Patent Description:
Acoustic panels may be used in various applications to attenuate noise. An acoustic panel, for example, may be configured with a nacelle of an aircraft propulsion system to attenuate noise generated by a gas turbine engine. Such an acoustic panel typically includes a honeycomb core connected between a perforated face skin and a solid, non-perforated back skin. The honeycomb core includes a plurality of resonating chambers. These resonating chambers are tuned by selecting a desired chamber length and, thus, core thickness that corresponds to a specific target frequency of noise to be attenuated. Increasing the core thickness, for example, will typically tune the resonating chambers for attenuating lower frequency noise. Conversely, decreasing the core thickness will typically tune the resonating chambers for attenuating higher frequency noise.

Recent trends in aircraft engine design such as higher bypass ratios, larger fan diameters, slower rotating fans and/or fewer number of fan blades have resulted in those aircraft engines generating relatively low frequency noise. Relatively strict space constraints for those engines, however, typically limit or prohibit increasing the thickness of an acoustic panel to tune its resonating chambers for such relatively low frequency noise. Reducing the thickness of the acoustic panel also has the concern of compromising structural integrity.

There is a need in the art for acoustic and structural panels with increased structural integrity and reduced thicknesses and methods for forming such panels.

<CIT> discloses a prior art method for forming a structural panel, where a cellular core structure is formed that comprises a corrugated ribbon configured with a plurality of baffles and a plurality of septums, where at least one element of the corrugated ribbon comprises a structural reinforcement, where the forming comprises feeding a ribbon of material between a first roller and a second roller, corrugating the ribbon of material with the first roller and the second roller.

According to the invention, a method is provided for forming a structured panel as set forth in claim <NUM>.

The first roller may include a plurality of first teeth arranged in a first array. The second roller may include a plurality of second teeth arranged in a second array. The first teeth may be configured to mesh with the second teeth to corrugate the ribbon of material.

At least one of the first teeth may include a female die portion. At least one of the second teeth may include a male die portion. The stamping may include mating the male die portion with the female die portion to stamp the structural reinforcement into the element.

The at least one of the first teeth may also include a second female die portion. The at least one of the second teeth may also include a second male die portion. The forming may also include stamping a second structural reinforcement into the element by mating the second male die portion with the second female die portion.

The at least one of the first teeth may also include a second male die portion. The at least one of the second teeth may also include a second female die portion. The forming may also include stamping a second structural reinforcement into the element by mating the second male die portion with the second female die portion.

During the method, the first roller and/or the second roller may be heated during the corrugating and the stamping.

The element may include a base. The structural reinforcement may project out from the base.

The structural reinforcement may be configured as or otherwise include a rib.

The structural reinforcement may include a first rib and a second rib that intersects with the first rib.

The cellular core may include a first wall and a second wall. The corrugated ribbon may be laterally between and bonded to the first wall and the second wall.

The corrugated ribbon may be configured from or otherwise include thermoplastic polymer material.

The corrugated ribbon may be configured from or otherwise include thermoset polymer material.

The structured panel may be configured as or otherwise include an acoustic panel configured to attenuate noise.

The first roller may include a plurality of first projections. The second roller may include a plurality of second projections configured to mesh with the first or second projections to corrugate the ribbon of material.

At least one of the first projections may include a female die portion. At least one of the second projections may include a male die portion configured to mate the female die portion to stamp the structural reinforcement into the element.

The forming may also include corrugating the ribbon of polymer material with the first roller and the second roller to provide the baffles and the porous septums.

The present disclosure includes structured panels and methods for forming structured panels and their components. An example of a structured panel is an acoustic panel for attenuating sound; e.g., noise. Such a structured panel may include one or more structural reinforcements, such as rib structures, for increasing rigidity, strength, stability (i.e., resistance to buckling) and/or other metrics of structural integrity of the panel. For ease of description, the following disclosure will first describe a general panel configuration without structural reinforcements and then describe how one or more structural reinforcements may be added to one or more elements (e.g., components) of the panel to increase rigidity, strength, stability and/or other metrics of structural integrity of that panel.

<FIG> is a partial, perspective schematic illustration of an acoustic panel <NUM> for attenuating noise. This acoustic panel <NUM> may be configured to attenuate noise generated by an aircraft propulsion system such as, for example, a turbofan propulsion system or a turbojet propulsion system. With such a configuration, the acoustic panel <NUM> may be configured with a nacelle of the propulsion system. The acoustic panel <NUM>, for example, may be configured as or with an inner or outer barrel, a translating sleeve of a thrust reverser, a blocker door, etc. Alternatively, the acoustic panel <NUM> may be configured with another component / structure of the aircraft such as its fuselage or a wing. Furthermore, the acoustic panel <NUM> may be configured to also or alternatively attenuate aircraft related noise other than that generated by the propulsion system. The acoustic panel <NUM> of the present disclosure, however, may alternatively be configured for non-aircraft applications.

The acoustic panel <NUM> extends longitudinally along an x-axis. The acoustic panel <NUM> extends laterally along a y-axis. The acoustic panel <NUM> extends vertically along a z-axis. The term "vertical" is used herein to describe a depthwise panel direction and is not limited to a gravitational up/down direction. Furthermore, for ease of illustration, the x-y plane is shown as a generally flat plane. However, in other embodiments, the x-y plane and, thus, the acoustic panel <NUM> may be curved and/or follow an undulating geometry. For example, the x-y plane and, thus, the acoustic panel <NUM> may be arcuate, cylindrical or conical with or without radial undulations. Thus, the vertical direction may change at different locations along the x-y plane; e.g., the vertical direction may be a radial direction for a cylindrical or conical acoustic panel.

The acoustic panel <NUM> includes a perforated first (e.g., face) skin <NUM>, a solid non-perforated second (e.g., back) skin <NUM> and a cellular core <NUM>. Briefly, the cellular core <NUM> is disposed and extends vertically between the first skin <NUM> and the second skin <NUM>. The cellular core <NUM> is also connected to the first skin <NUM> and the second skin <NUM>. The cellular core <NUM>, for example, may be fused, adhered, welded, brazed and/or otherwise bonded to the first skin <NUM> and/or the second skin <NUM>. The cellular core <NUM> may also or alternatively be mechanically fastened to the first skin <NUM> and/or the second skin <NUM>. Alternatively, the cellular core <NUM> may be formed integral with the first skin <NUM> and/or the second skin <NUM> as a monolithic body using, for example, additive manufacturing. However, the present disclosure is not limited to any particular manufacturing methods.

The first skin <NUM> may be configured as a relatively thin sheet or layer of material that extends longitudinally and laterally along the x-y plane. This first skin material may include, but is not limited to, a thermoplastic polymer, a thermoset polymer, a fiber reinforced polymer (thermoset or thermoplastic) matrix composite (e.g., fiberglass composite, carbon fiber composite, aramid fiber composite, composite reinforced by any combination of glass, carbon, aramid or other fibers, etc.), metal, alloys, metal matrix composite, ceramic, or ceramic matrix composite, or a combination thereof. Referring now to <FIG>, the first skin <NUM> has a vertical thickness <NUM> that extends vertically between opposing side surfaces <NUM> and <NUM>. The first skin <NUM> includes a plurality of perforations <NUM>; e.g., apertures such as through-holes (see also <FIG>). Each of these perforations <NUM> extends generally vertically through the first skin <NUM> between its side surfaces <NUM> and <NUM>. In other embodiments, the perforations <NUM> may be non-uniform through the thickness <NUM> and/or may be non-perpendicular to the side surfaces <NUM> and/or <NUM>.

The second skin <NUM> may be configured as a relatively thin sheet or layer of (e.g., continuous and uninterrupted) material that extends longitudinally and laterally along the x-y plane (see <FIG>). This second skin material may include, but is not limited to, a thermoplastic polymer, a thermoset polymer, a fiber reinforced polymer (thermoset or thermoplastic) matrix composite (e.g., fiberglass composite, carbon fiber composite, aramid fiber composite, composite reinforced by any combination of glass, carbon, aramid or other fibers, etc.), metal, alloys, metal matrix composite, ceramic, or ceramic matrix composite, or a combination thereof. The second skin material may be the same as or different than the first skin material. The second skin <NUM> has a vertical thickness <NUM> that extends vertically between opposing side surfaces <NUM> and <NUM>. This vertical thickness <NUM> may be substantially equal to or different (e.g., greater or less) than the vertical thickness <NUM> of the first skin <NUM>. The thickness <NUM> of the first skin <NUM> and/or the thickness <NUM> of the second skin <NUM> may be uniform or non-uniform along the x-y plane.

Referring to <FIG>, the cellular core <NUM> extends longitudinally and laterally along the x-y plane. Referring again to <FIG>, the cellular core <NUM> has a vertical thickness <NUM> that extends vertically between opposing core sides, which sides are respectively abutted against the first skin <NUM> and the second skin <NUM> and their side surfaces <NUM> and <NUM>. The vertical thickness <NUM> may be substantially greater than the vertical thicknesses <NUM> and <NUM> of the first skin <NUM> and/or the second skin <NUM>, respectively. The vertical thickness <NUM>, for example, may be at least ten to forty times (<NUM>-40x), or more, greater than the vertical thicknesses <NUM> and <NUM>; however, the acoustic panel <NUM> of the present disclosure is not limited to such an exemplary embodiment.

Referring to <FIG>, the cellular core <NUM> includes a plurality of solid non-perforated walls <NUM> (e.g., cavity sidewalls) and one or more arrays of corrugations <NUM>. The walls <NUM> and corrugations <NUM> are arranged together to configure the cellular core <NUM> as an open cavity (e.g., open cell) structure. This open cavity structure forms a plurality of cavities <NUM> (each including divided sub-cavities 128A and 128B) vertically between the first skin <NUM> and the second skin <NUM>. Each of these cavities <NUM> may be fluidly coupled with one or more respective perforations <NUM> in the first skin <NUM> (see <FIG>).

Referring to <FIG>, each of the walls <NUM> has a length that extends longitudinally along the x-axis. Each of the walls <NUM> has a thickness that extends laterally along the y-axis. Referring now to <FIG>, each of the walls <NUM> has a height <NUM> that extends vertically between the first skin <NUM> and the second skin <NUM>.

Each of the walls <NUM> is at least partially (or completely) connected to or otherwise engaged with the first skin <NUM> and/or the second skin <NUM>. Each of the exemplary walls <NUM> of <FIG> is orientated substantially perpendicular to the first skin <NUM> and the second skin <NUM>; e.g., at a ninety-degree angle to the skins <NUM> and <NUM>. However, in other embodiments, one or more of the walls <NUM> may be angularly offset from the first skin <NUM> and/or the second skin <NUM> by a non-ninety-degree angle; e.g., an acute angle or an obtuse angle.

The walls <NUM> are arranged generally parallel with one another; see also <FIG>. The walls <NUM> are laterally spaced from one another along the y-axis so as to respectively form the cavities <NUM> between the walls <NUM>. Each of the walls <NUM> shown in <FIG> therefore respectively forms lateral sides of adjacent cavities <NUM> on either side of the respective wall <NUM>. Each of the walls <NUM> thereby also fluidly separates those cavities <NUM> on either side of the wall <NUM>.

Referring to <FIG>, the corrugations <NUM> in each array are disposed and extend laterally between a laterally adjacent pair of the walls <NUM>; see also <FIG>. Each of the corrugations <NUM> includes a solid non-perforated baffle <NUM> and a porous (e.g., perforated) septum <NUM>. In another exemplary embodiment, one or more or each of the corrugations <NUM> includes only porous (e.g. perforated) septa <NUM>, or only solid non-perforated baffles <NUM> in an alternating periodic or non-periodic pattern along the y-axis or the x-axis or both.

Referring to <FIG> and <FIG>, the baffle <NUM> has a width extending laterally between opposing lateral sides. These lateral sides are at least partially (or completely) connected to or otherwise engaged with a respective laterally adjacent pair of the walls <NUM>. Referring to <FIG>, the baffle <NUM> has a length extending diagonally (e.g., vertically and longitudinally) between opposing top and bottom ends <NUM> and <NUM>. Note, the terms "top" and "bottom" are used above to describe ends of the baffle <NUM> as situated in the drawings and are not intended to limit the baffle <NUM> or the acoustic panel <NUM> to such an exemplary gravitational orientation.

The septum <NUM> has a width extending laterally between opposing lateral sides. These lateral sides are connected to or otherwise engaged with a respective laterally adjacent pair of the walls <NUM>. The septum <NUM> has a length extending diagonally (e.g., vertically and longitudinally) between opposing top and bottom ends <NUM> and <NUM>. Note, the terms "top" and "bottom" are used above to describe ends of the septum <NUM> as situated in the drawings and are not intended to limit the septum <NUM> or the acoustic panel <NUM> to such an exemplary gravitational orientation.

The septum <NUM> includes one or more perforations <NUM>. In the exemplary embodiment of <FIG>, the perforations <NUM> are configured as through holes. However, in other embodiments, the perforations <NUM> may be formed by interconnected pores in the septum <NUM> where the septum material, for example, has an open cell porous structure.

The top end <NUM> of the baffle <NUM> is connected at least partially (or completely) to or otherwise engaged with the first skin <NUM>. This top end <NUM> is also longitudinally connected to the top end <NUM> of the septum <NUM> at an interface <NUM> between the baffle <NUM> and the septum <NUM>. The bottom end <NUM> of the baffle <NUM> is connected to or otherwise engaged with the second skin <NUM>. This bottom end <NUM> is also longitudinally connected to the bottom end <NUM> of a septum <NUM> of an adjacent one of the corrugations <NUM> at an interface <NUM>. With the foregoing configuration, the baffle <NUM> extends vertically between the first skin <NUM> and the second skin <NUM> and longitudinally between the septums <NUM>. The baffle <NUM> is therefore angularly offset from the first skin <NUM> and the second skin <NUM> by an included angle <NUM>; e.g., between <NUM>-<NUM> degrees. This angle <NUM> is an acute angle such as, but not limited to, about forty-five degrees (<NUM>°).

The top end <NUM> of the septum <NUM> is at least partially (or completely) connected to or otherwise engaged with the first skin <NUM>. This top end <NUM> is also longitudinally connected to the top end <NUM> of the baffle <NUM> as described above. The bottom end <NUM> of the septum <NUM> is at least partially (or completely) connected to or otherwise engaged with the second skin <NUM>. This bottom end <NUM> is also longitudinally connected to the bottom end <NUM> of a baffle <NUM> of an adjacent one of the corrugations <NUM> at an interface; e.g., the interface <NUM>. With the foregoing configuration, the septum <NUM> extends vertically between the first skin <NUM> and the second skin <NUM> and longitudinally between the baffles <NUM>. The septum <NUM> is therefore angularly offset from the first skin <NUM> and the second skin <NUM> by an included angle <NUM>; e.g., between <NUM>-<NUM> degrees. This angle <NUM> may be an acute angle such as, but not limited to, about forty-five degrees (<NUM>°). The angle <NUM> may be substantially equal to the angle <NUM> as shown in <FIG>. Alternatively, the angle <NUM> may be different from the angle <NUM>; e.g., a larger or smaller acute angle, or a right angle. For example, the angle <NUM> may be about ninety degrees (<NUM>°) and the angle <NUM> may be about forty-five degrees (<NUM>°) as shown in <FIG>. In another example, the angle <NUM> may be about ninety degrees (<NUM>°) and the angle <NUM> may be about forty-five degrees (<NUM>°).

Referring to <FIG>, each of the cavities <NUM> extends longitudinally between and is formed by a longitudinally adjacent pair of the baffles <NUM>. Each septum <NUM> is disposed within and divides a respective one of the cavities <NUM> into fluidly coupled sub-cavities 128A and 128B. More particularly, the perforations <NUM> in the septum <NUM> fluidly couple the sub-cavities 128A and 128B together.

Each of the cavities <NUM> forms a resonance chamber <NUM>. A length <NUM> of the resonance chamber <NUM> extends diagonally (e.g., longitudinally and vertically) between the first skin <NUM> and the second skin <NUM> and through a respective one of the septums <NUM>. The length <NUM> of the resonance chamber <NUM> therefore is longer than the vertical thickness <NUM> of the cellular core <NUM>. This enables noise attenuation of relatively low frequency noise without increasing the vertical thickness <NUM> of the cellular core <NUM> and, thus, a vertical thickness of the acoustic panel <NUM>. For example, each resonance chamber <NUM> may receive noise waves through the perforations <NUM> in the first skin <NUM>. The resonance chamber <NUM> may reverse the phase of one or more frequencies of those sound waves using known acoustic reflection principles and subsequently direct the reverse phase sound waves out of the acoustic panel <NUM> through the perforations <NUM> to destructively interfere with other incoming noise waves.

The cellular core <NUM> may be constructed from any suitable material or materials. The cellular core <NUM>, for example, may be constructed from a thermoplastic polymer, a thermoset polymer, a fiber reinforced thermoset or thermoplastic polymer matrix composite (e.g., fiberglass composite, carbon fiber composite, aramid fiber composite, composite reinforced by any combination of glass, carbon, aramid or other fibers), metal, alloys, metal matrix composite, ceramic, or ceramic matrix composite, or a combination thereof. One or more of the components of the cellular core <NUM> may be constructed from the same or a like material. Alternatively, one or more of the components of the cellular core <NUM> may be constructed from a different material than one or more of the other components of the cellular core <NUM>. Furthermore, the cellular core <NUM> may be constructed from the same material(s) as the first skin <NUM> and/or the second skin <NUM>, or from a different material or materials.

Referring to <FIG>, one or more elements 156A-F (generally referred to as "<NUM>") of the acoustic panel <NUM> and, more particularly, the cellular core <NUM> may be configured with one or more structural reinforcements 158A-F (generally referred to as "<NUM>"). These structural reinforcements <NUM> are provided to increase rigidity, stability, strength and/or structural integrity of the corresponding element(s) <NUM> as well as the acoustic panel <NUM> as a whole. Examples of the one or more elements <NUM> include, but are not limited to: (A) one, some or each of the baffles <NUM>; (B) one, some or each of the septums <NUM>; (C) one, some or each of the arrays of corrugations <NUM>; and (D) a combination of any two or more of (A) to (C). In some embodiments, the elements <NUM> may also or alternatively include one, some or each of the walls <NUM>.

<FIG> illustrate a portion of the acoustic panel element 156A configured with an array of the structural reinforcements 158A. Each structural reinforcement 158A of <FIG> is configured as a discrete rib 160A. Each rib 160A may be stamped, molded and/or otherwise formed in the acoustic panel element 156A to project out from an exterior surface 162A of the acoustic panel element 156A. More particularly, each rib 160A is formed in the acoustic panel element 156A to project out from a (e.g., planar) base 164A of the acoustic panel element 156A, which base 164A defines the exterior surface 162A.

Each rib 160A extends along a trajectory 166A, where the trajectories 166A of the ribs 160A may be parallel with one another as shown in <FIG>. In other embodiments, however, the trajectories 166A of some of the ribs 160A may be non-parallel; e.g., angled to one another. Note, the term "trajectory" may describe a centerline that follows along a length of a feature, where that length is greater than other dimensions (e.g., a width and/or a thickness) of the feature. Each trajectory 166A of <FIG> is a straight-line trajectory. However, in other embodiments, the trajectory 166A of one or more of the ribs 160A may alternatively be a curved or otherwise convoluted line trajectory.

<FIG> illustrate a portion of the acoustic panel element 156B configured with an array of the structural reinforcements 158B and 158C. Each structural reinforcement 158B, 158C of <FIG> is configured as a discrete rib 160B, 160C. Each rib 160B may be formed in the acoustic panel element 156B to project out from an exterior surface 162B of the acoustic panel element 156B. More particularly, each rib 160B is formed in the acoustic panel element 156B to project out from a (e.g., planar) base 164B of the acoustic panel element 156B, which base 164B defines the exterior surface 162B and an opposite exterior surface 163B. Each rib 160C may be formed in the acoustic panel element 156B to project out from the exterior surface 163B. More particularly, each rib 160C is formed in the acoustic panel element 156B to project out from the base 164B such that each rib 160C is arranged on an opposing side of the base 164B from each rib 160B.

Each rib 160B extends along a trajectory 166B, where the trajectories 166B of the ribs 160B may be parallel with one another as shown in <FIG>. In other embodiments, however, the trajectories 166B of some of the ribs 160B may be non-parallel; e.g., angled to one another. Each rib 160C extends along a trajectory 166C, where the trajectories 166C of the ribs 160C may be parallel with one another as shown in <FIG>. In other embodiments, however, the trajectories 166C of some of the ribs 160C may be non-parallel; e.g., angled to one another. The trajectories 166B of the ribs 160B may also be parallel with the trajectories 166C of the ribs 160C as shown in <FIG>. In other embodiments, however, the trajectories 166B and 166C of some of the ribs 160B and 160C may be non-parallel; e.g., angled to one another. Each trajectory 166B, 166C of <FIG> is straight-line trajectory. However, in other embodiments, the trajectory 166B, 166C of one or more of the ribs 160B, 160C may alternatively be a curved or otherwise convoluted line trajectory.

Each structural reinforcement <NUM> described above includes a single discrete rib (generally referred to as "<NUM>"). However, in other embodiments, one or more of the structural reinforcements (e.g., 158C-F) may each include a plurality of interconnected ribs as shown, for example, in <FIG>. The structural reinforcement 158C of <FIG>, for example, includes a first rib 160D and a second rib 160E. The first rib 160D extends along a first trajectory 166D and the second rib 160E extends along a second trajectory 166E. The first trajectory 166D and the second trajectory 166E are straight-line trajectories; however, in other embodiments, one or both of these trajectories 166D and 166E may alternatively be curved or otherwise convoluted line trajectories. The first trajectory 166D of the first rib 160D is non-parallel with the second trajectory 166E of the second rib 160E. The first trajectory 166D and the first rib 160D of <FIG>, for example, are perpendicular and coincident with the second trajectory 166E and the second rib 160E. Of course, in other embodiments, an included angle between first and second trajectories 166F and <NUM> and ribs 160F and <NUM> of the structural reinforcement 158D may be acute (or obtuse) as shown in <FIG> for example. Referring again to <FIG>, the first rib 160D intersects and thereby runs into the second rib 160E. The first rib 160D of <FIG>, for example, bisects the second rib 160E and the second rib 160E bisects the first rib 160D.

<FIG> is a flow diagram of a method <NUM> for forming a structured panel such as, but not limited to, the structured panel <NUM> embodiments described above.

In step <NUM>, the first skin <NUM> is formed or otherwise provided. This first skin <NUM> may be constructed from polymer material such as, but not limited to, thermoplastic polymer material or thermoset polymer material. For example, the first skin <NUM> may be constructed from a layup of fiber reinforcement within a polymer (e.g., thermoplastic or thermoset) matrix. Examples of fiber reinforcement include, but are not limited to, continuous, long discontinuous, short chopped and/or fabric (woven) or other arrangement of fibers of fiberglass, carbon fibers, aramid fibers or any combination thereof. These fibers may be arranged in one or more plies, a three-dimensional (3D) woven body, or any other arrangement. In other embodiments, however, the first skin <NUM> may be formed from another non-polymeric material such as, but not limited to, sheet metal or ceramic material, or ceramic matrix composite material. The first skin <NUM> may be perforated during this step <NUM> using a perforation technique such as, but not limited to, mechanical or laser drilling. Alternatively, the first skin <NUM> may be perforated subsequent to being attached to the core <NUM>.

In step <NUM>, the second skin <NUM> is formed or otherwise provided. This second skin <NUM> may be constructed from polymer material such as, but not limited to, thermoplastic polymer material or thermoset polymer material. For example, the second skin <NUM> may be constructed from a layup of fiber reinforcement within a polymer (e.g., thermoplastic or thermoset) matrix. Examples of fiber reinforcement include, but are not limited to, continuous, long discontinuous, short chopped and/or fabric (woven) or other arrangement of fibers of fiberglass, carbon fibers, aramid fibers or any combination thereof. These fibers may be arranged in one or more plies, a three-dimensional (3D) woven body, or any other arrangement. In other embodiments, however, the second skin <NUM> may be formed from another non-polymeric material such as, but not limited to, sheet metal or ceramic material, or ceramic matrix composite material.

In step <NUM>, a plurality of corrugated ribbons <NUM> (see <FIG> and <FIG>) are formed or otherwise provided. Each of these corrugated ribbons <NUM> includes a respective one of the longitudinally extending arrays of the corrugations <NUM> and, thus, sets of baffles <NUM> and septums <NUM>. Each corrugated ribbon <NUM> may be constructed from polymer material such as, but not limited to, thermoplastic material or thermoset material. For example, each corrugated ribbon <NUM> may be constructed from a layup of fiber reinforcement within a polymer (e.g., thermoplastic or thermoset) matrix. Examples of fiber reinforcement include, but are not limited to, continuous, long discontinuous, short chopped and/or fabric (woven) or other arrangement of fibers of fiberglass, carbon fibers, aramid fibers or any combination thereof. These fibers may be arranged in one or more plies, a three-dimensional (3D) woven body, or any other arrangement. In other embodiments, however, each corrugated ribbon <NUM> may be formed from another non-polymeric material such as, but not limited to, sheet metal or ceramic material, or ceramic matrix composite material.

<FIG> schematically illustrates an exemplary sequence of processes for forming the corrugated ribbons <NUM>. At point <NUM>, a ribbon of material <NUM> (e.g., fiber-reinforced thermoplastic or thermoset polymer or polymer matrix composite) is provided. The ribbon of material <NUM> may be formed from a stock roll <NUM> of fiber-reinforced thermoplastic consolidate laminate, which may be processed (e.g., rolled and/or cut) to provide the ribbon with a predetermined width and thickness. Alternatively, short chopped fibers within a thermoplastic resin matrix may be extruded into the ribbon of material <NUM>. Still alternatively, the ribbon of material <NUM> may be formed from a stock roll <NUM> of fiber-reinforced thermoset polymer or polymer matrix composite fabric or matt or prepreg that is partially cured, which may be processed (e.g., rolled and/or cut) to provide the ribbon with a predetermined width and thickness. Of course, various other processes may also or alternatively be used to provide the ribbon of material <NUM>.

Also at point <NUM> or alternatively later downstream, a plurality of perforations are formed in discrete regions of the ribbon of material <NUM>. These perforations will become the perforations <NUM> in the septums <NUM>, and the perforated regions will become the septums <NUM>. The non-perforated regions of the ribbon of material <NUM> will become the baffles <NUM>. The perforations may be formed in the regions of the ribbon of material <NUM> via punching, or using any other suitable technique. For example, the ribbon of material <NUM> may be pressed against a roller <NUM> with punches thereon, or against one or more wheels with punches thereon. Of course, in alternative embodiments, the perforations may be formed (e.g., punch, mechanical or laser drilled, etc.) after corrugated ribbon <NUM> and/or core <NUM> formation.

At point <NUM>, a respective portion of the perforated ribbon of material <NUM> is corrugated to provide respective corrugations <NUM> and thereby form a corrugated ribbon <NUM>. For example, the perforated ribbon of material <NUM> may be fed between first and second rollers <NUM> and <NUM>; e.g., roller dies, gears. Each of these rollers <NUM> and <NUM> includes a plurality of teeth <NUM>, <NUM> or other radial projections arranged in a circular array thereabout. As the first teeth <NUM> mesh with the second teeth <NUM>, the ribbon of material <NUM> is bent back and forth thereby forming the corrugations <NUM>.

In addition to corrugating the perforated ribbon of material <NUM>, the first and the second rollers <NUM> and <NUM> are also configured to form one or more of the structural reinforcements <NUM> in one or more of the baffles <NUM> and/or one or more of the septums <NUM>. For example, referring to <FIG>, each of the first teeth <NUM> may include one or more female die portions <NUM> and each of the second teeth <NUM> may include one or more male die portions <NUM>. Each female die portion <NUM> may be configured as a shaped recess or indentation in a surface <NUM> of the first roller tooth <NUM>. Each male die portion <NUM> may be configured as a corresponding shaped projection out from a surface <NUM> of the second roller tooth <NUM>. With such a configuration, as the first teeth <NUM> and the second teeth <NUM> mesh together, each male die portion <NUM> mates with (projects into) a respective one of the female die portions <NUM> and thereby stamps a respective one of the structural reinforcements <NUM> in the corrugated ribbon <NUM>.

In the embodiment of <FIG>, the female die portions <NUM> are configured with the first roller <NUM> and the male die portions <NUM> are configured with the second roller <NUM>. However, in other embodiments, both the first roller <NUM> and the second roller <NUM> may each include both female die portions <NUM> and male die portions <NUM>. For example, referring to <FIG>, each first roller tooth <NUM> is configured with alternating female and male die portions <NUM> and <NUM> and each second roller tooth <NUM> is configured with alternative male and female die portions <NUM> and <NUM>. With such a configuration, the rollers <NUM> and <NUM> may configure the corrugated ribbon of material <NUM> with structural reinforcements <NUM> as shown, for example, in <FIG>. The present disclosure is not limited to the above die portions configuration. Alternate embodiments, for example, can include any combinations of male and female die portions and die patterns on all or select first and second rollers teeth.

Where the ribbon of material <NUM> is a ribbon of thermoplastic polymer material or fiber reinforced thermoset polymer matrix material or partially cured thermoset polymer material or fiber reinforced thermoset polymer matrix material, the first roller <NUM> and/or the second roller <NUM> may be heated during the corrugating and the stamping. When thermoplastic polymer material or thermoplastic matrix composite is used, the ribbon may be thermoformed to the desired corrugated shape. When thermoset polymer material or matrix is used, the ribbon may be shaped and partially cured. However, where the ribbon of material <NUM> is or otherwise includes an uncured thermoset material, the first roller <NUM> and/or the second roller <NUM> may not (or may under certain conditions) be heated during the corrugating and the stamping, depending on targeted degree of partial or no curing of the thermoset polymer or thermoset polymer matrix material, respectively.

Referring again to <FIG>, in step <NUM>, the walls <NUM> are formed or otherwise provided. Each wall <NUM> may be constructed from polymer material such as, but not limited to, thermoplastic polymer or fiber reinforced thermoplastic polymer matrix material or thermoset polymer or fiber reinforced thermoset polymer matrix material, or metal, or ceramic or ceramic matrix composite. For example, each wall <NUM> may be constructed from a layup of fiber reinforcement within a polymer (e.g., thermoplastic or thermoset) matrix. Examples of fiber reinforcement include, but are not limited to continuous, long discontinuous, short chopped and/or fabric (woven) or other arrangement of fibers of fiberglass, carbon fibers, aramid fibers or any combination thereof. These fibers may be arranged in one or more plies, a three-dimensional (3D) woven body, or any other arrangement.

In step <NUM>, the walls <NUM> are arranged with the corrugated ribbons <NUM>. In particular, each corrugated ribbon <NUM> is arranged laterally between an adjacent pair of the walls <NUM>.

In step <NUM>, the walls <NUM> are attached to the corrugated ribbons <NUM> to form the cellular core <NUM>. The walls <NUM>, for example, may be bonded to the corrugated ribbons <NUM> using, for example, ultrasonic welding, resistance welding, consolidation within an autoclave or other means (e.g., tooling with a device for exerting pressure such as a press), welding via induction heating, or adhering with an adhesive. Of course, other bonding techniques may also or alternatively be used to attach each wall <NUM> to the respective corrugated ribbon(s) <NUM>.

In step <NUM>, the first skin <NUM> is bonded or otherwise attached to the core <NUM>. In step <NUM>, the second skin <NUM> is bonded or otherwise attached to the core <NUM>. The steps <NUM> and <NUM> may be performed sequentially (e.g., either <NUM> and then <NUM>, or <NUM> and then <NUM>). Alternatively, the steps <NUM> and <NUM> may be performed substantially simultaneously.

Claim 1:
A method for forming a structured panel (<NUM>), comprising:
forming a cellular core (<NUM>) that comprises a corrugated ribbon (<NUM>) configured with a plurality of baffles (<NUM>) and a plurality of septums (<NUM>), each of the septums (<NUM>) extending longitudinally between and connected to a respective adjacent pair of the baffles (<NUM>), at least one element (<NUM>) of the corrugated ribbon (<NUM>) comprising a structural reinforcement (<NUM>), wherein the element (<NUM>) comprises one of the baffles (<NUM>) or one of the septums (<NUM>);
the forming comprising feeding a ribbon of material (<NUM>) between a first roller (<NUM>) and a second roller (<NUM>), corrugating the ribbon of material (<NUM>) with the first roller (<NUM>) and the second roller (<NUM>) to provide the baffles (<NUM>) and the septums (<NUM>), and stamping the structural reinforcement (<NUM>) into the element (<NUM>) with the first roller (<NUM>) and the second roller (<NUM>);
bonding the cellular core (<NUM>) to a first skin (<NUM>); and
bonding the cellular core (<NUM>) to a second skin (<NUM>);
wherein the cellular core (<NUM>) is vertically between the first skin (<NUM>) and the second skin (<NUM>), and the first skin (<NUM>) is configured with a plurality of perforations (<NUM>).