Composite airfoil structures and their forming methods

• US 20010017336A1
• Filed: 04/04/2001
• Published: 08/30/2001
• Est. Priority Date: 07/30/1998
• Status: Active Grant

• Current Assignee: Kazuaki Amaoka, Makoto Hirahara, Ryuhei Shimizu, Yasuo Isano
• Original Assignee: Kazuaki Amaoka, Makoto Hirahara, Ryuhei Shimizu, Yasuo Isano
• Inventors: Hirahara, Makoto, Amaoka, Kazuaki, Shimizu, Ryuhei, Isano, Yasuo
• Granted Patent: US 6,689,246 B2
• Time in Patent Office: Days
• US Class Current: 244/123
• CPC Class Codes: B64C 3/18 Spars; Ribs; Stringers
• CPC Class Codes: B64C 3/20 Integral or sandwich constructions
• CPC Class Codes: B64C 3/26 Construction, shape, or attachment of separate skins, e.g. panels

Abstract

A box-structure airfoil is constructed of a composite material upper skin, a composite material lower skin 12 and a spar. Ribs and an elongate projection are formed integrally on the inner surface of each of the two skins. The upper and lower skins and the spar are simultaneously bonded by an adhesive to form a single structure. Since the ribs and the elongate projection are one-piece formed with each skin, it is possible to reduce the number of principal constituent components. Furthermore, since assembly operation is made by using the adhesive, there is no need for fasteners or the like for assembling. Moreover, the spar is bonded not only to Moreover, because not only a web but also flanges on both sides of the spar are bonded to the respective skins, it is possible to obtain a large strength. According to the invention, it is possible to reduce the number of principal constituent components and that of assembling components of an airfoil, thereby achieving its cost reduction.

Claims

1. A composite material airfoil structure comprising:

a composite material skin forming a top surface of an airfoil;

a composite material skin forming a bottom surface of said airfoil;

a composite material spar having flanges and a web which together form a U-shaped cross section, said spar being attached to at least one terminal portion of said skins;

composite material ribs and an elongate projection for adhesive bonding of said spar, said ribs and elongate projection being located between said skins;

wherein said airfoil structure is characterized in that said ribs and elongate projection are formed integrally with at least one of said skins.

2. A composite material airfoil structure as recited in

claim 1

, said airfoil structure being characterized in that extreme ends of said ribs and elongate projection which are formed integrally with one skin are bonded to the other skin.

3. A composite material airfoil structure as recited in

claim 1

, said airfoil structure being characterized in that extreme ends of said ribs and elongate projection of one skin are bonded to those of the other skin.

4. A method of forming a composite material airfoil structure, said method being characterized by comprising:

a molding process in which a first composite material skin which forms one surface of an airfoil and a second composite material skin which has ribs and an elongate projection integrally formed on an inner surface and forms the other surface of said airfoil are separately formed; and

a bonding process in which bonding between extreme ends of said ribs and elongate projection and said first skin, bonding between individual flanges of a spar and said individual skins, and bonding between a web of said spar and said elongate projection are simultaneously done by using an adhesive to thereby form a single structure.

5. A method of forming a composite material airfoil structure as recited in

claim 4

, said method being characterized in that said first skin is formed by laminating composite material prepreg on a mold base having the same outer contours as said airfoil, placing a foam core covered with a glue film on an upper surface of the prepreg, laminating again composite material prepreg on top, and hardening an entire assembly by thermosetting operation.

6. A method of forming a composite material airfoil structure as recited in

claim 4

or

5

, said method being characterized in that said second skin is formed by laminating composite material prepreg on a mold base having the same outer contours as said airfoil, depositing layers of a foam core covered with a glue film, composite material prepreg, an intra-projection foam core covered with a glue film, composite material prepreg, intra-rib foam cores covered with a glue film, and composite material prepreg, one on top of another, in this order, and hardening an entire assembly by thermosetting operation.

9. A method of forming a composite material airfoil structure as recited in

claim 6

or

8

, said method being characterized in that pressure plates are placed at least on end surfaces of said ribs and elongate projection prior to the thermosetting operation, said pressure plates having shapes corresponding to the shapes of mating bond surfaces.

10. A method of forming a composite material airfoil structure as recited in one of

claims 4

to

9

, said method being characterized in that a pasty thermosetting adhesive is used as said adhesive.

7. A method of forming a composite material airfoil structure, said method being characterized by comprising:

a molding process in which a first composite material skin which forms one surface of an airfoil and a second composite material skin which has ribs and an elongate projection integrally formed on an inner surface and forms the other surface of said airfoil are separately formed; and

a bonding process in which bonding between extreme ends of ribs and elongate projections of said individual skins, bonding between individual flanges of a spar and said individual skins, and bonding between a web of said spar and said elongate projections are simultaneously done by using an adhesive to thereby form a single structure.

8. A method of forming a composite material airfoil structure as recited in

claim 7

, said method being characterized in that each of said first and second skins is formed by laminating composite material prepreg on a mold base having the same outer contours as said airfoil, laminating layers of a foam core covered with a glue film, composite material prepreg, an intra-projection foam core covered with a glue film, and composite material prepreg, one on top of another, in this order, and hardening an entire assembly by thermosetting operation.

11. An airfoil structure made from a composite material, having, an upper skin made from said composite material for forming an upper contour of said airfoil structure and for extending in a chord length direction, a lower skin made from said composite material for forming a lower contour of said airfoil structure and for extending in said chord length direction, and a rib interposed between said upper and lower skins and arranged in said chord length direction for supporting thereof, comprising:

a spar interposed between said upper and lower skins at either one of edge portions thereof in said chord length direction and extended in a span-wise direction;

a web formed in said spar and being approximately perpendicular to said both skins for making a space therebetween;

a flange formed on both edge portions of said web for supporting said upper or lower skin so as to adequately and continuously mate with said upper or lower contour; and

a protrusion integrally formed on said upper or lower skin for adhesively bonding said spar and said rib so as to effectively and economically maintain a sufficient strength against a peeling stress applied thereof.