Method of making a partial interlaminar separation composite system

• US 4,274,901 A
• Filed: 02/07/1980
• Issued: 06/23/1981
• Est. Priority Date: 03/24/1978
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Elber, Wolf
• Primary Examiner(s): Weston, Caleb
• Application Number:
  US06/119,337
• Time in Patent Office: 502 Days
• Field of Search: 156/228, 156/242, 156/245, 156/252, 156/264, 156/288, 156/290, 156/285
• US Class Current: 156/242
• 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 70/34 and shaping or impregnating by compression , i.e. combined with compressing after the lay-up operation
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/06 Unsaturated polyesters
• CPC Class Codes: B29K 2101/12 Thermoplastic materials
• CPC Class Codes: B29K 2105/108 arranged in parallel planes and crossing at substantial angles B29K2105/206 takes precedence
• CPC Class Codes: B29K 2307/00 Use of elements other than metals as reinforcement
• CPC Class Codes: B32B 2250/42 Alternating layers, e.g. ABAB(C), AABBAABB(C)
• CPC Class Codes: B32B 2260/046 Synthetic resin
• CPC Class Codes: B32B 2307/542 Shear strength
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 3/266 characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
• CPC Class Codes: B32B 7/04 Interconnection of layers
• CPC Class Codes: Y10T 156/1056 Perforating lamina
• CPC Class Codes: Y10T 156/1075 of plural laminae from single stock and assembling to each other or to additional lamina

Abstract

This invention relates to an interlaminar separation system for composites wherein a thin layer of a perforated foil film is interposed between adjacent laminae of a composite formed from prepreg tapes to thereby permit laminae adherence through the perforations and produce a composite structure having improved physical property characteristics.

Claims

1. A method for enhancing interlaminar shear strength for composite laminates comprising:

providing prepreg resin impregnated fiber tape material having the fibers therein running the length of the tape;

cutting the prepreg tape into a plurality of desired lengths;

laying up and stacking the plurality of lengths of tape in layers of the desired dimensions and to a predetermined thickness;

providing a layer formed by a plurality of thin perforated polyester film strips of essentially the same length and width dimensions as the prepreg tape layers;

positioning one layer of the perforated film strips between each layer of prepreg tape and curing the stacked tape and film strip assembly into a unitary mass under vacuum, pressure and an elevated temperature of at least 465°

K. for at least 60 minutes;

cooling the cured assembly to a minimum of 400°

K. while maintaining the vacuum and pressure and, after releasing the vacuum and pressure, permitting the assembly to cool to room temperature to thereby yield a composite laminate structure having improved physical property characteristics.

2. The process of claim 1 wherein the same fiber orientation is maintained for each prepreg tape layer during layup assembly.

3. The process of claim 1 wherein the fiber orientation of each prepreg tape layer is angularly disposed relative to the fiber orientation of each adjacent layer.