Molded product

Abstract

The present invention addresses the problem of providing a molded product that can be suitably applied to propeller blades for aircraft and AAMs and has excellent appearance quality and impact resistance. In order to solve the problem, a molded product is proposed that has a skin made of a fiber-reinforced composite material and that constitutes the outermost layer of the molded product, a first member disposed on the inner side of the skin, and that further has a core member disposed on the inner side of the first member.

Description

Molded product

[0001] The present invention relates to a molded article, and particularly to a molded article having a core material that can be suitably used for propeller blades for aircraft and AAM (Advanced Air Mobility).

[0002] Development of aircraft for AAMs is underway with the aim of easing traffic congestion in urban areas and securing transportation means to remote islands, and one of the challenges in this process is how to design propeller blades for AAMs.

[0003] Propeller blades used in conventional general-purpose aviation vehicles are available in two types: high-performance aircraft-certified types for Cessna aircraft and non-certified, low-cost types for small drones. However, AAM aircraft are a relatively new field, and AAM propeller blades are considered unsuitable for either type due to cost and reliability considerations. When an AAM aircraft flies over urban areas, if a flying object such as a bird destroys the propeller blade, making flight difficult, the damage to the pilot and the ground could be severe. In actual design, improving impact resistance is considered important. Furthermore, a structure consisting of a foam core and a fiber-reinforced composite skin is believed to be suitable for AAM propeller blades from the perspectives of moldability and light weight.

[0004] A look at conventionally known propeller blades includes, for example, the propeller blade disclosed in Patent Document 1. Patent Document 1 discloses a propeller blade for an unmanned aerial vehicle having a core containing a foamed body impregnated with a thermosetting resin inside a skin made of carbon fiber impregnated with a thermosetting resin. Patent Document 2 discloses a wind turbine blade composed of a skin material made of FRP containing a continuous carbon fiber layer and a core material made of a porous resin body.

[0005] Patent No. 6971840 Specification Patent No. 4561344 Specification

[0006] In the structure and method disclosed in Patent Document 1, the interior of the propeller blade is made of foam or a foaming agent, thereby reducing the weight of the entire wing, but the adhesiveness between the skin material and the core material is not taken into consideration, so the impact resistance effect is insufficient.Furthermore, the blade structure disclosed in Patent Document 2 is fundamentally significantly different from the propeller blades for AAM in terms of size, use, overall shape, and structure, making it difficult to apply to propeller blades for AAM.

[0007] An object of the present invention is to provide a molded article that is particularly suitable for use as a propeller blade for an aircraft or AAM, and that has excellent appearance quality and impact resistance.

[0008] In order to solve the above problems, the present invention employs any of the following means. [1] A molded article having a skin made of a fiber-reinforced composite material and constituting the outermost layer of the molded article, a first member disposed inside the skin, and a core member disposed further inside the first member. [2] The molded article according to [1] above, in which the surface roughness Ra of the outer surface side of the skin is 10 μm or less. [3] The molded article according to [1] or [2] above, in which the ratio (minimum / maximum) of the maximum thickness to the minimum thickness of the first member is 0.8 or less. [4] The molded article according to any of [1] to [3] above, in which the first member is a porous sheet, and the compressive deformation rate when a compressive stress of 0.1 MPa is applied is greater than the compressive deformation rate of the core member when a compressive stress of 0.1 MPa is applied. [5] The molded article according to any of [1] to [4] above, in which the compressive deformation rate of the first member when a compressive stress of 0.1 MPa is applied is 20% or more. [6] The molded article according to any one of [1] to [5], characterized in that the specific gravity of the first member is greater than the specific gravity of the core member. [7] The molded article according to any one of [1] to [6], characterized in that the first member contains organic fibers. [8] The weight of the organic fibers is 100 g / m ２[9] The molded article according to any one of [1] to [8], characterized in that the average thickness of the first member is 0.1 mm or more and 10 mm or less.

[10] The molded article according to any one of [1] to [9], characterized in that the porosity of the first member is 5% or more.

[11] The molded article according to any one of [1] to

[10] , characterized in that all or part of the reinforcing fibers of the fiber-reinforced composite material constituting the skin are carbon fibers.

[12] The molded article according to

[11] , characterized in that the carbon fibers are in the form of a braided substrate, a unidirectional substrate, or a woven substrate.

[13] The molded article according to any one of [1] to

[12] , characterized in that the molded article has a propeller blade structure including a shear web connecting an upper skin and a lower skin.

[14] The molded article according to

[13] , characterized in that the first member is disposed on all or part of the surface of the shear web.

[0009] The molded article according to the present invention can be suitably applied to propeller blades for aircraft and AAM, and can provide a molded article having excellent appearance quality and impact resistance.

[0010] 1 is a schematic top view of a propeller blade according to an embodiment of the present invention. It is an example of a cross-sectional view taken along line A-A' in FIG. 1. It is a diagram for explaining a method for measuring a skin-to-first member thickness ratio, in which (a) is a cross-sectional view of a propeller blade according to an embodiment of the present invention, and (b) is an enlarged view of the area indicated by the symbol A and surrounded by a dotted line in (a). It is an example of a cross-sectional view of a propeller blade having a shear web.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention should not be construed as being limited to these examples.

[0012] The molded article of the present invention is a molded article having a skin made of a fiber-reinforced composite material and constituting the outermost layer of the molded article, a first member arranged inside the skin, and a core member further arranged inside the first member.

[0013] It is permissible to cover a part of the outer surface of the skin with another member, for example, to attach a member to protect the leading edge or trailing edge when the molded product of the present invention is made into a propeller blade, or to attach a member to protect the tip of the propeller blade.

[0014] The molded article of the present invention will be described with reference to FIG.

[0015] Figure 1 shows one embodiment of the molded article of the present invention used as a propeller blade. Figure 1 shows a top view of a propeller blade 1, with a tip portion 2a on the side farther from the center of rotation and a base portion 2b on the side closer to the center of rotation. Note that in rotors, multiple blades are usually provided from the center of rotation.

[0016] The present invention will be described using FIG. 2 as an example, based on the A-A' cross section of the propeller blade 1 (i.e., a cross section perpendicular to the longitudinal direction of the propeller blade 1). In the example of FIG. 2, from the outer surface side, the skin 3 forming the surface of the molded product, the first member 4 arranged inside the skin 3, and the core member 5 arranged inside the first member 4 can be seen. In the example of FIG. 2, the core member 5 is a solid core material, and the space inside the first member 4 is filled with the core material 5. In the molded product of the present invention, the skin and the first member can be bonded together. The bonding method includes, but is not limited to, bonding using a resin such as an adhesive or an inorganic material, or bonding by fusion or welding. When the first member is a porous sheet, a preferred embodiment is bonding by infiltrating the matrix resin of the fiber-reinforced composite material constituting the skin into the voids. The first member and the core member can also be bonded together. The bonding method includes, but is not limited to, bonding using a resin such as an adhesive or an inorganic material, or bonding by fusion or welding.

[0017] The blade length of a propeller blade, which is an example of the molded product of the present invention, is preferably 2 m or less, more preferably 1.7 m or less, and even more preferably 1.5 m or less. If it exceeds 2 m, productivity may be poor and costs may increase. On the other hand, the lower limit of the blade length is preferably 0.5 m or more, more preferably 0.6 m or more, and even more preferably 0.7 m or more. If it is less than 0.5 m, it may lead to costs increasing in obtaining the required lift.

[0018] The surface roughness Ra of the outer surface side of the skin of the molded article of the present invention is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. If the surface roughness exceeds 10 μm, the desired aerodynamic performance may not be achieved when used as a propeller blade. There is no particular lower limit for this surface roughness Ra, but for practical purposes, it is preferable to set it to 0.01 μm or more. Here, the surface roughness Ra refers to the arithmetic mean roughness and is measured in accordance with JIS B0601. Furthermore, five measurement locations are selected over a reference length of 2.5 mm, from portions where the outer surface of the molded article is flat or from portions of the outer surface with small curvature. For example, in the case of a propeller blade, measurement locations are selected from the outer surface of the skin, excluding the curved portions at the leading and trailing edges of the blade, between 20 and 80% from the center of rotation toward the blade tip.

[0019] <First member> In the molded product of the present invention, the first member is present between the skin described above and the core material described below, and serves to suppress peeling between the skin and the core material when an impact is applied and to assist in resin impregnation of the skin during molding, thereby making the molded product advantageous in terms of impact resistance, appearance quality, and internal parts.

[0020] The first component constituting the molded product of the present invention is preferably a porous sheet, since this allows the FRP molded product to be lightweight. Furthermore, the porous sheet preferably contains organic fibers, since this improves impact resistance. Here, the term "porous sheet" refers to a sheet-like material whose true specific gravity is greater than its apparent specific gravity. Examples of such sheet-like materials include porous materials having voids or closed cells within the sheet, specifically porous materials with continuous or closed pores, as well as foams, nonwoven fabrics, and composites of these. The ratio of true specific gravity to apparent specific gravity (apparent specific gravity / true specific gravity) is preferably 0.01 to 0.6.

[0021] Furthermore, from the viewpoint of weight reduction, it is also preferable that the porous sheet contains hollow microparticles. The inclusion of hollow microparticles enables weight reduction. The type of hollow microparticles that can be contained in the first component is not particularly limited, and examples thereof include polymer particles, silica particles, glass particles, and metal particles. Methods for fixing the hollow microparticles include covering the hollow microparticles with an organic fiber nonwoven fabric, or attaching the hollow microparticles to the surface of the organic fiber nonwoven fabric using a matrix resin, fusion, welding, or adhesive.

[0022] The lower limit of the porosity of the first component is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. If it is less than 5%, the molded product will be heavy, and in the case of a propeller blade, this may have a negative impact on the fuel efficiency of the aircraft. The upper limit of the porosity of the first component is preferably 99% or less, more preferably 95% or less, and even more preferably 90% or less. If it exceeds 99%, it may be difficult to impart impact resistance.

[0023] From the viewpoint of suppressing deformation of the core member during molding, it is preferable that the compressive deformation rate of the first member when a compressive stress of 0.1 MPa is applied (hereinafter, "the compressive deformation rate when a compressive stress of 0.1 MPa is applied" will be simply referred to as "0.1 MPa compressive deformation rate") is greater than the 0.1 MPa compressive deformation rate of the core member. If the 0.1 MPa compressive deformation rate of the first member is smaller than that of the core member, the core member will be primarily deformed by the molding pressure, and there is a risk that the desired mechanical properties will not be exhibited.

[0024] From the viewpoint of suppressing variation in the thickness of the skin, the 0.1 MPa compressive deformation rate of the first member is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. If it is less than 20%, the molding pressure may not be applied firmly to the skin, resulting in poor appearance quality and the inability to exhibit the desired mechanical properties. There is no particular upper limit for the 0.1 MPa compressive deformation rate of the first member, but from the viewpoint of the mechanical properties of the molded product, it is preferable to set it to 60% or less. Here, the compressive deformation rate is measured in accordance with JIS K7220 (2006 edition) using a test piece with a bottom surface of (100±1 mm) x (100±1 mm) and a thickness of 10±1 mm, and the 0.1 MPa compressive deformation rate is the compressive deformation rate at the time of application of a compressive stress of 0.1 MPa.

[0025] When the first member contains organic fibers, the type of organic fibers that can be contained is not particularly limited, and examples thereof include aramid fibers, polyester fibers, polyamide fibers, polyethylene fibers, and acrylic fibers. The lower limit of the basis weight of the organic fibers is 100 g / m. ２ It is preferable that the weight is 150 g / m or more. ２ More preferably, 200 g / m ２ More preferably, it is 100 g / m or more. ２ If the weight is less than 1000 g / m, gaps in the organic fibers may occur and the desired impact resistance may not be obtained. ２ Preferably, the weight is 800 g / m or less. ２ More preferably, 600 g / m or less ２ More preferably, it is 1000 g / m ２ If it exceeds this limit, it may lead to an increase in the weight of the molded product.

[0026] The lower limit of the average thickness of the first member is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. If it is less than 0.1 mm, the basis weight of the organic fiber is low, which may cause gaps between the fibers and prevent the desired impact resistance from being achieved. On the other hand, the upper limit of the average thickness of the first member is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less. If it exceeds 10 mm, the molded product becomes heavy, and in the case of a propeller blade, this may adversely affect the fuel efficiency of the aircraft. The thickness of the first member is defined as the minimum length from a point on the outer surface of the first member to the inner surface in a cross section perpendicular to the center of gravity of the molded product, with respect to the line passing through the center of gravity that has the longest length between the intersections with the outer surface of the skin. The average thickness is calculated by averaging the thicknesses at five points in the cross section. Each measurement point is selected at a distance of 5 mm or more.

[0027] Furthermore, the ratio (min / max) of the maximum to minimum thickness of the first member is preferably 0.8 or less, more preferably 0.75 or less, and even more preferably 0.7 or less. If it exceeds 0.8, the molding pressure may not be applied properly to the skin surface, causing pits on the surface and resulting in poor appearance. Here, the maximum and minimum thickness values ​​of the first member are determined at the points where the thickness is maximum and minimum in the cross section.

[0028] Furthermore, the upper limit of the ratio of the thickness of the first component to the thickness of the skin (skin thickness / first component thickness; hereinafter referred to as the "skin-first component thickness ratio") is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. If the skin-first component thickness ratio exceeds 5, productivity may be poor and weight may increase. On the other hand, the lower limit of the skin-first component thickness ratio is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. If the skin-first component thickness ratio is less than 0.1, the required rigidity of the molded product may be insufficient. Here, a method for measuring the skin-first component thickness ratio will be explained using FIG. 3. A cross section (see Figure 3(a)) perpendicular to the center of gravity of a propeller blade, which is an example of a molded product, is taken with respect to the line that has the longest length between its intersections with the outer surface of the skin among the lines passing through the center of gravity, and a point (point x in Figure 3) on the outer surface of the skin for which the thickness is to be measured is selected within an 80% range from the leading edge 6 of the cross section (the distance from the leading edge 6 to the trailing edge 7 is taken as 100%). On the line that passes through point x and has the shortest length from point x to the inner surface of the first member, the length of the portion (segment) of the line that passes through the skin is taken as the thickness of the skin, 3t, and the length of the portion (segment) of the line that passes through the first member is taken as the thickness of the first member, 4t.

[0029] In addition, in the molded body of the present invention, the average thickness of the first member, the ratio of the maximum to minimum thickness of the first member (minimum / maximum), and the skin-to-first member thickness ratio may be within the preferred ranges in the cross section passing through the center of gravity of the molded article described above. In addition, it is preferable that each of these be independently within the preferred ranges described above as values ​​obtained in all or part (preferably, two or more cross sections) of each cross section at the quarter points of the line segment between the intersections with the outer surface of the skin of the line passing through the center of gravity of the molded article described above that has the longest length between the intersections with the outer surface of the skin.

[0030] <Core member> In the molded product of the present invention, the core member is located inside the first member described above and has the function of stiffening the molded product. In addition, by using a member with a small specific gravity, the molded product can be advantageous in terms of lightness.

[0031] The core member constituting the molded article of the present invention may be, for example, a wood core, but in order to make the molded article lightweight, it is desirable that the core member be made of a resin foam. The foam material is not particularly limited, and for example, polyimide, polyurethane, polystyrene, polyolefin, or acrylic may be used, but rigid polyurethane foam is most preferably used because it is easy to handle, has excellent physical properties, and is cost-effective, and is strong enough to withstand the pressure of the matrix resin.

[0032] The specific gravity of the core member constituting the molded article of the present invention is preferably 0.1 or less, more preferably 0.07 or less, and even more preferably 0.05 or less. If the specific gravity exceeds 0.1, the weight of the molded article increases, and in the case of a propeller blade, this may have a negative effect on the fuel efficiency and aerodynamic performance of the aircraft.

[0033] The specific gravity of the core member constituting the molded article of the present invention is preferably smaller than the specific gravity of the first member. Note that the specific gravity here means the apparent specific gravity.

[0034] Furthermore, a propeller blade, which is an example of a molded product of the present invention, preferably has one or more shear webs extending in the spanwise direction and connecting the upper and lower skins. In this case, when viewed in a vertical cross section in the spanwise direction, two or more regions separated by shear webs can be seen, as shown in Figure 4. Referring to Figure 4, the upper skin refers to skin 3a located on the upper surface of the wing, and the lower skin refers to skin 3b located on the lower surface of the wing. The boundaries between the upper skin 3a and the lower skin 3b are the leading edge 6 and trailing edge 7 of the wing. The example shown in Figure 4 has a shear web 8 extending in the spanwise direction. In the cross section, two regions 9a and 9b occupied by the core member can be seen. The provision of such a shear web 8 can increase the overall strength and rigidity of the propeller blade. The number of shear webs extending in the spanwise direction can be determined depending on the required rigidity and strength of the propeller blade, but one is preferred from the standpoints of moldability and cost.

[0035] Furthermore, when viewed as a rectangle with the smallest area circumscribing a projection obtained by irradiating a parallel beam perpendicular to the plane of rotation of the propeller blade, the shear web preferably exists over 70% or more of the length of the long side in the long side direction (spanwise direction) from the viewpoint of enhancing the rigidity of the propeller blade. Furthermore, in the short side direction (spanwise direction), it is preferable that the shear web exists over 30% or more of the length of the short side of the rectangle with the smallest area circumscribing the projection. In this case, when there are multiple shear webs, the proportion of the shear web in the long side direction is determined based on all of the shear webs.

[0036] The shear web is preferably made of a fiber-reinforced composite material reinforced with continuous reinforcing fibers, the components of which, the reinforcing fibers and resin, will be described later.

[0037] Furthermore, from the viewpoint of ensuring the bending rigidity and torsional rigidity of the propeller blade, it is preferable that the first member be disposed on all or part of the surface of the shear web.

[0038] Next, the fiber-reinforced composite material used in the molded article of the present invention and the method for producing the molded article will be described with examples.

[0039] <Reinforcing Fibers> The fibers (reinforcing fibers) used in the fiber-reinforced composite material constituting the skin of the molded article of the present invention are not limited as long as they have a reinforcing effect, but it is preferable to use carbon fibers, glass fibers, aramid fibers, and metal fibers. Of these, it is preferable to use carbon fibers. The carbon fibers are not particularly limited, but for example, polyacrylonitrile (PAN)-based, pitch-based, and rayon-based carbon fibers are preferably used from the viewpoint of improving mechanical properties and reducing weight, and these may be used alone or in combination of two or more types. Of these, PAN-based carbon fibers are more preferable from the viewpoint of the balance between strength and elastic modulus of the resulting molded article.

[0040] The single fiber diameter of the reinforcing fiber is preferably 0.5 μm or more, more preferably 2 μm or more, and even more preferably 4 μm or more. The single fiber diameter of the reinforcing fiber is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The strand strength of the reinforcing fiber is preferably 3.0 GPa or more, more preferably 4.0 GPa or more, and even more preferably 4.5 GPa or more. The strand modulus of the reinforcing fiber is preferably 200 GPa or more, more preferably 220 GPa or more, and even more preferably 240 GPa or more. If the strand strength or modulus of the reinforcing fiber is within this range, the mechanical properties of the molded product can be improved.

[0041] The reinforcing fibers may be continuous fibers (long fibers) or discontinuous fibers (short fibers). In particular, a substrate made of continuous fibers (long fibers) is preferred because it can exhibit mechanical properties such as strength. Specifically, braided substrates, unidirectional substrates, and woven substrates are preferred. Examples of woven fabrics include multiaxial woven fabrics such as orthogonal biaxial woven fabrics and non-crimp fabrics. Furthermore, knitted fabrics, such as multiaxial knitted structures, are also acceptable, not limited to woven fabrics.

[0042] In the fiber reinforced composite material, the lower limit of the weight of the reinforcing fiber is 50 g / m ２ More than 100 g / m ２ More preferably, 150 g / m or more ２ More preferably, it is 50 g / m or more. ２ If the weight is less than 1000 g / m, the desired rigidity and strength may not be obtained. ２ Preferably, 600 g / m or less ２ More preferably, 400 g / m or less ２ More preferably, it is 1000 g / m ２ If the thickness exceeds this value, heat may not be transferred uniformly to the inside during molding, and the desired quality may not be obtained. The basis weight of the reinforcing fiber is measured by cutting out a 10 cm square area from the reinforcing fiber sheet, measuring its mass, and dividing it by the area. The measurement is performed 10 times on different parts of the reinforcing fiber sheet, and the average value is the basis weight of the reinforcing fiber.

[0043] <Matrix Resin> The resin used in the fiber-reinforced composite material constituting the molded article of the present invention is used as a matrix material encapsulating the reinforcing fibers. The matrix resin is not particularly limited, and thermoplastic or thermosetting resins can be used. Examples include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenolic resins, epoxy acrylate resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, and cyanate resins; thermoplastic resins such as polyamide, polyacetal, polyacrylate, polysulfone, acrylonitrile-butadiene-styrene (ABS), polyester, acrylic, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), liquid crystal polymers, vinyl chloride, and fluorine-based resins such as polytetrafluoroethylene; and silicone. Copolymers or modified products of these polymers can also be used. Furthermore, the use of multiple resins is not precluded.

[0044] <Method for Producing Molded Article> Examples of molding methods for the molded article of the present invention include injection molding methods such as the RTM (Resin Transfer Molding) method and the Vacuum-assisted Resin Transfer Molding (VaRTM) method. The RTM method is a molding method in which a laminate made of a reinforcing fiber substrate that has not been pre-impregnated with a matrix resin is placed in a mold, and a liquid, low-viscosity matrix resin is injected into the mold, and the matrix resin is subsequently impregnated and solidified to produce CFRP. The RTM (Resin Transfer Molding) process will be described below as an example. This manufacturing process includes (1) preparation of a core material, (2) a preforming process, and (3) a resin impregnation process in a mold. Each of these processes will be described below using specific examples.

[0045] (1) Preparation of Core Member The shape of the core material can be obtained by cutting or carving it out from a block, or by injecting a mixed and stirred foaming material concentrate into an injection foaming mold made to the desired shape and foaming it inside the mold. When using core materials with complex shapes, the latter method allows for efficient production.

[0046] (2) Preforming Process: First, a first member is placed on the outer surface of the core material. For example, a 2 mm thick Lantor Soric SF (registered trademark) can be used as the first member. Next, a reinforcing fiber fabric, such as a woven fabric, braiding substrate, or NCF (non-crimp fabric), which may be coated with a binder, is laminated on top of the first member. It is preferable to heat the layers while laminating them, or to heat them after laminating them, in order to bond the layers together.

[0047] (3) Resin impregnation process in the mold: After placing the preform in the mold, the mold is closed. A low-viscosity resin is injected into the mold to impregnate the reinforcing fiber fabric and harden. The viscosity of the resin is preferably 500 mPa / s or less from the viewpoint of the resin's impregnation into the reinforcing fiber substrate. The mold temperature, the resin inlet, and the outlet can be adjusted to improve the resin impregnation. To shorten the mold occupancy time, the molded product can be removed from the mold and post-cured in an oven.

[0048] In addition, in the (2) preforming step, a resin-impregnated reinforcing fiber fabric can be laminated instead of the reinforcing fiber fabric, and this can be clamped in a mold. If a thermosetting resin is used, the resin can be cured to obtain a molded body.

[0049] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment in any way, and any modifications are possible within the scope of satisfying the requirements defined in the present invention.

[0050] Molded articles having the core material according to the present invention are particularly suitable as propeller blades for aircraft and AAMs.

[0051] REFERENCE SIGNS LIST 1 Propeller blade 2a Tip of propeller blade 2b Root of propeller blade 3 Skin 3t Skin thickness 4 First member 4t First member thickness 5 Core member 6 Leading edge 7 Trailing edge 8 Shear web 9a Core member on the trailing edge side 9b Core member on the leading edge side

Claims

1. A molded product having a skin made of a fiber-reinforced composite material that forms the outermost layer of the molded product, a first member arranged inside the skin, and a core member arranged further inside the first member.

2. The molded product according to claim 1, wherein the surface roughness Ra of the outer surface of the skin is 10 μm or less.

3. The molded product according to claim 1 or 2, wherein the ratio of the maximum value to the minimum value of the thickness of the first member (minimum / maximum) is 0.8 or less.

4. A molded product according to claim 1 or 2, characterized in that the first member is a porous sheet, and the compressive deformation rate when a compressive stress of 0.1 MPa is applied is greater than the compressive deformation rate of the core member when a compressive stress of 0.1 MPa is applied.

5. A molded product according to claim 1 or 2, characterized in that the compressive deformation rate of the first member when a compressive stress of 0.1 MPa is applied is 20% or more.

6. The molded product according to claim 1 or 2, wherein the specific gravity of the first member is greater than the specific gravity of the core member.

7. The molded article according to claim 1 or 2, characterized in that the first member contains organic fibers.

8. The weight of the organic fiber is 100 g / m ２ The molded article according to claim 7, characterized in that:

9. The molded product according to claim 1 or 2, characterized in that the average thickness of the first member is 0.1 mm or more and 10 mm or less.

10. A molded product according to claim 1 or 2, characterized in that the porosity of the first member is 5% or more.

11. A molded product according to claim 1 or 2, characterized in that all or part of the reinforcing fibers of the fiber-reinforced composite material forming the skin are carbon fibers.

12. The molded article according to claim 11, wherein the carbon fiber is in the form of a braided substrate, a unidirectional substrate, or a woven substrate.

13. The molded article of claim 1 or 2, which is a propeller blade structure including a shear web connecting the upper and lower skins.

14. The molded article according to claim 13, wherein the first member is disposed on all or part of the surface of the shear web.

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