Patent Description:
Solid laminate stringers are used in in the aerospace industry as structural components of aircraft and/or to stiffen composite panels, such as fuselage, skin, and/or wing sections. Solid laminate stringers may be formed by stacking multiple layers of composite materials, such as resin-impregnated carbon fiber-reinforced plies.

However, current methods for fabricating solid laminate stringers require manual or semi-manual placement of the composite material layers or plies, may be limited to straight and/or constant width composite material layers or plies, and may require splicing the composite material layers or plies to account for curvatures in the composite panels or overall length of the solid laminate stringer. In addition, manual or semi-manual placement and splicing may generate flaws and wrinkling due to splicing or misalignment of the composite material layers or plies over curved surfaces during curing. The additional labor required by manual or semi-manual placement and splicing makes it harder to meet high volume and high rate production of airplane structures presently demanded.

Patent document <CIT>, according to its abstract, states a method and apparatus for fabricating a composite structure which includes a tape placement machine including a delivery head configured to dispose a composite tape and a backing plate coupled to the tape placement machine and selectively located relative to the delivery head to react to a placement force applied by the tape placement machine as the composite tape is being disposed.

Patent document <CIT>, according to its abstract, states a system for fabrication of an aerospace structure which incorporates a mold having a surface and at least one unidirectional SFL head adapted to lay down a plurality of collimated tows in a predetermined laminated pattern on the mold surface to produce a fuselage skin. At least one cross plied laminate SFL head is adapted to lay down a cross plied laminate base interface on the fuselage skin to establish a lattice rib shape for each of a plurality of lattice ribs. The cross plied laminate SFL head has a band placement head steerable to avoid structural design features and to maintain spacing from adjacent steered lattice ribs. The unidirectional SFL head is further adapted to lay down a plurality of collimated tows on the base interface of each of the plurality of lattice ribs for a first plurality of unidirectional tow plies in each lattice rib. The unidirectional SFL head has a fiber placement head steerable to match the lattice rib shape to avoid structural design features and to maintain spacing from adjacent steered lattice ribs.

Patent document <CIT>, according to its abstract, states a system and method of performing a ply layup for a composite panel. The system and method may include attaching an electronically identifiable tag to at least one of a plurality of plies, and checking, using the electronically identifiable tag, to ensure the proper sequence of plies for the panel is being followed.

Patent document <CIT>, according to its abstract, states a manual auxiliary method for producing laminated composite product mainly including: a supporting table device and a superposition device, the superposition device is positioned on the supporting table device, the superposition device is equipped with a data group to define a material layer position marked by laser beams projected from all points, a composite laminated material layer is manually placed on the superposition device according to the position marked by laser beams, and a forming/pressurizing bag device is used to implement forming and pressurizing operation, and the supporting table device is vacuum-pumped.

Patent document <CIT>, according to its abstract, states a solid laminate stringer which includes a base segment that forms a first generally trapezoidal cross section. The solid laminate stringer also includes a transition segment abutting the base segment, with concave sides that are continuous with the sides of the base segment. The solid laminate stringer also includes a top segment abutting the transition segment, where the top segment forms a second generally trapezoidal cross section with sides that are continuous with the concave sides of the transition segment. The solid laminate stringer also includes a first overwrap layer covering the top segment, the transition segment, and at least a portion of the base segment. The solid laminate stringer also includes a second overwrap layer overlapping at least a portion of the first overwrap layer covering the base segment. Accordingly, there is a need for improved methods for fabricating solid laminate stringers that are less labor intensive and are able to accommodate widths, lengths and curvatures of the composite panels without splicing.

Patent document <CIT>, according to its abstract, states systems and apparatuses for manufacturing aircraft support structures. An example robotic end effector comprises a rotatable reel with a flat strip of material wound around the reel. The end effector further includes a forming shoe including a forming surface contacting the strip of material. A first end of the forming surface corresponds to a start shape and a second end of the forming surface corresponds to an end shape. As the strip of material passes from the first end of the forming surface to the second end of the forming surface, the strip of material transitions from the first shape to the end shape and is deposited as a formed stringer ply onto an application surface. The forming shoe may further include a vacuum system to suction air through a plurality of ports along the forming surface to urge the strip of material against the forming surface.

This summary is intended merely to introduce a simplified summary of the present disclosure.

The foregoing and/or other aspects and utilities exemplified in the present disclosure may be achieved by providing a method according to claim <NUM>.

The unspooling one or more composite layers onto the composite panel may include using overhead laser projection to synchronize the unspooling one or more composite layers according to at least one of a move speed, a rotation rate, a compacting pressure, and a heating temperature.

The unspooling one or more composite layers onto the composite panel further includes aligning at least one of edges and centerlines of the one or more composite layers on the composite panel to curved lines.

The unspooling one or more composite layers onto the composite panel may include using computer controlled spools to execute unspooling along pre-specified almost straight and slightly curved lines according to at least one of pre-determined move speeds, rotation rates, compacting pressures, and heating temperatures.

The curing one or more composite layers unspooled onto the composite panel may include placing a vacuum bag over the one or more composite layers and applying a compaction pressure to the one or more composite layers.

The vacuum bag may cover at least a portion of the composite panel, and the curing the one or more composite layers unspooled onto the composite panel may further include simultaneously curing the composite panel.

The solid laminate stringer may include two or more composite layers, and each of the two or more composite layers may include one or more composite plies.

The two or more composite layers may include spooled pre-pregs.

Each of the two or more composite layers may be spooled according to a lay-up design for the solid laminate stringer, and a length of the two or more composite layers may correspond to at least a length of the solid laminate stringer.

The solid laminate stringer does not include spliced composite layers.

A width of the solid laminate stringer may be from about <NUM> to about <NUM>.

The solid laminate stringer may include one or more lateral edges, and the one or more lateral edges may include a slope angle from about <NUM> ° to about <NUM> °.

The solid laminate stringer may include one or more concave or convex curvatures along at least one of an x-axis, a y-axis, and a z-axis.

The curvature along the x-axis may have a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches).

The curvature along the y-axis may have a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches).

The one or more composite layers may include at least one of a base wrap layer and a top wrap layer.

Further areas of applicability will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred example of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

The accompanying drawings, illustrate the present disclosure. In the figures:.

It should be noted that some details of the figures have been simplified and are drawn to facilitate understanding of the present teachings rather than to maintain strict structural accuracy, detail, and scale.

Reference will now be made in detail to the present teachings, examples of which are illustrated in the accompanying drawings. Generally, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

As used herein, the term "or" is an inclusive operator, and is equivalent to the term "and/or," unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In the specification, the recitation of "at least one of A, B, and C," includes examples containing A, B, or C, multiple examples of A, B, or C, or combinations of A/B, A/C, B/C, A/B/B/ B/B/C, A/B/C, etc. In addition, throughout the specification, the meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on.

It will also be understood that, although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. For example, a first object, component, or step could be termed a second object, component, or step, and, similarly, a second object, component, or step could be termed a first object, component, or step, without departing from the scope of the disclosure. The first object, component, or step, and the second object, component, or step, are both objects, components, or steps, respectively, but they are not to be considered the same object, component, or step. It will be further understood that the terms "includes," "including," "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. Further, as used herein, the term "if" can be construed to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context.

All physical properties that are defined hereinafter are measured at <NUM>° to <NUM>° Celsius unless otherwise specified.

When referring to any numerical range of values herein, such ranges are understood to include each and every number and/or fraction between the stated range minimum and maximum, as well as the endpoints. For example, a range of <NUM>% to <NUM>% would expressly include all intermediate values of, for example, <NUM>%, <NUM>%, and <NUM>%, all the way up to and including <NUM>%, <NUM>%, and <NUM>%, among many others. The same applies to each other numerical property and/or elemental range set forth herein, unless the context clearly dictates otherwise.

It should be appreciated that all numerical values and ranges disclosed herein are approximate values and ranges. The terms "about" or "substantial" and "substantially" or "approximately," with reference to amounts or measurement values, are meant that the recited characteristic, parameter, or values need not be achieved exactly. Rather, deviations or variations, including, for example, tolerances, measurement error, measurement accuracy limitations, and other factors known to those skilled in the art, may occur in amounts that do not preclude the effect that the characteristic was intended to provide.

The percentages and amounts given are based on the active weight of the material. For example, for an active ingredient provided as a solution, the amounts given are based on the amount of the active ingredient without the amount of solvent or may be determined by weight loss after evaporation of the solvent.

With regard to procedures, methods, techniques, and workflows that are in accordance with the present disclosure, some operations in the procedures, methods, techniques, and workflows disclosed herein can be combined and/or the order of some operations can be changed.

The inventors have created new methods for fabricating solid laminate stringers on a composite panel. The methods can use automated digital model controlled processes to spool, unspool, compact, and cure multiple solid laminate stringers simultaneously on a skin substrate directly as one piece composite structure. The methods may streamline the fabrication process by eliminating manual or semi-manual placements and splicing of composite layers as they lie over curved surfaces. The methods may reduce the labor required, minimizing injuries, errors, and consequent defects, as well as wrinkling, during fabrication of high-quality and safe integrated composite parts. The methods may require less labor, materials, and fabrication floor space and may reduce the associated fabrication costs to enable large volume production at high rates.

<FIG> illustrates a composite panel with solid laminate stringers according to the present disclosure. <FIG> illustrates a curved solid laminate stringer on a composite panel according to the present disclosure.

<FIG> illustrates a close-up of a solid laminate stringer on a composite panel according to the present disclosure. <FIG> illustrates a widthwise cross-sectional view of a solid laminate stringer on a composite panel according to the present disclosure. As illustrated in <FIG>, one or more solid laminate stringers <NUM> may be formed on a composite panel <NUM> and each solid laminate stringer <NUM> may include two or more composite layers <NUM>.

Each solid laminate stringer <NUM> may include two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or <NUM> or more composite layers <NUM>. For example, the solid laminate stringer <NUM> may include from <NUM> to about <NUM> composite layers <NUM>. A solid laminate stringer <NUM> may include <NUM> or less, <NUM> or less, <NUM> or less, or six or less composite layers <NUM>. For example a solid laminate stringer <NUM> may include <NUM> composite layers <NUM>, <NUM> composite layers <NUM>, or <NUM> composite layers <NUM>.

For example, as illustrated in <FIG>, a solid laminate stringer <NUM> may include a first composite layer <NUM>, a second composite layer <NUM>, a third composite layer <NUM>, and a fourth composite layer <NUM>.

The composite layers <NUM> may include strong, light-weight, materials created by combining two or more functional components which may be cured into a single structure. For example, a composite layer <NUM> may include a filler bound in a resin matrix. Resins used in the composite layers <NUM> may include thermoplastic or thermoset resins, such as epoxy resins. The fillers may be reinforcing or non-reinforcing in nature and may be in a variety of shapes, for example, powders, particulates, flakes, foams, nano or micro tubes, continuous and discontinuous fibers reinforced tapes or fabrics, and the like.

The composite layers <NUM> preferably include carbon fiber-reinforced plies of composite material or composite plies. For example, as illustrated in <FIG>, a composite layer <NUM> may include one or more composite plies <NUM>. The composite plies <NUM> may be made from unidirectional composite tape material impregnated with an epoxy resin.

The composite plies <NUM> may be made from woven fabric materials finished with a resin, such as fiberglass, carbon, or aramid fabrics infused with an epoxy resin.

The composite layers <NUM> may include pre-pregs. As used herein, the term "pre-preg" refers to pre-impregnated stacks of composite plies, such as epoxy impregnated unidirectional composite tape. A pre-preg may be flexible until it is cured, often by heat and pressure curing or curing within an autoclave.

Each composite layer <NUM> may include one or more composite plies <NUM>. A composite layer <NUM> may include <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, or <NUM> or more composite plies <NUM>. A composite layer <NUM> may include <NUM> or less, <NUM> or less, <NUM> or less, or five or less composite plies <NUM>. For example, a composite layer <NUM> may include <NUM> composite ply, <NUM> composite plies, or <NUM> composite plies.

The composite plies <NUM> forming each composite layer <NUM> may have a traditional orientation layup. For example, the composite plies <NUM> may be positioned at angles to the x-axis of the solid laminate stringer <NUM> including <NUM>°, <NUM>°, -<NUM>°, and <NUM>°. The composite plies <NUM> forming each composite layer <NUM> may have a non-traditional orientation layup, and/or a mix of traditional and non-traditional orientation layups. The number of composite plies <NUM> positioned at these orientation angles maybe evenly distributed or may be unevenly distributed. Accordingly, each composite layer <NUM> may have one or more composite plies <NUM> and the one or more composite plies <NUM> may have different orientations.

The composite panel <NUM> may also include strong, light-weight, materials created by combining two or more functional components which may be cured into a single structure. For example, the composite panel <NUM> may include a plurality of composite layers laminated and cured into a single structure. The composite panel <NUM> may be configured to be compatible and/or bond to the solid laminate stringer <NUM> when cured.

The composite panel <NUM> may have a same or similar curing process than the solid laminate stringer <NUM>. The composite panel <NUM> may be formed of same or similar composite layers <NUM> or composite plies <NUM> to reduce material incompatibility between the composite panel <NUM> and the solid laminate stringer <NUM>, such as thermal cracking and bonding issues.

As illustrated in <FIG>, a length L of the solid laminate stringer <NUM> may correspond to a length of the composite panel <NUM>. For example, the length L of the solid laminate stringer <NUM> may extend and/or equal the full length of the composite panel <NUM>.

A length of the one or more composite layers <NUM> corresponds to at least a length of the solid laminate stringer <NUM>. For example, at least one of the one or more composite layers <NUM> may have a length equal to the length of the solid laminate stringer <NUM>. All composite layers <NUM> may have a length at least equal to the length of the solid laminate stringer <NUM>. Alternatively, at least one of the one or more composite layers <NUM> can have has a length longer than the length of the solid laminate stringer <NUM>.

A length of the composite plies <NUM> forming each composite layer <NUM> can be uniform. Alternatively the length of the composite plies <NUM> forming each composite layer <NUM> can vary. For example, the length of the composite plies <NUM> may vary along the x-axis (see <FIG>).

The composite layers <NUM> are not spliced. For example, the solid laminate stringer <NUM> may not include spliced composite layers <NUM>. That is, a composite layer <NUM> may not be formed from one or more composite layers <NUM> spliced together along a length of the solid laminate stringer <NUM>. The composite layers <NUM> may be single continuous composite layers <NUM>. The composite layers <NUM> may be single continuous layers of composite plies <NUM>.

A width of the solid laminate stringer <NUM> may be from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>. For example, a width of the solid laminate stringer <NUM> may be about <NUM>. The width of the solid laminate stringer <NUM> may be uniform along a length L of the stringer. The solid laminate stringer <NUM> may have a variable width. For example, as illustrated in <FIG>, the solid laminate stringer <NUM> may have one or more widths (W1, W2, W3) along a length L of the solid laminate stringer <NUM>.

The width of the solid laminate stringer <NUM> may vary from about <NUM> to about <NUM> along a length L of the solid laminate stringer <NUM>. For example, a maximum width of the solid laminate stringer may be at least <NUM> times, <NUM> times, <NUM> times, <NUM> times, or <NUM> times the minimum width of the solid laminate stringer <NUM>. A maximum width of a composite layer <NUM> may be at least <NUM> times, <NUM> times, or <NUM> times the minimum width of the composite layer <NUM>.

The width of the solid laminate stringer <NUM> may vary along at least one of the x-axis and the z-axis. The width of the solid laminate stringer may vary along both the x-axis and the z-axis.

A width of the composite layers <NUM> forming the solid laminate stringer <NUM> can be uniform along the z-axis. Alternatively, the width of the composite layers <NUM> forming the solid laminate stringer <NUM> may vary along the z-axis. For example, a width of the solid laminate stringer <NUM> may be wider at the base, where it contacts the composite panel <NUM>, than at the top.

Accordingly, as illustrated in <FIG>, a width of a first composite layer <NUM> at a base of the solid laminate stringer <NUM> may be equal to or wider than a width of a second composite layer <NUM>, a third composite layer <NUM>, and/or a fourth composite layer <NUM>. Similarly, a width of the second composite layer <NUM> may be equal to or wider than a width of the third composite layer <NUM> and/or the fourth composite layer <NUM>. A width of the third composite layer <NUM> may also be equal to or wider than a width of the fourth composite layer <NUM>.

As illustrated in <FIG>, the solid laminate stringer <NUM> may include lateral edges <NUM>. The lateral edges <NUM> of the solid laminate stringer <NUM> are formed by the lateral edges of the composite layers <NUM> forming the solid laminate stringer <NUM>. For example, as illustrated in <FIG>, a lateral edge <NUM> is formed by a first lateral edge <NUM> of a first composite layer <NUM>, a second lateral edge <NUM> of a second composite layer <NUM>, a third lateral edge <NUM> of a third composite layer <NUM>, and a fourth lateral edge <NUM> of a fourth composite layer <NUM>.

The lateral edges <NUM> may have a slope angle from about <NUM> ° to about <NUM> °. The lateral edges <NUM> may have a slope angle from about <NUM> ° to about <NUM> °, from about <NUM> ° to about <NUM> °, or from about <NUM> ° to about <NUM> °.

The slope angle of the lateral edges <NUM> may vary along z-axis. The slope angle of the lateral edges <NUM> may vary along at least one of the x-axis, y-axis, and the z-axis. The slope angle of the lateral edges <NUM> may vary along both the x-axis and the z-axis.

As illustrated in <FIG>, the slope angle of the lateral edges <NUM> can be symmetrical. As also illustrated in <FIG>, a first slope angle of a first lateral edge <NUM> may be different from a second slope angle of a second lateral edge <NUM>.

A slope angle of the lateral edges <NUM> may be lowest at the base, where it contacts the composite panel <NUM>, than at the top. Accordingly, a slope angle of the lateral edge of the composite layer <NUM> at a base of the solid laminate stringer <NUM> may be equal or lower than a slope angle of the lateral edge of the other composite layers <NUM> forming the solid laminate stringer.

For example, as illustrated in <FIG>, a slope angle of the first lateral edge <NUM> of a first composite layer <NUM> is lower than a slope angle of the second lateral edge <NUM> of the second composite layer <NUM>, a slope angle of the third lateral edge <NUM> of a third composite layer <NUM>, and a slope angle of the fourth lateral edge <NUM> of a fourth composite layer <NUM>. Similarly, the slope angle of the second lateral edge <NUM> may be lower than the slope angle of the third lateral edge <NUM> and the fourth lateral edge <NUM>.

The lateral edges <NUM> may be continuous. That is, the lateral edges of the composite layers <NUM> forming the solid laminate stringer <NUM> form continuous lateral edges <NUM> of the solid laminate stringer. For example, the first lateral edge <NUM> may be continuous with the second lateral edge <NUM>, the third lateral edge <NUM>, and the fourth lateral edge <NUM>.

As illustrated in <FIG>, the composite panel <NUM> may include one or more concave or convex curvatures along at least one of the x-axis, y-axis, and z-axis. Accordingly, the solid laminate stringer <NUM> may include one or more curvatures <NUM> to correspond to the curvatures of the composite panel <NUM>. The curvatures <NUM> may be along at least one of the x-axis, y-axis, and z-axis, and the curvatures <NUM> may be convex or concave. For example, the solid laminate stringer may have a curvature <NUM> along the y-axis, a curvature <NUM> along the x-axis, and/or a curvature <NUM> along the z-axis.

The curvatures <NUM> along the x-axis may have a curvature in the x-z plane and/or the x-y plane with a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM>inches). For example, the curvature <NUM> may have a curvature with a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM>inches), from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches) or from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches). For example, as illustrated in <FIG>, the solid laminate stringer <NUM> may have a centerline curvature <NUM> along the x-axis in the x-y plane.

The curvatures <NUM> along the y-axis in the y-z plane may have a curvature with a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches). For example, the curvature <NUM> may have a curvature with a radius from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches), from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches), or from about <NUM> (<NUM> inches) to about <NUM> ×<NUM><NUM> cm (<NUM><NUM> inches).

The one or more composite layers <NUM> may include one or more wrap layers <NUM>, and the solid laminate stringer <NUM> may include one or more wrap layers <NUM>. For example, as illustrated in <FIG>, the solid laminate stringer <NUM> may include a base wrap layer <NUM> and a top wrap layer <NUM> as examples of the one or more wrap layers <NUM>.

The top wrap layer <NUM> may be configured to cover a top surface and lateral edges of the solid laminate stringer <NUM>. For example, as illustrated in <FIG>, the top wrap layer <NUM> is disposed over the lateral edges <NUM>, <NUM>, <NUM>, and <NUM> of the first, second, third, and fourth composite layers <NUM>, <NUM>, <NUM>, and <NUM> (forming the lateral edges <NUM>) and over a top surface <NUM> of the fourth composite layer <NUM>. In some implementations, the top wrap layer <NUM> may cover at least a portion of the composite panel <NUM>. The top wrap layer <NUM> may cover exposed fiber ends present in the composite layers <NUM> due to trimming.

As illustrated in <FIG>, the base wrap layer <NUM> may be disposed over the top wrap layer <NUM> along a lower portion of the lateral edges <NUM>. The base wrap layer <NUM> may cover at least a portion of the top wrap layer <NUM>. The base wrap may also be disposed over at least a portion of the composite panel <NUM>. The base wrap layer <NUM> may cover at least a portion of the composite panel <NUM>. The bottom wrap layer <NUM> can enhance a connection of the solid laminate stringer <NUM> to the composite panel <NUM> to prevent delamination.

As described above, a length of the composite plies <NUM> forming each composite layer <NUM> may vary. <FIG> illustrates a lengthwise stacking configuration to form composite layers of a solid laminate stringer according to the present disclosure.

As illustrated in <FIG>, the length of the composite plies <NUM> forming the second composite layer <NUM> and the third composite layer <NUM> may vary along an axis of symmetry <NUM> along the x-axis. For example, the length of the composite plies <NUM> forming the second composite layer <NUM> and the third composite layer <NUM> may be successively terminated along the x-axis around the axis of symmetry <NUM>. The length of the composite plies <NUM> forming the first composite layer <NUM> and the fourth composite layer <NUM> may be uniform and may correspond to at least the length L of the solid laminate stringer <NUM> and/or the length of the composite panel <NUM>.

<FIG> illustrates runout ends of a solid laminate stringer according to the present disclosure. <FIG> illustrates a lengthwise cross-sectional view of runout ends of a solid laminate stringer according to the present disclosure. As illustrated in <FIG>, the approximately symmetric arrangement of the composite plies in the composite layers <NUM> described above with respect to <FIG> may be advantageous at the runout ends of the solid laminate stringer <NUM>. For example, as the composite plies <NUM> of the second and third composite layers <NUM> and <NUM> are successively terminated, a height of the solid laminate stringer <NUM> (along the z-axis) may be reduced along the x-axis. The termination of the composite plies <NUM> alternating from just above the line of symmetry <NUM> to just below the line of symmetry <NUM> may help maintain an approximate symmetry of the remaining composite plies <NUM> forming the composite layers <NUM>.

For the purposes of illustrated the stepwise configuration of the successively terminated composite plies <NUM>, the schematic view illustrated in <FIG> does not illustrate the remaining composite plies <NUM> converging at the line of symmetry <NUM>, and thereby reducing the height of the solid laminate stringer <NUM> once formed. However, this effect is illustrated in <FIG>.

As illustrated in <FIG>, as the composite plies <NUM> of the second and third composite layers <NUM> and <NUM> are successively terminated along the line of symmetry <NUM>, the height of the solid laminate stringer <NUM> is reduced in the x-axis toward a runout end <NUM>. The runout end <NUM> may correspond to a total length of the solid laminate stringer <NUM> and/or may correspond to a total length of the composite panel <NUM>. As illustrated in <FIG>, a width of the solid laminate stringer <NUM> may increase as the height decreases towards the runout end <NUM>. Further, the first composite layer <NUM> and the fourth composite layer <NUM> remain the lowermost and uppermost composite layers <NUM> of the solid laminate stringer <NUM>. <FIG>, showing a lengthwise cross-sectional view in the x-z plane, illustrates the fourth composite layer <NUM> and the first composite layer <NUM> converging to the line of symmetry <NUM> at the runout end <NUM>. A top wrap layer <NUM> (not illustrated) may be disposed over the fourth composite layer <NUM>.

<FIG> illustrates a system for forming a solid laminate stringer on a composite panel according to the present disclosure. As illustrated in <FIG>, a system <NUM> for forming a solid laminate stringer <NUM> on a composite panel <NUM> includes a spool <NUM>, a cutter <NUM>, a roller <NUM>, and a computer <NUM>.

<FIG> illustrates a method for forming a solid laminate stringer on a composite panel according to the present disclosure. <FIG> illustrates an example of a method that, for instance, could be used to fabricate a solid laminate stringer <NUM> as described above and as illustrated in <FIG>. As illustrated in <FIG>, a method <NUM> for forming a solid laminate stringer <NUM> on a composite panel <NUM> may be described with respect to the system <NUM> of <FIG> and the solid laminate stringer of <FIG>.

It should be understood that for this and other processes and methods disclosed herein, the methods of <FIG> and <FIG>, show functionality and operation of one or more possibilities of the present disclosure. In this regard, each block in the methods of <FIG> and <FIG> may represent a module, segment, or portion of a program code, which includes one or more instructions executable by a processor for implementing or causing specific logical functions or steps in the process. For example, the methods of <FIG> and <FIG> may be implemented by one or more computing devices of a robotic assembly system. Alternatives are included within the scope of the present disclosure, in which function may be executed out of order from that shown or discussed, including substantially concurrently, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

The method <NUM> may start with operation <NUM>. Operation <NUM> includes unspooling one or more composite layers <NUM> onto a composite panel <NUM>.

The one or more composite layers <NUM> may be unspooled continuously along a length corresponding to a length of the solid laminate stringer <NUM>. As used herein, the terms "unspooled continuously" refers to unspooling a composite layer <NUM> as a single continuous composite layers <NUM>. A composite layer <NUM> unspooled continuously is not spliced. That is, a composite layer <NUM> unspooled continuously is not formed from one or more composite layers <NUM> spliced together along a length corresponding to a length of the solid laminate stringer <NUM>.

As illustrated in <FIG>, a spool <NUM> may be configured to hold the one or more composite layers <NUM>. The spool <NUM> may be configured to deposit the one or more composite layers <NUM> onto the composite panel <NUM>. For example, the spool <NUM> may be part of a robotic assembly configured to move above the composite panel <NUM> and deposit the one or more composite layers <NUM> from the spool <NUM> onto the composite panel <NUM> by unspooling the spool <NUM>.

Unspooling the one or more composite layers <NUM> onto the composite panel <NUM> may include aligning edges and/or center lines of the one or more composite layers <NUM> in a pre-specified stacking sequence when unspooled onto the composite panel <NUM>. For example, overhead laser projection may be used to align the edges of the one or more composite layers <NUM> when unspooled onto the composite panel <NUM>. The spool <NUM> (or larger robotic assembly) which may be configured to move and rotate over the composite panel <NUM> can include one or more laser receivers configured to receive a continuous laser beam from an Overhead Laser Projector (OLP). The angle and distance to the OLP are automatically calculated by processor in the spool <NUM>. The calculated angle and distance information can then be compared to a map or layout corresponding to the pre-defined solid laminate stringer <NUM> to determine the position of the spool <NUM> in relation to target locations of the unspooled one or more composite layers <NUM> of the pre-defined solid laminate stringer <NUM>. The spool <NUM> can then be guided and moved while adjusting speed, rotation rate, compacting pressure, heating temperature, etc. based on streaming data according to a deposition width/thickness and surface curvature requirements to align edges or position of the one or more composite layers <NUM> when unspooled in the pre-specified stacking sequence onto the composite panel <NUM> and/or onto the one or more composite layers <NUM> already partially forming the solid laminate stringer <NUM> on the composite panel <NUM>.

Accordingly, unspooling of the one or more composite layers <NUM> onto the composite panel <NUM> may include using overhead laser projection of the target locations to align edges and/or centerlines of the one or more composite layers <NUM> in a pre-specified sequence on the composite panel <NUM>.

For example, as illustrated in <FIG>, a first composite layer <NUM> may be deposited onto a composite panel <NUM> by unspooling the first composite layer <NUM> from a spool <NUM>. The spool <NUM> may use overhead laser projection to align front edge <NUM> of the first composite layer <NUM> to correspond to the composite panel <NUM>. For example, the spool <NUM> may deposit the first composite layer <NUM> starting at a front edge <NUM> of the composite panel <NUM>.

As illustrated in <FIG>, the system <NUM> may include one or more spools <NUM>, and the one or more spools <NUM> may be configured to simultaneously deposit the one or more composite layers <NUM> onto the composite panel <NUM> to form one or more solid laminate stringers <NUM>.

The computer <NUM> can be used to guide and control the spool <NUM> to move along pre-specified path lines at pre-determined speed or rates. The path lines may include almost straight and/or slight curvatures <NUM> (see <FIG>). For example, the computer <NUM> may be used to store a map or layout corresponding to the solid laminate stringer <NUM>, pre-specified slightly curved path lines, pre-determined move speeds, rotation rates, compacting pressure, heating temperature etc., a stacking sequence or indices, a layout order, pre-defined geometry locations of edge lines and centerlines, pre-calculated width, curvature, and length, or design for the one or more composite layers <NUM>, and an overall geometry or shape for the solid laminate stringer. The computer <NUM> can store a length for the one or more composite layers <NUM> corresponding to a length of the solid laminate stringer <NUM>. The computer <NUM> may be used to guide and move the spool <NUM> in pre-determined move speeds, rotation rates, compacting pressure, heating temperature on pre-specified path lines according to the unspooling command steps executed in sequence and the stored information described above.

Accordingly, the unspooling of the one or more composite layers <NUM> onto the composite panel <NUM> may include using overhead laser projection to synchronize the unspooling one or more composite layers <NUM> according to at least one of a move speed, a rotation rate, a compacting pressure, and a heating temperature. The unspooling of the one or more composite layers <NUM> onto the composite panel <NUM> may align edges of the one or more composite layers <NUM> on the composite panel <NUM> to curvatures <NUM>. The unspooling of the one or more composite layers <NUM> onto the composite panel <NUM> may include using a computer <NUM> to control spools <NUM> to execute unspooling along pre-specified almost straight and/or slight curvatures <NUM> according to at least one of pre-determined move speeds, rotation rates, compacting pressures, and heating temperatures.

Operation <NUM> includes compacting the one or more composite layers <NUM> unspooled onto the composite panel <NUM>.

As illustrated in <FIG>, the system <NUM> may include a compacting roller <NUM>. The compacting roller <NUM> may be configured to compact a composite layer <NUM> unspooled onto the composite panel <NUM> and/or to compact a composite layer <NUM> unspooled onto other composite layers <NUM> already partially forming the solid laminate stringer <NUM> on the composite panel <NUM>. The compacting roller <NUM> may be configured to apply a pressure and/or heating temperature to the unspooled composite layer <NUM>.

Operation <NUM> includes cutting the one or more composite layers <NUM> unspooled onto the composite panel <NUM>.

As illustrated in <FIG>, the system <NUM> may include a cutter <NUM>. The cutter <NUM> may be configured to cut a composite layer <NUM> unspooled onto the composite panel <NUM> and/or to cut a composite layer <NUM> unspooled onto other composite layers <NUM> already partially forming the solid laminate stringer <NUM> on the composite panel <NUM>.

In operation <NUM>, the cutter <NUM> cuts the composite layer <NUM> to a desired length. For example, as illustrated in <FIG>, the cutter <NUM> may cut the first composite layer <NUM> to a length corresponding to a length of the solid laminate stringer <NUM> and/or the composite panel <NUM>. The length of the first composite layer <NUM> may correspond to the full length of the solid laminate stringer <NUM> and/or the composite panel <NUM>.

The one or more composite layers <NUM> can be continuous within the spool <NUM>. That is, a composite layer <NUM> may include the first, second, third, and/or fourth composite layer <NUM>, <NUM>, <NUM>, and <NUM> as a continuous composite layer <NUM>. Cutting the first composite layer <NUM> exposes a front edge <NUM> (not illustrated) of the second composite layer <NUM>. The spool <NUM> may then align a front edge <NUM> of the second composite layer <NUM> with the front edge <NUM> of the first composite layer <NUM> or a front edge <NUM> of the composite panel <NUM> when depositing the second composite layer <NUM>. However, as illustrated in <FIG>, the spool <NUM> may include one or more spools <NUM>, and each spool <NUM> may include a composite layer <NUM>. For example, one or more spools <NUM> may include the first, second, third, and/or fourth composite layers <NUM>, <NUM>, <NUM>, and <NUM>, and the one or more spools <NUM> may work together in sequence to deposit solid laminate stringers <NUM> onto the composite panel <NUM>.

While the operation above are described with respect to the first composite layer <NUM>, it is understood that other composite layers <NUM> may be similarly unspooled, compacted, and cut onto the composite panel <NUM>, including the second, third, and fourth composite layers <NUM>, <NUM>, and <NUM>, and the base wrap layer <NUM> and top wrap layer <NUM>, as illustrated in <FIG>.

Operation <NUM> includes curing the one or more composite layers <NUM> unspooled and compacted onto the composite panel <NUM>.

Curing of the one or more composite layers <NUM> may include applying heat and pressure to the one or more composite layers <NUM>. For example, curing may include using an autoclave under heat and pressure processing conditions corresponding to the material of the one or more composite layers <NUM> and/or the composite panel <NUM>.

As illustrated in <FIG>, operation <NUM> may include placing a vacuum bag <NUM> over the one or more composite layers <NUM> forming the solid laminate stringer <NUM> and the composite panel <NUM>. The vacuum bag <NUM> can cover at least a portion of the composite panel <NUM>. The vacuum bag <NUM> may be used to apply a compaction pressure to the one or more composite layers <NUM> prior to and during curing under operation <NUM>. Accordingly, the curing of the one or more composite layers <NUM> unspooled onto the composite panel <NUM> can include placing a vacuum bag <NUM> over the one or more composite layers <NUM> and applying a compaction pressure to the one or more composite layers <NUM>.

Operation <NUM> can include simultaneously curing the one or more composite layers <NUM> forming the solid laminate stringer <NUM> with the curing of the composite panel <NUM>. Accordingly, the vacuum bag <NUM> may cover at least a portion of the composite panel <NUM>, and curing the one or more composite layers <NUM> unspooled onto the composite panel <NUM> may include simultaneously curing the composite panel <NUM>.

<FIG> illustrates a system for spooling a composite layer according to the present disclosure. As illustrated in <FIG>, a system <NUM> for spooling a composite layer <NUM> includes a spool <NUM>, one or more cutters <NUM>, one or more rollers <NUM>, a forming table <NUM>, and a computer <NUM>.

<FIG> illustrates a method for spooling a composite layer according to the present disclosure. <FIG> illustrates an example of a method that, for instance, could be used to spool a composite layer <NUM> as described above and as illustrated in <FIG>. As illustrated in <FIG>, a method <NUM> for spooling a composite layer may be described with respect to the system <NUM> of <FIG> and the composite layers <NUM> of <FIG>.

Method <NUM> may start with placing one or more composite plies onto a forming table in operation <NUM>. As illustrated in <FIG>, one or more composite plies <NUM> may be placed onto a forming table <NUM> as part of forming a composite layer <NUM>. The one or more composite plies <NUM> may be placed on the forming table <NUM> via automated fiber placement (AFP) or automated tape layup (ATL). Operation <NUM> can include applying a vacuum through the forming table <NUM> and to the one or more composite plies <NUM> to hold them in position.

The one or more composite plies may be placed continuously along a length of the forming table. As used herein, the terms "placed continuously" refers to placing a composite ply <NUM> as a single continuous composite ply <NUM>. A composite ply <NUM> placed continuously is not spliced. That is, a composite ply <NUM> placed continuously is not formed from one or more composite plies <NUM> spliced together along a length of the forming table.

Operation <NUM> may include placing the one or more composite plies <NUM> according to a particular orientation layup. The orientation layup may be stored in the computer <NUM> and may be used to control the AFP and/or ATL machines to form the composite layer <NUM>.

Operation <NUM> includes trimming the one or more composite plies placed on the forming table. As illustrated in <FIG>, one or more cutters <NUM> may be used to trim the one or more composite plies <NUM> placed on the forming table <NUM>. The one or more cutters <NUM> may include ultrasonic cutters <NUM>.

The one or more cutters <NUM> may be used to define a width of the one or more composite plies <NUM> placed on the forming table <NUM> and/or the resulting composite layer <NUM>. The width may be uniform, or as illustrated in <FIG>, the width may include one or more widths (W1, W2, W3) along a length of the one or more composite plies <NUM>.

The one or more cutters <NUM> may be used to define lateral edges for the one or more composite plies <NUM> placed on the forming table <NUM> and/or the resulting composite layer <NUM>. The lateral edges may be uniform, or as illustrated in <FIG>, the lateral edges may have a slope angle between <NUM>° and <NUM>°.

The one or more cutters <NUM> may be used to define the shape for the one or more composite plies <NUM> placed on the forming table <NUM> and/or the resulting composite layer <NUM>. The shape may be substantially symmetric. For example, both lateral edges may be at about the same distance of a half layer width from a layer centerline along a longitudinal direction and may have about the same slope angle.

The one or more cutters <NUM> may be used to define a length of the one or more composite plies <NUM> placed on the forming table <NUM> and/or the resulting composite layer <NUM>. The length may correspond to a length of the solid laminate stringer <NUM> and/or the composite panel <NUM> A length of the one or more composite plies <NUM> may correspond to runout ends of the solid laminate stringer <NUM>.

Operation <NUM> includes compacting the one or more composite plies <NUM> placed on the forming table. As illustrated in <FIG>, the system <NUM> may include one or more rollers <NUM>. The one or more rollers <NUM> may be configured to compact the one or more composite plies <NUM> placed the forming table <NUM> into a composite layer <NUM>.

The one or more rollers <NUM> may impart or maintain a tension to the one or more composite plies <NUM> while compacting in operation <NUM>. Compacting or tensioning the one or more composite plies <NUM> may mitigate wrinkling when the resulting composite layer <NUM> is spooled.

The one or more rollers <NUM> may prevent ply wrinkles and drive out remaining air voids within and between the composite plies <NUM> to reduce ply distortion or defects. The one or more rollers <NUM> may also generate tension to straighten out the composite plies <NUM> to prevent wrinkling and slippage when the resulting composite layer <NUM> is spooled.

Operation <NUM> includes spooling the one or more composite plies <NUM> compacted into a composite layer <NUM> onto a spool <NUM>. As illustrated in <FIG>, a composite layer <NUM> (resulting from the compacting and tensioning of the composite plies <NUM>) is spooled onto a spool <NUM>. The one or more composite layers <NUM> may include spooled pre-pregs.

Operation <NUM> may include heating and cooling the compacted one or more composite plies <NUM>. For example, in order to mitigate wrinkling of the one or more composite plies <NUM> compacted into a composite layer <NUM> when spooled, the one or more composite plies <NUM> may be heated first during or after a compacting operation <NUM>. Similarly, in order to mitigate tackiness, the one or more composite plies <NUM> may be cooled during or before spooling operation <NUM>.

The composite layer <NUM> resulting from the compacting of the one or more composite plies <NUM> may include a pre-preg.

The composite layer <NUM> spooled on the spool <NUM> may include a continuous composite layer <NUM> including one or more composite plies <NUM>.

The composite layer <NUM> resulting from the compacting of the one or more composite plies <NUM> may include variable widths and curvatures to correspond to the widths or curvatures of a solid laminate stringer <NUM>.

The computer <NUM> can store a lay-up design for the solid laminate stringer <NUM>, and the composite layer <NUM> is spooled onto the spool <NUM> to correspond to the shape, curves, and geometry of the desired solid laminate stringer <NUM>. One or more composite layers <NUM> can be spooled onto one or more spools <NUM>, and the computer <NUM> controls the lay-up of the one or more composite layers <NUM> by the one or more spools <NUM> to create a solid laminate stringer <NUM> on a composite panel <NUM>. Accordingly, the composite layers <NUM> can be spooled according to a lay-up design for the solid laminate stringer <NUM>.

The present disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine, automotive applications, and other application where solid laminate stringers are desired. Thus, referring now to <FIG> and <FIG>, the disclosure may be used in the context of an aircraft manufacturing and service method <NUM> as shown in <FIG> and an aircraft <NUM> as shown in <FIG>. During pre-production, exemplary method <NUM> may include specification and design <NUM> of the aircraft <NUM> and material procurement <NUM>. During production, component and subassembly manufacturing <NUM> and system integration <NUM> of the aircraft <NUM> takes place. Thereafter, the aircraft <NUM> may go through certification and delivery <NUM> in order to be placed in service <NUM>. While in service by a customer, the aircraft <NUM> is scheduled for routine maintenance and service <NUM>, which may also include modification, reconfiguration, refurbishment, and so on.

As shown in <FIG>, the aircraft <NUM> produced by exemplary method <NUM> may include an airframe <NUM> with a plurality of systems <NUM> and an interior <NUM>. Examples of systems <NUM> include one or more of a propulsion system <NUM>, an electrical system <NUM>, a hydraulic system <NUM>, and an environmental system <NUM>. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine and automotive industries.

Systems and methods exemplified herein may be employed during any one or more of the stages of the aircraft manufacturing and service method <NUM>. For example, components or subassemblies corresponding to production process <NUM> may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft <NUM> is in service. Also, one or more apparatus examples, method examples, or a combination thereof may be utilized during the production stages <NUM> and the <NUM>, for example, by substantially expediting assembly of or reducing the cost of an aircraft <NUM>. Similarly, one or more of apparatus examples, method examples, or a combination thereof may be utilized while the aircraft <NUM> is in service, for example and without limitation, to maintenance and service <NUM>.

While <FIG> and <FIG> describe the disclosure with respect to aircraft and aircraft manufacturing and servicing, the present disclosure is not limited thereto. The solid laminate stringers systems and methods of the present disclosure may also be used for spacecraft, satellites, submarines, surface ships, automobiles, tanks, trucks, power plants, and any other suitable type of objects.

Claim 1:
A method (<NUM>, <NUM>) of fabricating a solid laminate stringer (<NUM>) on a composite panel (<NUM>) comprising:
unspooling one or more composite layers (<NUM>) onto a composite panel (<NUM>), which comprises aligning at least one of edges and centerlines of the one or more composite layers (<NUM>) on the composite panel (<NUM>) to one or more curved lines (<NUM>), and wherein the one or more composite layers are unspooled continuously along a length corresponding to a length of the solid laminate stringer;
compacting the one or more composite layers (<NUM>) unspooled onto the composite panel (<NUM>);
cutting the one or more composite layers (<NUM>) unspooled onto the composite panel (<NUM>); and
curing the one or more composite layers (<NUM>) unspooled onto the composite panel (<NUM>).