetermined particle diameter (average particle diameter of 3 to 10 μm) and an imidazolesilane compound. The fiber reinforced resin layer 3 is composed of a composite material composed of reinforced fibers and a matrix resin (for example, thermosetting resin such as epoxy resin). Here, the particle diameter of the thermoplastic resin particles in the intermediate resin layer can be measured by observing the cross section of the aircraft structure with an optical microscope, a microscope using a CCD camera, SEM, or TEM. The average particle diameter of the thermoplastic resin particles in the intermediate resin layer in the present invention is an average value obtained by measuring the particle diameters of at least 10 particles.

Here, as the resin constituting the intermediate resin layer, it is preferable to use a resin composition in which thermoplastic resin particles having an average particle diameter of 3 to 10 μm are blended in advance. At this time, the average particle diameter of the thermoplastic resin particles to be blended in the resin composition is preferably measured by the median diameter obtained from the particle size distribution measured using a laser diffraction / scattering particle size distribution analyzer.

FIG. 2 shows a cross section of an aircraft structure according to another embodiment of the present invention, and particularly shows an example in which the present invention is applied to an aircraft structural member (for example, a primary structural member). Yes. In FIG. 2, 21 shows the whole structural member as an aircraft structure. The structural member 21 is formed in an I-type or H-type cross-sectional shape, and has a single-layer or multiple-layer (two layers in the illustrated example) metal layer 22 and a single-layer or multiple-layer (illustrated example). Then, a total of one fiber reinforced resin layer 23 having a cross-sectional shape of I type or H type, and a metal layer 22 and a fiber reinforced resin layer interposed between the metal layer 22 and the fiber reinforced resin layer 23. The intermediate resin layer 24 has a single layer or a plurality of layers (in the illustrated example, a total of two layers). However, this metal layer 22 may also be in the outermost layer as shown in the drawing, may be provided as an inner layer, or may be provided in a fiber reinforced resin layer. In this case, the thickness of the metal layer 22 is not particularly limited. However, the metal layer 22 is preferably made of titanium, particularly a titanium alloy, from the viewpoint of lightning resistance, high strength characteristics, light weight, and the like. In addition, this embodiment has shown the aspect by which the water-repellent layer H was formed in the surface of the fiber reinforced resin layer 23 which has I type or H type cross-sectional shape.

  Examples of the bonding structure between the intermediate resin layers 4 and 24 and the metal layers 2 and 22 and the fiber reinforced resin layers 3 and 23 are shown in FIGS. FIG. 4 is a more preferable example. 3 and 4 show an example of an adhesive structure between the intermediate resin layer 4 and the metal layer 2 and the fiber reinforced resin layer 3 shown in FIG. 1, the intermediate resin layer 24 shown in FIG. It can be similarly applied to an adhesive structure between the metal layer 22 and the fiber reinforced resin layer 23.

  In the example shown in FIG. 3, a thermoplastic resin is used as a base resin between the metal layer 2 and the fiber reinforced resin layer 3 including the reinforcing fiber (group) 5 and the thermosetting matrix resin 6. An intermediate resin layer 4 serving as an adhesive resin layer including the resin 8 (the thermoplastic resin continuous phase 8a and the thermoplastic resin particle phase 8b) is interposed. When the thermoplastic resin particles having a predetermined particle diameter are blended in the intermediate resin layer 4, the particles serve as a spacer to ensure a desired thickness of the intermediate resin layer 4, and the metal layer 2 and the fiber reinforced resin layer 3. A desirable interlayer thickness can be ensured between Moreover, the intermediate resin layer 4 can be toughened by blending the thermoplastic resin particles, and the contained particles can also exhibit a pinning effect against cracks, for example. The thermoplastic resin particles having the predetermined particle diameter contained in the intermediate resin layer 4 are at least partially in a continuous phase form (linear or film-like continuous phase form) by, for example, fusion as shown in the figure. The thermoplastic resin continuous phase portion 8a and the thermoplastic resin particle phase portion 8b that are substantially left in the form of particles are mixed. Thus, by including the thermoplastic resin in the intermediate resin layer 4 in the form of a continuous phase, the adhesion between the metal layer 2 and the fiber reinforced resin layer 3 is improved. In particular, when a stress in a peeling mode such as peeling from the fiber reinforced resin layer 3 is applied to the metal layer 2, the thermoplastic resin in the intermediate resin layer 4 has the form of the continuous phase 8a. It is considered that it acts as an anchor for the thermosetting base material resin 7 to be configured, and the adhesiveness is improved. Here, the thermosetting matrix resin 6 constituting the fiber reinforced resin layer 3 and the thermosetting matrix resin 7 constituting the intermediate resin layer 4 may have the same resin composition or different thermosetting resins. It may be.

  The thermosetting resin 7 constituting the intermediate resin layer 4 contains an imidazole silane compound. By including this imidazole silane compound, the adhesion between the intermediate resin layer 4 and the metal layer 2, particularly the metal layer 2 containing titanium, is improved. In particular, deterioration of adhesiveness after exposure to high temperature and high humidity can be suppressed, and the resistance to environmental exposure can be improved. The blending amount of the imidazole silane compound in the thermosetting resin is preferably 0.1% by weight or more and 2.0% by weight or less with respect to the weight of the resin composition. That is, when the amount of the imidazole silane compound is less than 0.1% by weight, the effect of improving adhesiveness is small, which is not preferable. If it exceeds 2.0% by weight, especially when an epoxy resin is used as the thermosetting resin, the imidazole silane compound also acts as a curing agent or a curing accelerator, so that curing is excessively accelerated. Therefore, it is not preferable. In this case, it is also one of preferable usage forms that a solution obtained by melting an imidazolesilane compound in an organic solvent such as ethanol is applied to a metal adhesion surface, dried and subjected to a surface treatment. Thus, the purpose of use of the imidazolesilane compound in the present invention is to improve the adhesion to the metal layer 2 in particular, and is used as a curing agent or curing accelerator for a thermosetting resin or as a rust preventive for metals. is not.

  FIG. 4 shows a more preferable embodiment. That is, in the aircraft structural body 11 shown in FIG. 4, the intermediate resin layer 12 is formed at the boundary between the fiber reinforced resin layer 3 and the reinforced fibers 5 of the fiber reinforced resin layer 3 and the thermoplastic resin, particularly the continuous phase. The mixed layer 12b in which the thermoplastic resin 8a is mixed is unevenly formed. The portion closer to the metal layer 2 than the mixed layer 12b has substantially the same form as the intermediate resin layer 4 shown in FIG. Thus, by mixing the reinforcing fiber 5 and the thermoplastic resin continuous phase 8a, the thermoplastic resin continuous phase 8a acts as an anchor for the reinforcing fiber group 5, and the intermediate resin layer 12 and the fiber reinforced resin layer 3 Adhesion is greatly improved. It is more preferable that each thermoplastic resin continuous phase 8a is in contact with a plurality of reinforcing fibers 5.

  The thickness of the intermediate resin layer 12 is preferably 15 μm or more and 150 μm or less, for example, and the maximum thickness of the mixed layer 12b is preferably 10 μm or more and 100 μm or less. FIG. 4 shows the thickness of the intermediate resin layer 12 as Ta and the thickness of the mixed layer 12b with the thermoplastic resin continuous phase 8a as the reinforcing fiber group 5 as Tpf. Ta and Tpf can be measured by observing the cross section of the composite material with an optical microscope, a microscope using a CCD, SEM, and TEM.

  If the thickness Ta of the intermediate resin layer 12 is less than 15 μm, the intermediate resin layer 12 is too thin and the layer is easily broken, which is not preferable. On the other hand, when the thickness is larger than 150 μm, the intermediate resin layer 12 is too thick, so that the weight of the intermediate resin layer 12 increases and the weight reduction as a composite material is impaired.

  Furthermore, the thickness Tpf of the mixed layer 12b in which the reinforcing fiber 5 and the thermoplastic resin continuous phase 8a are mixed may be less than 10 μm, but is preferably 10 μm or more because the adhesiveness is further improved. On the other hand, if it is thicker than 100 μm, it is not preferable because it is too thick and the weight of the intermediate resin layer 12 increases. Moreover, it is not preferable to mix the thermoplastic resin continuous phase 8a thicker than 100 μm between the reinforcing fibers because it may be very difficult from the viewpoint of molding.

Regarding the thermoplastic resin particles blended in the intermediate resin layer 12, it is preferable that a continuous phase having the above-described continuous shape and a particle shape having an average particle diameter of 3 μm or more and 10 μm or less are mixed. The intermediate resin layer 12 is composed of a base resin 7 made of a thermosetting resin and a thermoplastic resin. The thermoplastic resin has a particle shape with an average particle size of 3 μm to 10 μm and is mixed with the thermosetting resin. Has been. By making the particle shape 3 μm or more and 10 μm or less, it is easy to process the intermediate resin layer 12 into a film shape or the like before molding. Further, in the curing and molding process, the thermoplastic resin is interposed between the reinforcing fibers. It becomes easy to form the layer 12b in which the reinforcing fiber and the thermoplastic resin are mixed after molding. For this reason, it is preferable that the thermoplastic resin mixed in the particle shape forms a continuous phase having a continuous shape, and a part of the thermoplastic resin is present in the particle shape.
The shape of the thermoplastic resin in the intermediate resin layer after molding can be measured by observing with an optical microscope, a microscope using a CCD, SEM, and TEM, similarly to the measurement of the thickness of the intermediate resin layer.

In addition, the resin composition itself constituting the intermediate resin layer 12 in the present invention is measured based on ASTM D 5045-96 “Standard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Rate of Matter Release”. The rate (Strain Energy Release Rate) G _IC is preferably 400 J / m ² or more and 1000 J / m ² or less. A G _IC of less than 400 J / m ² is not preferable because the strain energy release rate is too low and the destruction of the intermediate resin layer 12 proceeds relatively easily. G _IC can be improved by mixing the thermoplastic resin in the intermediate resin layer 12 in a continuous phase having a continuous shape. Further, by increasing the mixing amount of the thermosetting resin of the thermoplastic resin, it is possible to improve the G _IC. On the other hand, in order to make G _IC larger than 1000 J / m ^2, it is necessary to mix a larger amount of thermoplastic resin. However, if the amount of the thermoplastic resin mixed is too large, the resin composition may have a film shape or the like. This is not preferable because it becomes difficult to process and there is a concern that the heat resistance or elastic modulus of the resin layer may decrease.

  The molding temperature of the epoxy resin, which is a matrix resin constituting the fiber reinforced resin layer used in ordinary aircraft structures, is often 200 ° C. or less. In this case, at least the thermoplastic resin is fused or the like. In order to partially form a continuous phase, it is preferable to mold at a temperature equal to or higher than the melting point (or softening point) of the thermoplastic resin particles. When the intermediate resin layer 12 and the fiber reinforced resin layer 3 are molded simultaneously in order to allow the particles to enter between the reinforced fibers, or when a cured fiber reinforced resin is used, the surface roughness is equal to or larger than the particle diameter of the particles. A method of blasting the adhesive surface can also be adopted.

  If it is difficult to measure the strain energy release rate of the intermediate resin layer itself, pull the metal layer from the fiber reinforced resin layer using a test piece in which the fiber reinforced resin layer and the metal layer are bonded and integrated through the intermediate resin layer. It is also possible to evaluate the adhesion by performing a peeling test.

  In this case, the peeling torque measured by the climbing drum peel method based on ASTM D 1781-98 (1998) is preferably 10 N · mm / mm or more, more preferably 20 N · mm / mm or more. When evaluating the adhesiveness of the intermediate resin layer, an evaluation method using an opening mode such as a strain energy release rate and a peeling torque is more preferable than a shear mode evaluation method.

  Moreover, it is preferable that the metal layer in this invention is inserted in the fiber reinforced resin layer. By interpolating the metal layer in the fiber reinforced resin layer, compared to the case where the metal layer is provided only in the outermost layer or the innermost layer, the adhesion area between the fiber reinforced plastic layer and the metal layer can be increased. When a bending load is applied to the aircraft structure, it is possible to reduce the load applied to the aircraft structure per intermediate resin layer, and the metal layer and the fiber reinforced resin layer are separated and suppressed. This is preferable.

  On the other hand, the metal layer is preferably laminated on the outermost layer. It is conceivable that an aircraft structure is damaged by a collision of a bird or the like during a flight or an impact caused by a fall of an instrument during maintenance. Therefore, it is required to maintain a certain level of strength after impact, but by laminating a metal layer on the outermost layer, the impact energy is absorbed by the metal layer and the fiber reinforced resin layer is damaged. Since it can reduce as much as possible, it is preferable.

  The melting point or softening point of the thermoplastic resin is preferably 200 ° C. or lower. In the present invention, the thermoplastic resin in the intermediate resin is once melted or softened by molding a composite material at a temperature equal to or higher than the melting point or softening point of the thermoplastic resin and an appropriate pressure condition. A thermoplastic resin can be easily mixed in the form of a continuous phase. On the other hand, when the aircraft structure is required to have particularly high heat resistance, the molding temperature of the fiber reinforced resin may be higher than 200 ° C. For example, when the fiber reinforced resin layer is required to have a heat resistance of 170 ° C. or higher, a polyimide resin having high heat resistance may be used as the matrix resin, and the molding temperature may be 350 ° C. or higher. In this case, the melting point or softening point of the thermoplastic resin is not limited to 200 ° C. or lower, and it is possible to use a thermoplastic resin having a melting point or softening point lower than the molding temperature in view of heat resistance. It is.

  The melting point of the thermoplastic resin in the present invention is a value measured by DSC at a heating rate of 10 ° C./min in accordance with JIS-K7121. The softening point is a value obtained by measuring the Picad softening temperature in accordance with JIS-K7206.

  In the present invention, the reinforcing fibers constituting the reinforcing fiber group include inorganic fibers such as carbon fibers, glass fibers, and alumina fibers, organic fibers such as aramid fibers and polyamide synthetic fibers, and a combination of two or more thereof. Although it can be used, carbon fiber is particularly preferable as the reinforcing fiber. Since carbon fiber has low specific gravity, high strength, and high elastic modulus, the specific strength and specific elastic modulus are large, and the composite material of the aircraft structure according to the present invention can be reduced in weight, increased in strength, and increased in elastic modulus. Therefore, it can be preferably used and it is easy to control these characteristics.

  In the present invention, the thermoplastic resin is selected from the group of polyamide resin, polyester resin, polycarbonate resin, styrene resin, EVA resin, urethane resin, acrylic resin, polyolefin resin, and PPS resin. At least one kind of resin is preferred. In particular, a polyamide-based resin is more preferable because it has excellent adhesion to a thermosetting resin.

  The polyamide resin of the present invention includes polyamide 11, polyamide 12, polyamide 610, polyamide 612, and their copolyamide resins such as polyamide 66/6, 6/66/610, 6/66/612, 6/66 / Resin selected from 610/612.

  Of these, polyamide 11 and polyamide 12 are preferred because of their low water absorption. In the aircraft structure according to the present invention, steel, aluminum, an aluminum alloy, or the like can be used as the metal constituting the metal layer, but titanium or a titanium alloy is particularly preferable. That is, in the case of using the fiber reinforced resin having a light weight, high strength, and high elastic modulus as in the present invention, a titanium alloy having a light weight, high strength, and high elastic modulus is more preferable. Titanium alloys are also excellent in lightning protection. Of these, β-15 alloy Ti-15V-3Cr-3Al-3Sn and α + β alloy Ti-6Al-4V are more preferred because of their high strength among titanium alloys.

  The aircraft structure manufacturing method of the present invention is a manufacturing method for manufacturing an aircraft structure by thermoforming a thermosetting resin prepreg, and the temperature is equal to or higher than the melting point or softening point of the thermoplastic resin. And heat molding. By thermoforming to a temperature equal to or higher than the melting point or softening point of the thermoplastic resin, it is possible to form a continuous phase by fusing the thermoplastic resins in the intermediate resin layer in the molding step. Even at a temperature equal to or higher than the softening point, the thermoplastic resin can be deformed and mixed between the reinforcing fibers by applying an appropriate pressure.

  In particular, when a thermoplastic resin in the form of particles is blended with the thermosetting resin constituting the intermediate resin layer, the viscosity of the thermosetting resin decreases during the temperature rise process, and the thermoplastic resin particles move. It becomes easy, can be mixed between the reinforcing fibers, and further by heating to above the melting point of the thermoplastic resin, by fusing the particles of the adjacent thermoplastic resin, by forming a continuous phase, The adhesion between the metal layer and the fiber reinforced resin layer can be further improved.

[Example 1]
Assuming a skin panel for an aircraft horizontal tail, after forming a panel in which a titanium alloy layer is bonded and integrated on both surfaces of a carbon fiber reinforced plastic layer, the panel is cut and processed to a width of 38.10 mm, long Ten test pieces of 304.80 mm were prepared. Furthermore, assuming that the skin panel is joined and integrated with other members by rivets, for all the test pieces, at the center of the test piece (position of 19.05 mm in the width direction and 152.40 mm in the length direction). A hole with a diameter of 6.35 mm was formed.

A compression test was performed using the test piece subjected to the hole processing, and the compression strength was measured.
First, the materials used and the panel forming method will be described.

As the carbon fiber reinforced plastic layer, 180 ° C. unidirectional prepreg sheet A (fiber basis weight: 190 g / m ² , resin content: 35% by weight, fiber tensile elastic modulus: 294 GPa, matrix resin: epoxy resin) was used.

  However, the unidirectional prepreg sheet B in which the resin film for forming the intermediate resin layer was previously laminated on the surface of one side of the unidirectional prepreg sheet A was used as the prepreg sheet forming the layer to be bonded to the titanium alloy layer.

The resin composition constituting the resin film is that nylon fine particles (polyamide 12 fine particles SP500 manufactured by Toray Industries, Inc., average particle diameter 5 μm, melting point 165 ° C.) are added to the epoxy resin of the matrix resin constituting the unidirectional prepreg sheet A 20 A resin composition in which 1% by weight of an imidazole silane compound (IS-1000 manufactured by Nikko Materials Co., Ltd.) is blended in an amount of 1% by weight with respect to the epoxy weight is processed into a film having a basis weight of 60 g / m ² . This resin film was placed on one surface of the unidirectional prepreg sheet A and laminated by pressing with a calender roll heated to 80 ° C. to prepare a unidirectional prepreg sheet B.

  The titanium alloy layer was a titanium alloy sheet (Ti-15V-3Cr-3Al-3Sn, thickness: 0.13 mm). The adhesive surface of the titanium alloy sheet was polished with # 800 sanding paper and then washed with acetone.

These prepreg sheets A and titanium alloy sheets were laminated according to a laminated structure [Ti / (45/0 / −45 / 90) ₂ ] _S. Here, Ti means a titanium alloy sheet, and the numbers 45, 0, -45, and 90 mean the lamination angles of the reinforcing fibers. The subscript 2 means that the lamination is repeated twice, and the subscript S means a mirror-symmetric lamination. That is, the laminated structure is obtained by laminating titanium alloy sheets on both surfaces of a carbon fiber reinforced plastic layer composed of 16 prepreg sheets. It laminated | stacked so that the side which laminated | stacked the resin film of the unidirectional prepreg sheet B in the case of lamination | stacking may arrange | position to the side which adhere | attaches a titanium alloy layer.

After the lamination, the titanium alloy layer and the carbon fiber are cured through the resin film constituting the intermediate resin layer while curing the prepreg using an autoclave at a temperature of 180 ° C., a pressure of 6 kg / cm ² , and a holding time of 2 hours. A reinforced plastic layer was bonded and integrated to form a panel.

  Next, using an auto cutter, a test piece was prepared by cutting into a shape having a width of 38.10 mm and a length of 304.80 mm. The length direction was the 0 ° direction of the reinforcing fiber. Further, a hole having a diameter of 6.35 mm was formed at a position of 19.05 mm in the width direction and 152.40 mm in the length direction. The end face of the hole was treated with a reamer.

As a result of cross-sectional observation of the obtained test piece, an intermediate resin layer having a thickness (corresponding to Ta in FIG. 4) of 100 μm is formed between the outermost titanium alloy layer and the carbon fiber reinforced plastic layer. In the layer, nylon fine particles were integrated with each other over a wide range to form a nylon continuous phase (corresponding to 8a in FIG. 4).
Further, nylon fine particles (corresponding to 8b in FIG. 3) having an average particle diameter of 5 μm were observed in part. Furthermore, a part of the nylon continuous phase entered the carbon fiber group constituting the carbon fiber plastic, and a mixed layer (corresponding to the mixed layer 12b in FIG. 4) in which carbon fibers and nylon fine particles were mixed was formed. The thickness of the mixed layer was 40 μm.
Moreover, peeling of the titanium alloy sheet or the like was not observed on the cut surface or the end surface of the hole processing.

  After observing the cross section, all 10 specimens were placed in an Instron universal material testing machine and subjected to a compression test, and the average value of the 10 compressive strengths was determined. The crosshead speed was tested at 1.0 mm / min.

As a result, it was confirmed that the compressive strength was 1.2 times that of the test piece having only the carbon fiber reinforced plastic layer on which the titanium alloy sheet was not laminated.
[Example 2]
A test piece was prepared in the same manner as in Example 1 except that the laminated structure was [Ti / (45/0 / −45 / 90) ₂ Ti] _S. Here, the underline of Ti means that there is only one layer. The titanium alloy layer is inserted in the outermost layer of the carbon fiber reinforced plastic layer and in the middle of the laminated thickness. Similarly to Example 1, the prepreg sheet B was used as the carbon fiber plastic layer to be bonded to the titanium alloy layer.
As a result of cross-sectional observation of the obtained test piece, the thickness (corresponding to Ta in FIG. 4) is 100 μm between the outermost titanium alloy layer and the intercalated titanium alloy layer and the carbon fiber reinforced plastic layer. A resin layer was formed, and a nylon continuous phase (corresponding to 8a in FIG. 4) was formed by integrating nylon fine particles over a wide range in the intermediate resin layer.
Further, nylon fine particles (corresponding to 8b in FIG. 3) having an average particle diameter of 5 μm were observed in part. Furthermore, a part of the nylon continuous phase entered the carbon fiber group constituting the carbon fiber plastic, and a mixed layer (corresponding to the mixed layer 12b in FIG. 4) in which carbon fibers and nylon fine particles were mixed was formed. The thickness of the mixed layer was 40 μm.
Moreover, peeling of the titanium alloy sheet or the like was not observed on the cut surface or the end surface of the hole processing.

  After observing the cross section, all 10 specimens were placed in an Instron universal material testing machine and subjected to a compression test, and the average value of the 10 compressive strengths was determined. The crosshead speed was tested at 1.0 mm / min.

As a result, it was confirmed that the compressive strength was 1.3 times that of the test piece having only the carbon fiber reinforced plastic layer on which the titanium alloy sheet was not laminated.
[Comparative Example 1]
A panel was formed in the same manner as in Example 1 except that the unidirectional prepreg sheet B was not used as the prepreg sheet for forming the layer bonded to the titanium alloy layer, and the carbon fiber reinforced plastic layer was all composed of the unidirectional prepreg sheet A. A test piece was prepared.
As a result of cross-sectional observation of the obtained test piece, no intermediate resin layer was formed between the outermost titanium alloy layer and the carbon fiber reinforced plastic layer.
As in Example 1, the test piece was cut from the panel using an auto cutter, and as a result, it was confirmed that the titanium alloy sheet peeled from the carbon fiber reinforced plastic layer in all the test pieces. Moreover, since the peeling of the titanium alloy sheet was also observed on the end face of the hole processing, the compression test could not be performed.

1 is a cross-sectional view of an aircraft structure according to an embodiment of the present invention. It is a cross-sectional view of the aircraft structure which concerns on another embodiment of this invention. FIG. 3 is an enlarged partial cross-sectional view illustrating a configuration example of each layer bonding portion of the aircraft structure of FIG. 1 or FIG. It is an expanded partial sectional view which shows another structural example of each layer adhesion part of the structure for aircrafts.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Panel member 2 as an aircraft structure, 22 Metal layer 3, 23 Fiber reinforced resin layer 4, 12, 24 Intermediate resin layer 5 Reinforcing fiber (group)
6 Matrix resin of fiber reinforced resin layer 7 Base resin of intermediate resin layer 8 Thermoplastic resin 8a Thermoplastic resin continuous phase 8b Thermoplastic resin particle phase 12a Middle resin layer portion 12b near metal layer Mixed layer 21 As an aircraft structure Structural member H Water repellent layer

Claims (13)

  An aircraft structure composed of a metal / fiber reinforced resin composite material in which a metal layer and a fiber reinforced resin layer are bonded and integrated through an intermediate resin layer, the intermediate resin layer having an average particle size of 3 to 10 μm A structure for aircraft, comprising particles of thermoplastic resin and an imidazolesilane compound.   The boundary part of the said intermediate | middle resin layer and the said fiber reinforced resin layer forms the mixed layer in which the thermoplastic resin which comprises the said particle | grain, and the reinforced fiber of the said fiber reinforced resin layer were mixed. Aircraft structures.   3. The aircraft structure according to claim 1, wherein the thermoplastic resin particles are present in the intermediate resin layer in the form of a continuous phase at least partially by fusion or the like. The aircraft structure according to claim 1, wherein the thermoplastic resin particles are made of a polyamide-based resin.   The aircraft structure according to any one of claims 1 to 4, wherein the matrix resin of the fiber reinforced resin layer and the base resin of the intermediate resin layer are made of the same kind of resin.   The aircraft structure according to claim 5, wherein the same kind of resin is made of a thermosetting resin.   The aircraft structure according to claim 1, wherein the metal layer includes a layer containing titanium.   The aircraft structure according to any one of claims 1 to 7, wherein the metal layer is inserted in a fiber reinforced resin layer.   The aircraft structure according to any one of claims 1 to 8, wherein the fiber reinforced resin layer comprises a layer containing carbon fibers.   The aircraft structure according to any one of claims 1 to 9, wherein a water-repellent layer is formed on the surface of the outermost fiber reinforced resin layer.   The aircraft structure according to any one of claims 1 to 10, which is a panel member.   The aircraft structural body according to claim 1, wherein the aircraft structural body is a structural member.   It is a manufacturing method which manufactures the aircraft structure in any one of Claims 1-12 by heat-molding a thermosetting resin prepreg, Comprising: It heats at the temperature more than melting | fusing point or a softening point of the said thermoplastic resin. A method for manufacturing an aircraft structure, comprising molding.

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