Patent Description:
An aircraft propulsion system may include an acoustic panel for attenuating noise. A typical acoustic panel includes a cellular core (e.g., a honeycomb core) located between and bonded to a perforated exterior skin and an interior skin. Various method are known in the art for forming such an acoustic panel. While these known formation methods have various benefits, there is still room in the art for improvement. There is a need in the art, in particular, for methods for rapidly forming a cellular core, particularly where the cellular core has complex and/or alternative (e.g., non-honeycomb) core configurations.

<CIT> discloses a formation method comprising: forming a cellular core for a structured panel by depositing core material with a first mold.

According to an aspect of the present disclosure, a formation method is provided during which a pattern is formed by folding a sheet of material. A first mold is formed by depositing mold material with the pattern. The pattern is separated from the first mold. A cellular core for a structured panel is formed by depositing core material with the first mold.

According to another aspect of the present disclosure, which the Applicant expressly reserves the right to claim independently, another formation method is provided during which a first skin and a second skin are provided. A cellular core is formed. During the forming of the cellular core, a sheet of material is folded to provide a pattern and material is splashed against the pattern. The cellular core is arranged between the first skin and the second skin. The cellular core is bonded to the first skin and the second skin to form a structured panel.

According to still another aspect of the present disclosure, which the Applicant expressly reserves the right to claim independently, another formation method is provided during which a sheet of material is embossed to provide a plurality of fold lines. The sheet of material is folded along the fold lines to provide a pattern. The pattern includes a first sidewall, a second sidewall, a first endwall, a second endwall and a recess. The recess extends longitudinally within the pattern along the first sidewall and the second sidewall between the first endwall and the second endwall. The recess has a polygonal cross-sectional geometry. Material is deposited with the pattern to form an article. The article is separated from the pattern.

The sheet of material may be configured as or otherwise include sheet metal.

The pattern may also be formed by embossing the sheet of material to provide a plurality of fold lines. The sheet of material may be folded along the fold lines.

The formation method may also include constraining the pattern to provide the pattern with a predetermined configuration. The mold material may be deposited while the pattern is constrained.

The formation method may also include releasing constrainment of the pattern to facilitate the separating of the pattern from the first mold.

The mold material may be deposited with the pattern by splashing the mold material against the pattern.

The mold material may be configured as or otherwise include a polymer.

The mold material may be configured as or otherwise include a ceramic.

The core material may be configured as or otherwise include a polymer.

The core material may also include fiber-reinforcement embedded within the polymer.

The depositing of the core material may include laying up the core material onto the first mold.

The cellular core may also be formed by consolidating the core material under an elevated pressure and an elevated temperature.

The cellular core may also be formed by pressing the core material between the first mold and a second mold.

The formation method may also include: providing a first skin and a second skin; arranging the cellular core between the first skin and the second skin; and bonding the cellular core to the first skin and the second skin.

The structured panel may be configured as or otherwise include an acoustic panel configured as a component of an aircraft.

The pattern may include a plurality of recesses. A first of the recesses may have a triangular cross-sectional geometry.

The pattern may include a plurality of recesses. A first of the recesses may extend longitudinally through the pattern.

The pattern may include a plurality of recesses. At least a portion (or an entirety) of a first of the recesses (or each recess) may extend along a convoluted or otherwise non-straight trajectory within or through the pattern.

The pattern may include a first recess and a second recess longitudinally adjacent the first recess. The first recess may extend within the pattern along a first centerline. The second recess may extend within the pattern along a second centerline that is laterally offset from the first centerline.

The pattern may include a plurality of recesses and a plurality of endwalls. A first of the recesses may extend longitudinally within the pattern between a first of the endwalls and a second of the endwalls.

<FIG> is a partial perspective schematic illustration of a structured panel <NUM>. This structured panel <NUM> may be an acoustic panel for attenuating sound; e.g., noise. The structured panel <NUM>, for example, may be configured to attenuate sound generated by an aircraft propulsion system such as, for example, a turbofan propulsion system or a turbojet propulsion system. With such a configuration, the structured panel <NUM> may be part of a nacelle of the aircraft propulsion system. The structured panel <NUM>, for example, may be configured as or may otherwise be included as part of an inner barrel, an outer barrel, a translating sleeve or a blocker door. Alternatively, the structured panel <NUM> may be included as part of another aircraft component / structure such as, for example, an aircraft fuselage, an aircraft wing or a pylon mounting the aircraft propulsion system to the aircraft fuselage or the aircraft wing. The structured panel <NUM>, of course, may also or alternatively be configured to attenuate sound other than that generated by the aircraft propulsion system. It should also be understood, the structured panel <NUM> of the present disclosure is not limited to such exemplary structured panel configurations or applications.

The structured panel <NUM> extends longitudinally along an x-axis. The structured panel <NUM> extends laterally along a y-axis. The structured panel <NUM> extends vertically along a z-axis. Note, 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 structured panel <NUM> may be curved and/or follow an undulating geometry. For example, the x-y plane and, thus, the structured panel <NUM> may be arcuate, cylindrical, conical, frustoconical, or tapered with or without radial undulations. In such embodiments, a solely vertical direction (e.g., z-axis direction) is defined relative to a position of interest on the x-y plane. For example, on a spherical x-y plane, the vertical direction (e.g., z-axis) direction is a radial direction.

The structured panel <NUM> of <FIG> includes a perforated first skin <NUM> (e.g., a face, front and/or exterior skin with one or more through-holes), a solid, non-perforated second skin <NUM> (e.g., a back and/or interior skin without any through-holes) and a structural cellular core <NUM> (e.g., a multi-layer corrugated core). Briefly, the cellular core <NUM> is arranged 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/or the second skin <NUM>. The cellular core <NUM>, for example, may be welded, brazed, fused, adhered or otherwise bonded to the first skin <NUM> and/or the second skin <NUM>.

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

The second skin <NUM> may be configured as a relatively thin sheet or layer of (e.g., continuous and uninterrupted) material that extends laterally and longitudinally along the x-y plane. This second skin material may include, but is not limited to, metal, polymer (e.g., thermoplastic or thermoset material), a fiber reinforced composite (e.g., fiber reinforcement such as, but not limited to, fiberglass fibers, carbon fibers and/or aramid fibers within a polymer matrix), 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>. This second skin vertical thickness <NUM> extends vertically between opposing side surfaces <NUM> and <NUM> of the second skin <NUM>. The second skin vertical thickness <NUM> may be substantially equal to or different (e.g., greater or less) than the first skin vertical thickness <NUM>.

The cellular core <NUM> extends laterally and longitudinally along the x-y plane. The cellular core <NUM> has a vertical thickness <NUM>. This core vertical thickness <NUM> extends vertically between opposing sides of the cellular core <NUM>, which core sides are respectively abutted against the interior first skin side <NUM> and the interior second skin side <NUM>. The core vertical thickness <NUM> may be substantially greater than the first skin vertical thickness <NUM> and/or the second skin vertical thickness <NUM>. The core vertical thickness <NUM>, for example, may be at least ten to forty times (<NUM>-40x), or more, greater than the vertical thickness <NUM>, <NUM>; however, the structured 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 corrugations <NUM> forming a plurality of internal chambers <NUM> (e.g., acoustic resonance chambers, cavities, etc.) vertically between the first skin <NUM> and the second skin <NUM>. Each of the corrugations <NUM> of <FIG> includes a first panel <NUM> and a second panel <NUM>. Each of the internal chambers <NUM> of <FIG> extends vertically through the cellular core <NUM> between and to the first skin <NUM> and the second skin <NUM>. Each of the internal chambers <NUM> may thereby be fluidly coupled with one or more respective first skin perforations <NUM>. Each of the internal chambers <NUM> extends laterally within the cellular core <NUM> between a respective set of the first panels <NUM> of a laterally neighboring pair of the corrugations <NUM>. Each of the internal chambers <NUM> extends longitudinally within the cellular core <NUM> along the respective set of the first panels <NUM>.

The core panels <NUM> and <NUM> are arranged together and are interconnected (e.g., in a zig-zag pattern) to provide at least one corrugated ribbon <NUM> (or multiple corrugated ribbons <NUM>). Each of the first panels <NUM> may be configured as a baffle. Each first panel <NUM> of <FIG>, for example, is a fluid impermeable (e.g., non-perforated) segment of the corrugated ribbon <NUM>. Each of the second panels <NUM> may be configured as a septum. Each second panel <NUM> of <FIG>, for example, is a fluid permeable (e.g., perforated) segment of the corrugated ribbon <NUM>. More particularly, each of the second panels <NUM> may include one or more panel perforations <NUM>; e.g., apertures such as through-holes. Each of these panel perforations <NUM> extends through the respective second panel <NUM>. The cellular core <NUM> of the present disclosure, however, is not limited to such an exemplary baffle-septum arrangement. For example, in other embodiments, each of core panels <NUM> and <NUM> may be configured as a septum. In still other embodiments, each of the core panels <NUM> and <NUM> may be configured as a baffle where, for example, the structured panel <NUM> is provided for non-sound attenuation purposes.

The first panels <NUM> are interspersed with the second panels <NUM>. Each of the first panels <NUM> (unless configured at a lateral end of the cellular core <NUM>), for example, is disposed and may extend laterally between and to a respective laterally neighboring pair of the second panels <NUM>. Similarly, each of the second panels <NUM> (unless configured at a lateral end of the cellular core <NUM>) is disposed and may extend laterally between and to a respective laterally neighboring pair of the first panels <NUM>.

Referring to <FIG>, within the same corrugation <NUM>, each first panel <NUM> is connected to and may meet a respective second panel <NUM> at a peak <NUM> adjacent the first skin <NUM>. Each first panel <NUM>, for example, extends to a first end thereof. Each second panel <NUM> extends to a first end thereof. Each first panel first end is (e.g., directly) connected to the first end of the second panel <NUM> in the same corrugation <NUM> at the first skin peak <NUM>. The first panel <NUM> is angularly offset from the respective second panel <NUM> by an included angle <NUM>; e.g., an acute angle, a right angle or an obtuse angle. This first skin peak angle <NUM> of <FIG>, for example, may be between sixty degrees (<NUM>°) and one-hundred and twenty degrees (<NUM>°); e.g., ninety degrees (<NUM>°). In the specific embodiment of <FIG>, the first skin peak angle <NUM> is selected and the respective first and second panels <NUM> and <NUM> are arranged such that those panels <NUM> and <NUM> both (e.g., equally) structurally support the first skin <NUM> in the vertical direction. The present disclosure, however, is not limited to such an exemplary first skin peak angle <NUM> nor first and second panel arrangement. The first skin peak angle <NUM> of <FIG>, for example, may be between twenty degrees (<NUM>°) and seventy degrees (<NUM>°); e.g., thirty degrees (<NUM>°), forty-five degrees (<NUM>°), sixty degrees (<NUM>°). In the specific embodiment of <FIG>, the first skin peak angle <NUM> is selected and the respective first and second panels <NUM> and <NUM> are arranged such that (e.g., substantially only) one of the panels <NUM> and <NUM> (e.g., the second panel <NUM>) structurally supports the first skin <NUM> in the vertical direction.

Each first panel <NUM> of <FIG> is connected to and may meet the second panel <NUM> in a laterally neighboring corrugation <NUM> at a peak <NUM> adjacent the second skin <NUM>. Each first panel <NUM>, for example, extends to a second end thereof. Each second panel <NUM> extends to a second end thereof. Each first panel second end is (e.g., directly) connected to the second end of the second panel <NUM> in the laterally neighboring corrugation <NUM> at the second skin peak <NUM>. The first panel <NUM> is angularly offset from the respective second panel <NUM> by an included angle <NUM>; e.g., an acute angle, a right angle or an obtuse angle. This second skin peak angle <NUM> may be equal to or otherwise complementary with the first skin peak angle <NUM>. The second skin peak angle <NUM> of <FIG>, for example, may be between sixty degrees (<NUM>°) and one-hundred and twenty degrees (<NUM>°); e.g., ninety degrees (<NUM>°). In the specific embodiment of <FIG>, the second skin peak angle <NUM> is selected and the respective first and second panels <NUM> and <NUM> are arranged such that those panels <NUM> and <NUM> both (e.g., equally) structurally support the second skin <NUM> in the vertical direction. The present disclosure, however, is not limited to such an exemplary second skin peak angle <NUM> nor first and second panel arrangement. The second skin peak angle <NUM> of <FIG>, for example, may be between twenty degrees (<NUM>°) and seventy degrees (<NUM>°); e.g., thirty degrees (<NUM>°), forty-five degrees (<NUM>°), sixty degrees (<NUM>°). In the specific embodiment of <FIG>, the second skin peak angle <NUM> is selected and the respective first and second panels <NUM> and <NUM> are arranged such that (e.g., substantially only) one of the panels <NUM> and <NUM> (e.g., the second panel <NUM>) structurally supports the second skin <NUM> in the vertical direction.

Each corrugation <NUM> at its first skin peak <NUM> of <FIG> radially engages (e.g., contacts) and is connected (e.g., bonded) to the first skin <NUM>. Each corrugation <NUM> at its second skin peak <NUM> of <FIG> radially engages (e.g., contacts) and is connected (e.g., bonded) to the second skin <NUM>. With this arrangement, each of the corrugations <NUM> extends across the vertical thickness <NUM> of the cellular core <NUM> between the first skin <NUM> and the second skin <NUM>. The corrugated ribbon <NUM> may thereby divide each internal chamber <NUM> into a first sub-chamber 46A (e.g., cavity) and a corresponding second sub-chamber 46B (e.g., cavity). The first sub-chambers 46A of <FIG> are located within the cellular core <NUM> on the first skin side of the corrugated ribbon <NUM>. The second sub-chambers 46B are located within the cellular core <NUM> on the second skin side of the corrugated ribbon <NUM>. Each of the second sub-chambers 46B is fluidly coupled with a respective one of the first sub-chambers 46A through the panel perforation(s) <NUM> in a respective one of the second panels <NUM>. Thus, each of the second sub-chambers 46B is fluidly coupled with respective first skin perforation(s) <NUM> through the respective first sub-chamber 46A.

With the foregoing configuration, each of the internal chambers <NUM> of <FIG> may have a length <NUM> within the cellular core <NUM> that is longer than the core vertical thickness <NUM>. This may facilitate tuning the cellular core <NUM> and, more generally, the structured panel <NUM> for attenuating sound (e.g., noise) with relatively low frequencies without changing (e.g., proportionally increasing) the overall vertical height <NUM> of the cellular core <NUM> and, thus, the structured panel <NUM> as may be required, for example, for a traditional acoustic panel with a honeycomb core. The structured panel <NUM> of the present disclosure, however, is not limited to such an exemplary relationship.

<FIG> is a flow diagram of a method <NUM> for forming a structured panel. For ease of description, the formation method <NUM> is described with respect to forming the structured panel <NUM>. The formation method <NUM> of the present disclosure, however, is not limited to forming any particular structure panel types or configurations.

In step <NUM>, referring also to <FIG>, a mold pattern <NUM> is formed. For example, referring to <FIG>, a sheet of material <NUM> is provided. This sheet of material <NUM> may be constructed from metal; e.g., the sheet of material <NUM> may be sheet metal. Alternatively, the sheet of material <NUM> may be constructed from a non-metal such as, for example, a polymer (e.g., thermoplastic) or any other suitable (e.g., foldable, relatively stiff) material. Referring to <FIG>, the sheet of material <NUM> may be embossed (e.g., e.g., stamped, perforated, scored, etc.) to provide a plurality of fold lines <NUM>. Referring to <FIG>, the sheet of material <NUM> is folded (e.g., bent) using, for example, a bending brake, a die and/or one or more other folding tools to provide the pattern <NUM>. The (e.g., embossed) sheet of material <NUM>, for example, is folded along the fold lines <NUM>. Alternatively, the sheet of material <NUM> may be folded without use of the embossed fold lines <NUM> in other embodiments. Once the sheet of material <NUM> has been folded, the pattern <NUM> and the cellular core <NUM> (e.g., see <FIG> and <FIG>) to be formed using the pattern <NUM> may have substantially or exactly a common (e.g., the same) configuration; e.g., shape, size, features, etc. For example, the pattern <NUM> may be a substantial replica of the cellular core <NUM> without, for example, the panel perforations <NUM> (when included in the cellular core <NUM>). Using this folding process, the pattern <NUM> may be rapidly manufactured with relatively little expense compared to a traditional pattern casting and/or machining forming process. It is contemplated, however, that the folded pattern <NUM> may also be paired with a cast, machined and/or otherwise formed pattern and/or feature(s).

In step <NUM>, referring also to <FIG>, the pattern <NUM> may be constrained as needed. The material of the pattern <NUM>, for example, may have a certain degree of resiliency. As a result, the folded sheet of material <NUM> forming the pattern <NUM> may slightly spring back to a slightly unfolded state. This resiliency may be accommodated by constraining the pattern <NUM>. The lateral ends <NUM> and <NUM> of the pattern <NUM>, for example, may be pressed (e.g., compressed) laterally together using one or more constraints <NUM> and <NUM> and/or otherwise manipulated to provide the pattern <NUM> with its predetermined configuration; e.g., the configuration of the cellular core <NUM>. Of course, one or more individual pattern corrugations 44A or sets of the pattern corrugations 44A may also or alternatively be laterally or otherwise manipulated to provide the pattern <NUM> with its predetermined configuration. In addition or alternatively, the sheet of material <NUM> may be overfolded during the pattern formation step <NUM> such that in its slightly unfolded (e.g., relaxed) state the pattern <NUM> has its predetermined configuration.

In step <NUM>, referring also to <FIG>, a first mold <NUM> is formed using the pattern <NUM>. For example, referring to <FIG>, mold material is deposited with (e.g., splashed against) the pattern <NUM> to make an inverse mold (e.g., a negative) of a respective (e.g., a top) side of the pattern <NUM>; see also <FIG>. The mold material, for example, may at least partially or completely fill one or more recesses <NUM> (see also <FIG>) (e.g., channels, depressions, etc.) and/or any other apertures in the pattern <NUM>. The depositing may be performed via coating (e.g., spraying), dipping and/or various other known deposition techniques. The mold material may be or otherwise include a polymer; e.g., thermoplastic or thermoset material. Alternatively, the mold material may be or otherwise include a ceramic or any other suitable material.

In step <NUM>, the pattern <NUM> is separated from the first mold <NUM>. For example, where the pattern <NUM> is constrained during the optional step <NUM>, the pattern <NUM> may be released; e.g., unconstrained. The pattern <NUM> may then by pulled away from (or otherwise manipulated) to disengage the pattern <NUM> from the first mold <NUM>. To facilitate the separation of the pattern <NUM> from the first mold <NUM>, the pattern <NUM> may be coated with a release agent prior to the first mold formation step <NUM>.

In step <NUM>, a second mold <NUM> may be formed (e.g., see <FIG>). This second mold <NUM> may be formed by repeating the mold formation step <NUM> on a back side of the pattern <NUM>. Alternatively, the second mold <NUM> may be formed following formation of a new pattern; e.g., repeating steps <NUM>, <NUM>, <NUM>.

In step <NUM>, referring also to <FIG>, the cellular core <NUM> is formed. Core material <NUM>, for example, may be deposited with the first mold <NUM> and/or the second mold <NUM>. This core material <NUM> may be or otherwise include a polymer; e.g., a thermoplastic or a thermoset. The core material <NUM> may also include fiber-reinforcement embedded within the polymer; e.g., a polymer matrix. Examples of the fiber-reinforcement include, but are not limited to, fiberglass fibers, carbon fibers and/or aramid fibers. The present disclosure, however, is not limited to the foregoing exemplary core materials.

The core material <NUM> may be manually laid up, placed using an automated fiber / tape placement (AFP / ATP) device and/or otherwise disposed with the respective mold(s) <NUM>, <NUM>. The core material <NUM> may be pressed between the first mold <NUM> and the second mold <NUM> and/or otherwise compressed against the respective mold(s) <NUM>, <NUM> (e.g., using a vacuum bag, etc.). The core material <NUM> may also be heated. The core material <NUM> may thereby be consolidated together under an elevated pressure and/or an elevated temperature to form a preform <NUM> of the cellular core <NUM>. This core preform <NUM> may be separated (e.g., released) from the respective mold(s) <NUM>, <NUM>. The core preform <NUM> may then be machined, trimmed and/or otherwise finished to provide the cellular core <NUM>. The core preform <NUM>, for example, may be perforated (e.g., drilled, laser ablated, punched, etc.) to form the panel perforations <NUM> (e.g., see <FIG>) when included.

In step <NUM>, the first skin <NUM> is provided.

In step <NUM>, the second skin <NUM> is provided.

In step <NUM>, the cellular core <NUM> is arranged vertically between the first skin <NUM> and the second skin <NUM>.

In step <NUM>, the cellular core <NUM> is bonded (e.g., welded, adhered, etc.) to the first skin <NUM> and the second skin <NUM> to form the structured panel <NUM>.

The pattern <NUM> and, thus, the cellular core <NUM> may have various configurations other than that described above. For example, any one or more or all of the folds and, thus, the resulting corrugation(s) <NUM> may extend longitudinally along the x-axis. Any one or more or all of the folds / corrugation(s) <NUM> may also or alternatively extend laterally along the y-axis. Any one or more or all of the folds / corrugation(s) <NUM> may still also or alternatively extend diagonally (or otherwise) within the x-y plane. Some or all of the folds / corrugation(s) <NUM> may be parallel with one another. Alternatively, some of the folds / corrugation(s) <NUM> may be angularly offset from one another (e.g., perpendicular or acutely angled to one another) to provide a variable (e.g., bumpy) topography in multiple directions along the x-y plane. Examples of such alternative configurations include, but not limited to, the patterns <NUM> / cellular cores <NUM> shown in <FIG>, <FIG> and <FIG>. The pattern <NUM> of <FIG> may be formed using the exemplary folding technique partially depicted in <FIG>. The pattern <NUM> of <FIG> may be formed using the exemplary folding technique partially depicted in <FIG>. The pattern <NUM> of <FIG> may be formed using the exemplary folding technique partially depicted in <FIG>.

In some embodiments, referring to <FIG>, <FIG>, <FIG> and <FIG>, each recess <NUM> may project vertically (e.g., partially) into the pattern <NUM>. Each recess <NUM> may extend laterally within the pattern <NUM> between a respective laterally adjacent pair of the pattern panels 48A, 50A; e.g., sidewalls. Referring to <FIG>, <FIG> and <FIG>, each recess <NUM> may extend longitudinally through the pattern <NUM> along the respective pair of pattern panels 48A, 50A. Alternatively, referring to <FIG>, one or more or all of the recesses <NUM> may each extend longitudinally within the pattern <NUM> between a respective longitudinally adjacent pair of pattern endwalls <NUM>; e.g., stringers, etc. As each recess <NUM> of <FIG>, <FIG>, <FIG> and <FIG> extends longitudinally within / through the pattern <NUM>, that recess <NUM> may follow a recess trajectory <NUM>; e.g., a centerline of the respective recess <NUM>. Referring to <FIG> and <FIG>, at least a portion or an entirety of the recess trajectory <NUM> may be straight. Alternatively, referring to <FIG> and <FIG>, at least a portion or an entirety of the recess trajectory <NUM> may be non-straight; e.g., convoluted (e.g., zigzagged, sinusoidal, wavy, etc.), bent, curved, etc. In some embodiments, referring to <FIG>, the recess trajectories <NUM> of longitudinally neighboring recesses <NUM> may be laterally misaligned; e.g., offset. These misaligned recess trajectories <NUM> may be parallel with one another or angularly offset from one another.

In some embodiments, referring to <FIG>, one or more or all of the recesses <NUM> may each have a polygonal cross-sectional geometry when viewed, for example, in a reference plane perpendicular to the pattern panels 48A, 50A forming the respective recess <NUM>. Examples of the polygonal cross-sectional geometry include, but are not limited to, a triangular cross-sectional geometry (e.g., see <FIG>), a rectangular cross-sectional geometry (e.g., see <FIG>) and a trapezoidal cross-sectional geometry (e.g., see <FIG>).

Claim 1:
A formation method, comprising:
forming a pattern (<NUM>) by folding a sheet of material (<NUM>);
forming a first mold (<NUM>) by depositing mold material with the pattern (<NUM>);
separating the pattern (<NUM>) from the first mold (<NUM>); and
forming a cellular core (<NUM>) for a structured panel (<NUM>) by depositing core material (<NUM>) with the first mold (<NUM>).