Cross reinforcement in a graphite-epoxy laminate

• US 4,350,728 A
• Filed: 10/02/1980
• Issued: 09/21/1982
• Est. Priority Date: 10/02/1980
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Huang, Shih L., Richey, Robert J. Jr., McQuillen, Edward J.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US06/193,324
• Time in Patent Office: 719 Days
• Field of Search: 428/284, 428/285, 428/292, 428/293, 428/294, 428/295, 428/364, 428/365, 428/367, 428/408, 428/416, 428/105, 428/401, 428/902, 428/114, 428/223, 244/123, 244/124, 244/133
• US Class Current: 428/105
• CPC Class Codes: B29C 65/564 hidden in the joint, e.g. dowels or Z-pins B29C65/603 takes precedence
• CPC Class Codes: B29C 66/112 Single lapped joints
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/131 Single flanged joints, i.e. one of the parts to be joined being rigid and flanged in the joint area
• CPC Class Codes: B29C 66/45 Joining of substantially the whole surface of the articles methods or apparatus for laminating B32B37/00
• CPC Class Codes: B29C 66/474 said single elements being substantially non-flat
• CPC Class Codes: B29C 66/524 Joining profiled elements
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/721 Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29C 66/7212 characterised by the composition of the fibres
• CPC Class Codes: B29C 66/72141 Fibres of continuous length
• CPC Class Codes: B29C 70/24 oriented in at least three directions forming a three dimensional structure
• CPC Class Codes: B29D 99/0003 Producing profiled members, e.g. beams
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2307/00 Use of elements other than metals as reinforcement
• CPC Class Codes: B29K 2307/04 Carbon
• CPC Class Codes: B29L 2031/3082 Fuselages
• CPC Class Codes: B29L 2031/3085 Wings
• CPC Class Codes: B32B 2605/18 Aircraft blades, propellers B32B2603/00
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B64C 3/20 : Integral or sandwich constructions
• CPC Class Codes: Y02T 50/40 : Weight reduction
• CPC Class Codes: Y10T 428/24058 : including grain, strips, or filamentary elements in respective layers or components in angular relation
• CPC Class Codes: Y10T 428/24132 : including grain, strips, or filamentary elements in different layers or components parallel
• CPC Class Codes: Y10T 428/2913 : Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2915 : including textile, cloth or fabric
• CPC Class Codes: Y10T 428/298 : Physical dimension
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 428/31522 : Next to metal

Abstract

Interlaminar shear strength of an aircraft wing made of graphite-epoxy laate is significantly increased by embedding thin steel wires in preselected locations of high stress in alternating rows ±45° to the plane of the laminate before it is cured. This cross wire reinforcement prevents brittle delamination, arrests propagation of delamination and reduces scatter of interlaminar strength.

Claims

1. A lightweight reinforced composite material for use in structures having high stress applications, comprising:

a plurality of plies of a fibrous resin adhesively bonded together to form a laminate; and

a plurality of reinforcing rods embedded in said laminate to span the distance between the outer surfaces thereof, said rods being positioned in adjacent pairs along measured critically highest stress planes in said laminate, said pairs being parallel to said stress planes on opposite sides thereof and angularly displaced in opposite directions to planes normal to said stress planes.

2. A composite material according to claim 1 further comprising:

a substructure bonded to said laminate for reinforcing said structures.

3. A composite material according to claim 2, further comprising:

said stress planes being located along the bonded interface of said substructure and said laminate.

4. A composite material according to claim 1, further comprising:

said stress planes being located along the areas of hgh interlaminar stress.

5. The composite material according to claim 1 further comprising:

said rods being angularly displaced alternately plus forty-five and minus forty-five degrees to a plane normal to the stress planes.

6. The composite material according to claim 5 further comprising:

said rods being metallic.

7. The composite material according to claim 6 further comprising:

said rods being of steel wire and having a diameter in the range of 0.008-0.020.