Fibre reinforced composites

Abstract

A reinforcing composite comprising a plurality of layers of reinforcing composite material forming a stack wherein at least one layer of the stack comprises a moulding compound (114) comprising consolidated resin impregnated fiber elements, wherein the resin impregnated fiber elements are obtained from off-cuts or scrap material (112) derived from cutting single layers of reinforcing composite material and/or stacks comprising multiple layers of reinforcing composite material (110).

Claims

1. A moulding compound comprising consolidated resin impregnated fiber elements, wherein the resin impregnated fiber elements are obtained from off-cuts or scrap material derived from cutting single layers of reinforcing composite material and/or stacks comprising multiple layers of reinforcing composite material; wherein the resin impregnated fiber elements are derived from separating off-cuts or scrap material comprising multiple layers of reinforcing composite material; and wherein the individual resin impregnated fiber elements comprise unidirectional fibers; and wherein the resin impregnated fiber elements are randomly oriented in the moulding compound.

2. A method of manufacturing a moulding compound comprising: a) providing one or more single layers of reinforcing composite material and/or one or more stacks comprising multiple layers of reinforcing composite material; b) cutting the one or more single layers and/or one or more stacks to obtain a net-shape preform and off-cuts or scrap material; c) separating the off-cuts or scrap material into resin impregnated fiber elements; d) consolidating the resin impregnated fiber elements to form a layer; further comprising: orientating the resin impregnated fiber elements before they are consolidated.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The present invention is illustrated by reference to the accompanying drawings in which

(2) FIG. 1 shows four reinforcing parts of composite reinforcing material according to an embodiment of the invention.

(3) FIG. 2 is a cross section on the line A-A of FIG. 1.

(4) FIG. 3 is a cross section on the line B-B of FIG. 1.

(5) FIG. 4 is a cross section on the line C-C of FIG. 1.

(6) FIG. 1 shows 4 parts each having a base section (1) from which a section of material has been removed from locations (2).

(7) FIG. 5 shows a method of forming a moulding compound according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIGS. 2, 3 and 4 show how the resulting multilayer composite provides additional reinforcement along the lines B-B and localized additional reinforcement at various locations along line A-A and C-C. FIGS. 2, 3 and 4 also illustrate how the orientation of the fibres in the various layers can be varied as required. One or more of the layers of reinforcing composite materials shown in FIGS. 2 to 4 may be replaced by one or more layers of moulding compound according to the present invention.

(9) The materials shown are suitable for lamination to a substrate such as a metal automobile component, to provide structural reinforcement with localized additional reinforcement as shown for parts 1 and 3 in FIGS. 2 and 4.

(10) Moulding of a part 120 in multiple steps 102,104,106 and 108 is shown in FIG. 5.

(11) A carbon moulding compound in sheet form 114 is combined with a reinforcing composite 110. The moulding compound 114 is formed from the off-cuts 112 of the reinforcing composite 110 which is die cut to the desired shape in step 102. The moulding compound 114 is combined with the reinforcing composite 110 and the integral moulding material is applied inside a compression mould 116 in step 104. The compression mould comprises an aperture 118 for forming a protrusion in the final moulded part 120. The aperture 118 faces the sheet moulding compound 114. Following closure of the mould 116 and applied an increased temperature over a period of time in step 106, the cured part 120 is removed in step 108.

(12) In this way a part 120 can be molded which contains a protrusion such as a rib.

(13) In an example of a process according to the present invention a plurality of prepreg layers comprising unidirectional carbon fibre impregnated with a curable thermosetting epoxy resin are laid up to form stacks each comprising multiple layers. The stacks are then die-cut to obtain net-shape preforms and this produces off cuts of material. These off-cuts may be processed to produce single ply resin impregnated unidirectional fibre elements, which may be mixed together randomly and arranged to form a quasi-isotropic layer. The quasi-isotropic layer may be consolidated to form a layer of moulding compound having a thickness equivalent to five prepreg layers. The moulding compound may be formed as a blank and die-cut to a desired net-shape after consolidation, or it may be formed directly in the desired net-shape before consolidation. The net-shaped layer of moulding compound may then be combined with a stack of seven layers of prepreg which has been die-cut to the desired net-shape to provide a reinforcing composite comprising seven layers of prepreg and one layer of moulding compound having the thickness of a stack of twelve layers of prepreg. This reinforcing composite may be adhered to a metal substrate to act as reinforcement for an automotive part, and the use of this process provides a large saving in waste prepreg materials, with concomitant environmental and economic benefits.