Patent Description:
Landing gear composite components may be designed as composite cylindrical elements with a tubular shape. Typical composite material comprises, but not limited to polymer matrix composite, or other hybrid material. These components may undergo complex conditions including axial, torsional, and bending loads. Typical wedge joint designs utilized primarily to handle and transfer axial loads may be associated with a risk of excessive slipping between the composite tube and the metallic or composite wedge parts when exposed to bending loads, leading to potentially severe stress re-distribution and risk of damage or tube/joint separation. <CIT> relates to connecting rods for the transmission of force or power.

A composite tube joint is provided in claim <NUM>, comprising an end of a composite tube, an inner member disposed within the end, wherein an outer surface of the inner member has a complementary shape to an inner surface of the end, an outer member concentrically surrounding the end of the composite tube, and a first undulated surface configured to mitigate movement of the end relative to at least one of the inner member and the outer member.

The first undulated surface is disposed on the outer surface of the inner member, the first undulated surface is configured to physically restrict the end from moving relative to the inner member.

In various embodiments, the composite tube joint further comprises a second undulated surface disposed on an inner surface of the outer member, the second undulated surface configured to physically restrict the end from moving relative to the outer member.

In various embodiments, the end is compressed between the outer member and the inner member, and the first undulated surface is configured to physically restrict the end from moving relative to at least one of the inner member and the outer member in response to a bending moment being applied to the composite tube joint.

In various embodiments, the inner member comprises at least one of a first metallic material or a first composite material, and the outer member comprises at least one of a second metallic material or a second composite material.

In various embodiments, the outer surface of the inner member engages the inner surface of the end.

In various embodiments, the inner surface of the outer member engages an outer surface of the end.

In various embodiments, the end comprises a flared end, a converging end, a cylindrical end, or combinations thereof.

A method for forming a composite tube joint is provided in claim <NUM>, comprising disposing at least one composite layer to concentrically surround an inner member, disposing an outer member to concentrically surround an end of the composite layer, compressing the at least one composite layer between the inner member and the outer member, and forming an undulated surface on the composite layer in response to the compressing.

The undulated surface is formed on an outer surface of the composite layer in response to an undulated inner surface of the outer member engaging the composite layer in response to the compressing.

In various embodiments, a second undulated surface is formed on an inner surface of the composite layer in response to an undulated outer surface of the inner member engaging the composite layer in response to the compressing.

In various embodiments, the method further comprises removing the outer member from the composite layer.

In various embodiments, the method further comprises removing the inner member from the composite layer.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this invention and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not for limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

The present disclosure describes composite components having at least one end of a composite tube and at least one composite tube joint formed thereon. The composite tube joint may include an end of the composite tube, an inner member, and an outer member. The inner member and the outer member may be made from a material including, but not limited to, metals, composites, ceramics, wood, polymers, and glass. A composite may comprise a polymer matrix composite. The composite may comprise a polymer matrix composite reinforced by fibers such as a carbon, glass, organic fibers, or combinations thereof. Such composite tube joints may be used in aircraft systems, such as, for example, landing gear systems. However, the systems and methods of the present disclosure may be suitable for use in non-aircraft systems as well.

A composite tube joint of the present disclosure includes an end of a composite tube, an inner member, and an outer member. A composite tube joint may experience bending loads. Composite tube joints having undulated surfaces, of the present disclosure, may mitigate slipping of the composite tube with respect to an inner member and/or an outer member of the composite tube joint.

In various embodiments, a composite tube joint of the present disclosure may be useful for various components including, but not limited to, linkages, connecting rods, actuator rods, struts, and structural supports.

With reference to <FIG>, a schematic view of a composite tube joint <NUM> and a composite tube joint <NUM> are illustrated, in accordance with various embodiments. Composite tube joint <NUM> and composite tube joint <NUM> may be disposed at either end of a composite tube <NUM>. Although illustrated as having a composite tube joint <NUM> at a first end and a composite tube joint <NUM> at a second end, it is contemplated herein that composite tube <NUM> may comprise only one composite tube joint <NUM>. With additional reference to <FIG>, composite tube joint <NUM> may experience an axial load, represented by arrow <NUM>. The axial load may be a tensile load or a compressive load. Composite tube joint <NUM> may experience a bending moment, represented by arrow <NUM>. Composite tube joint <NUM> may experience a torque load, represented by arrow <NUM>.

With reference to <FIG>, a composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> may include an end of composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. Composite tube <NUM> may extend along a centerline axis <NUM>. In various embodiments, composite tube <NUM>, inner member <NUM>, and outer member <NUM> may be concentric with respect to centerline axis <NUM>. Composite tube <NUM> may comprise a composite material, such as a polymer matrix composite for example. Inner member <NUM> and outer member <NUM> may comprise a metallic material or a composite material. Inner member <NUM> and outer member <NUM> may comprise a polymer matrix composite. Composite tube <NUM> may comprise an end (also referred to herein as a flared end) <NUM>. In various embodiments, inner member <NUM> may be positioned within flared end <NUM>. Flared end <NUM> may comprise a frustoconical geometry. Inner member <NUM> may comprise a frustoconical geometry. The geometry of inner member <NUM> may be complementary to the geometry of flared end <NUM>. Inner member <NUM> may be positioned within flared end <NUM> and held under compression by components located outside of composite tube <NUM>. As will be discussed in greater detail, in various embodiments, inner member <NUM> may be placed within flared end <NUM> during formation of composite tube <NUM> and flared end <NUM>. In various embodiments, inner member <NUM> may be placed within flared end <NUM> after formation of composite tube <NUM> and flared end <NUM>.

Inner member <NUM> may comprise an outer surface <NUM>. Outer surface <NUM> may engage with flared end <NUM>. In various embodiments, outer surface <NUM> may engage with an inner surface <NUM> of composite tube <NUM>. Inner member <NUM> may be configured to be pushed into (in the negative z-direction) composite tube <NUM> by components located outside of composite tube <NUM> (e.g., outer member <NUM>). Flared end <NUM> may be compressed between inner member <NUM> and outer member <NUM>.

Composite tube joint <NUM> may experience a bending moment M. For example, in the illustrated embodiment, outer member <NUM> may rotate in the counter-clockwise direction relative to composite tube <NUM>. In this regard, outer surface <NUM> may slip (directions of the slip are represented by arrows N) relative to inner surface <NUM> in response to bending moment M.

In various embodiments, outer member <NUM> may be coupled to inner member <NUM> via one or more fasteners <NUM>. Fastener <NUM> may comprise a bolt, for example. In various embodiments, fastener <NUM> may hold inner member <NUM> in compression with outer member <NUM>.

With reference to <FIG>, a composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> may include an end of a composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. Composite tube <NUM> may extend along a centerline axis <NUM>. In various embodiments, composite tube <NUM>, inner member <NUM>, and outer member <NUM> may be concentric with respect to centerline axis <NUM>. Composite tube joint <NUM> may be similar to composite tube joint <NUM> except that composite tube <NUM> comprises an end (also referred to herein as a converging end) <NUM>, instead of a flared end <NUM>, with momentary reference to <FIG>. In this regard, an outer surface <NUM> of inner member <NUM> may comprise a geometry which is complementary to the geometry of an inner surface <NUM> of converging end <NUM>, an inner surface <NUM> of outer member <NUM> may comprise a geometry which is complementary to the geometry of an outer surface <NUM> of converging end <NUM>.

Composite tube joint <NUM> may experience a bending moment M. For example, in the illustrated embodiment, inner member <NUM> may move in the counter-clockwise direction relative to composite tube <NUM>. In this regard, inner surface <NUM> may slip relative to outer surface <NUM> in response to bending moment M. Similarly, outer surface <NUM> may slip relative to inner surface <NUM>, in response to bending moment M.

In various embodiments, outer member <NUM> may be coupled to inner member <NUM> via one or more fasteners <NUM>. Fasteners <NUM> may comprise a bolt, for example. In various embodiments, fasteners <NUM> may hold inner member <NUM> in compression with outer member <NUM>.

With respect to <FIG>, embodiments of a composite tube joint are illustrated, in accordance with various embodiments, with respect to a composite tube having a flared end. It is contemplated herein that similar embodiments may be used for a composite tube joint having a composite tube with a converging end. Furthermore, it is contemplated herein that a composite tube joint of the present disclosure may comprises a composite tube having a combination of a flared end and converging end, for example, having an end that increases in diameter and then decreases in diameter along a direction. Furthermore, although described with respect to an inner member, the undulations described in <FIG> may be equally applicable to an outer member as well.

With respect to <FIG>, elements with like element numbering are intended to be the same and will not necessarily be repeated for the sake of clarity.

With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> includes an end of a composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. In various embodiments, outer member <NUM> may comprise an undulated inner surface <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> includes an end of a composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. In various embodiments, inner member <NUM> may comprise an undulated outer surface <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> includes composite tube <NUM>, inner member <NUM>, and outer member <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated in a compressed position, in accordance with various embodiments. Flared end <NUM> of composite tube <NUM> may be compressed between inner member <NUM> and outer member <NUM> (e.g., in response to inner member <NUM> moving in the negative Z-direction with respect to outer member <NUM>, and/or in response to outer member <NUM> moving in the positive Z-direction with respect to inner member <NUM>). Outer surface <NUM> of flared end <NUM> may become deformed in response to flared end <NUM> being compressed between outer member <NUM> and inner member <NUM>. Stated differently, the geometry of outer surface <NUM> may become complementary to undulated inner surface <NUM> in response to flared end <NUM> being compressed between outer member <NUM> and inner member <NUM>. In this regard, outer surface <NUM> may comprise an undulated surface in response to flared end <NUM> being compressed between outer member <NUM> and inner member <NUM>. It should be appreciated that inner surface <NUM> may similarly deform in accordance with the geometry of inner member <NUM>. Thus, inner surface <NUM> may comprise an undulated surface in response to flared end <NUM> being compressed between outer member <NUM> (or outer member <NUM>) and inner member <NUM>, with momentary reference to <FIG>. In this regard, flared end <NUM> may comprise an undulated outer surface <NUM> and a smooth inner surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>). Furthermore, flared end <NUM> may comprise an undulated inner surface <NUM> and a smooth outer surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>). Furthermore, flared end <NUM> may comprise both an undulated outer surface <NUM> and an undulated inner surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>).

In various embodiments, inner member <NUM> may be similar to inner member <NUM>, with combined reference to <FIG> and <FIG>. In various embodiments, inner member <NUM> may be similar to inner member <NUM>, with combined reference to <FIG> and <FIG>.

With reference to <FIG>, undulations <NUM> are illustrated, in accordance with various embodiments. Undulations <NUM> may comprise a plurality of periodically displaced waves <NUM>. Undulations <NUM> may be oriented in the hoop direction. In various embodiments, undulations <NUM> may be oriented perpendicular with respect to centerline axis <NUM>. Orienting undulations <NUM> perpendicular with respect to centerline axis <NUM> may mitigate slipping between inner member <NUM> and an adjacent member (e.g., composite tube <NUM>, see <FIG>) in response to a bending moment being applied to inner member <NUM> (e.g., as described with respect to <FIG> and <FIG>). Stated differently, undulations <NUM> may physically restrict inner member <NUM> from slipping relative to composite tube <NUM> in response to bending moment M, with momentary reference to <FIG> and <FIG>.

With reference to <FIG>, undulations <NUM> are illustrated, in accordance with various embodiments. Undulations <NUM> may comprise groupings of waves <NUM>, each group spaced apart from the adjacent group.

With reference to <FIG>, undulations <NUM> are illustrated, in accordance with various embodiments. Undulations <NUM> may comprise a plurality of non-periodically displaced waves <NUM>.

Although illustrated as an inner member, it is contemplated herein that the features described with respect to <FIG> may similarly apply to an outer member.

With reference to <FIG>, an inner member <NUM> comprising an undulated outer surface <NUM> is illustrated, in accordance with various embodiments. Although illustrated as inner member <NUM>, it is contemplated herein that the features described with respect to <FIG> may similarly apply to an outer member. Undulations <NUM> may be oriented at an angle different than ninety degrees with respect to centerline axis <NUM>. Stated differently, undulations <NUM> may be oriented at a non-zero angle β with respect to the hoop direction (i.e., the tangential direction with respect to centerline axis <NUM>). Orienting undulations <NUM> at angle β with respect to the hoop direction may mitigate slipping of inner member <NUM> with respect to an adjacent member (e.g., composite tube <NUM>, see <FIG>) in response to a torque being applied to inner member <NUM>. Stated differently, undulations <NUM> may physically restrict inner member from rotating about centerline axis <NUM> with respect to composite tube <NUM>. In various embodiments, angle β may be variable along centerline axis <NUM>.

In various embodiments, with combined reference to <FIG> and <FIG>, when angle β is zero, undulations <NUM> may be optimal for helping mitigate movement of the inner member in the Z-direction relative to the composite tube (e.g., inner member <NUM> from moving relative to flared end <NUM>), in response to a bending moment applied to the inner member. When angle β is ninety degrees, undulations <NUM> may be optimal for helping mitigate movement of the inner member relative to the composite tube (e.g., inner member <NUM> from moving relative to flared end <NUM>) in response to a torque applied to the inner member. Thus, angle β may be chosen according to a predetermined ratio, or a range of such ratios, of moment and torque being applied to the composite tube joint.

With reference to <FIG>, an inner member <NUM> comprising an undulated outer surface <NUM> is illustrated, in accordance with various embodiments. Undulated outer surface <NUM> may comprise a first plurality of undulations <NUM> oriented at an angle different than ninety degrees with respect to centerline axis <NUM> and a second plurality of undulations <NUM> oriented at an angle different than ninety degrees with respect to centerline axis <NUM>. Stated differently, undulated outer surface <NUM> may comprise a first plurality of undulations <NUM> oriented at a non-zero angle β<NUM> with respect to the hoop direction and a second plurality of undulations <NUM> oriented at a non-zero angle β<NUM> with respect to the hoop direction. In this regard, first plurality of undulations <NUM> may overlap second plurality of undulations <NUM>. In various embodiments, angle β<NUM> may be between zero and ninety degrees (<NUM>°-<NUM>°). In various embodiments, angle β<NUM> may be between zero and ninety degrees (<NUM>°-<NUM>°). In various embodiments, angle β<NUM> may be variable along centerline axis <NUM>. In various embodiments, angle β<NUM> may be variable along centerline axis <NUM>.

With reference to <FIG>, an inner member <NUM> comprising an undulated outer surface <NUM> is illustrated, in accordance with various embodiments. Undulated outer surface <NUM> comprise a first plurality of undulations <NUM> oriented perpendicular with respect to centerline axis <NUM> and a second plurality of undulations <NUM> oriented perpendicular with respect to first plurality of undulations <NUM>. First plurality of undulations <NUM> may circumferentially surround centerline axis <NUM>. First plurality of undulations <NUM> will be oriented concentric with respect to centerline axis <NUM>. Second plurality of undulations <NUM> may be defined by projections of centerline axis <NUM> onto undulated outer surface <NUM>. In this regard, inner member <NUM> may resist both moments and torques. <FIG> illustrates a cross-section view of inner member <NUM> taken parallel to centerline axis <NUM>. <FIG> may best illustrate a profile of first plurality of undulations <NUM>. <FIG> illustrates a cross-section view of inner member <NUM> taken perpendicular to centerline axis <NUM>, in accordance with various embodiments. <FIG> may best illustrate a profile of second plurality of undulations <NUM>. In various embodiments, plurality of undulations <NUM> may define a continuously wavy surface, as illustrated in <FIG>. However, it is contemplated herein that plurality of undulations <NUM> may define distinct channels <NUM> disposed circumferentially along a circular surface <NUM>, as illustrated in <FIG>. Undulations <NUM> may be implemented through a subtractive manufacturing process. Undulations <NUM> may be implemented through an additive manufacturing process.

With reference to <FIG>, an inner member 820a is illustrated, in accordance with various embodiments. Inner member 820a may comprise an original profile <NUM> before undulations are formed onto inner member 820a. With combined reference to <FIG>, a plurality of undulations <NUM> may be formed into inner member 820a via a subtractive manufacturing process. In this regard, inner member 820b may be formed from inner member 820a by forming plurality of undulations <NUM> into inner member 820a via a subtractive manufacturing process. In this regard, plurality of undulations <NUM> may extend towards centerline axis <NUM> with respect to original profile <NUM>.

With combined reference to <FIG>, a plurality of undulations <NUM> may be formed onto inner member 820a via an additive manufacturing process. In this regard, inner member 820c may be formed from inner member 820a by forming plurality of undulations <NUM> onto inner member 820a via an additive manufacturing process. In this regard, plurality of undulations <NUM> may extend away from centerline axis <NUM> with respect to original profile <NUM>.

With combined reference to <FIG>, a plurality of undulations <NUM> may be formed onto inner member 820a via both an additive manufacturing process and a subtractive manufacturing process. In this regard, inner member 820d may be formed from inner member 820a by forming plurality of undulations <NUM> onto inner member 820a via both an additive manufacturing process and a subtractive manufacturing process. In this regard, plurality of undulations <NUM> may extend both towards centerline axis <NUM> and away from centerline axis <NUM> with respect to original profile <NUM>.

With combined reference to <FIG>, a composite tube <NUM> may be formed by laying composite sheets or layers in a desired shape and bonding the layers together using resins, adhesives, or other bonding agents. In various embodiments, composite tube <NUM> may be formed using a fiber-wound fabrication process, wherein fiber is continuously wound onto a form and bonded together using resins, adhesives, or other bonding agents. Any manner of forming composite tube <NUM> is within the scope of the present disclosure. An exemplary form <NUM>, comprising an internal liner <NUM> and an internal end part <NUM>, for forming composite tube <NUM> is illustrated in <FIG>. In various embodiments, internal liner <NUM> may be made from a metal. In various embodiments, internal end part <NUM> may be made from a metal. Liner <NUM> and internal end part <NUM> may be made from a composite, ceramic, wood, or other material. Internal liner <NUM> and internal end part <NUM> may aid in maintaining a shape of composite tube <NUM> during a composite layup process. For example, a composite layup process may include spinning composite fibers around internal liner <NUM> and/or internal end part <NUM> and/or placing composite pre-preg sheets around internal liner <NUM> and/or internal end part <NUM> to form a composite layer <NUM>. In various embodiments, the composite layup process may further include disposing an external end part <NUM> to surround composite layer <NUM>. In various embodiments, composite layer <NUM> may be compressed between internal end part <NUM> and external end part <NUM>. Undulations, such as those described herein with respect to <FIG> may be disposed on the outer surface of internal end part <NUM> and/or the inner surface of external end part <NUM>. Thus, undulations may be formed onto composite layer <NUM> as a result of the compression, similar to undulated outer surface <NUM> of <FIG> for example. In various embodiments, internal liner <NUM> and/or internal end part <NUM> may comprise a mandrel configured to be removed during the layup process (e.g., after the composite fibers are partially cured or fully cured). In various embodiments, internal liner <NUM> and/or internal end part <NUM> may remain within composite tube <NUM> after the composite layup process, for example to increase strength and/or stiffness properties of composite tube <NUM>. In various embodiments, inner member <NUM> may be similar to internal end part <NUM>, with momentary reference to <FIG>.

With respect to <FIG>, elements with like element numbering are intended to be the same and will not necessarily be repeated for the sake of clarity. With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> may include an end (also referred to herein as a cylindrical end) <NUM> of a composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. Composite tube <NUM> may comprise the end <NUM>. In various embodiments, composite tube <NUM>, inner member <NUM>, and outer member <NUM> may each comprise a cylindrical geometry. In various embodiments, outer member <NUM> may comprise an undulated inner surface <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> may include the end of a composite tube <NUM>, an inner member <NUM>, and an outer member <NUM>. In various embodiments, inner member <NUM> may comprise an undulated outer surface <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated, in accordance with various embodiments. Composite tube joint <NUM> may include the end of composite tube <NUM>, inner member <NUM>, and outer member <NUM>.

With reference to <FIG>, composite tube joint <NUM> is illustrated in a compressed position, in accordance with various embodiments. End <NUM> of composite tube <NUM> may be compressed between inner member <NUM> and outer member <NUM> (e.g., in response to inner member <NUM> moving in the negative Z-direction with respect to outer member <NUM>, and/or in response to outer member <NUM> moving in the positive Z-direction with respect to inner member <NUM>). Outer surface <NUM> of end <NUM> may become deformed in response to end <NUM> being compressed between outer member <NUM> and inner member <NUM>. Stated differently, the geometry of outer surface <NUM> may become complementary to undulated inner surface 982in response to end <NUM> being compressed between outer member <NUM> and inner member <NUM>. In this regard, outer surface <NUM> may comprise an undulated surface in response to end <NUM> being compressed between outer member <NUM> and inner member <NUM>. It should be appreciated that inner surface <NUM> may similarly deform in accordance with the geometry of inner member <NUM>. Thus, inner surface <NUM> may comprise an undulated surface in response to end <NUM> being compressed between outer member <NUM> (or outer member <NUM>) and inner member <NUM>, with momentary reference to <FIG>. In this regard, end <NUM> may comprise an undulated outer surface <NUM> and a smooth inner surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>). Furthermore, end <NUM> may comprise an undulated inner surface <NUM> and a smooth outer surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>). Furthermore, end <NUM> may comprise both an undulated outer surface <NUM> and an undulated inner surface <NUM>, for example using the composite tube joint <NUM> (see <FIG>).

With reference to <FIG>, a method <NUM> is illustrated for forming a composite tube joint, in accordance with various embodiments. Method <NUM> includes disposing a composite layer to surround an inner member (step <NUM>). Method <NUM> includes disposing an outer member to surround an end of the composite layer (step <NUM>). Method <NUM> includes compressing the composite layer between the inner member and the outer member (step <NUM>). Method <NUM> includes forming an undulated surface on the composite layer in response to the compressing (step <NUM>).

With combined reference to <FIG> and <FIG>, step <NUM> may include disposing one or more composite layers <NUM> to concentrically surround internal end part (also referred to herein as an inner member) <NUM>. Step <NUM> may include disposing external end part (also referred to herein as an outer member) <NUM> to concentrically surround an end of composite layer <NUM>. Step <NUM> may include compressing the one or more composite layers <NUM> between internal end part <NUM> and external end part <NUM>. Step <NUM> may include forming an undulated surface (e.g., undulated outer surface <NUM> of <FIG>) on composite layer <NUM> in response to the compressing. The forming process at step <NUM> may include curing in the case of thermoset polymeric matrix. The forming process at step <NUM> may include solidification in the case of thermoplastic polymeric matrix.

With reference to <FIG>, a method <NUM> is illustrated for forming a composite tube joint, in accordance with various embodiments. Method <NUM> may be similar to method <NUM> of <FIG>, except that method <NUM> further includes removing the outer member from the composite layer (step <NUM>) and/or removing the inner member from the composite layer (step <NUM>).

With combined reference to <FIG> and <FIG>, step <NUM> may include removing external end part <NUM> from composite layer <NUM>. Step <NUM> may include removing internal end part <NUM> from composite layer <NUM>.

With reference to <FIG>, a method <NUM> is illustrated for forming a composite tube joint, in accordance with various embodiments. Method <NUM> may be similar to method <NUM> of <FIG>, except that method <NUM> further includes forming a second undulated surface on the composite layer in response to the compressing (step <NUM>).

With combined reference to <FIG> and <FIG>, step <NUM> may include forming an undulated surface (e.g., undulated inner surface <NUM> of <FIG> and/or <FIG>) on composite layer <NUM> in response to the compressing.

However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more.

Claim 1:
A composite tube joint (<NUM>), comprising:
an end of a composite tube (<NUM>);
an inner member (<NUM>) disposed within the end, wherein an outer surface of the inner member has a complementary shape to an inner surface of the end;
an outer member (<NUM>) concentrically surrounding the end of the composite tube; and
a first undulated surface (<NUM>) configured to mitigate movement of the end relative to at least one of the inner member (<NUM>) and the outer member (<NUM>), wherein the composite tube (<NUM>) extends along a centerline axis (<NUM>), wherein the first undulated surface (<NUM>) is disposed on the outer surface of the inner member (<NUM>), the first undulated surface (<NUM>) configured to physically restrict the end from moving relative to the inner member (<NUM>); characterized in that the first undulated surface (<NUM>) comprises a first plurality of undulations (<NUM>) orientated perpendicular with respect to the centerline axis (<NUM>) and the first undulated surface comprises a second plurality of undulations (<NUM>) orientated at a non-zero angle with respect to the first plurality of undulations (<NUM>).