FIBRE MATERIAL

TECHNICAL FIELD

The present invention relates to a method of manufacturing a sheet of a fibre material.

The present invention also relates to a sheet of a fibre material.

The present invention also relates to a method of manufacturing a 3 -dimensional (3D) fibre reinforced composite article from a sheet of a fibre material.

The present invention also relates to a 3 -dimensional (3D) fibre reinforced composite article that includes a sheet of a fibre material.

BACKGROUND ART

The manufacture and use of fibre reinforced composite materials is well known in a number of industries.

Basically, fibre reinforced composite materials comprise fibres embedded in a matrix.

By way of example, a mud brick is a fibre reinforced composite material that comprises straw or plant-based fibres in a mud matrix.

Mud bricks and carbon or glass-fibre composite materials have the same basic characteristics.

These characteristics include that tensile stress on the composite materials is carried by the fibres and the stress is transferred from one fibre to another by the matrix. In the case of mud bricks, the mud is the matrix. In the case of glass-fibre composite materials, the matrix is a polymeric or other material in which the fibres are impregnated.

The final strength of a fibre reinforced composite material is a complex relationship involving several factors, such as:

• Fibre length.

• Fibre length to diameter ratio.

• The strength of the fibre/matrix bond. • Fibre to matrix ratio.

• Overlap distance of fibres in the matrix

• Fibre strength.

• Matrix strength.

Additionally, when a fibre reinforced composite material is used to produce 3- dimensional (3D) shaped article, further factors include, by way of example, fibre distribution and orientation, fibre/matrix ratio and overlap of the fibres in the material. For a complex 3D shaped article, the required distribution and orientation of the fibres varies depending on the strength required in different directions.

Traditional methods of manufacturing fibre reinforced composite material 3D articles include manually laying up fibres and placing bundles of fibres on a 3D mould and then applying a suitable matrix material and applying heat as required to form the 3D articles.

However, with these methods, it is difficult to control the position and the quantity of fibres placed in a particular location in a mould due to the lack of precision of manual input.

Strips of woven cloths of fibre material are sometimes used instead of individual fibres but have limitations in terms of being positioned in a mould.

The use of pre-impregnated composite fibres (prepregs) sections have also not been efficient because they cannot be placed around shapes with curves in more than two dimensions.

Additionally, prepreg sections are generally produced from continuous fibres and the addition of a highly viscous resin. Therefore, the fibres in prepreg sections are not capable of movement with respect to each other or the surrounding material.

Moreover, the manufacturing method is mechanically slow and very labour intensive.

The above description is not to be taken as an admission of the common general knowledge in Australia and elsewhere.

SUMMARY OF THE INVENTION

The invention provides a method of manufacturing a sheet of a fibre material that comprises connecting together a plurality of sections formed from a fibre material so that the sections are capable of relative movement to each other, with each section comprising a plurality of fibres capable of relative movement with respect to each other in the longitudinal and/or transverse directions of the fibres.

The sections may be any suitable length, width and thickness dimensions. The selection of the dimensions is dependent on a number of factors including, for example, the end-use article to be made from the sheet, the composition of the fibre material, and the dimensions of the fibre material.

By way of example, in the case of an end use in the manufacture of articles in the form of vehicle wheel hubs, the sections may be at least 25 cm long, typically at least 30 cm long. In addition, typically, the sections may be at least 15 cm wide, typically at least 18 cm wide.

The fibres in each section may be held together by stitching the fibres together or by any other suitable binding, such as with a binder material.

The method may include connecting together the plurality of sections of the fibre material by partially overlapping and connecting together the plurality of sections.

The method may include connecting together the plurality of sections of the fibre material by positioning the plurality of sections side by side in an overlapping relationship along a first direction to form the sheet as a strip.

The method may include positioning multiple strips in side by side overlapping relationship and connecting together the strips to form the sheet as a layer of the strips.

The method may include positioning multiple sheets one on top of the other to form multiple layers and connecting together the layers to form the sheet as a multiple- layer construction.

The method may include connecting together the plurality of sections of the fibre material by positioning the plurality of sections in a roof shingle type of arrangement and connecting together adjacent sections of the plurality of sections to form one or more layers of the fibre material.

The method may include connecting together the plurality of sections of the fibre material and/or the strips by stitching together the plurality of sections of the fibre material and/or the strips.

The method may include connecting together the plurality of sections of the fibre material and/or the strips with a binder. In each section, a percentage of the plurality of fibres of the reinforcement material may be aligned parallel to each other so that the mechanical properties, such as tensile strength, are in the direction of the fibres.

The percentage of the plurality of fibres aligned parallel to each other in each section may be at least 50%, typically at least 60%, and more typically at least 70% of the total amount of fibres in the section.

The method may include positioning a first percentage of the plurality of sections in a first selected direction.

The method may include positioning a second percentage of the plurality of sections along a second selected direction.

The method may include stitching together the plurality of fibres in the plurality of sections.

The method may include stitching together the plurality of fibres with a predetermined stitching pattern to control, for example by limiting, transverse stretching of the sections.

The method may include connecting together the plurality of fibres in the plurality of sections with a binder.

The invention also provides a sheet of a fibre material that includes a plurality of sections of a fibre material connected together so that the sections are capable of relative movement to each other, with each section including a plurality of fibres capable of relative movement with respect to each other in the longitudinal and/or transverse directions of the fibres.

The sheet may include a resin impregnated into and connecting together the plurality of fibres, wherein a percentage of the plurality of fibres in each section is at least 50%, typically at least 60%, and more typically at least 70%.

The invention also provides a method of manufacturing a 3 -dimensional (3D) fibre reinforced composite article from the above-described sheet of the fibre material that includes placing the sheet of the fibre material manufactured by the above- described method into a mould so that the sheet adopts the shape of the mould due to relative movement of the fibres in each section of the sheet and the relative movement of the sections of the sheet and applying heat of otherwise forming a shaped article from the sheet in the mould. The invention also provides a 3 -dimensional (3D) fibre reinforced composite article that includes the above-described sheet of the fibre material.

Advantages and other features of the invention will become apparent from the following drawing, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly ascertained, embodiments of the invention are now described, by way of example, with reference to the accompanying drawings, of which:

Figure 1 is a perspective view of an embodiment of a sheet of a fibre material in accordance with the invention;

Figure 2 shows a step of an embodiment of a method of manufacturing the sheet of a fibre material shown Figure 1 in accordance with the invention;

Figure 3 is an enlarged view of the section of the sheet in the box 3 shown in Figure 1;

Figure 4 is a side view of the section of the sheet shown in Figure 3 viewed in the direction 4 in Figure 1; Figure 5 is a top view of the section of the sheet shown in Figure 3 ;

Figure 6 is an enlarged perspective view of another section of the sheet shown in Figure 1;

Figure 7 is a side view of the section of the sheet shown in Figure 6;

Figure 8a is a side view of a section of another embodiment of a sheet of a fibre material in accordance with the invention;

Figure 8b is a perspective view of the underside of the sheet shown in Figure 8a which illustrates further the variable length extended fibres of the sheet shown in Figure 8a to allow higher fibre density or build height in the 3D structure to accommodate a fitment or load stress; Figure 8c is a top perspective view of the sheet shown in Figure 8a, with a section of the sheet cut-away to show the variable length extended fibres of the sheet shown in Figure 8a;

Figure 9 is a perspective view of another embodiment of a sheet of a fibre material in accordance with the invention, with the Figure showing a step of another embodiment of a method of manufacturing the sheet in accordance with the invention;

Figure 10 is a perspective view of another embodiment of a sheet of a fibre material in accordance with the invention, with the sheet being formed from a plurality of the sheets shown in Figure 9; Figure 11 is a perspective view of another embodiment of a sheet of a fibre material in accordance with the invention, with the Figure showing a step of another embodiment of a method of manufacturing the sheet in accordance with the invention;

Figure 12 shows a step of another embodiment of a method of manufacturing the sheet in accordance with the invention; Figure 13 shows a step of another embodiment of a method of manufacturing the sheet in accordance with the invention;

Figure 14 shows a step of another embodiment of a method of manufacturing the sheet in accordance with the invention;

Figure 15 shows an exemplary mould with bossed and embossed features; Figure 16 shows the sheet shown in Figure 1 presented for forming over the mould shown in Figure 15;

Figure 17 shows sections of a fibre material on top the sheet shown in Figure 16;

Figure 18 shows the sheet shown in Figure 1 formed on the mould shown in Figure 15; Figure 19 shows the moulded sheet formed on the mould shown in Figure 18 being removed from the mould;

Figure 20 shows conceptually the relative movement of sections of a conventional sheet of a fibre material in accordance with the invention when formed over a dome shaped mould; and Figure 21 shows the relative movement of sections of a sheet of a fibre material shown in Figure 1 over the dome-shaped mould shown in Figure 20.

DETAILED DESCRIPTION OF EMBODIMENTS

The Figures show different embodiments of sheets of a fibre material in accordance with the invention and different embodiments of methods of manufacturing the sheets.

A feature of the sheet of the fibre material of the invention is that it is flexible and can readily be positioned into moulds for forming 3 -dimensional (3D) articles, such as wheel hubs, and readily adopt the shapes of the moulds.

In particular, the sheet of the fibre material is able to adjust to the shapes of moulds. This is important, for example, to ensure that there are controlled and optimised properties in the final moulded articles. In general terms, the method of manufacturing a sheet of a fibre material of the invention comprises connecting together a plurality of sections formed from a fibre material so that the sections are capable of relative movement to each other, with each section comprising a plurality of fibres capable of relative movement with respect to each other in the longitudinal and/or transverse directions of the fibres. It is the relative movement of the fibres in each section and the relative movement of the sections that provides the flexibility mentioned above.

In some embodiments the fibres in each section exhibit the same relative movement in both longitudinal and transverse directions to each other.

When a conventional two-dimensional sheet of fibre material is formed into a complex 3D shape, the length of the sheet of material is required to increase in order to conform to the desired shape in at least some areas of the 3D shape. This will not be possible if the sheet is not able to stretch (or stretch sufficiently). For those sheets that can stretch, the result will be that the fibre sheet thickness will decrease in certain areas, particularly in curved areas, and an optimum configuration for a final reinforced composite material may not be obtained.

Embodiments of the invention include 3D fibre reinforced composite articles, such as wheel hubs, manufactured from sheets of the fibre material and a matrix material, such as a polymeric binder or another suitable type of matrix-forming material.

Embodiments of the invention include sheets of the fibre material that are shaped into a preform for manufacturing a complex 3D shaped fibre reinforced composite article, such as wheel hubs.

The sections 3 may be formed by any suitable means that holds the fibres together in the sections. By way of example, the fibres in each section 3 may be held together by stitching the fibres together or by any other suitable binding, such as with a binder material.

In some embodiments the fibres in each section are at least in part aligned parallel to each other and connected together by stitching or any other suitable form of binding, for example including with a binder material.

In other embodiments the sections comprise woven fibre material.

Embodiments of the invention comprise a “build mat” that comprises a plurality of sheets of the fibre material in layers of the sheets.

The term “section”, as used herein, is understood to mean a section of a fibre material that comprises a plurality of fibres, typically of a reinforcement material. The section may be any suitable shape and size. For example, the section may be an elongate strip or a more squared shape. Typically, at least 40%, more typically at least 45%, more typically at least 50%, of the fibres are parallel in each section.

The term “reinforcement material”, as used herein, includes any material that improves the strength and the rigidity of a composite material.

Non-limiting examples of fibres of a reinforcement material are carbon fibres, glass fibres, carbon/glass fibre hybrid composite fibres. The invention is not limited to fibres of these materials.

The embodiment of the sheet 1 of the fibre material shown in Figure 1 comprises a plurality of sections 3 of a fibre material that are connected together in side-by-side partially overlapping relationship to form a row 5 (which may also be described as a strip) of connected-together sections 3 that form the sheet 1. Adjacent sections 3 are connected together at the overlap of the sections 3. Adjacent sections 3 are capable of relative movement. Each section 3 comprises a plurality of fibres capable of relative movement. The fibres are fibres of a reinforcement material.

Each section 3 may be any suitable length, width and thickness dimensions. The selection of the dimensions is dependent on a number of factors including, for example, the end-use article to be made from the sheet, the composition of the fibre reinforcement material, and the dimensions of the fibre reinforcement material.

By way of example, in the case of an end use in the manufacture of articles in the form of vehicle wheel hubs, the sections may be at least 25 cm long, typically at least 30 cm long. In addition, typically, the sections may be at least 15 cm wide, typically at least 18 cm wide.

The sections 3 are formed from any suitable fibre reinforcement material.

The plurality of fibres are generally non-continuous fibres that are connected together by stitching and/or by using a binder or any other suitable binding means. A percentage of the reinforcement material fibres are aligned parallel to each other to define a single direction for the mechanical properties, particularly tensile strength, of each section and consequently of the final sheet.

In the described embodiment of Figure 1, a zigzag stitching pattern 7 is used to hold the fibres in each section together and to hold adjacent sections together and to control the longitudinal and transverse relative movement of the fibres.

Zig zag stitching 7 allows control of the fibre spread perpendicular to the direction of strength.

Zig zag stitching 7 also keeps the fibres positioned in the direction of strength and ensures an even distribution of fibre spread perpendicular to the direction of strength.

In other embodiments, other types of stitching, such as non-stretchable straight stitching, are used to limit the transverse thinning of the fibres in a specific area.

Any other predetermined stitching pattern may be used.

The invention is not limited to these methods of connecting together the fibres.

The embodiment shown in Figure 1 comprises rectangular sections of the fibre material partially overlapped and connected together. However, as mentioned above, the sections may have any shape of form. For example, the sections can have a more squared shape or any suitable regular or irregular shape, as described in more detail below. Figure 2 shows a step in a method of manufacturing the sheet 1 shown in Figure 1. The Figure shows a new section 3 to extend an existing row of sections 3 positioned at the end of the row of sections 3, with the new section in alignment above an end section 3 of the existing row 5, ready to be positioned in overlapping relationship with and stitched or otherwise connected to the end section 3.

As shown in more detail in Figures 3 to 5, in the Figure 1 embodiment, the zigzag stitching pattern 7 is used to connect the fibres in each section 3. Stitching also connects together adjacent sections 3 to form the row 5 of sections 3 capable of relative movement. Other types stitching patterns or binding means may be used.

Figure 6 shows the overlap of adjacent sections 3 of the Figure 1 embodiment.

The overlap is illustrated by the letter “Y” in a section length “X”. However, it is noted that the overlap of the sections can be varied as desired. Typically, the overlap length Y is at least one third of the section length X.

With reference to Figures 1-6, the overlap is constant along the row of sections. However, in other embodiments the overlap varies in different sections of the sheet, as may be required to achieve particular requirements of end-use articles.

In the embodiment shown in Figure 7, adjacent sections 3 are overlapped approximately over a third of their length and adjacent overlapping sections 3 are stitched together.

In the embodiment shown in Figure 8 A, adjacent sections are overlapped approximately over half of their length and adjacent overlapping sections 3 are stitched together.

As can best be seen from the underside perspective view in Figure 8b, selected sections 3a-3e have longer groups of fibres in parts of the sections. These longer fibre sections allow higher fibre density or build height in the 3D structure to accommodate a fitment or load stress. The partially cut-away perspective view in Figure 8c shows selected sections 3a-3e further.

As mentioned above, a percentage of the fibres in each section 3 are aligned parallel to each other to define a single direction for the mechanical properties of the individual section. In some embodiments, the sections 3 are disposed to form a layer of the sheet 1 of the fibre material so that the mechanical properties of the sheet 1 are engineered by arranging the orientation and position of the sections. Figures 9 to 11 are perspective views of other embodiments of sheets 1 of a fibre material in accordance with the invention, with Figures 9 and 11 showing a step of another embodiment of a method of manufacturing the sheet in accordance with the invention.

In conventional sheets of fibre material, the use of woven fibre material, for example a standard 90° weave, would result in a sheet with very limited stretching ability.

However, the construction of the embodiments shown in Figures 9 to 11, sections 3 of woven fibre material are connected together to form a sheet 1 of connected sections 3, where the sections 3 are capable of relative movement. The relative movement of the sections 3 provides the sheet 1 with the ability to stretch and conform to a 3D mould.

As shown in Figure 9, the sections 3 are positioned substantially parallel to each other in an arrangement in which the sections are partially overlapped and laterally shifted relative to each other. Adjacent sections 3 are connected together to form a sheet 1 of connected sections capable of relative movement. This construction is similar to the previously described embodiments.

In the described embodiment shown in Figure 9, a zigzag stitching pattern 7 is used to connect adjacent sections to form a row 5 of sections that form the sheet 1.

Other types of stitching patterns or binding means may be used.

Figures 9 to 11 show sections overlapped by substantially the same length in the longitudinal and in the latitudinal direction. However, the overlap between adjacent sections 3 may be varied as desired.

In some embodiments, for example as shown in Figure 9, the row 5 of connected sections 3 is used as the final sheet 1 of fibre material.

Alternatively, as shown for example in Figures 10 and 11, multiple rows 5 are connected to form the final sheet 1 of fibre material.

As mentioned above, and as shown in Figures 10 and 11, the sections 3 are positioned in a series of rows 5 with a controlled overlap, and multiple rows 5 are then disposed parallel partially overlapped and laterally shifted relative to an adjacent row 5 to produce the sheet 1 of fibre material. It is noted that in an alternative embodiment, not shown, the sections 3 are disposed in a shingle type of arrangement without the intermediate step of forming rows 5 of connected sections 3 and then connecting multiple rows 5.

The process of layering the sections 3 and the rows 5 (in the embodiments shown in Figures 10 and 11) can be completed robotically and by mechanical automation equipment. This automation of the manufacturing system is highly advantageous over exiting methods are it is precisely repeatable and requires no skill labour.

Figure 10 shows rows 5 disposed substantially parallel to each other, partially overlapped and laterally shifted relative to a preceding row.

In some embodiments, the rows 5 are disposed at different angles relative to each other.

As more clearly shown in Figure 11, the shift is in a perpendicular direction with respect to the overlapping of the sections 3 in a row 5.

Adjacent rows 5 are shifted by a pre-determined length, which, in the described embodiment, is half of the length of the sections 3. However, it is noted that the overlap of adjacent rows 5 can be varied as desired.

Adjacent rows 5 of sections 3 are generally stitched together by a criss-cross or zig zag type of stitching. However, the invention is not limited to this type of stitching or binding means.

The resulting sheet of fibre material have the characteristic form of “shingles” or scales types of arrangement.

In Figures 9 to 11, the overlap is maintained constant throughout the sheet. However, in other embodiments the overlap varies in different areas of the sheet.

It is noted that, although the embodiments described in Figure 9 to 11 relate to sections 3 of woven fibre material, the same method can be applied to the sections 3 of parallel fibres shown in Figures 1 to 8.

In the embodiments shown in Figures 12 to 14, a sheet 13 of fibre material is formed from multiple layers 9, 11 of sheets 1, with each sheet 1 comprising rows 5 of sections 3 of the fibre material.

In particular, Figure 12 shows two sheets 1 manufactured with the methods described above, combined to form multiple layers of sheets 1. The layers 9, 11 are overlapped with a substantially perpendicular orientation relative to the rows of sections and connected by stitching or any other binding means.

Similarly, Figure 13 shows three layers 21, 23, 25 of sheets 1 manufactured with the methods described above, combined to form a multiple-layer sheet 17, with each sheet 1 comprising rows 5 of connected sections 3 of a fibre material. The layers 21, 23, 25 are overlapped with adjacent layers oriented perpendicularly to each other. The layers 21, 23, 25 are connected by stitching or any other binding means.

In another embodiment shown in Figure 14, the sheet 27 of the fibre material is formed by overlapping and connecting together three layers 29, 31, 33 of the sheet 1, with successive layers disposed at an angle of 60° relative to each other.

It is noted that the invention is not limited to the number of layers or orientation of the layers of sheets 1, described in the exemplary embodiments presented above.

The number of layers and their orientation relative to each other can be selected according to the desired characteristics of the final composite material to be used to produce the end-use article.

The layers are connected together by either sewing or by using a binder, in particular a thermal binder.

The binder may be placed between layers or sprinkled on top of each layer and activated by an external source of heating.

Any other type of binding means or mechanism may be used.

The overlapping of layers makes it possible to achieve better uniformity in the spread of fibres. As a consequence, the sheets of the fibre material can be substantially unidirectional or multi-directional in terms of mechanical properties of the final composite material.

The arrangement of the rows and the sections and the layers in the final sheets shown in all the embodiments described herein allows relative movement of the sections, thereby resulting in a sheet of a composite material that can be readily shaped into complex shaped article.

In particular, the relative movement of the sections gives the sheet of the fibre material the flexibility to conform to different shapes without compromising the continuity of overlapping fibres on the surface of the adopted shape. For example, as shown in Figures 15 to 21, a sheet 1 of the fibre material and the final composite material article formed from the sheet 1 is able to adapt to concave and convex surfaces maintaining a desired fibre overlap and density.

Figure 15 shows a mould 35 with bossed features 37 and embossed features 39 used to produce an article from the sheet of a fibre material. The mould of Figure 15 is used only as an example of a complex 3D shape and it is not intended to be limiting the type of shape of the article.

The sheet 1 of the fibre material is presented to the mould 35 in Figure 16 and conformed to the mould without any additional steps.

Figure 17 shows an alternative embodiment where sections or patches 41 of the fibre material are positioned on top of the sheet 1 of the fibre material to provide additional coverage. These patches 41 have various shapes, noting that the shape and dimensions may be varied as desired.

In this embodiment, the patches 41 are positioned on the top of the sheet 1 to produce a continuous sheet of the fibre material with varying thickness. The position of the patches 41 and consequently the tackiness of the final sheet of the fibre material are engineered in relation to the shape of the mould and the final composite material article.

Calculation of section overlap in a sheet of a fibre material prior to forming a shape is described in more detailed below.

The sheet of the fibre material, with or without the additional patches, is conformed to the mould 35, as shown in Figure 18 and forms a fibre mat sheet and is then removed from the mould 35 once the sheet of a fibre material has set in the shape of the mould, as shown in Figure 19.

Generally, the fibre mat sheet is allowed to cool before being removed from the mould 35.

The cooling of the binder material in the mould 35 ensures that the fibre mat sheet remains in the shape of the mould when released from the mould 35.

In some embodiments, the sheet 1 of material, either comprising a single or multiple layer, is sprinkled with a thermal binder and heated in an oven or any other source of heat before being moulded in the final product.

The binder is, for example, in the form of a powder that is sprinkled on one or both side of the sheet. However, any other suitable type of binder can be used.

The time and temperature of the heating process are varied according to the binder requirements and the sheet characteristics.

The heating process allows for the sheet to soften and for the reinforcement material fibres in the sheet 1 to relax to better conform to a 3D shape.

It is noted that sprinkling the sheet 1 with the thermal binder and the heating process are not essential steps of the method of manufacturing the sheet of the fibre material in accordance with the invention.

When the sheet 1 is placed into the mould 35, the patches move relative to each other to conform to the 3D shape of the mould. The fibres are also allowed restricted movement relative to each other. These characteristics of the sheet allow for the mat to cover the surface of the mould with a controlled density of fibres in specified directions with an optimum fibre overlap.

Figure 20 illustrates the deformation of a conventional sheet 49 of a fibre material over a domed-shaped element 47. The sheet 1 is marked with a grid of one set of parallel lines and a second set of parallel lines that perpendicular to the first set. The figure shows the displacement required to form over the dome-shaped element 47.

Figure 21 shows the sheet 1 of a fibre material as shown in Figure 1 over the domed-shaped element 47 and the way in which the rows 5 and sections 3 of the fibre material that form the sheet 1 of the fibre material can move relative to each other to conform to the element 47 and form complex 3D shapes.

Example

Calculating section overlap in a sheet of a fibre material prior to forming a shape ensures that the fibre overlap remains at optimum lengths after forming.

The optimum overlap is the overlap required to transfer stresses from fibre to fibre through the structure and maintain maximum strength of the final composite material.

If the overlap is higher than the optimum overlap, then the fibre system is not operating at an optimum efficiency and contains redundant fibre in respect to strength and stiffness.

An example of relevant calculations is given below. The Optimum Fibre overlap distance required is H.

The flat manufactured “mat” starting strip overlap distance co-efficient is R.

For example, if an optimum fibre or strip overlap distance required in an embodiment is 10mm and a starting overlap is 20mm, then R=2) If the R value for the final formed shape structure falls below 1 , then fibre stress transfer efficiency is lost in some embodiments.

If the co-efficient is higher than 1, then the fibre system is not operating at an optimum efficiency in these embodiments.

Fibre length (L) is a co-efficient multiple C of the minimum overlap (or a system will not obtain efficient transfer).

Fibre length L = C x H where C > 1.

For example, if the minimum overlap required in an embodiment is 10mm and the fibre length is 50mm, then C = 5.

Effective fibre length (G) = (L) - (H x R). This term defines the pitch at which the strips of fibres are layered in the fibre longitudinal direction.

(G) = (C x H) - (H x R) when calculating the overlap system for a flat layer along the mat length.

Stretching co-efficient (M) for a flat sheet is 1. Stretching to twice its length, it has (M) = 2. For example, if the mat required in an embodiment is 150mm long, then the

Multiple (A) = 15 with an optimum overlap of 10mm.

(K) is the initial number of fibre strips and the starting length is expressed as a multiple (A) of the optimum overlap distance (H).

K = Ax H / G K A/ (C x H) - (HxR)

A = (L - H) x A/L - R x H)

A = (C x H - H) x A/C x H - R x H)

Using the co-efficient, it is possible to determine an efficiency ratio (P)for the stretched carbon mat structure after forming to the desired 3 -dimensional shape (stretching).

The co-efficient allows the development of the following formula: b = (H x C - M x (H x C - H x R))/ H Calculation of the reduction of overlap co-efficient during forming a 3D dome shape to determine the change in overlap co-efficient fR).

Part to be formed minimum cord length: Q = 1 (no movement of fibres in overlap)

Design boss is a half- spherical dome with diameter = 0.5 Q

Cord length Maximum across the desired article (centre over the boss)

= 0.5 A + 0.5(2 x p x (0.52 x A)) or 0.5 A + p x 0.25 A or approx.1.28 x Q If an optimised fibre overlap of 10 units (H) is required in an embodiment, select a Fibre Length Co-efficient ratio of 5(C) = 5 (Fibre = 50 units long). Solving with b = (H x C - M x (H x C - H x R))/ H .

To obtain an optimisation ratio b = 1 in some embodiments, an initial sheet overlap ratio (R) of 1.875 units or an overlap pitch of the fibre strips at 18.75 units is required. This overlap will ensure that the optimum fibre overlap will occur at the maximum deformation of the fibre mat in these embodiments. Areas of lesser stretch ratio will have a b value of greater than 1.0.

The method of manufacturing an article described herein is designed to produce highly efficiency fibre reinforced complex parts. These parts can range from small mechanical components, such as automotive engine parts, up to large aircraft panels or boat hulls.

Many modifications may be made to the embodiments described above within departing from the spirit and the scope of the invention. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove.

It is to be understood that the reference to prior art herein does not constitute an admission that such prior art forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims that follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.