Patent Description:
Thermoplastic materials are increasingly being used in various aerospace applications. Forming fiber-reinforced thermoplastic structures, however, may be time consuming and costly using known formation processes. For example, various welding techniques are being developed for welding fiber-reinforced thermoplastic aircraft structures. These welding techniques include resistance welding, induction welding, ultrasonic welding and laser welding. These welding techniques, however, may require a relatively high capital investment and relatively long welding times in minutes to tens of minutes to achieve each weld. There is a need in the art therefore for improved processes for forming fiber-reinforced thermoplastic structures which may decrease formation time, complexity and/or expense.

<CIT> discloses a pipe welding method where two fiber-reinforced thermoplastic pipe halves each comprising ribs are positioned such that their ribs are in contact and then vibration welded. <CIT> discloses the vibration welding of two fiber-reinforced thermoplastic pieces with continuous fibers. Yet other vibration welding methods are disclosed in <CIT> and <CIT>.

According to the present invention, a formation method is provided according to claim <NUM>.

At least the first component has a material buildup prior to the vibration welding. At least a portion of the material buildup is consumed by the vibration welding to provide a weld joint between the first component and the second component.

The portion of the first surface may be adjacent the portion of the second surface.

The providing of the first component may include stamp forming the first component from a first preform. In addition or alternatively, the providing of the second component may include stamp forming the second component from a second preform.

The material buildup may at least or only include one or more pure thermoplastic resin layers.

The material buildup may at least or only include one or more fiber-reinforced thermoplastic composite layers.

The portion of the material buildup may be displaced to at least one side of the weld j oint during the vibration welding.

Prior to the vibration welding, a geometry of a perimeter of the material buildup may match a geometry of a perimeter of a portion of the second component that is vibration welded to the first component.

Prior to the vibration welding, a size of a perimeter of the material buildup may be equal to, or within fifteen percent of, a size of a perimeter of a portion of the second component that is vibration welded to the first component.

The base may have a base thickness prior to the vibration welding at a location where the second component is to be vibration welded to the first component. The first component may have a component thickness at the location following the vibration welding that is equal to, or within five or fifteen percent of, the base thickness.

The first fiber-reinforced thermoplastic composite may at least or only include fiber reinforcement embedded within thermoplastic material. The base may be at least or only formed from or otherwise include the fiber reinforcement and some of the thermoplastic material. The material buildup may be at least or only formed from or otherwise include some of the thermoplastic material.

The first fiber-reinforced thermoplastic composite may at least or only include fiber reinforcement embedded within thermoplastic material. The base may be at least or only formed from or otherwise include some of the fiber reinforcement and some of the thermoplastic material. The material buildup may be at least or only formed from or otherwise include some of the fiber reinforcement and some of the thermoplastic material.

The second component may include a second base and a second material buildup on a portion of the base. The material buildup may abut the second material buildup prior to the vibration welding. At least a portion of the second material buildup may be displaced during the vibration welding.

The vibration welding may also provide a second weld joint between the first component and the second component. The second weld joint may be angularly offset from the weld joint.

The weld joint may be disposed along a first curved surface of the first component. The second weld joint may be disposed along a second curved surface of the first component.

The vibration welding may also provide a second weld joint between the first component and the second component. The second weld joint may be spaced from the weld joint.

The providing of the first component may include stamping the first component from a first preform. In addition or alternatively, the providing of the second component may include stamping the second component from a second preform.

The first component and the second component may be included in a structure for an aircraft.

The first component and/or the second component may each include at least one of glass fibers, carbon fibers, aramid fibers, basalt fibers, mineral fibers, fibers from renewable raw mate rials, metal fibers or polymer fibers.

The first component and/or the second component may each include a thermoplastic material. The thermoplastic material may at least include polyimide (PA), polypropylene (PP), polyethylene (PE), polyoxymethylene (POM), polyphenylene sulphide (PPS), polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene terephthalate (PET), polyphthalamide (PPA), poly ether ketone ketone (PEKK), or poly aryl ether ketone (PAEK).

The present disclosure includes methods for vibration welding fiber-reinforced thermoplastic structures together. By contrast to other welding techniques such as resistance welding, induction welding, ultrasonic welding and/or laser welding, vibration welding may have a lower instrument cost and/or provide higher speed welding times; e.g., within seconds to tens of seconds. Vibration welding processes, however, are typically performed for pure thermoplastic parts or short-fiber reinforced thermoplastic composite parts, and not performed on continuous fiber-reinforced composite aircraft parts. One challenge to implementing vibration welding is that a welding surface may be consumed during the welding, which consumption may reduce a thickness of the composite laminate and/or reduce mechanical properties of the composite laminate. In some cases, the consumed interface layers may change a symmetry of the composite laminate and introduce asymmetric bending, which bending may further impact performance of the composite laminate. The methods of the present disclosure may address one or more of these challenges as described below in further detail.

<FIG> illustrates a portion of a fiber-reinforced thermoplastic structure <NUM> for an aircraft. This structure <NUM> may be arranged within a cabin of the aircraft. The structure <NUM>, for example, may be configured as or may otherwise be part of an aircraft seat; e.g., a seat frame. The structure <NUM> may alternatively be configured as a part of a fuselage or a wing of the aircraft. The structure <NUM> may still alternatively be configured as a part of a propulsion system for the aircraft; e.g., a component of a nacelle, etc. The present disclosure, however, is not limited to the forgoing exemplary aircraft structures. Furthermore, it is contemplated the structure <NUM> of the present disclosure may also be configured for non-aircraft applications. However, for ease of description, the structure <NUM> may be referred to below as an aircraft structure.

The aircraft structure <NUM> of <FIG> includes a plurality of components including an exterior skin <NUM> and a support member <NUM>; e.g., a stringer. The support member <NUM> extends longitudinally along a longitudinal centerline <NUM> of the support member <NUM>; e.g., along an x-axis. The support member <NUM> extends laterally (e.g., along a y-axis) between and to a first side <NUM> of the support member <NUM> and a second side <NUM> of the support member <NUM>. The support member <NUM> extends vertically (e.g., along a z-axis) between and to an exterior side <NUM> of the support member <NUM> and an interior side <NUM> of the support member <NUM>.

The support member <NUM> of <FIG> includes a channeled base <NUM> and one or more mounts <NUM>; e.g., flanges. The channeled base <NUM> extends longitudinally along the longitudinal centerline <NUM>. The channeled base <NUM> extends laterally between and to a first side <NUM> of the channeled base <NUM> and a second side <NUM> of the channeled base <NUM>. The channeled base <NUM> extends vertically between and to (or about) the support interior side <NUM> and the support exterior side <NUM>. The channeled base <NUM> is configured with a U-shaped cross-sectional geometry when viewed, for example, in a reference plane perpendicular to the longitudinal centerline <NUM>. This configuration provides the channeled base <NUM> with a channel <NUM> that extends longitudinally in (e.g., through) the support member <NUM> and its channeled base <NUM>. The channel <NUM> extends laterally in (e.g., within) the support member <NUM> and its channeled base <NUM> between opposing sidewalls <NUM> of the channeled base <NUM>. The channel <NUM> projects vertically into the support member <NUM> and its channeled base <NUM> from the support interior side <NUM> to an endwall <NUM> of the channeled base <NUM>.

Each of the mounts <NUM> is connected to (e.g., formed integral with) the channeled base <NUM>. Each of the mounts <NUM> is disposed at (e.g., on, adjacent or proximate) the support interior side <NUM>. Each of the mounts <NUM> projects laterally out from a respective one of the base sidewalls <NUM> to a distal end of that mount <NUM>. Each of these mounts <NUM> is vibration welded to the exterior skin <NUM> at / along an interior surface <NUM> of the exterior skin <NUM>.

Referring to <FIG>, each of the aircraft structure components <NUM>, <NUM> is constructed from a common (e.g., the same) or a unique component material. The component material may be a fiber-reinforced thermoplastic composite. Fiber-reinforcement <NUM>, for example, may be embedded within a thermoplastic material <NUM>; e.g., a thermoplastic matrix. Examples of the fiber-reinforcement <NUM> include, but are not limited to, metal fibers (e.g., aluminum fibers, brass fibers, and stainless steel fibers), carbon fibers (including graphite fibers such as polyacrylonitrile (PAN)-based carbon fibers, rayon-based carbon fibers, lignin-based carbon fibers, and pitch-based carbon fibers(, insulating fibers (e.g., glass fibers), organic fibers (e.g., aramid fibers, polyparaphenylene benzoxazole (PBO) fibers, polyphenylene sulfide fibers, polyester fibers, acrylic fibers, nylon fibers, and polyethylene fibers), and inorganic fibers (e.g., silicon carbide fibers and silicon nitride fibers). Some or all of these fibers may be continuous fibers. Some or all of the fibers may also or alternatively be chopped fibers.

Examples of the thermoplastic material <NUM> include, but are not limited to, a semicrystalline thermoplastic resin and an amorphous thermoplastic resin. Examples of the semicrystalline thermoplastic resin include, but are not limited to, polyester, polyolefin, polyoxymethylene (POM), polyamide (PA), polyarylene sulfide, polyketone (PK), polyetherketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyaryletherketone (PAEK), polyether nitrile (PEN), fluororesin, and liquid crystal polymer (LCP). Examples of the polyester include, but are not limited to, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terphthalate (PTT), polyethylene naphthalate (PEN), and liquid crystal polyester. Examples of the polyolefin include, but are not limited to, polyethylene (PE), polypropylene (PP), and polybutylene. An example of the polyarylene sulfide includes, but is not limited to, polyphenylene sulfide (PPS). An example of the fluororesin includes, but is not limited to, polytetrafluoroethylene. Examples of the amorphous thermoplastic resin include, but are not limited to, polystyrene, polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene ether (PPE), polyimide (PI), polyamide imide (PAI), polyetherimide (PEI), polysulfone (PSU), polyether sulfone (PES), and polyarylate (PAR). The thermoplastic material <NUM> to be used for the control surface may also be phenoxy resin, polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, fluorine resin, acrylonitrile, or other thermoplastic elastomers, or copolymers and/or modified resin thereof.

Each of the aircraft structure components <NUM>, <NUM> may be constructed from one or more layers 56A-F (generally referred to as "<NUM>"). Each of these component layers <NUM> of <FIG> may include the fiber-reinforcement <NUM> within the thermoplastic material <NUM>. Within each component layer <NUM>, the fiber-reinforcement fibers may be unidirectional. The fiber-reinforcement fibers may alternatively be multi-directional (e.g., in a woven sheet, a mat of chopped fibers, etc.) in one or more of the component layers <NUM>. In some embodiments however, referring to <FIG>, one or more of the component layers <NUM> (e.g., 56F) may alternatively be configured without any fiber-reinforcement fabrics; e.g., the respective outer component layer 56F may substantially or only include the thermoplastic material <NUM>.

Referring to <FIG>, one or more of the aircraft structure components <NUM> and <NUM> may each include between thirty-five percent (<NUM>%) and ninety-five percent (<NUM>%) of the fiber-reinforcement <NUM> (e.g., fibers) per unit of volume and between five percent (<NUM>%) and sixty-five percent (<NUM>%) of the thermoplastic material <NUM> per unit of volume. For example, each aircraft structure components <NUM>, <NUM> may include at least forty percent (<NUM>%), forty-five percent (<NUM>%), fifty percent (<NUM>%), fifty-five percent (<NUM>%) or more of the fiber-reinforcement <NUM> (e.g., fibers) per unit of volume. Such a relatively high volume fraction of the fiber-reinforcement <NUM> (e.g., fibers) may increase a structural strength and/or a stress tolerance of the respective aircraft structure component. Similarly, one or more or all of the component layers <NUM> in a respective one of the aircraft structure components <NUM>, <NUM> may each include the foregoing (or different) percentages of fiber-reinforcement <NUM> (e.g., fibers) per unit of volume and the thermoplastic material <NUM> per unit of volume. The present disclosure, however, is not limited to the foregoing exemplary relationships between the fiber-reinforcement <NUM> and the thermoplastic material <NUM>. One or more of the component layers <NUM> in a respective one of the aircraft structure components <NUM>, <NUM>, for example, may include less than thirty-five percent (<NUM>%) of the fiber-reinforcement <NUM> (e.g., fibers) per unit of volume. For example, referring to <FIG>, the component layer(s) <NUM> (e.g., 56F) that substantially or only include the thermoplastic material <NUM> may include up to zero percent of the fiber-reinforcement <NUM> (e.g., fibers) per unit of volume. Such a component layer (or layers) may be used for / in a material buildup (e.g., see <NUM> in <FIG>) as described below in further detail.

<FIG> is a flow diagram of a method <NUM> for forming a fiber-reinforced thermoplastic structure. For ease of description, the method <NUM> may be described below with reference to the aircraft structure <NUM> described herein. The method <NUM> of the present disclosure, however, is not limited to forming any particular types or configurations of aircraft structures nor fiber-reinforced thermoplastic structures in general.

In step <NUM>, a first component 58A such as the exterior skin <NUM> is provided. The first component 58A of <FIG> may be formed using one or more formation processes. Examples of these formation processes include, but are not limited to, laminating, molding, pressing, injection molding, and overmolding. Where the first component 58A has a three-dimensional geometry, the first component 58A may also or alternatively be formed by stamping between a plurality of dies. The present disclosure, however, is not limited to the foregoing exemplary first component formation techniques.

In step <NUM>, a second component 58B such as the support member <NUM> is provided. The second component 58B of <FIG> may be formed using one or more formation processes. Examples of these formation processes include, but are not limited to, laminating, molding, pressing, injection molding, overmolding, and stamping between a plurality of dies. For example, referring to <FIG>, a fiber-reinforced thermoplastic preform <NUM> (e.g., a sheet, plate, etc. of the fiber-reinforced thermoplastic) may be arranged between a top die <NUM> and a bottom die <NUM> of a die assembly <NUM>. One or more of these dies <NUM> and <NUM> may be moved (e.g., vertically) from a first (e.g., open) arrangement of <FIG> to a second (e.g., closed) arrangement of <FIG> to stamp the preform <NUM> into the second component 58B. One or more of the dies <NUM> and <NUM> may subsequently by moved (e.g., vertically) back from the second arrangement of <FIG> to the first arrangement of <FIG> to facilitate release of the now stamped second component 58B from the die assembly <NUM>. Such a stamping process may also or alternatively be performed to form the first component 58A or another component of the fiber-reinforced thermoplastic structure. The present disclosure, however, is not limited to the foregoing exemplary second component formation techniques.

In step <NUM>, the second component 58B is disposed with the first component 58A. The support member <NUM> of <FIG>, for example, may be arranged next to the exterior skin <NUM>. One or more of the mounts <NUM> may (e.g., longitudinally and/or laterally) overlap and engage (e.g., abut against, contact, etc.) the interior surface <NUM> of the exterior skin <NUM>. An interior surface <NUM> of each of the mounts <NUM>, for example, may be laid flush against the interior surface <NUM> of the exterior skin <NUM>.

In step <NUM>, the second component 58B is vibration welded to the first component 58A. One or more of the mounts <NUM>, for example, may each be linear vibration welded to the exterior skin <NUM> to provide a respective weld joint <NUM> (see also <FIG>) between the respective mount <NUM> and the exterior skin <NUM>. For example, referring to <FIG>, the first component 58A (e.g., the exterior skin <NUM>) is arranged with first tooling 72A (e.g., a fixture), which first tooling 72A locates and/or holds the first component 58A for the vibration welding. The second component 58B (e.g., the support member <NUM>) is arranged with second tooling 72B (e.g., a fixture), which second tooling 72B locates and/or holds the second component 58B for the vibration welding. During the vibration welding, the first tooling 72A and/or the second tooling 72B is moved (e.g., laterally and/or longitudinally; horizontally in <FIG>) to generate heat (via frictional rubbing) at each interface between the first component 58A and the second component 58B. This heat locally melts the thermoplastic material <NUM> at the respective interface. The tooling 72A, 72B (generally referred to as "<NUM>") movement is subsequently terminated. The tooling <NUM> may hold the first component 58A and the second component 58B in position until the thermoplastic material <NUM> at each interface cools under pressure, resolidifying and thereby providing the respective weld joint <NUM>. The now welded components 58A and 58B (generally referred to as "<NUM>") are subsequently released from the tooling <NUM>, for example, for further processing; e.g., machining, finishing, etc..

Referring to <FIG>, interfacing portions of the fiber-reinforced thermoplastic composite of the first component 58A and the second component 58B may be consumed during the vibration welding step <NUM>. In other words, the interfacing portions of the fiber-reinforced thermoplastic composite of the first component 58A and the second component 58B may (e.g., slightly) collapse during the vibration welding step <NUM>. The term "collapse" may describe a distance one (e.g., a vibrating) part moves into another (e.g., a stationary) part during vibration welding. These material portions <NUM> (see <FIG>), for example, may be (e.g., laterally and/or longitudinally) displaced to one or more sides of the weld joint <NUM>; e.g., to one or more sides of a respective mount <NUM>. This consumption / displacement of the fiber-reinforced thermoplastic composite (e.g., see <NUM> in <FIG>) may decrease a thickness of each component 58A, 58B at the weld joint <NUM>. The mount <NUM> of <FIG>, for example, has a vertical first mount thickness 76A at (e.g., on, adjacent or proximate) a location of the to-be-formed weld joint <NUM> prior to the vibration welding. The mount <NUM> of <FIG>, by contrast, may have a vertical second mount thickness 76B at the weld joint location that is different (e.g., less) than the first mount thickness 76A subsequent to the vibration welding. Thus, a portion of the first component 58A at the weld joint <NUM> may be consumed / collapse during the vibration welding step <NUM>. Similarly, the exterior skin <NUM> of <FIG> has a vertical first skin thickness 78A at the weld joint location prior to the vibration welding. The exterior skin <NUM> of <FIG>, by contrast, may have a vertical second skin thickness 78B at the weld joint location that is also or alternatively different (e.g., less) than the first skin thickness 78A subsequent to the vibration welding. Thus, a portion of the second component 58B at the weld joint <NUM> may be consumed / collapse during the vibration welding step <NUM>. Such a diminution in component thickness(es) may adversely affect structural properties of the aircraft structure <NUM> if not accounted as well as lead to unwanted bending of the aircraft structure <NUM>.

The diminution in component thickness(es) may be accounted for by increasing an overall thickness of each component <NUM> to be vibration welded. Such an overall increase in component thickness, however, also increases cost, size and weight of the respective component <NUM> as well as the aircraft structure <NUM> in general. Alternatively, a thickness of one or more or all of the components <NUM> to be vibration welded together may be locally increased. For example, referring to <FIG>, the first component 58A (e.g., the exterior skin <NUM>) may include a base <NUM> and one or more material buildups <NUM> (one visible in <FIG>) prior to the vibration welding. Each material buildup <NUM> is extra material that is added to the design of the aircraft structure <NUM>; e.g., the laminate. For example, where too much of an outer layer of one of the components <NUM> may be sacrificed during the vibration welding leading to a relatively large collapse as discussed above, the material buildup <NUM> is provided. That material buildup <NUM> may be a ply (or multiple plies) of the laminate with fiber reinforcement (e.g., continuous and/or unidirectional fibers) in the same direction as the outer layer of the base <NUM>. This extra material is included to provide symmetry and/or satisfy other design requirements following the vibration welding. The material buildup <NUM>, for example, is included as a consumable for the vibration welding such that, for example, dimensions of the final aircraft structure <NUM> remains substantially constant along the weld. By contrast, the consumption of material shown in <FIG> may lead to unwanted bending of the aircraft structure <NUM>, particular where the aircraft structure <NUM> and its components <NUM> are formed from a continuous fiber-reinforced composite. Note, the aircraft structure <NUM> may be less prone to such bending where the aircraft structure <NUM> and its components <NUM> are formed from a chopped fiber-reinforced composite or a pure thermoplastic material (e.g., without fiber reinforcement).

The base <NUM> may be constructed from the one or more component layers <NUM> (see <FIG>) of fiber reinforcement embedded within the thermoplastic material <NUM>; e.g., thermoplastic matrix. The material buildup <NUM> is a localized buildup of the thermoplastic material <NUM> (or a shortened layer of the fiber reinforcement embedded within the thermoplastic material <NUM>) on a select portion of the base <NUM>; e.g., see layer 56F in <FIG>. More particularly, a (e.g., longitudinal and/or lateral) section <NUM> of the first component 58A at a respective weld location includes a respective (e.g., longitudinal and/or lateral) section of the base <NUM> and the respective material buildup <NUM>. One or more sections <NUM> of the first component 58A (e.g., longitudinally and/or laterally) adjacent the built up section <NUM>, however, each include (e.g., only) a respective (e.g., longitudinal and/or lateral) section of the base <NUM> without the material buildup <NUM>. A vertical thickness <NUM> of the built up section <NUM> is thereby greater than a vertical thickness <NUM> of the adjacent nominal (e.g., non-built up) section(s) <NUM>. Referring to <FIG>, the amount of material locally built up on the base <NUM> in the built up section <NUM> may be selected such that the material buildup <NUM> is partially or completely consumed (e.g., displaced) during the vibration welding. More particularly, the amount of material locally built up on the base <NUM> in the built up section <NUM> of <FIG> may be selected such that a vertical thickness <NUM> of the first component 58A at the respective weld location subsequent to the vibration welding (see <FIG>) is exactly equal to or substantially equal to (e.g., within <NUM>%, <NUM>%, <NUM>%, <NUM>% of) a vertical thickness <NUM> of the base <NUM> at or about the respective weld location prior to the vibration welding (see <FIG>), where the thickness <NUM> may be equal to (or different than) the thickness <NUM>. In other words, the respective material buildup <NUM> of <FIG> may be provided to maintain the dimensions of the first component 58A of <FIG> even through / across the weld joint <NUM>. Similarly, referring to <FIG>, the second component 58B may also or alternatively be provided with a base <NUM> and one or more material buildups <NUM> (one visible in <FIG>) prior to the vibration welding to be at least partially or completely consumed (e.g., displaced) during the vibration welding.

In some embodiments, referring to <FIG>, a geometry of a perimeter <NUM> of a respective material buildup <NUM> may match (e.g., be the same as) a geometry of a perimeter <NUM> of a portion <NUM> of another component (e.g., <NUM>, 58B) to be vibration welded to the material buildup area. The perimeter <NUM> of the material buildup <NUM> and the perimeter <NUM> of the portion <NUM> of <FIG>, for example, each have a polygonal (e.g., rectangular, square, triangular, etc.) perimeter geometry. The perimeters <NUM> and <NUM>, of course, may have various other geometries.

In some embodiments, a size of a respective material buildup <NUM> may be exactly equal to or approximately equal to (e.g., within <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% of) a size of a geometry of the portion <NUM> of other component (e.g., <NUM>, 58B) to be vibration welded to the material buildup area. Dimensions of the perimeter <NUM> of the material buildup <NUM> and dimensions of the perimeter <NUM> of the portion <NUM> of <FIG>, for example, may be exactly or approximately equal. The perimeters <NUM> and <NUM>, of course, may alternatively have different dimensions in other embodiments.

The structure <NUM> and its components <NUM> may have various configurations other than that described above. Examples of such alternative structure and component configurations are illustrated in <FIG>. The present disclosure, however, is not limited to such exemplary component configurations nor to such exemplary structure configurations.

In some embodiments, referring to <FIG>, each of the weld joints <NUM> may be arranged along / lay within a common plane; e.g., the x-y plane. In other embodiments, referring to <FIG>, two or more of the weld joints <NUM> may be arranged along / lay within different planes. The first weld joint 70A of <FIG>, for example, is arranged along / lays within a first plane and the second weld joint 70B is arranged along / lays within a second plane. The second weld joint 70B and its second plane of <FIG> may be parallel with the first weld joint 70A and its first plane, but vertically offset (e.g., spaced) from the first weld joint 70A and its first plane by a vertical gap. The second weld joint 70B of <FIG> is also laterally offset (e.g., spaced) from the first weld joint 70A by a vertical gap; or course, the second weld joint 70B may also or alternatively be longitudinally offset from the first weld joint 70A. By contrast, the second weld joint 70B of <FIG>, is laterally aligned with (e.g., laterally overlaps, centered with respect to, etc.) the first weld joint 70A.

In some embodiments, referring to <FIG>, the plane of at least one of the weld joints <NUM> may be parallel with the plane of at least another one of the weld joints <NUM>; see also <FIG>. In other embodiments, referring to <FIG>, the plane of at least one of the weld joints <NUM> may be angularly offset from the plane of at least another one of the weld joints <NUM>. The first weld joint 70A and its first plane of <FIG>, for example, is angularly offset from the second weld joint 70B and its second plane by an included angle, which included angle may be an acute angle, a right angle or an obtuse angle.

In some embodiments, referring to <FIG>, one or more or each of the weld joints <NUM> may extend longitudinally along a straight centerline <NUM>. The weld joints <NUM> of <FIG>, for example, are formed along flat, planar surfaces (e.g., <NUM> and <NUM> in <FIG>) of the components <NUM>. In other embodiments, referring to <FIG>, one or more or each of the weld joints <NUM> (e.g., 70A and 70B) may each extend longitudinally along a curved centerline. The weld joints 70A and 70B of <FIG>, for example, are arranged along respective component surfaces, where at least a portion or an entirety of each component surface has a curved (e.g., partially circular, arcuate, splined, etc.) sectional geometry.

In some embodiments, referring to <FIG>, the welded components <NUM> may have a common (e.g., the same, mirrored, etc.) configuration. In other embodiments, referring to <FIG> and <FIG>, the welded components <NUM> may have unique (e.g., different) configurations.

Claim 1:
A formation method, comprising:
providing a first component (58A) comprising a first fiber-reinforced thermoplastic composite, the first component (58A) including a base (<NUM>) and a material buildup (<NUM>) on a portion of the base (<NUM>), wherein the material buildup (<NUM>) is a localized buildup of thermoplastic material on the portion of the base such that a built up section (<NUM>) of the first component (58A) includes a respective section of the base (<NUM>) and the material buildup (<NUM>) and one or more sections (<NUM>) of the first component (58A) adjacent the built up section (<NUM>) include a respective section of the base (<NUM>) without the material buildup (<NUM>);
providing a second component (58B) comprising a second fiber-reinforced thermoplastic composite;
arranging the second component (58B) with the first component (58A), the second component (58B) abutting the material buildup (<NUM>); and
vibration welding the second component (58B) to the first component (58A) to provide a weld joint (<NUM>) between the first component (58A) and the second component (58B), wherein at least a portion (<NUM>) of the material buildup (<NUM>) is displaced during the vibration welding,
characterised in that at least one of:
the first fiber-reinforced thermoplastic composite comprises at least thirty-five percent by unit volume continuous fibers; or
the second fiber-reinforced thermoplastic composite comprises at least thirty-five percent by unit volume continuous fibers.