The present invention relates to a composite material, a method for producing a composite material, and a method for curing a composite material.
In recent years, a composite honeycomb sandwich panel exhibiting good strength against bending stress, shear stress, and the like is used as a structural material of an aircraft and the like. The composite honeycomb sandwich panel has a sandwich structure where high-strength skin materials are disposed on upper and lower surfaces of a lightweight core material (honeycomb core). A film adhesive may be used to bond the skin material and the honeycomb core. As an example of such a composite honeycomb sandwich panel, for example, a composite honeycomb sandwich panel described in PTL 1 has been reported.
In order to prevent damage by lightning stroke, in the composite honeycomb sandwich panel used in the aircraft structure, generally, a lightning protection mesh is attached to an aerodynamic surface. In the related art, when the lightning protection mesh is attached to the composite honeycomb sandwich panel, in the composite honeycomb sandwich panel (hereinafter, simply referred to as a “composite material”) before curing, the lightning protection mesh and a resin material (for example, a film adhesive (adhesive that integrates the lightning protection mesh with the composite material) or a surface conditioner) are applied to the aerodynamic surface.
[PTL 1] U.S. Pat. No. 9,539,769 specification
Hereinafter, a method for producing the above composite honeycomb sandwich panel will be described with reference to
In the production method by the secondary adhesive molding, first, as illustrated in step of
Thereafter, the resin material 108, the lightning protection mesh 107, the cured prepreg 113, a second film adhesive 105, a honeycomb core 102, a first film adhesive 103, and the cured prepreg 113 are laminated in order from below to form a composite material 101 (step of
In producing the composite honeycomb sandwich panel, currently, the production method by the secondary adhesive molding as illustrated in
In the one-shot molding, as illustrated in the step of
Here, usually, in molding the composite honeycomb sandwich panel, in order to reduce core crash occurring due to pressure being applied to a side surface of the honeycomb core, chamfering is performed to obliquely cut off an end portion of the honeycomb core at an angle of approximately 30°. A case where a composite material including the honeycomb core subjected to such chamfering is molded by one-shot molding will be described below with reference to
The invention has been made in light of such circumstances, and an object of the invention is to provide a composite material and a method for producing a composite material by which fibers of a skin material can be suppressed from being bent to cause a reduction in strength during curing of the composite material.
In order to solve the above problem, the invention employs the following means.
According to one aspect of the invention, there is provided a composite material including: a honeycomb core; a first skin material disposed on one surface of the honeycomb core to be bonded to the honeycomb core; a second skin material disposed on an opposite surface of the honeycomb core from the one surface to be bonded to the honeycomb core; a lightning protection mesh disposed on an opposite surface of the second skin material from a surface of the second skin material, the surface being bonded to the honeycomb core; and a resin material disposed on an opposite surface of the lightning protection mesh from a second skin material side. A filler is disposed between the honeycomb core and the first skin material, between the honeycomb core and the second skin material, or in both locations so as to overlap a tip of an end portion of the honeycomb core.
In the composite material of the invention, the filler is disposed between the honeycomb core and the first skin material, between the honeycomb core and the second skin material, or in both locations so as to overlap the tip of the end portion of the honeycomb core. In the composite material used in the aircraft structure, the lightning protection mesh and the resin material are generally applied to an aerodynamic surface. In the composite material, particularly when the end portion of the honeycomb core is chamfered, a portion to which the pressure of an autoclave is relatively less likely to be applied occurs at the tip of the end portion. In this state, when the composite material is cured, the resin material (for example, a film adhesive or a surface conditioner) disposed in an outermost layer may be accumulated (adhesive accumulation occurs) in the portion. When the adhesive accumulation occurs, fibers of the skin material are bent (wrinkled) to cause a reduction in strength, which is a concern. Here, as in the invention, when the filler is disposed between the honeycomb core and the first skin material (in a portion above the end portion of the honeycomb core), the pressure of the autoclave is easily transmitted via the filler to the portion where the adhesive accumulation occurs; and thereby, the adhesive accumulation can be suppressed from occurring. When the filler is disposed between the honeycomb core and the second skin material (in a portion below the end portion of the honeycomb core), the rigidity of the filler provides the effect of suppressing adhesive accumulation; and thereby, the skin material can be suppressed from being bent. When the filler is disposed in the composite material in such a manner, during curing of the composite material, the fibers of the skin material can be suppressed from being bent to cause a reduction in strength. Therefore, the composite material of the invention can be suitably used in the aircraft structure.
In the composite material, it is preferable that in a horizontal view, the filler disposed between the honeycomb core and the second skin material protrudes outside the composite material by a length equal to or less than a length of a portion of the filler, the portion overlapping the tip of the end portion of the honeycomb core.
As described above, when the filler is disposed between the honeycomb core and the second skin material, the skin material can be sufficiently suppressed from being bent. Since the size of the filler can be set to an appropriate size, excessive overlapping can be suppressed from occurring in the composite material.
In the composite material, it is preferable that the first film adhesive bonding the first skin material to the honeycomb core is disposed between the first skin material and the honeycomb core, and the second film adhesive bonding the second skin material to the honeycomb core is disposed between the second skin material and the honeycomb core.
As described above, in the invention, two skin materials can be bonded to the honeycomb core by using the film adhesives.
In the composite material, it is preferable that the end portion of the honeycomb core is chamfered so as to be inclined toward the second skin material side.
As described above, in the invention, the end portion of the honeycomb core can be chamfered.
According to another aspect of the invention, there is provided a method for producing a composite material, the method including: a preparation step of preparing a composite material including a honeycomb core, a first skin material disposed on one surface of the honeycomb core to be bonded to the honeycomb core, a second skin material disposed on an opposite surface of the honeycomb core from the one surface to be bonded to the honeycomb core, a lightning protection mesh disposed on an opposite surface of the second skin material from a surface of the second skin material, the surface being bonded to the honeycomb core, and a resin material disposed on an opposite surface of the lightning protection mesh from a second skin material side; and an alignment step of disposing a filler between the honeycomb core and the first skin material, between the honeycomb core and the second skin material, or in both locations so as for the filler to overlap a tip of an end portion of the honeycomb core.
In the method for producing a composite material according to the invention, in the alignment step, the filler is disposed between the honeycomb core and the first skin material, between the honeycomb core and the second skin material, or in both locations so as to overlap the tip of the end portion of the honeycomb core. In the composite material used in the aircraft structure, the lightning protection mesh and the resin material are generally applied to an aerodynamic surface. In the composite material, particularly when the end portion of the honeycomb core is chamfered, a portion to which the pressure of an autoclave is relatively less likely to be applied occurs at the tip of the end portion. In this state, when the composite material is cured, the resin material (for example, a film adhesive or a surface conditioner) disposed in an outermost layer may be accumulated (adhesive accumulation occurs) in the portion. When the adhesive accumulation occurs, fibers of the skin material are bent (wrinkled) to cause a reduction in strength, which is a concern. Here, as in the invention, when the filler is disposed between the honeycomb core and the first skin material (in a portion above the end portion of the honeycomb core), the pressure of the autoclave is easily transmitted via the filler to the portion where adhesive accumulation occurs; and thereby, the adhesive accumulation can be suppressed from occurring. When the filler is disposed between the honeycomb core and the second skin material (in a portion below the end portion of the honeycomb core), the rigidity of the filler provides the effect of suppressing adhesive accumulation; and thereby, the skin material can be suppressed from being bent. When the filler is disposed in the composite material in such a manner, during curing of the composite material, the fibers of the skin material can be suppressed from being bent to cause a reduction in strength. Therefore, the method for producing a composite material in the invention can be suitably used in the aircraft structure.
It is preferable that in the alignment step, in a horizontal view, the filler is disposed between the honeycomb core and the second skin material so as to protrude outside the composite material by a length equal to or less than a length of a portion of the filler, the portion overlapping the tip of the end portion of the honeycomb core.
As described above, when the filler is disposed between the honeycomb core and the second skin material, the skin material can be sufficiently suppressed from being bent. Since the size of the filler can be set to an appropriate size, excessive overlapping can be suppressed from occurring in the composite material.
It is preferable that in the preparation step, the composite material in which the first film adhesive bonding the first skin material to the honeycomb core is disposed between the first skin material and the honeycomb core and the second film adhesive bonding the second skin material to the honeycomb core is disposed between the second skin material and the honeycomb core is prepared.
As described above, in the invention, two skin materials can be bonded to the honeycomb core by using the film adhesives.
It is preferable that in the preparation step, the composite material in which the end portion of the honeycomb core is chamfered so as to be inclined toward the second skin material side is prepared.
As described above, in the invention, the end portion of the honeycomb core can be chamfered.
According to still another aspect of the invention, there is provided a method for curing a composite material, the method including collectively curing the above-described composite material.
Even if the composite material of the invention is collectively cured and molded (one-shot molding), during curing of the composite material, the fibers of the skin material can be sufficiently suppressed from being bent to cause a reduction in strength. Therefore, one-shot molding is performed, and thus in addition to reducing the operation cost of the autoclave, a curing operation with a bag for curing is performed once; and thereby, the molding cost can be reduced. There is no need to perform a rough trim operation and a jig cleaning operation after the skin material is cured, which are required in secondary adhesive molding, and thus the process is simple.
According to the composite material and the method for producing a composite material in the invention, during curing of the composite material, the fibers of the skin material can be suppressed from being bent to cause a reduction in strength.
Hereinafter, embodiments of a composite material and a method for producing a composite material according to the invention will be described with reference to the drawings.
Hereinafter, a composite material according to a first embodiment of the invention will be described with reference to
As illustrated in
An end portion of the honeycomb core 2 is, as will be described later, chamfered so as to be inclined toward the second skin material 6 side. The first skin material 4 and the second skin material 6 are, for example, a plurality of laminated uncured prepregs.
Next, the configuration of the vicinity of a tip of the end portion of the honeycomb core 2 in the composite material 1 according to the present embodiment will be specifically described with reference to
The material of the filler 9 is not particularly limited, and composite materials (for example, carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), and the like), film adhesives, resin materials, and the like can be provided as examples of the material. The curing state of the filler 9 may be a cured state or an uncured state. The number of laminated layers (ply number) of the filler 9 is determined according to the height of an adhesive accumulation that is expected to occur, and when the thickness of the filler 9 is 0.3 mm/ply or less, approximately one to three plies are desirable. When a plurality of the fillers 9 are applied in a laminated manner, the lengths of the plies may be the same or different.
According to the present embodiment with the above-described configuration, the following effects are obtained.
In the composite material 1 of the present embodiment, the filler 9 is disposed between the honeycomb core 2 and the second skin material 6 so as to overlap the tip of the end portion of the honeycomb core 2. As in the present embodiment, when the filler 9 is disposed between the honeycomb core 2 and the second skin material 6 (in a portion below the end portion of the honeycomb core 2), the rigidity of the filler 9 provides the effect of suppressing the adhesive accumulation; and thereby, the skin material (second skin material 6) can be suppressed from being bent. When the filler 9 is disposed in the composite material 1 in such a manner, during curing of the composite material 1, fibers of the second skin material 6 can be suppressed from being bent to cause a reduction in strength. Therefore, the composite material 1 of the present embodiment can be suitably used in the aircraft structure.
In the present embodiment, in a horizontal view, the filler 9 protrudes outside the composite material 1 by a length equal to or less than the length of the portion of the filler 9, the portion overlapping the tip of the end portion of the honeycomb core 2. When the filler 9 is disposed in such a manner, the second skin material 6 can be sufficiently suppressed from being bent. Since the size of the filler 9 can be set to an appropriate size, excessive overlapping can be suppressed from occurring in the composite material 1.
Incidentally, in the first embodiment described above, the case where in a horizontal view, the filler 9 protrudes outside the composite material 1 by a length equal to or less than the length of the portion of the filler 9, the portion overlapping the tip of the end portion of the honeycomb core 2, has been described as an example; however, the invention is not limited thereto. Specifically, as long as the filler 9 overlaps the vicinity of the tip of the end portion of the honeycomb core 2, in which the adhesive accumulation occurs, the length of the filler 9 is not particularly limited.
Next, a second embodiment of the invention will be described with reference to
The basic configuration of the present embodiment is basically the same as that of the first embodiment; however, the present embodiment differs from the first embodiment in that instead of the filler 9, a filler 9′ is disposed between the first film adhesive 3 and the first skin material 4. Therefore, in the present embodiment, the different part will be described and the description of other duplicate parts will be omitted.
Incidentally, the same reference signs are assigned to the same components as those of the first embodiment and duplicate descriptions will be omitted.
According to the present embodiment with the above-described configuration, the following effects are obtained.
In the composite material 21 of the present embodiment, the filler 9′ is disposed between the honeycomb core 2 and the first skin material 4 so as to overlap the tip of the end portion of the honeycomb core 2. As in the present embodiment, when the filler 9′ is disposed between the honeycomb core 2 and the first skin material 4 (in a portion above the end portion of the honeycomb core 2), the pressure of an autoclave is easily transmitted via the filler 9′ to a portion where adhesive accumulation occurs. As a result, the adhesive accumulation can be suppressed from occurring. When the filler 9′ is disposed in the composite material 21 in such a manner, during curing of the composite material 21, the fibers of the second skin material 6 can be suppressed from being bent to cause a reduction in strength. Therefore, the composite material 21 of the present embodiment can be suitably used in the aircraft structure.
Next, a third embodiment of the invention will be described with reference to
The basic configuration of the present embodiment is basically the same as that of the first embodiment; however, the present embodiment differs from the first embodiment in that in addition to the filler 9, the filler 9′ of the second embodiment is also disposed. Therefore, in the present embodiment, the different part will be described and the description of other duplicate parts will be omitted.
Incidentally, the same reference signs are assigned to the same components as those of the second embodiment and duplicate descriptions will be omitted.
According to the present embodiment with the above-described configuration, the following effects are obtained.
In the composite material 31 of the present embodiment, the filler 9′ and 9 are disposed both between the honeycomb core 2 and the first skin material 4 and between the honeycomb core 2 and the second skin material 6 so as to overlap the tip of the end portion of the honeycomb core 2. As in the present embodiment, when the filler 9 is disposed between the honeycomb core 2 and the first skin material 4 (in a portion above the end portion of the honeycomb core 2), the pressure of the autoclave is easily transmitted via the filler 9 to a portion where adhesive accumulation occurs. As a result, the adhesive accumulation can be suppressed from occurring. When the filler 9′ is disposed between the honeycomb core 2 and the second skin material 6 (in a portion below the end portion of the honeycomb core 2), the rigidity of the filler 9′ provides the effect of suppressing the adhesive accumulation; and thereby, the second skin material 6 can be suppressed from being bent. When the fillers 9 and 9′ are disposed in the composite material 31 in such a manner, during curing of the composite material 31, the fibers of the second skin material 6 can be suppressed from being bent to cause a reduction in strength. Therefore, the composite material 31 of the present embodiment can be suitably used in the aircraft structure.
The composite material of the invention as described above can be collectively cured. Even if the composite material of the invention is collectively cured and molded (one-shot molding), during curing of the composite material, the fibers of the skin material can be sufficiently suppressed from being bent to cause a reduction in strength. Therefore, one-shot molding is performed, and thus in addition to reducing the operation cost of the autoclave, a curing operation with a bag for curing is performed once; and thereby, the molding cost can be reduced. There is no need to perform a rough trim operation and a jig cleaning operation after the skin material is cured, which are required in secondary adhesive molding, and thus the process is simple.
The composite material of the invention as described above is suitably applicable to products, such as a control surface structure for future commercial aircrafts, a panel for future helicopters and space shuttles, aircraft floor materials, floor materials and frame materials for new transportation and railway vehicles, which require a lightweight and high-rigidity composite honeycomb sandwich panel.
[Method for Producing Composite Material]
Next, one embodiment of a method for producing a composite material in the invention will be described.
The method for producing a composite material in the invention includes a preparation step and an alignment step. In the preparation step, the above-described composite material of the invention is prepared. In the alignment step, a filler is disposed between the honeycomb core and the first skin material, between the honeycomb core and the second skin material, or in both locations so as to overlap the tip of the end portion of the honeycomb core.
Incidentally, hereinafter, a case where the method for producing a composite material in the invention is applied to producing the composite material 1 illustrated in
(Preparation Step)
In the preparation step, the composite material 1 of the first embodiment described above is prepared. Here, as one example, the composite material 1 illustrated in
(Alignment Step)
In the alignment step, as illustrated in
In the alignment step, specifically, as illustrated in
According to the present embodiment with the above-described configuration, the following effects are obtained.
In the method for producing the composite material 1 of the present embodiment, in the alignment step, the filler 9 is disposed between the honeycomb core 2 and the second skin material 6 so as to overlap the tip of the end portion of the honeycomb core 2. As in the present embodiment, when the filler 9 is disposed between the honeycomb core 2 and the second skin material 6 (in a portion below the end portion of the honeycomb core 2), the rigidity of the filler provides the effect of suppressing the adhesive accumulation; and thereby, the skin material (second skin material 6) can be suppressed from being bent. When the filler 9 is disposed in the composite material 1 in such a manner, during curing of the composite material 1, the fibers of the second skin material 6 can be suppressed from being bent to cause a reduction in strength. Therefore, the method for producing the composite material 1 of the present embodiment can be suitably used in the aircraft structure.
Incidentally, in one embodiment of the method for producing a composite material in the invention described above, the case where the filler 9 is provided between the second film adhesive 5 and the second skin material 6 has been described as an example; however, the invention is not limited thereto. As illustrated in
In the composite material and one embodiment of the method for producing a composite material in the invention described above, the case where the first film adhesive 3 and the second film adhesive 5 are used has been described as one example; however, a mode where the two film adhesives are not used may be adopted. In such a case, since the film adhesives are not required, the cost can be lowered. In addition, also in the mode where the above two film adhesives are not used, molding can be performed by one-shot molding. In this case, the two skin materials (uncured prepregs) are directly bonded to the honeycomb core.
In the composite material and one embodiment of the method for producing a composite material in the invention described above, the case where the end portion of the honeycomb core 2 is chamfered has been described as one example; however, chamfering may not be performed. Also when the honeycomb core is not chamfered, above-described adhesive accumulation is expected to occur; however, when the filler is provided as described above, such adhesive accumulation can be prevented from occurring.
Number | Date | Country | Kind |
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2018-123066 | Jun 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/007159 | 2/26/2019 | WO | 00 |