GB2617059A

GB2617059A - Joint assembly and method

Info

Publication number: GB2617059A
Application number: GB2202111.7A
Authority: GB
Inventors: Peter Gladwell Glen; Leon Nicholson Harlan
Original assignee: Emtek Solutions Ltd
Current assignee: Emtek Solutions Ltd
Priority date: 2022-02-17
Filing date: 2022-02-17
Publication date: 2023-10-04
Also published as: GB202202111D0

Abstract

A joint assembly 10 comprising a metal part 20, a composite part 30 connected to the metal part, a plurality of protrusions 40 connected to the metal part and extending towards the composite part, wherein each protrusion has a base 41 connected to the metal part, a shaft 42 extending from the base toward the composite part and a head 45 on the end of the shaft opposite to the base, wherein the shaft has a circular cross section, wherein the head is at least partially spherical, wherein the shaft comprises a neck 44 and a body 43, wherein the neck is between the body and the head, wherein the neck has opposite sides which are mutually parallel, wherein the body adjoins the neck and the base, and wherein the body has opposite sides which are tapered. A method of joining a metal part and composite part, comprising engaging fibres with the protrusions, tensioning the fibres around the protrusions, compressing the fibres in a direction along the axis of the saft toward the head of the protrusion, applying a bonding agent to the resin engaged with the protrusions, and curing the boding agent while the fibres are under tension.

Description

I

JOINT ASSEMBLY AND METHOD

This disclosure relates to a joint assembly and a method for joining metal and composite parts. Joints between composites and metals applied within a structure need to provide sufficient strength and maintain integrity over time.

Summary

The invention provides a joint assembly comprising: a metal part; a composite part connected to the metal part; a plurality of protrusions connected to the metal part and extending towards the composite part; wherein each protrusion has a base connected to the metal part, a shaft extending from the base toward the composite part and a head on the end of the shaft opposite to the base; wherein the shaft has a circular cross section; wherein the head is at least partially spherical; wherein the shaft comprises a neck and a body; wherein the neck is between the body and the head; wherein the neck has opposite sides which are mutually parallel; wherein the body adjoins the neck and the base; and wherein the body has opposite sides which are tapered.

Optionally the opposite sides of the body taper from a tapering point to an end of the body adjoining to the neck. Optionally the tapering point is located along the length of the body, optionally at an end of the body adjoining the base.

Optionally the body comprises parallel opposite sides optionally between the tapering point and an end of the body adjoining to the base.

Optionally the body comprises a tapered portion having opposite sides which are tapered and optionally a parallel portion having opposite sides which are mutually parallel. Optionally the tapered portion is between the neck and the parallel portion.

Optionally each protrusion extends from the base along a central axis.

Optionally the base extends from an end adjoining the body to the base optionally along the central axis of the protrusion and optionally in a direction away from the composite part Optionally the diameter of the base is within 5% to the diameter of the head and optionally equal to the diameter of the head.

Optionally the neck comprises at least 33% of the length of the protrusion extending from the base towards the composite part.

Optionally the length of the protrusion extending from the base towards the composite part is at least 300% of the base diameter Optionally the diameter of the head is at least 33% larger than the diameter of the neck.

Optionally the neck adjoins the head.

Optionally the composite part includes a fibre component and a bonding agent.

Optionally the fibre component is embedded in the bonding agent. Optionally the bonding agent is a thermosetting polymer, optionally a resin such as an epoxy resin.

Optionally the fibre component is engaged with the plurality of protrusions, optionally in a weaving pattern. Optionally the fibre component is engaged with the shafts of the protrusions. Optionally the tapered opposite sides of the body cause the fibre component to slide along the protrusion, causing compression of the layers of the fibre component engaged with the body along the central axis towards the head of the protrusion, optionally when tension is applied to the fibre component. This optionally concentrates the contiguous layers of the fibre component wrapped around the neck resulting in a reduction of airspaces within the composite part generally and thus a reduction in potential moisture ingress into the composite part that would normally degrade the joint assembly.

Optionally, the protrusions are arranged in rows which are circumferentially arranged on the metal part. Optionally the rows are circular, and optionally parallel, typically concentric with the axis of the metal part. Optionally the protrusions are arranged on a tapered section of the metal part, with adjacent rows at different radial spacings with respect to the axis of the metal part. This is particularly useful where the metal part is at least partially cylindrical. Optionally the joint assembly can comprise a tubular, for example a cylindrical tube with a throughbore.

Optionally the joint assembly comprises an adhesive layer between the composite part and the metal part. Suitable adhesives can be sprayable and can be sprayed onto the metal part before assembly. Suitable adhesives include epoxies, structural acrylics, cyanoacrylates and polyurethanes.

The invention also provides a method of joining a metal part and composite part, the metal part comprising a plurality of protrusions connected to the metal part and extending towards the composite part; wherein each protrusion has a base connected to a surface of the metal part, a shaft extending from a base toward the composite part and a head on the end of the shaft extending from a base toward the composite part and a head on the end of the shaft opposite to the base; wherein the shaft has a circular cross section; wherein the head is at least partially spherical; wherein the shaft comprises a neck and a body; wherein the neck is between the body and the head; wherein the neck has opposite sides which are mutually parallel; wherein the body adjoins the neck and the base; and wherein the body has opposite sides which are tapered; wherein the method comprises: engaging one or more fibres with one or more protrusions tensioning the one or more fibres around the one or more protrusions; compressing the fibres in a direction along the axis of the shaft toward the head of the protrusion; applying a bonding agent to the resin engaged with the protrusions and curing the bonding agent while the fibres are under tension.

Tensioning the fibres in this way compresses the layers of fibre together to form contiguous layers as a result of the tapered sections of the shaft (i.e. the body) and thereby reduces the voids in the compressed layers that reduces the susceptibility of the finished joint to ingress of fluids which tends to degrade the joint.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

Various aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

Language such as "including", "comprising", "having", "containing", or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word "comprise" or variations thereof such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially or, "consisting", "selected from the group of consisting or, "including", or "is" preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words "typically" or "optionally" are to be understood as being intended to indicate optional or non-essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

References to directional and positional descriptions such as upper and lower and directions e.g. "up", "down" etc. are to be interpreted by a skilled reader in the context of the examples described to refer to the orientation of features shown in the drawings, and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee.

Introduction to the Drawings

In the accompanying drawings, Fig. 1 shows two joint assemblies used within an isolation sub; Fig. 2 shows a side sectional view (through line A-A in Fig. 1) of the Fig. 1 joint assemblies; Fig. 3 shows a detailed view of a protrusion used in the joint assembly. Fig. 4 shows relevant dimensions of the protrusion of Fig. 3.

Fig. 5-Fig. 9 show sequential side sectional views of the isolation sub being assembled.

Fig. 10 shows a side view of the assembled isolation sub.

Fig. 11 shows apparatus used for forming a tow of composite material and assembling another example of an isolation sub with two joint assemblies. Fig. 12 shows a tow of composite material wound on to another embodiment of the metal parts at an angle close to 0° relative to the shared central axis of the metal parts.

Fig. 13 shows the Fig. 12 embodiment with the tow of composite material wound at +45° relative to the central axis.

Fig. 14 shows the Figs. 12-13 embodiment with the tow of composite material wound at -45° relative to the central axis.

Fig. 15 shows the Figs. 12-14 embodiment with the tow of composite material wound at 900 relative to the central axis.

Fig. 16 shows a detailed view of the Figs. 12-15 embodiment of a pin end portion and indicates the position of different protrusion rows.

Description

Referring now to Fig. 1 and Fig. 2, a joint assembly 10 is typically used in the formation of an isolation sub 1 incorporating a metal part 20 and a composite part 30. The embodiment shown in Fig. 1 and Fig. 2 shows two metal parts 20 at respective ends of a composite part 30. The metal and composite parts in this example are in the form of tubulars sharing a central axis and having an axial bore 2.

The isolation sub 1 comprises two individual metal-composite joints 10 located at each axial end of the composite part 30.

Each metal part 20 comprises a pin end portion 21 and a body portion 22 separated by a radial step. The radius along the axial length of the pin end portion 21 is less than the radius along the axial length of the body portion 22. The metal parts 20 are arranged such that joining ends 23 located on the pin end portions 21 of each metal part 20 are facing each other.

The composite part 30 typically comprises a composite material such as fibre-reinforced plastic. The composite material typically comprises a fibre component 31 (such as carbon fire, fibreglass or any other suitable material) and a bonding agent 32. The bonding agent 32 is typically a thermosetting polymer such as epoxy resin, but others can be used instead.

As seen in Fig. 2, each metal part 20 is provided with a plurality of protrusions 40 located across at least part of the axial length of the pin end portion 21. Each protrusion 40 comprises a base 41 at which the protrusion 40 is connected to the metal part 20 and from which extends towards the composite part 30. In this embodiment, the plurality of protrusions 40 are arranged in a cylindrical array with aligned rows although the skilled person will recognise that the plurality of protrusions 40 can be arranged in other forms within alternative examples of the invention. In this embodiment, each protrusion 40 optionally extends in a radial direction to a radius substantially equal to the radius of the body portion 22 of the metal part, or at least not extending beyond that radius; shorter protrusions 40 can optionally be used in some examples. The plurality of protrusions 40 may be formed in situ with the metal part 20 (through methods such as 3D printing, pressing, moulding, casting or any other suitable method) or by attaching each protrusion to the metal part (through methods such as cold welding, spot welding, screwing, cold fitting, hot fitting, gluing or any other suitable method).

In order to form the joint assembly 10, the protrusions 40 extend from the metal part 20 such that they are embedded in the composite part 30.

Fig. 3 shows a side view of a protrusion 40 in accordance with the present invention. The protrusion 40 comprises a base 41, a shaft 42 extending from the base 41 along a shared central axis and a head 45 joining at the end of the shaft 42 opposite to the base 41. The shaft 42 has a circular cross section and comprises a neck 44 and a body 43. The neck 44 is located between the body 43 and the head 45 and is adjoined to the base 41 by the body 43. The neck 44 comprises opposite sides that are mutually parallel and the body 43 comprises opposite sides that are tapered. In this embodiment of the protrusion 40, the opposite sides of the body 43 taper along the total length of the body 43. Other embodiments of the invention may have opposite sides that are partially tapered (i.e. from a point along the axial length of the body 43 to the neck 44).

In this embodiment of the protrusion 40, the base 41 extends from an end adjoining the base 41 and the body 43 along central axis and in a direction away from the head 45. The base 41 of Fig. 3 has a circular cross section but other embodiments may have other forms of cross section (i.e. square, rectangular or elliptical).

Embodiments of the protrusion 40 that comprise an extending base 41 as shown in Fig. 3 are typically found in embodiments of the metal part 20 where the protrusions have been attached to the metal part 20. In embodiments of the invention where the protrusions 40 have been formed in situ with the metal part 20, the base 41 typically does not extend.

Fig. 4 shows relevant dimensions of the protrusion of Fig. 3. The base 41 has a diameter DB; the neck 44 has a diameter ON and the head 45 has a radius RH that is equal to half of the diameter of the head DH. The total length L of the protrusion 40 is defined as the axial length between an uppermost end of base 41 and the uppermost point of the head 45. The body has an axial length T and the neck has an axial length N. When an embodiment of the protrusion 40 comprises an extending base 41, the base will have an axial length B. Typically, the diameter of the head Dry can either be equal to or within 5% of the diameter of the base OB. The length of the neck N is typically at least 33% of the total length L. The total length L is typically at least 300% of the diameter of the base OB.

The diameter of the head DH is typically at least 33% larger than the diameter of the neck DN.

The skilled person will recognise that the specific measurements suitable for a protrusion 40 in accordance with the present invention is determined by the structural requirements of the joint assembly 10.

A layer of adhesive (not shown) is typically located between the pin end portion 21 of each metal part 20 and the composite part 30. This acts to improve the structural integrity of each joint assembly 10. Types of suitable adhesives include structural acrylics, epoxies, cyanoacrylates and polyurethanes.

In one example of the invention, and with reference to Fig 5, an isolation sub 1 comprising two metal-composite joint assemblies 10 is optionally formed by initially providing two metal parts 20 wherein a mandrel 3 has been run through the axial bore 2 of each metal part 20. Additionally, the metal parts 20 are arranged such that the joining ends 23 of each metal part 20 are facing each other across the length of the central axis. Each metal part 20 is secured to the mandrel 3 such that relative movement (both axial and rotational) across each of these components is prevented.

The axial length between each metal part 20 determines the total axial length of the composite part 30. The mandrel 3 is coupled to a winder spindle 4 at each axial end of the isolation sub 1. Each winder spindle 4 is able to apply torque to the mandrel in order to cause rotational movement of the mandrel 3 and metal parts 20 (see Fig. 6).

In this embodiment of the invention, the composite part 30 comprises a single tow of the composite material 33, although other embodiments of the invention have the composite part 30 comprising multiple tows of the composite material. Fig. 6 shows a tow of composite material 33 being fed out of a feed head 5 of a robotic winder.

Typically, forming the tow of composite material 33 involves passing a tow 34 of the fibre component 31 through a bath 7 (See Fig. 11) of the bonding agent 32 prior to being fed out through the feed head 5. The feed head 5 is part of a robotic winder apparatus comprising a robotic winder arm 6 (See Fig. 11).

Fig. 11 shows another embodiment of the metal part 20 in accordance with the present invention where the sides of the pin end portion 21 taper to the joining end 23 instead of being parallel throughout the axial length of the pin end portion 21 as seen in Figs. 1-2 & 5-10.

Typically, the robotic winder is a 3D 5-axis or 7-axis robotic winder capable of moving the feed head 5 along the central axis and rotate the feed head 5 around an additional 4 or 6 axes in order to wind the tow of composite material 33 in a desired pattern (see Figs. 12-15) across the axial length of each joint assembly 10.

Before the winding procedure begins, the respective surfaces of the metal parts 20 are cleaned thoroughly (typically with acetone) in order to remove contaminants (typically dust and/or machining oils) that will weaken the resulting joint assemblies 10. An adhesive (not shown, typically a sprayable epoxy) is applied to the respective surfaces of the pin end portions 21 in order to improve the bond between the metal and composite material, and to strengthen the resulting joint assemblies 10.

As seen in Fig. 6, the winding procedure begins with an operator making an initial connection between the tow of composite material 33 and the mandrel 3, commencing rotation of the mandrel 3 and the metal parts 20 optionally at a constant rate and starting movement of the feed head 5 across central axis. The tow of composite material 33 is wound between the joining ends 23 of the metal parts 20 until the composite part 30 extends to a radius equal to the radius of the pin end portion 21 of the metal parts 20, from which the tow of composite material 33 will be wound across the axial length of the pin end portions 21 (see Fig. 7). At this point in the weaving process, the tow of composite material 33 begins to wrap around individual protrusions 40, typically by hooking the tow of composite material 33 under the head 45 of each protrusion 40, and typically around the neck 44.

As the weaving process progresses, the tow of composite material 33 will wrap around each protrusion multiple times, forming layers of the fibre component 31 around each protrusion 40.

Periodically during the weaving process, or continuously, the robotic winding arm 6 applies tension to the tow of composite material 33 such that the tow 34 of the fibre component 31 is pulled taut around each protrusion 40. This causes the tow 34 of the fibre component 31 to ride up the tapered sides of the shaft 42, compressing the layers of the fibre component 31 into contiguous rows along the neck 44 of the protrusions 40. Having the layers of the fibre component 31 concentrated at the neck 44 advantageously reduces the occurrence of airspaces within the finished composite part 30, thereby reducing potential moisture ingress into the composite part 30 that would normally degrade the joint assembly 10.

The operator may stop the weaving process when the radius of the composite part 30 reaches the radius of the body portion 22 of the metal parts 20.

Once the radius of the composite part 30 reaches the radius of the body portion 22 of the metal parts 20, the operator stops movement of the feed head 5, stops rotation of the mandrel 3 and disconnects the feed head 5 from the composite part 30. The plurality of protrusions are now fully embedded within the composite part 30.

The composite part 30 undergoes a curing process in order to solidify the bonding agent 32 (see Fig. 8). This process involves placing the isolation sub 1 in a suitable oven (not shown). The oven has its own set of oven spindles 14 to which the mandrel 3 can couple to and operate in a way similar to that seen in Fig. 5-Fig.7.

Heat from the oven is applied to the composite part 30. Rotating the mandrel as heat is applied to the composite part results in a more uniform curing. Applying tension to the fibre component 31 during the curing process ensures the fibre component 32 is pulled taut around the protrusions 40 as the bonding agent 32 sets. This causes the fibre component 31 to move axially up the tapered shaft of the protrusion toward the head, thereby compressing the layers together so that they are contiguous, which reduces the occurrence of airspaces within the finished composite part 30 and thereby reduces the risk of moisture ingress.

After the curing process is completed, the mandrel 3 is decoupled from the oven spindles 14 and removed from the oven. The metal parts 20 are disengaged from the mandrel 3 to allow the mandrel 3 to be pulled out from the axial bore 2.

The completed isolation sub 1 is then in the configuration shown in Figs. 1 & 10.

In order to enhance the strength of the isolation sub 1, the tow of composite material 33 is woven to the metal parts 20 such that the composite part 30 comprises a number of layers of composite material. The layers may be formed from a single tow of composite material 33 but may also be formed from multiple tows of composite material.

Figs. 12-15 show detailed views of how individual layers of the composite material can optionally be arranged on to the metal parts 20. The metal parts 20 of Figs. 1215 are similar to the metals parts shown in Fig. 11 but differ in that the plurality of protrusions 40 are arranged in a cylindrical array with interlocking rows.

As shown in Figs. 12-15, there are metal parts 20 designated here L and R on respective left and right sides of a central portion of the mandrel 3. Each metal part L, R has multiple rows of protrusions 40 arranged on its circumference. The narrowest row 1 on each part L, R is adjacent the joining end 23 of each metal part, and the widest rows N (with N being the total number of rows on each metal part) are furthest from the respective joining end 23. Thus the protrusions 40 in the first (narrowest) row on the left are designated L1, and the pins in the first (narrowest) row are designated R1 (see Fig. 16). In the example shown in Figs. 12-16, N = 32, but can vary in different examples.

One method of winding the tow of composite material 33 on to the metal parts 20 is described below: 1) Wind the tow of composite material 33 between the protrusions 40 in row L1 and the corresponding protrusions 40 in row R1 at approximately 0° (relative to the central axis A-A -noting that each pass is slightly more or less than 0°) as shown in Fig. 12 to form layer 1; 2) Wind the tow (optionally the same continuous tow) of composite material 33 between the protrusions 40 in row L1 and the corresponding protrusions 40 on row R1 at +45° as shown in Fig. 13 to form layer 2; 3) Repeat for layers 3 and 4, winding the tow of composite material 33 between L1 and R1 at respective angles of -45° and optionally 90° (not exactly 90° across the central portion of the mandrel 3 as it crosses between the metal parts 20) to form layers 3 and 4 (see Figs. 14 & 15 respectively); noting that layers 1-4 are all attached between the protrusions 40 in rows L1/R1; 4) Optionally repeat steps 1-3 for additional layers at different angles (e.g. -45°, +45°, and optionally 0°, all connecting L1 and R1) depending on how many layers are required in the composite part 30 (some simple thin composite parts 30 could in principle be formed with fewer layers per pin row (e.g. 2-4); 5) Repeat the sequence in steps 1-3 and optionally 4 but with the tow of composite material 33 connecting the protrusions 40 in the next adjacent rows i.e. rows L2 and R2 (see Fig. 16); 6) Repeat sequence with pins in sequentially adjacent rows 3 onwards, e.g. connecting pins in L3 and R3; 7) Winding sequence is completed when the tow of composite material 33 is connected at each of the desired angles for the desired number of layers, typically the final layer will be between the last row of protrusions 40 (rows LN and RN) furthest from the each respective joining end 23 (i.e. on the largest diameter of the metal parts 20).

More than 7 layers per protrusion 40 row (e.g. 8-12 or more at different angles) or fewer than 4 (e.g. 2 or 3) can be connected between each row of pins, dependent on the desired thickness of the composite part, which can vary in different examples.

Another way of describing this winding process can be seen in the following table (including the optional layers/angles): Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15... 7N Angle 0 45 -45 90-45 45 0 0 45 -45 90-45 45 0 0 0 Row 1 1 1 1 1 1 1 2 2 2 2 2 2 2 3... N In another example of a metal-composite joint assembly 10, the fibre component 31 optionally comprises multiple layers of fibre sheets (not shown) which can optionally be pre-formed before being applied to the joint, instead of being woven onto the joint.

To form the joint assembly 10, a fibre sheet is typically pushed over the plurality of protrusions 40 such that the plurality of protrusions 40 penetrate through the fibre sheet. The bonding agent 32 is then applied to that fibre sheet. Tension is then applied to the sheet to pull the fibres relative to the protrusions 40, so that the fibres ride up the tapered portions of the shaft and are pressed together in contiguous rows on the neck of the protrusion 40. Another fibre sheet is pushed over the plurality of protrusions 40 but at a different angular orientation (i.e. 45° relative to the preceding fibre sheet) and the bonding agent 32 is then applied to that fibre sheet, which is again tensioned as described above. The total number of fibre sheets pushed over the plurality of protrusions 40 is dependent on the desired thickness of the composite part 30. The angular orientation of the fibre sheets can follow a desired sequence (i.e. 0°, +45°,-45°, 90°, -45°, +45°, 0°). After the final fibre sheet has been pushed over the plurality of protrusions 40, tension is applied to each fibre sheet such that fibres of each fibre sheet are pulled taut around each protrusion 40, causing the fibres to ride up the tapered parts of the shaft 42, thereby compressing the layers in contiguous rows on the necks 44 of the protrusions 40. A curing process is carried out to solidify the bonding agent 32, resulting in a completed metal-composite joint assembly 10.

When tension is applied to the fibre component 31, the tapered sides of the body 43 advantageously guide and compress the contiguous layers of the fibre component 31 wrapped around each protrusion 40 along the axial length of shaft 42 and towards the head 45. This concentrates the contiguous layers of the fibre component 31 at the neck 44, resulting in a reduction of airspaces within the composite part 30 and thus a reduction in potential moisture ingress into the composite part 30 that would normally degrade the joint assembly 10.

In use, the at least partially spherical head 45 advantageously reduces severing of the fibre component 31 normally caused by contact between the fibre component 31 and a head comprising of at least one sharp edge. This is particularly advantageous in embodiments of the invention where the fibre component is pushed over the plurality of protrusions 40.

Claims

CLAIMS1. A joint assembly comprising: a metal part; a composite part connected to the metal part; a plurality of protrusions connected to the metal part and extending towards the composite part; wherein each protrusion has a base connected to the metal part, a shaft extending from the base toward the composite part and a head on the end of the shaft opposite to the base; wherein the shaft has a circular cross section; wherein the head is at least partially spherical; wherein the shaft comprises a neck and a body; wherein the neck is between the body and the head; wherein the neck has opposite sides which are mutually parallel; CO wherein the body adjoins the neck and the base; and wherein the body has opposite sides which are tapered.
The joint assembly of claim 1, wherein the body comprises a tapered portion having opposite sides which are tapered and a parallel portion having opposite sides which are mutually parallel.
The joint assembly of claim 2, wherein the tapered portion is between the neck and the parallel portion.
4. The joint assembly of claim 1, wherein the opposite sides of the body taper from a tapering point to an end of the body adjoining the neck; and wherein the tapering point is located at an end of the body adjoining the base.
5. The joint assembly of claim 15 wherein the opposite sides of the body taper from a tapering point to an end of the body adjoining to the neck; wherein the tapering point is located along the length of the body; and wherein the body comprises opposite parallel sides between the tapering point and an end of the body adjoining to the base.
6. The joint assembly of any preceding claim, wherein the diameter of the base is within 5% of the diameter of the head.
7. The joint assembly of claim 6, wherein the diameter of the base is equal to the diameter of the head.
8. The joint assembly of any preceding claim, wherein the neck comprises at least 33% of the length of the protrusion extending from the base towards the composite part.
9. The joint assembly of any preceding claim, wherein the length of the protrusion extending from the base towards the CO composite part is at least 300% of the base diameter.
10. The joint assembly of any preceding claim, wherein the diameter of the head is at least 33% larger than the diameter of the neck.
11. The joint assembly of any preceding claim, wherein the composite part includes a fibre component embedded in a bonding agent; wherein the fibre component is engaged with the plurality of protrusions.
12. The joint assembly of claim 11, wherein the fibre component is engaged with the plurality of protrusions in a weaving pattern.
13. The joint assembly of either claim 11 or 12, wherein the fibre component is engaged with the shafts of the plurality of protrusions.
14. The joint assembly of any of claims 11-13, wherein the fibre component comprises multiple layers of fibre sheets.
15. The joint assembly of any preceding claim, wherein the protrusions are arranged in rows which are circumferentially arranged on the metal part; and wherein the protrusions are arranged on a tapered section of the metal part with adjacent rows at different radial spacings with respect to an axis of the metal part.
16. The joint assembly of any preceding claim, comprising an adhesive layer between the composite part and the metal part.
17. A method of joining a metal part and composite part, the metal part comprising a plurality of protrusions connected to the metal part and extending towards the composite part; wherein each protrusion has a base connected to a surface of the metal part, CO a shaft extending from a base toward the composite part and a head on the end of the shaft extending from a base toward the composite part and a head on the end of the shaft opposite to the base; wherein the shaft has a circular cross section; wherein the head is at least partially spherical; wherein the shaft comprises a neck and a body; wherein the neck is between the body and the head; wherein the neck has opposite sides which are mutually parallel; wherein the body adjoins the neck and the base; and wherein the body has opposite sides which are tapered; wherein the method comprises: engaging one or more fibres with one or more protrusions tensioning the one or more fibres around the one or more protrusions; compressing the fibres in a direction along the axis of the shaft toward the head of the protrusion; applying a bonding agent to the resin engaged with the protrusions; and curing the bonding agent while the fibres are under tension.
18. The method of claim 17, comprising the step of spraying a sprayable adhesive onto the metal part.
19. The method of any of claims 17-18, comprising the step of engaging the one or more fibres with the one or more protrusions in a weaving pattern.
20. The method of any of claims 17-19, comprising the step of engaging the one or more fibres with the shafts of the one or more protrusions
21. The method of any of claims 17-20, wherein the one or more fibres comprises multiple layers of fibre sheets; and wherein the method comprises pushing at least one fibre sheet over the one or more protrusions such that the one or more protrusion penetrate through the fibre sheet.CO C C\ CO