Z-pin-reinforced sandwich structure

• US 5,958,550 A
• Filed: 03/05/1997
• Issued: 09/28/1999
• Est. Priority Date: 11/01/1995
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Childress, James J.
• Primary Examiner(s): Morris, Terrel
• Assistant Examiner(s): RUDDOCK, ULA CORINNA
• Application Number:
  US08/811,643
• Time in Patent Office: 937 Days
• Field of Search: 428/119, 428/120, 428/116, 428/309.9, 428/102, 428/223, 428/110, 428/111
• US Class Current: 428/119
• CPC Class Codes: B29C 31/08 of preforms to be moulded, e.g. tablets, fibre reinforced preforms, extruded ribbons, tubes or profiles; Manipulating means specially adapted for feeding preforms, e.g. supports conveyors B29C31/066, B29C37/001, B29C43/085 take precedence
• CPC Class Codes: B29C 70/086 and with one or more layers of pure plastics material, e.g. foam layers applying a non-preformed coating, e.g. a gel-coat, B29C37/0025; with foam blocks B29C70/86
• CPC Class Codes: B29C 70/24 oriented in at least three directions forming a three dimensional structure
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B32B 2305/022 Foam
• CPC Class Codes: B32B 5/00 Layered products characterised by the non- homogeneity or physical structure , i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
• CPC Class Codes: B32B 5/18 characterised by features of a layer of foamed material
• CPC Class Codes: B32B 5/32 at least two layers being foamed and next to each other
• CPC Class Codes: B64C 1/12 Construction or attachment of skin panels
• CPC Class Codes: B64C 2001/0072 from composite materials
• CPC Class Codes: E04C 2/296 composed of insulating material and non-metallic or unspecified sheet-material E04C2/288 takes precedence
• CPC Class Codes: Y02T 50/40 Weight reduction
• CPC Class Codes: Y10T 428/233 Foamed or expanded material encased
• CPC Class Codes: Y10T 428/23914 Interlaminar
• CPC Class Codes: Y10T 428/24008 including fastener for attaching to external surface
• CPC Class Codes: Y10T 428/24033 including stitching and discrete fastener[s], coating or bond
• CPC Class Codes: Y10T 428/24099 On each side of strands or strand-portions
• CPC Class Codes: Y10T 428/24107 including mechanically interengaged strands, strand-portions or strand-like strips
• CPC Class Codes: Y10T 428/24149 Honeycomb-like
• CPC Class Codes: Y10T 428/24174 including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/24182 : Inward from edge of web or sheet
• CPC Class Codes: Y10T 428/249923 : Including interlaminar mechanical fastener
• CPC Class Codes: Y10T 428/249953 : Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/24996 : With internal element bridging layers, nonplanar interface between layers, or intermediate layer of commingled adjacent foam layers
• CPC Class Codes: Y10T 428/249961 : With gradual property change within a component
• CPC Class Codes: Y10T 428/249981 : Plural void-containing components
• CPC Class Codes: Y10T 428/249987 : With nonvoid component of specified composition
• CPC Class Codes: Y10T 428/249991 : Synthetic resin or natural rubbers

Abstract

A method of forming a pin-reinforced foam core sandwich structure (10) including placing first and second face sheets (12), (14) on opposite sides of a foam core (16), the foam core (16) having at least one low density sublayer (28), an optional high density foam sublayer (26), and a plurality of Z-pins (20) positioned therein. The combination of the foam core (16) and face sheets (12), (14) forming a preliminary structure. Autoclave curing the preliminary structure according to a particular temperature and pressure regime, to crush the at least one low density sublayer (28) and to force the plurality of Z-pins (20) into the first and second face sheets (12), (14). Also provided is a pin-reinforced foam core sandwich structure (10) formed by the above process. In a second embodiment, all, or a portion, of the foam core (16) is removed using a solvent to dissolve the foam core (16), but not the Z-pins, to create a column structure (40).

Claims

1. A sandwich structure having a hollow core, comprising:

first and second, spaced apart face sheets generally oriented parallel to one another, the face sheets being fiber-reinforced resin composites; and

a plurality of rigid pins extending between and into both the first and second face sheets, providing reinforcement for the face sheets, and holding the face sheets apart to define the hollow core wherein the reinforcement forms a column structure.

2. A sandwich structure having a hollow core, comprising:

first and second, spaced apart face sheets generally oriented parallel to one another; and

a plurality of rigid pins placed between the first and second face sheets, the plurality of pins extending into both the first and second face sheets, providing reinforcement for the face sheets, and holding the face sheets apart to define the hollow core

wherein the pins have an areal density of about 0.75% and a Young'"'"'s modulus of elasticity greater than 10⁷ lb/in².

3. A sandwich structure according to claim 2, wherein the plurality of pins extends into, but not entirely through, the first and second face sheets.

4. A sandwich structure according to claim 2, wherein at least some pins are oriented at an angle offset from perpendicular relative to the face sheets.

5. The sandwich structure of claim 2 wherein the pins are barbed.

6. The sandwich structure of claim 2 wherein the face sheets are separated about 0.125-1.25 inches by the pins.

7. The sandwich structure of claim 2 wherein face sheets are separated about 0.125-1.25 inches and the pins are about 0.010-0.030 inches in diameter.

8. The sandwich structure of claim 2 wherein the face sheets are fiber-reinforced resin composites.