Composite construction with a honeycomb core and method for the production thereof

Abstract

A sound-absorbing composite component (1) comprising a honeycomb body (10) and at least one corresponding insert (18;... 68) in at least some of the honeycomb cells (16), and a production method therefor. The corresponding insert has a main axis (H), a first end (21;... 61), a second end (22;... 62) and a continuous face (25;... 65) and is placed with the main axis (H) in the direction of the honeycomb depth (T). According to the invention, the continuous face (25;... 65) has face regions (25a, 25b;... 65a, 65b) which are spaced apart from one another in the axial direction and face one another, which overlap in a projection onto a plane perpendicular to the main axis (H) in order to delimit a passage (20;... 60) for sound waves in the axial direction. The course of the continuous face (25;... 65) from the first end (21;... 61) to the second end (21;... 61) through the face regions (25a, 25b;... 65a, 65b) encircles the main axis (H) and / or crosses the main axis a plurality of times.

Description

Technical Field

[0001] The present invention relates to a composite component for absorbing sound waves, particularly for absorbing operating noise of aircraft (e.g., passenger aircraft with jet engines). Background Technology

[0002] To reduce noise emissions in jet engines, it is known to place sound-absorbing shrouds on the inside of the engine casing or at other suitable locations. This invention is not limited to this application, but is particularly suitable for absorbing operating noise from aircraft engines.

[0003] Such a sound-absorbing cover can be in the form of, for example, a panel. The panel typically comprises a sandwich arrangement having a honeycomb core between two covering layers, wherein, in most cases, the covering layer facing the sound source is sound-permeable, for example, perforated. Here, the honeycomb cells of the honeycomb core function as acoustic resonators based on the Helmholtz resonator principle, which absorb or reduce sound.

[0004] To improve sound absorption, it is known to arrange sound-transparent acoustic baffles inside the cellular unit.

[0005] Typically, aircraft jet engines generate noise in the frequency range of approximately 300–6300 Hz. The lower the frequency, the greater the depth of the cellular cells must be to achieve the desired sound absorption. However, this is not always possible or desirable, partly due to the associated increase in weight and partly due to the desired small component size (e.g., due to limited installation space).

[0006] In order to achieve sound absorption in the lower frequency range without increasing the depth of the cellular unit or the thickness of the cellular body, it is known to introduce acoustic inserts into the cellular unit.

[0007] US2015 / 0041247A1 describes a composite structure for sound absorption comprising a honeycomb disk between two overlay layers, one of which is sound-reflective and the other is acoustically transparent (perforated). Each honeycomb cell receives a conical insert, the wider edge of which connects to the edge of the honeycomb and the acoustically transparent overlay layer, and its narrower edge, or the tip of the opening, opens inside the honeycomb. This insert reflects sound and divides the honeycomb cell into two acoustic chambers, thereby increasing the resonator length or effective acoustic length of the honeycomb cell.

[0008] According to US2015 / 0041247A1, the frequency range of absorbed sound can be altered by changing the position of the insert along the depth of the cell. However, this strongly limits the possibility of matching even lower frequencies. Summary of the Invention

[0009] Therefore, the objective of this invention is to provide an acoustic system with a compact and lightweight construction for absorbing sound, especially the operating noise of aircraft, which can be adapted to different frequency ranges as easily as possible.

[0010] This task is solved by the composite component as described in claim 1 and, independently of this, by the insert body as described in claim 2.

[0011] Advantageous embodiments are the subject of the dependent claims.

[0012] This type of composite component includes at least one cell or cell core having multiple cellular cells and a number of acoustic inserts, wherein at least one insert is arranged in each of at least some of the cellular cells. The insert has a main axis defining an axial direction. The insert is arranged in or mounted into a corresponding cellular cell such that the main axis of the insert extends in the depth direction of that cellular cell. The insert includes a continuous surface and has a first end and a second end in the direction of the main axis. The insert extends through the first end and the second end, particularly as a continuous or one-piece component.

[0013] In this type of composite component, the aforementioned task has been solved by having the coherent surface of the insert having surface regions spaced apart from each other in the axial direction or in the direction of the main axis, the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis, in particular aligning with each other, so as to limit the channel for sound waves between the surface regions in the axial direction or in the direction of the main axis.

[0014] Here, according to the invention, the connecting surface is particularly arranged or shaped such that the orientation of the connecting surface surrounds the main axis and / or crosses the main axis multiple times. Here, the considered orientation extends from the first end of the insert through the surface region according to the invention and reaches the second end of the insert.

[0015] Alternatively or additionally, the aforementioned tasks are also addressed in this type of composite component by having a coherent surface of the insert having surface regions spaced apart from each other in the direction of the main axis, the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis, in particular aligned with each other, so as to define a channel for sound waves between the surface regions in the direction of the main axis, wherein the insert divides the cellular unit into multiple cavities, the multiple cavities being defined in the direction of the main axis by the surface regions facing each other. The insert is capable of dividing the cellular unit into three or more cavities.

[0016] The present invention also relates to acoustic inlays themselves or to objects thereof, which are used to be incorporated into a cellular structure to absorb sound waves, particularly to absorb aircraft operating noise.

[0017] This type of insert has a main axis defining the axial direction and can be installed along its main axis in the direction of the depth of the cellular cell, particularly in a hexagonal cellular cell. Here, the insert includes a continuous surface and has a first end and a second end in the axial direction.

[0018] According to the invention, the coherent surface of the insert has surface regions spaced apart from each other in the axial direction, the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis, in particular aligned, so as to limit the channel for sound waves between the surface regions in the axial direction or in the direction of the main axis, and the coherent surface is configured such that the orientation of the coherent surface surrounds the main axis and / or crosses the main axis multiple times.

[0019] Here, the considered path extends from the first end of the insert through the surface region according to the invention and to the second end of the insert. The continuous surface can also extend through other surface regions of the insert, not just through the surface region that limits the acoustic wave passage in the axial direction.

[0020] Alternatively or supplementally, in this type of embedding, the coherent surface of the embedding has surface regions spaced apart from each other in the direction of the main axis, the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis, in particular aligned, so as to limit the channels for sound waves between the surface regions in the direction of the main axis and divide the cellular unit into multiple cavities, preferably three or more cavities, the cavities being limited in the direction of the main axis by the surface regions facing each other.

[0021] The corresponding cellular cells are bounded by their cell walls in a direction transverse to the depth direction of the cellular structure (L / W direction). Typically, a cellular structure or cellular disk comprises a large number of cellular cells, which are adjacent to the nearest cellular cell by their walls. The composite member can include at least one planar layer, such as a cover layer, and at least one cellular structure. The walls of the cellular cells can be arranged transversely to the planar layer, and in particular perpendicularly to the planar layer. The edges of the cellular walls in the composite member can be in contact with the planar layer, and in particular fixedly connected.

[0022] The insert can be mounted or can be installed into a cellular cell such that its main axis is oriented in the direction of the cell depth. In the case of a flat, unbent or unreflected composite member, the main axis can extend parallel to the cell wall and / or perpendicular to the surface layer, such as the cover layer.

[0023] The insert is particularly capable of working in conjunction with the walls of a cellular cell (in which the insert is received) to guide sound waves within the cellular cell. The face or surface of the insert can work together with the walls of the corresponding cellular cell as a guiding or directing surface for sound waves.

[0024] The insert is specifically designed to prevent sound waves entering the cell from passing through the cell in a straight line in the depth direction when it is embedded in the cell.

[0025] Therefore, the insert according to the invention enables sound waves to be redirected onto extended segments, such as curved, arc-shaped, or zigzag paths. Consequently, the insert allows for a significant increase in the resonator length or the effective acoustic length of the cell unit in a structurally relatively simple manner. The insert allows for optimized utilization of the given hollow space of the cell unit in terms of acoustic effects, particularly sound absorption. In particular, the 30 to 50 mm cell thickness typically used for sound absorption in the frequency range of around 2000 Hz in aircraft engines can be reduced by one-third or even half, for example, to a cell thickness of 15 mm, by using the insert.

[0026] Embedded bodies can aid in sound absorption by redirecting sound waves, particularly through reflections on the surface areas of the embedded body. Furthermore, embedded bodies can also partially receive the energy of sound.

[0027] Unless otherwise stated, the terms "radial direction" and "axial direction" generally refer to the main axis of the insert. Here, "main axis" can be understood as the axis of the center, which is substantially or nearly parallel to the wall of the cell when the insert is oriented in a given cellular cell of a planar cellular structure. Currently, the main axis does not necessarily mean the direction of the maximum extension of the insert. The insert can, for example, have a greater extension in the radial direction than in the axial direction. However, the main axis can also correspond to the longitudinal axis. The main axis does not necessarily have to be the axis of symmetry of the insert; however, the main axis is preferably located approximately centrally within the longitudinal section.

[0028] If the insert is intentionally arranged in the cellular cell such that the main axis of the insert extends in the direction of the cell depth, then the radially outer edge of the insert can and should abut against or be in contact with the walls of the cellular cell with a minimal gap size, and in particular, be connected to them, for example, by adhesive. If necessary, minute gaps or voids may also exist between at least some sections of the radially outer edge of the insert and the cellular cell wall. These gaps or voids can be sound-transparent.

[0029] The main axis can correspond in particular to the main axis of inertia of the embedded body. The planar arrangement of the embedded body can in particular be rotationally symmetric with respect to the main axis.

[0030] Preferably, the dominant majority of the cellular cells each include at least one inlay. Each cellular cell is capable of receiving more than one inlay. Cellular cells can also receive different inlays simultaneously, which increases the flexibility in matching the composite member with the desired, to-be-absorbed frequency region. The position of the corresponding inlay at the depth of the cellular cell can also be matched with the to-be-absorbed frequency region. In particular, the inlay can only occupy a portion of the cellular cell depth.

[0031] Once the honeycomb structure is manufactured, inserts can be assembled into it later. However, inserts can also be embedded or fitted into the honeycomb structure during the manufacturing process, or they can be produced together with the honeycomb structure in a single step. Regardless of the manufacturing method, an insert can be understood as a body that can also exist as a body outside the honeycomb structure due to its coherent geometry.

[0032] The insert, in particular, has an independent, continuous surface or continuous plane. This continuous surface has an uninterrupted orientation or extends uninterruptedly from a first end of the insert to its second end. This orientation can be understood as an uninterrupted spatial curve: the uninterrupted spatial curve lies within the continuous surface of the insert or defines its orientation. Here, the cell walls, in particular, do not contribute to the continuous surface.

[0033] The connecting surface can be formed by different body segments of the embedded body, and these different body segments can be shaped differently. In the strip-shaped body segments, both sides of the strip can contribute to the connecting surface. Channel openings can be provided so that sound waves can pass through these channel openings from one side of the strip to the other side.

[0034] The continuous surface configuration of the insert allows for the drawing of uninterrupted spatial curves or directional curves on or within the surface, these curves encircling and / or traversing the main axis of the insert multiple times. Here, the directional curves also extend through surface regions of the continuous surface that face each other and are axially defined as channels or pathways for sound waves. However, additional surface regions can be arranged between these surface regions in the axial direction. Preferably, the channels can also encircle and / or traverse the main axis multiple times.

[0035] The spacing between the surface regions of two mutually boundarying sound channels can be of different sizes in the axial direction or along the main axis. This spacing can be individually adjusted to allow the embedding to be specifically matched to the frequency region to be absorbed.

[0036] Hexagonal honeycomb cells are preferred. However, the honeycomb structure can include honeycomb cells with different cell geometries. The honeycomb cells may have irregular or regular shapes in cross-section in the direction perpendicular to the honeycomb depth, especially circular or polygonal shapes, which may be, for example, rectangular, and especially square.

[0037] The cell walls of a cellular unit can be soundproof or sound-permeable, for example, perforated, to allow sound waves to diffuse in the L and W directions of the cellular structure.

[0038] In a preferred embodiment, the connecting surface substantially covers the cross-section of the honeycomb cell, allowing the insert to be mounted or installed into the cell. Here, the projection of the connecting surface onto a plane perpendicular to the main axis or onto the planar arrangement of the honeycomb cell is considered. The corresponding coverage can be achieved, in particular, by at least one, preferably multiple, loops of the connecting surface. Thus, in a top view, the insert preferably has a planar arrangement that coincides with or maximizes the filling of the planar arrangement of the honeycomb cell (except for small gaps to the cell walls).

[0039] In one embodiment, the insert has a centrally elongated trunk or skeleton that extends longitudinally along the main axis, particularly from a first end of the insert to a second end. The trunk contributes to the reinforcement of the insert. This is advantageous for improving shape stability. The main axis of the insert can extend within the trunk.

[0040] In a preferred embodiment, the coherent surface includes a generalized helicoid. A helicoid is understood to be a surface created by the spiral of a space curve. The helicoid can be not only right-handed or right-traveled but also left-handed or left-traveled. The insert can have two or more helicoids. The helices can be intertwined.

[0041] Alternatively or supplementally, a continuous surface can include or constitute a deployable surface. Geometrically, a deployable surface is one that can be smoothly laid on a flat surface without compression or distortion. Deployable geometry particularly allows for specific manufacturing techniques, such as those using folding techniques.

[0042] The continuous surface of the inlay can be, in particular, ruled surface in a geometric sense, preferably a developable ruled surface.

[0043] A tangent surface can include a tangent developable surface and / or a helical surface or a surface of revolution.

[0044] A helical surface does not necessarily have to be ruled. In one embodiment, the helical surface is curved along multiple axes. The helical surface can be particularly shaped with irregularities. The helical surface can be constructed at least in sections in a stepped or spiral staircase manner. The helical surface can particularly be at least partially corrugated.

[0045] A helical surface can have a regular or irregular pitch. Different turns of the helical surface can have varying axial spacing. This provides a particular degree of flexibility and design freedom in matching the geometry of the insert to the frequency region of the sound wave to be absorbed. Without being bound by theory, it is conceivable that the varying axial spacing between the turns of the helical surface can affect not only the intensity of the sound wave but also its frequency.

[0046] The helical surface can have a helical axis that extends in the direction of the main axis of the insert or extends parallel to the main axis and preferably coincides with the main axis.

[0047] A helical surface can have radially inward edges and radially outward edges about the main axis.

[0048] The insert can include a helical or spiral portion (the helical or spiral portion coils around a main axis, providing a helical surface) and has a radially outward edge along the radially outward edge of the helical surface. This radially outward edge of the insert, received in a cellular cell, can be connected to the wall of the cellular cell, particularly in a material-locking manner, such as by adhesive. However, in one embodiment, the radially outward edge of the insert can have a gap to at least one of the cellular walls and allow sound waves to pass through.

[0049] The helical axis of the helical surface can extend inside the trunk, so that the helical surface spirals around the trunk.

[0050] In one embodiment, the radially built-in edge can be fully or partially connected to, extend on, or be supported by the trunk. In this embodiment, if necessary, the helical surface can be integrally transitioned onto the surface of the trunk.

[0051] In another embodiment, the radially built-in edges can be fully or partially suspended. This embodiment is advantageous because the honeycomb with inserts can be deformed later, for example, to adapt the honeycomb to the curved inner surface of an aircraft engine. A honeycomb with inserts having free, radially built-in edges has greater flexibility than a honeycomb with inserts having a central trunk. In particular, in this embodiment, the radially built-in edges in the insert can be fully suspended, that is, without a central or centered trunk for reinforcement, to improve subsequent deformability.

[0052] In one embodiment with a fully suspended helical surface at the inner edge, the insert can have a free space extending through the main axis in the axial direction, around which the helical surface spirals. The free space can have different geometries perpendicular to the main axis in a top view and can be of different sizes at different locations along the main axis. This embodiment is advantageous for improving the deformability and flexibility of the honeycomb structure, as well as for ventilation, degassing, and dehydration or drainage of the honeycomb structure.

[0053] The orientation of the continuous surface—especially when using a helical surface—can rotate around the main axis by at least 360°, preferably significantly more than 360°. That is, the rotation angle of the entire helical surface around the main axis can be significantly greater than one revolution, preferably at least 720°, or two revolutions. Therefore, the acoustically effective length or path of sound waves passing through the honeycomb unit can be significantly extended. Consequently, significantly lower sound frequencies can be absorbed by the composite component.

[0054] In one embodiment, the insert can be configured to divide the cellular cell into cavities. The cavities can be bounded by a coherent surface, at least in the axial direction or in the direction of the main axis. The respective cavities can be bounded by at least one wall of the insert and the cellular cell.

[0055] In one embodiment, the insert divides the cellular cells into a number of identical or equivalent cavities. In another embodiment, different cavities are constructed.

[0056] At least some cavities are preferably acoustically interconnected, for example, by means of at least one channel opening between corresponding two cavities.

[0057] The channel opening can be positioned so that the path of sound waves through the cell unit is meandering, serpentine, or sawtooth-shaped. In this way, the path of sound within the cell unit is also lengthened.

[0058] The surface region under consideration can generally have a curved or generally flat geometry. At least some surface regions of the coherent surface of the insert can extend at an angle relative to the principal axis.

[0059] At least some of the face regions facing each other (where sound waves travel between the face regions) are able to extend at an angle relative to each other.

[0060] In one embodiment, the insert has at least two funnel-shaped or pyramidal body segments that are staggered relative to each other, particularly coaxial with respect to the main axis, and provide facet areas facing each other. These body segments can have the shape of hollow, bottomless pyramids with closed tips, having polygonal bases that correspond in shape to the cross-section of the cellular cell into which the insert is to be mounted, for example, hexagonal or quadrilateral. The sides of the pyramids can be adjacent to each other by their edges or be circular. The funnel-shaped or pyramidal body segments can be arranged to interlock with each other, such that channels for sound waves remain open between the body segments. At least some of the funnel-shaped or pyramidal body segments can be in contact with the walls of the cellular cell at their periphery and thus divide the cellular cell into cavities that are mutually bounded in the axial direction.

[0061] Successive pyramidal body segments can have channel openings, particularly alternating between having channel openings either in the central region or on their periphery. These channel openings allow sound waves to propagate within a cavity along facet regions facing each other (the facet regions being formed by the nearest funnel-shaped or pyramidal body segments) and to the next cavity, preferably only along zigzag paths.

[0062] The pyramidal or funnel-shaped segments can be interconnected by at least one connecting segment. The at least one connecting segment can be a centrally located or centrally positioned main trunk extending along a main axis. The main axis can extend through the main trunk. To save weight, the main trunk can be hollow. The main trunk can have different cross-sectional shapes.

[0063] Alternatively or supplementally, the embedding can have multiple eccentrically or dispersedly arranged, especially peripheral, connecting segments. A central backbone is advantageous because it can be used for gripping when the embedding is installed into the cellular unit.

[0064] At least some of the surface regions can be curved, for example, concave or convex in shape.

[0065] At least some of the surface areas can be bent or have curved edges and / or steps.

[0066] The surface area can preferably function as a rebound surface and deflect sound waves so that the sound is deflected from a straight path to the bottom of the honeycomb.

[0067] In one implementation, the coherent surface of the embedding includes a ruled surface. Currently, by geometric definition, a "ruled surface" is understood as a surface in which a straight line completely contained can extend through every point of the surface.

[0068] Alternatively or additionally, the coherent surface of the insert may have convex and / or concave surface regions.

[0069] Furthermore, the continuous surface of the embedding can at least segmentally include trapezoidal and / or corrugated surfaces.

[0070] The insert can preferably be manufactured as a single piece or as an integral unit.

[0071] Embedded bodies can be manufactured using uniform materials or from regions with different materials.

[0072] The insert can be made of plastics, such as thermoplastics, preferably high-temperature thermoplastics, and also thermosetting plastics. Furthermore, the insert can be made of fibrous materials, such as fabrics, woven cloth, paper, or nonwoven fabrics, especially glass fibers and / or carbon fibers.

[0073] Preferably, the insert is made of a composite material, such as a composite material composed of glass fiber or carbon fiber and thermoplastic or thermosetting plastic.

[0074] Embedded components can be manufactured, in particular, through additive manufacturing processes, such as 3D printing. As an additive manufacturing process, AM (additive manufacturing process) is particularly relevant to processes defined in the sense of standard VDI 3405 or DINEN ISO 17296-2 (Part 2). AM processes allow for the automated, computer-aided production of complex, virtually arbitrary geometries, typically based on layered coating structures. As an AM process, direct printing (with self-curing of the printing material) is also possible, as well as 3D printing via polymerization, bonding, sintering / melting, and so on.

[0075] The advantage of additive manufacturing is that the shape of the insert can be freely chosen or adapted to acoustic requirements.

[0076] In one implementation, the insert can be directly pressed into the cellular cell, for example. If necessary, the cellular structure can also be manufactured by 3D printing, for example, in a single step together with the insert.

[0077] Inserts can be manufactured entirely or integrally during additive manufacturing. Extrusion-based processes (EB) are particularly suitable for this, either through chemical hardening or physical reinforcement of heated thermoplastics. For example, fused deposition modeling (FDM) is also considered suitable. Material jetting (MJ) processes, such as those using photopolymers reinforced by light, are also conceivable. Similarly, so-called binder jetting (BJ), sometimes referred to as 3DP, can also be considered. Essentially, all so-called 3D printing technologies can be considered.

[0078] The following materials are particularly suitable for additive manufacturing processes: metals such as aluminum and titanium; thermosetting plastics (especially epoxy resins, phenols, benzoxazine, cyanate esters, and polyimides); high-temperature resistant thermoplastics such as PEEK or PEI; elastomers such as thermoplastic polyurethanes and polysiloxanes; and ceramic materials such as oxide ceramics or carbide ceramics. These materials can incorporate fibers, especially glass fibers, carbon fibers, aramid fibers, and / or ceramic fibers, to improve mechanical or vibration-related properties when needed.

[0079] However, the insert can be manufactured using any technique, such as by suitable folding techniques and / or embossing processes. The insert can be manufactured, for example, by folding a metal foil (e.g., aluminum foil or plastic foil) and / or by embossing. Other materials used for manufacturing the insert by folding can be, for example... Paper and The aromatic polyamide paper (aromatic polyamide) is preferably 1.1 to 3.9 mils thick, wherein 1 mil is equivalent to 0.0254 mm.

[0080] Furthermore, the insert can be manufactured from thermoplastic foil by folding and / or embossing. Additionally, the latter can also be performed by thermoforming a thermoplastic material under temperature influence. The "foil" can have a thickness from several micrometers to approximately 1 millimeter and is made, for example, from polyetherimide (PEI); polyimide (PI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polycarbonate, polyamide, and / or polyester.

[0081] The connecting surface can be, for example, partially or entirely composed of a strip made of plastic, especially thermoplastic plastic and / or fiber, especially glass fiber, carbon fiber, plastic fiber, aramid fiber or ceramic fiber, and / or metal.

[0082] In one embodiment, the insert can include, at least in sections, a breathable material. Breathable materials can include, for example, open-cell materials and / or micro-perforated materials (with pores having a diameter of 0.01 to 0.5 mm) or large-perforated materials (with pores having a diameter > 0.5 mm). Breathable materials can be used, particularly as sound-permeable partitions.

[0083] In one embodiment, the composite member includes at least one cover and / or intermediate layer connected to a honeycomb cell. The composite member can include a sandwich-structure arrangement in which the honeycomb cell or honeycomb core is arranged between two cover layers, particularly covered or closed on both sides by cover layers. One of the cover layers can be perforated and / or made of a breathable material.

[0084] Composite components can include multiple honeycomb cells, such as two honeycomb cell layers on either side of a surface intermediate layer, wherein each honeycomb cell layer is connected to one side of the intermediate layer, for example, by bonding.

[0085] Composite components can particularly comprise a layer arrangement consisting of multiple honeycomb layers and multiple faceted intermediate layers, wherein the intermediate layers can be acoustically transparent, particularly perforated or closed. Composite components can particularly be constructed as multi-layered sandwich structures. One, more, or all of the honeycomb layers can be equipped with acoustic inserts.

[0086] The cover and / or intermediate layer can be made of, for example, plastics, composites, metals and / or ceramics.

[0087] The overlay or intermediate layer and / or honeycomb layer can be made of plastic, and particularly include fabrics, woven fabrics, paper, or nonwoven fabrics made of fibers, or made solely of plastic or solely of fibers, for example, in the form of fabrics, woven fabrics, paper, or nonwoven fabrics. The overlay and / or intermediate layer and / or honeycomb layer can be made of composite materials, particularly composite materials including fibers, for example, in the form of fabrics, woven fabrics, paper, or nonwoven fabrics. The overlay or intermediate layer can include metal foil, such as aluminum, titanium, or from Special Metals Corp. manufacture.

[0088] As plastics, thermoplastics such as PE (polyethylene), PP (polypropylene), PA (polyamide), PET (polyester), and PC (polycarbonate) are particularly suitable, with high-temperature thermoplastics such as PI, PPS, PEI, PEEK, and PEKK being preferred. Thermosetting plastics such as phenolic resins, epoxy resins, benzoxazine resins, bismaleimide resins, cyanate ester resins, and polyimide resins, or thermoplastic thermosetting plastics such as phenoxy resins, can also be used in the manufacture of cover layers or honeycomb structures.

[0089] The honeycomb structure and / or the covering or interlayer can incorporate ceramic materials, especially composites made of ceramics. The ceramic structure is advantageous for high-temperature applications.

[0090] The insert itself can be bonded to the adjacent wall of the corresponding cellular cell and / or to the cover or intermediate layer. Alternatively, the insert can be held in the corresponding cell by frictional or force-locking to the cellular wall (and if necessary, without adhesive).

[0091] Furthermore, the present invention relates to a method for manufacturing a composite component for absorbing sound waves. The method includes at least providing a prefabricated honeycomb structure in most cases and embedding an acoustic insert into the honeycomb cells of the honeycomb structure.

[0092] The method is characterized by manufacturing the insert according to AM (Advanced Microfabrication) or additive manufacturing processes, resulting in inserts having continuous surfaces, particularly surfaces of one of the geometries explained above. Specifically, the inserts can be constructed in situ within a cellular cell using AM processes.

[0093] In one embodiment of the method, the honeycomb structure is also manufactured using an AM process. The provision of the honeycomb structure and the embedding or formation of acoustic inserts within the honeycomb cells can preferably be performed in a single step using an additive manufacturing process.

[0094] Additive manufacturing processes can be 3D printing processes, or other AM processes as explained above.

[0095] Additive manufacturing allows for extremely different geometries in which the coherent surface of the insert has surface regions spaced apart from each other in the direction of the main axis of the insert, the surface regions facing each other and overlapping, in particular aligning, in their projection onto a plane perpendicular to the main axis, so as to limit the channel for sound waves between the surface regions in the axial direction, wherein the coherent surface configuration is such that the orientation of the coherent surface surrounds the main axis and / or crosses the main axis multiple times.

[0096] This method can include creating perforations in the cover layer and / or in the insert. Perforations or channel openings can be created, for example, during additive manufacturing by omitting the corresponding location. However, perforations or channel openings can also be created later, for example, by mechanical piercing or by laser processing, etc.

[0097] In one implementation, a certain degree of sound transmission can be achieved by using a porous material.

[0098] The manufacturing method can, in particular, include bonding the insert to the adjacent wall of the corresponding cellular cell and / or to one or two cover layers or (possibly) intermediate layers under temperature influence, if necessary. Furthermore, the insert can be thermally connected to the adjacent wall of the corresponding cellular cell and / or to one or two cover layers or (possibly) intermediate layer materials, for example, by welding in the case of metal cellular cells or cover layers and inserts, or by fusion bonding in the case of thermoplastic cellular cells or cover layers and inserts.

[0099] Preferably, the insert is able to be locked to or at least in contact with the wall material of the cellular cell at all its edges to prevent sound waves from propagating linearly along the wall of the cellular cell.

[0100] The insert can be manufactured with widened, for example, rolled edges, which can be advantageously used for bonding.

[0101] In particular, through 3D printing, the insert can also be manufactured together with and inside the "cell," which corresponds in shape to the cellular cell and can be installed into the cellular cell of the cellular layer. To reduce weight, the walls of the "cell" can have openings.

[0102] Manufacturing composite components by embedding inserts into prefabricated honeycomb cells has the following advantages: Existing, mass-produced honeycomb cells can be used; manufacturing methods for honeycomb cells that have been tested and, where necessary, certified need not be changed; and the manufacturing of the inserts does not depend on the honeycomb cell manufacturing process.

[0103] It is possible to achieve very different geometries for the inserts, especially through additive manufacturing. The inserts can be configured to match the frequency region to be absorbed. If needed, other inserts with potentially different configurations can be introduced into the same cell. Attached Figure Description

[0104] Further features and advantages of the invention will emerge from the subsequent description of some preferred embodiments based on the accompanying drawings, without limiting the scope of protection. These are shown herein:

[0105] Figure 1A-1C In stereoscopic view ( Figure 1A In the partial view of area B () Figure 1B In ) and in the perspective view of the honeycomb structure used for composite components ( Figure 1C Examples of composite components in )

[0106] Figures 2A-2E Used according to Figure 1A The first embodiment of the acoustic embedding of the composite component, in side view ( Figure 2A In the stereoscopic view () Figure 2B In the top view () Figure 2C In the stereoscopic view inside the cellular unit () Figure 2D (in the image) and the top view of the intermediate form of the embedded body in its unfolded state ( Figure 2E )middle;

[0107] Figure 2F :according to Figures 2A-2E The variant of the embedded body, in the top view of the intermediate form in the unfolded state;

[0108] Figures 3A-3D Used according to Figure 1A Another embodiment of the acoustic embedding of the composite component (having a helical surface and a central trunk), in the front view ( Figure 3A In the longitudinal section () Figure 3B In the top view () Figure 3C ) and a stereoscopic view inside the cellular unit ( Figure 3D )middle;

[0109] Figures 4A-4B Used according to Figure 1AAnother embodiment of the acoustic embedding of the composite component (having a concave-convex helical surface and a central trunk), in the front view ( Figure 4A In ) and in the longitudinal section ( Figure 4B )middle;

[0110] Figures 5A-5D Used according to Figure 1A Another embodiment of the acoustic embedding of the composite component (having a helical surface and suspended, radially built-in edges), in the front view ( Figure 5A In the longitudinal section () Figure 5B In the top view () Figure 5C ) and a stereoscopic view inside the cellular unit ( Figure 5D )middle;

[0111] Figures 6A-6D Used according to Figure 1A Another embodiment of the acoustic embedding of the composite component (having a helical surface and a through free space around the main axis), in the front view ( Figure 6A In the longitudinal section () Figure 6B In the top view () Figure 6C ) and a stereoscopic view inside the cellular unit ( Figure 6D ); and

[0112] Figure 7 Used according to Figure 1A Another embodiment of the acoustic embedding of the composite component (having surface regions that extend at an angle to each other) is shown in a partial view.

[0113] Figures 8A-8E Used according to Figure 1A Another embodiment of the acoustic embedding of the composite component (having multiple pyramidal body segments), in the longitudinal section ( Figure 8A In the viewpoint from below along the main axis H, Figure 8B In the top view () Figure 8C In ) and in the stereoscopic view below ( Figure 8D In; and another variant of the schematic diagram ( Figure 8E ). Detailed Implementation

[0114] Figure 1A-1B An embodiment of a composite member 1 with a sandwich structure is shown, having a honeycomb layer 10 arranged between two covering layers 12, 14. The composite member 1 is suitable, for example, as a sound-absorbing drive mechanism cover. The composite member 1 is bent or folded about a theoretical bending axis U with a radius of curvature R and thus can be fitted into a concave inner surface, such as the drive mechanism housing of an aircraft. Facing the bending axis U, in... Figure 1BThe inner cover layer 14, shown below, is perforated and therefore sound-permeable. The composite member 1 is arranged in a predetermined operating position such that the inner cover layer 14 faces a sound source, such as a sound source inside the drive mechanism housing. Sound waves can enter through the perforations (not shown) into the cell cells 16 of the honeycomb structure 10 arranged below the cover layer 14. Opposite to the bending axis U, in Figure 1A In 1B, the outer cover 12 shown above is closed and functions to reflect sound. In a given operating position, this cover is farther from the sound source than the perforated inner cover 14. Sound waves can diffuse from the sound source through the perforated cover 14 and through the honeycomb 10 to the outer cover 12 and then diffuse in the opposite direction.

[0115] According to Figure 1B In the embodiment of 1C, the cellular layer 10 includes cellular cells 16, each having a hexagonal cross-section. Thus, each cellular cell 16 has six walls 17 that extend substantially perpendicular to the cover layers 12, 14 and demarcate the interior of the respective cellular cell 16 from adjacent cellular cells. The height of the walls 17 of the cellular cell 16, or the depth T of the cellular cell 16, corresponds to the spacing between the cover layers 12, 14.

[0116] In one embodiment, the two cover layers 12, 14 have a thickness of 1 mm. The outer cover layer 12 is a laminate made of three layers of carbon fiber fabric in an epoxy resin matrix. In one embodiment, the inner cover layer 14 similarly comprises three layers of carbon fiber fabric in an epoxy resin matrix. In another embodiment, the inner cover layer 14 is made of aluminum, here made of “covered” or “bare” aluminum 2024T3, T6, or T351, T81. Aluminum alloys 5052 or 5056 are also suitable for cover layer 14. Furthermore, the two cover layers 12, 14 can be made of three layers of carbon fiber fabric prepreg with a high-temperature resistant polyimide resin. Cover layer 14 preferably has perforations. The diameter of the perforations is, for example, 0.5 to 1 mm, forming a regular grid and spaced apart from each other, for example, 2.25 or 2.5 mm depending on the direction.

[0117] The honeycomb cell 10 is made of a composite material including aramid fibers and phenolic resin. In this embodiment, the applicant's deformable honeycomb cell ECA9.6-48 for aviation use (cell size 9.6 mm, unit volume weight 48 kg / m³) is used. 3 The cell wall thickness, height, or depth T of the cell unit is 11 mm. The cell 10 is connected to the two covering layers 12 and 14 by an epoxy adhesive film. The resin components are cured within 120 minutes in a pressurizer at at least 6 bar and 176°C.

[0118] In another embodiment, the cover layers 12, 14 are made of a prepreg comprising bismaleimide resin (BMI) and bonded with a BMI adhesive film.

[0119] In principle, different types of honeycomb cells 10 can be used. Preferably, within the framework of the present invention, the cell size of the honeycomb cells 16 can be 3.2 mm to 50 mm, especially up to 25.4 mm, and the unit volume weight of the honeycomb cells 10 can be 16 to 256 kg / m³. 3 The honeycomb structure.

[0120] The thickness or dimension of the honeycomb cell in the depth direction (= depth: in the T direction, perpendicular to the L / W plane of the honeycomb cell) can be between 5 and 50 mm. For the drive mechanism cover, the depth of the honeycomb cell 10 is preferably between 8 and 35 mm. In one embodiment, the honeycomb cell 10 is made of metal foil. In embodiments used for extremely high operating temperatures (e.g., 600 to 1200°C or 1200°C to 2000°C), the honeycomb cell 10 is made of oxide ceramic or carbide ceramic material.

[0121] The honeycomb cell 10 can be manufactured in particular using an expansion process. In one embodiment of the manufacturing method, a layer arrangement including the honeycomb cell 10 and an outer cover layer 12 is first prepared.

[0122] Then, the insert 18 is installed into each cell 16 such that its main axis H extends parallel to the cell depth T. The insert 18 can then, if necessary, be connected to, in particular, bonded to, the cell wall of the cell. This layer arrangement is accomplished by bonding it to the cover layer 14.

[0123] If necessary, the honeycomb 10 can achieve a desired shape, such as being bent into a desired shape, or it can be manufactured directly with curvature. An insert can be introduced into a flat honeycomb, and then the honeycomb can be bent if necessary. However, an insert can be embedded into a honeycomb that already has a desired curvature.

[0124] According to another embodiment of the manufacturing method, the insert is directly 3D printed into a prefabricated layered cellular cell consisting of an outer cover layer 12 and a cellular body 10.

[0125] According to another embodiment of the manufacturing method, the honeycomb structure and the insert are manufactured together by 3D printing in one step. According to another embodiment of the manufacturing method, the honeycomb structure is manufactured by pre-imprinting individual foils (manufacturing half-cells), bonding the insert to the pre-imprinted foil, and placing the next pre-imprinted foil on top (to complete the honeycomb cell), etc.

[0126] In all the embodiments shown here, the embedding can be inserted into the cellular unit such that one end faces the sound source.

[0127] The embedding can occupy the entire depth of the cellular cell or only a portion of it and, for example, be arranged centrally at the depth of the cellular cell or closer to one or the other edge of the cellular cell.

[0128] Figure 2A-2C An insert 18 according to a first embodiment is shown, comprising six plate-like and flattened hexagonal body segments 23 arranged at acute angles α relative to each other and interconnected by narrow quadrilateral body segments 24. However, the body segments 24 may also have different shapes than those shown, or different body segments 24 may have different shapes. The angle α does not necessarily have to be the same between the different body segments 23. The insert 18 has a first end 21 and a second end 22 extending through between the first end and the second end. The body segments 23 and 24 together form a connecting surface 25, which includes surface regions 25a, 25b arranged obliquely to each other. Figure 2A The orientation of the clearly visible, continuous surface 25 crosses the main axis H multiple times (here, for example, six times). The main axis H extends approximately centrally through all surface regions 25a and 25b.

[0129] like Figure 2D As shown, the insert 18 is arranged inside the cellular cell 16 such that each hexagonal body segment 23 abuts against or terminates flush with the wall 17 of the cellular cell 16 with its edge or narrow side. Thus, in Figure 2C In the top view shown, the insert 18 has a profile along its main axis H corresponding to the cross-section of the cell 16. Here, corresponding quadrilateral body segments 24 extend along and surface-fit against corresponding walls 17. The insert 18 is bonded to the walls 17 of the cell 16 via the narrow sides 27 of the quadrilateral body segments 24 and hexagonal body segments 23. Additional body segments similar to body segments 24 can be located on multiple or all of the narrow sides 27 of the insert 18 to achieve better circumferential bonding with the walls 17 of the cell 16. Thus, the cell 16 is divided by the insert 18 into multiple cavities 29 or sub-volumes. The cavities 29 are interconnected via channel openings 26 provided in the hexagonal body segments 23. Figure 2B-2EThe channel openings 26 constructed in the honeycomb cell 16 are circular, but they can have any shape, such as slits. The face regions 25a and 25b facing each other, as well as the edges of the channel openings 26 and the inner surfaces of the honeycomb walls 17, divide the interior of the honeycomb cell 16 into channels 20 for sound waves. Sound waves are guided from one cavity 29 to another through the inserts 18 within the honeycomb cell 16, and from one channel opening 26 to another through the corresponding cavities 29 between the two face regions 25a and 25b of the connecting surface 25. Therefore, the sound waves do not traverse the cell volume of the honeycomb cell 16 in a straight line from the perforated cover layer 12 to the cover layer 14, but are guided along a spiral or zigzag track on the connecting surface 25, which similarly traverses the main axis H multiple times.

[0130] The coherent surface 25 of the three-dimensional embedding 18 is geometrically a so-called unfoldable ruled surface; it can, for example... Figure 2E It unfolds without distortion on such a plane.

[0131] The insert 18 is preferably manufactured integrally and from a uniform material. One feasible method of manufacturing the insert 18 is by folding a planar shape ( Figure 2E ).

[0132] Figure 2F A schematic sketch of another embodiment of the shape 18' of a plane with a continuous surface is shown, in which the hexagonal volume segment 23 is... Figure 2F The corresponding planes rotate 60° relative to each other. Shape 18' can be folded into a three-dimensional insert (not shown) with a continuous surface orientation, which not only crosses the main axis multiple times but also rotates around the main axis multiple times.

[0133] Fold line 28 Figure 2E-2F The image is shown in dashed lines. For example, aluminum foil made of alloy 5052, 25 micrometers thick (for a honeycomb cell with a unit diameter of 9.9 mm), anodized with PAA, and treated with corrosion inhibitor EC800 is suitable as a material for folding. For example, it can be cut by an ultrasonic cutting device with a cutting blade according to... Figure 2E The foil is cut to its basic shape. The foil can be perforated to obtain channel openings 26. Preferably, pre-defined fold lines 28 are introduced into the foil using an embossing tool. The insert 18 is then folded manually or automatically.

[0134] The folded insert is installed into the cell 16 and bonded to the wall 17 of the cell 16.

[0135] The adhesive used to bond the insert 18 is selected based on the expected operating temperature of the composite component. For the required operating temperature of 90°C to 200°C, liquid epoxy adhesives such as the applicant's EC 690 or EC 662 can be used. For the temperature range of 200°C to 400°C, bismaleimide (BMI) based adhesives are advantageous, as are adhesives based on polyimide and cyanate esters, which can be combined with epoxy adhesives if necessary.

[0136] Other materials used to manufacture the insert 18 by folding could be and Paper, such as N636 paper (DuPont) with a thickness of 1.1, 1.4, 1.8, 2.8, or 3.9 mils, or paper with a thickness of 1.5, 2, 2.5, 3, or 4 mils. T412 paper (1 mil is equivalent to 0.0254 mm).

[0137] Furthermore, the insert 18 can be folded from a thermoplastic foil, for example from...

[0138] - Polyetherimide (PEI), for example 1000B thin film, 25-50 μm or 4 to 10 μm thick. Thin film UTF120 (Salbic, Tekra);

[0139] Polyimide (PI) with a thickness of -25 to 127 μm, for example, used to improve adhesive strength. B or FPC or for a wide temperature range of -269°C to 400°C. HN (DuPont); and

[0140] - Polyetheretherketone (PEEK), such as Thin films in the 1000, 1100, 1300, 2000, and 2100 series, with thicknesses ranging from 6 to 750 μm, preferably from 8 to 100 μm (Vitrex).

[0141] However, the insert 18 can also be manufactured in the desired 3D geometry using additive manufacturing processes such as 3D printing.

[0142] Figure 7A partial view shows another embodiment of the insert 78, which has a continuous surface 75 and surface regions 75a, 75b that are inclined relative to each other and extend obliquely relative to the main axis H, the surface regions 75a, 75b facing each other. The insert 78 can be manufactured by folding two narrow strips together, the two narrow strips being cross-stacked and alternately folded back onto each other, and the insert is particularly suitable for cellular cells with a square cross-section. However, the insert 78 can also be manufactured by 3D printing. When the insert 78 is installed into a cellular cell (not shown), the outer edges 79 of the strips and the folded edges 77 are bonded to the inner surfaces of the cellular walls, thereby dividing the cellular cell into cavities, wherein the surface regions 75a, 75b facing each other and the inner surfaces of the cellular walls define the cavities. The insert 78 can have channel openings (not shown) that provide a pre-defined zigzag path for sound waves. Alternatively or additionally, the insert 78 can be manufactured from an open-cell material.

[0143] Figure 3A-6D Another embodiment is shown in which a one-piece insert 38; 48; 58; 68 is provided with a sound-conducting surface according to the configuration of the present invention. Figure 3A-6D In the middle, the continuous surface is basically a spiral surface with angles of 35°, 45°, 55°, and 65°.

[0144] According to Figures 3A-3C Another embodiment of the insert 38 has a central trunk 36 extending along a main axis H. The main axis H extends through the trunk 36. Furthermore, the insert 38 includes a helical or spiral portion in the form of a band 33, which wraps around the trunk 36 and has or forms a continuous helical surface 35. Preferably, the helical band 33 forms multiple helices around the trunk 36 or the main axis H, approximately 2.5 helices in the current embodiment. The insert 38 has a hexagonal planar arrangement in a top view along the main axis H. Figure 3C The planar arrangement corresponds to the cross-section of the cellular unit 16.

[0145] Figure 3D An insert 38 is shown in a predetermined position within the cellular cell 16; here, for clarity, each insert is shown individually. The radially outward edge 34 of the band 33 terminates flush with or contacts the wall 17 of the cellular cell 16 along its length. Between the spirals of the insert 38, channels 30 for acoustic waves are upper bounded in the axial direction or in the direction of the main axis H by the face regions 35a, 35b of the spiral surfaces 35 facing each other. In the radial direction, the channels 30 are bounded by the surface of the trunk 36 and the inner surface of the cellular wall 17.

[0146] In the current embodiment, the helical surface 35 is a deployable ruled surface. The longitudinal ends of the elongated main stem 36 form the first end 31 and the second end 32 of the insert 38 and contact the cover layers 12, 14 inside the completed composite member 1.

[0147] The helical surface 35 is radially defined by a radially inward edge 37 and a radially outward edge 39. The radially outward edge 39 abuts the edge 34 or narrow side of the band 33, which rests against the honeycomb wall 17. The radially inward edge 37 abuts the trunk 36. The trunk 36 carries the inner edge 37 of the helical surface 35. The helical surface 35 transitions into the surface of the trunk 36.

[0148] According to Figures 4A-4B In another embodiment, the embedding 48 and in Figures 3A-3D The only difference of the insert 38 is that it has a helical surface 45, which is not a ruled surface, but is irregularly curved. The channel 40 for sound waves is defined in the axial direction by the convex surface region 45a and the concave surface region 45b of the helical surface 45.

[0149] According to Figures 5A-5D In another embodiment, the embedding 58 and in Figures 3A-3D The only difference between the insert 38 and the insert 58 is that the insert 58 does not have a central trunk. The radially built-in edge 57 of the helical surface 55 is suspended along its entire length, or rather, completely.

[0150] According to Figures 6A-6D In another embodiment, the embedding 68 and in Figures 3A-3D The difference in the insert 38 lies only in that, instead of the central trunk 36, a free space 66 is provided, which extends cylindrically along the main axis or helical axis H. Here, the radially built-in edge 67 of the helical surface 65 is completely suspended. (As in...) Figure 6C and Figure 6D As can be seen in the top view, the insert 68 does not cover the entire cross-section of the cell 16. A central opening is retained, which is defined in the top view by the radially built-in edge 67 of the helical surface 65. During subsequent deformation of the cell 10 with the insert 68 attached, this opening can be closed on the side of the cell 10 facing the bending axis U (see [reference]). Figure 1C Furthermore, it continues to open on the side opposite to the bending axis U. Thus, the free space 66 achieves particularly good deformability of the honeycomb 10.

[0151] Figures 8A-8DAn insert 88 according to another embodiment is shown, comprising four hollow, interlocking pyramidal or funnel-shaped body segments 83, the body segments being coaxial with and coaxially arranged with each other with a main axis H and interconnected by a connecting segment in the form of a central trunk 86. The main axis H extends through the trunk 86. The body segments 83 and the trunk 86 together form a connecting surface 85, which extends through from a first end 81 of the insert 88 to a second end 82. The insert 88 can be arranged to face the sound source not only with its first end 81 but also with its second end 82.

[0152] The connecting segments can also have different shapes as shown and be arranged dispersedly. The insert 88 can have multiple dispersed, especially peripheral, connecting segments that extend parallel or transverse to the main axis H and allow the pyramidal body segments 83 to connect to each other. The pyramidal body segments 83 can, for example, be enclosed in a so-called front unit, which is part of the insert 88. Here, the shape of the front unit corresponds to the shape of the honeycomb cell 16 into which the insert 88 is to be installed. For weight-saving purposes, the walls of the front unit cannot be fully constructed (not shown).

[0153] In the top view along the main axis H, the insert 88 has a hexagonal planar arrangement. Figure 8C The planar arrangement corresponds to the cross-section of the cell 16. Furthermore, the insert 88 has fastening sections 84, which are respectively connected to pyramidal body sections 83 and extend parallel to the main axis H. If the insert 88 is intentionally received in the cell 16, the fastening sections 84 are respectively face-attached to the cell wall 17 and thus can be circumferentially bonded. Between the pyramidal body sections 83 of the insert 88, channels 80 for sound waves are defined in the direction of the main axis H by mutually facing surface regions 85a, 85b.

[0154] Successive pyramidal body segments 83 alternately have channel openings 87 either in the central region or on their periphery, as in Figure 8B As can be seen in 8C. Therefore, the cellular unit 16 can be divided into multiple cavities by the embedding body 88, the cavities being separated from each other by pyramidal body segments 83, wherein the channel openings 87 allow sound waves to diffuse in a zigzag path. Figure 8E A variation of the insert 98 in a cellular cell is shown. The acoustic pathways are indicated by dotted lines. The insert 98 lacks a central trunk; pyramidal segments 93 are interconnected by their pointed tips, forming a continuous surface 95. In other respects, this variation is essentially equivalent to... Figures 8A-8DThe embodiment in the text. If the insert 88, 98 is oriented with its wider first end 81, 91 toward the source of the sound wave, it can be considered as the opposite of the sound tube, which not only attenuates the sound waves, but also increases their frequency if necessary.

[0155] The inserts 38, 48, 58, and 68 in Figures 3 through 6 can be manufactured from plastic or metal via 3D printing. In one embodiment, an aluminum powder alloy ALSi10Mg with a particle size of 90 μm and an EOS M 290 3D printer are used to manufacture the inserts 38, 48, 58, and 68. In another embodiment, a titanium powder alloy Ti64 with a particle size of 63 μm and an EOS M100 3D printer are used. In yet another embodiment, polyetherimide (PEI) filament Ultem 9085, 1.75 mm, and a Stratasys F900 device are used. In yet another embodiment, polyetheretherketone (PEEK) filament 3DXTEX 1.75 mm and a Stratasys Fortus 450mc device are used.

[0156] Other manufacturing methods, especially those that are not AM processes, such as relatively inexpensive die casting or injection molding, or manufacturing methods such as those using folding techniques, are also within the framework of this invention.

[0157] List of reference numerals

[0158] Figure 1A-1C :

[0159] 1. Composite components

[0160] 10. Honeycomb

[0161] 12. External Covering Layer

[0162] 14. Internal Covering Layer

[0163] 16 Cellular Units

[0164] 17. The wall of a honeycomb cell

[0165] 18 Embedded

[0166] R (radius of curvature)

[0167] The bending axis of U theory

[0168] T-cell depth

[0169] Figures 2A-2F :

[0170] 16 Cellular Units

[0171] 17. The wall of a honeycomb cell

[0172] 18; 18' Inlay

[0173] 20 Channels for Sound Waves

[0174] 21 First end of the insert

[0175] 22 The second end of the insert

[0176] 23. Hexagonal volume segment

[0177] 24. Quadrilateral segment

[0178] 25 Continuous surfaces

[0179] Surface regions 25a and 25b

[0180] 26 Channel openings

[0181] 27. Narrow side of the volume section of a hexagon

[0182] 28 Fold lines

[0183] 29. Cavity

[0184] α is the angle between body segments.

[0185] H-shaped inlay main axis

[0186] Figure 3A-6D :

[0187] 16 Cellular Units

[0188] 17. The wall of a honeycomb cell

[0189] 30; 40; 50; 60 Channels used for sound waves

[0190] 31; 41; 51; 61 First end of the insert

[0191] 32; 42; 52; 62 The second end of the insert

[0192] 33 belts

[0193] 34; 44; 54; 64 The edge of the band

[0194] 35; 45; 55; 65 Spiral surface

[0195] Surface regions 35a, 35b; 45a, 45b; 55a, 55b; 65a, 65b

[0196] 36; 46 Main trunk

[0197] 37; 47; 57; 67 Radial built-in edges

[0198] 38; 48; 58; 68 Embedded bodies

[0199] 39; 49; 59; 69 Radially outward-facing edges

[0200] 66 Free Space

[0201] H-shaped inlay main axis

[0202] Figure 7 -8:

[0203] 17. The wall of a honeycomb cell

[0204] 29. Cavity

[0205] 80; 90 Channels used for sound waves

[0206] 81; 91 First end of the insert

[0207] 82; 92 The second end of the insert

[0208] 83; 93 Pyramidal body segments

[0209] 84 Fastening Section

[0210] 75; 85; 95 Continuous surfaces

[0211] Surface regions 75a; 75b; 85a, 85b; 95a, 95b

[0212] 76 Channel Openings

[0213] 86 Main trunk

[0214] 87; 97 Channel openings

[0215] 77 Folded edges

[0216] 78; 88; 98 Embedded

[0217] 79 Edge

[0218] H-shaped inlay main axis

Claims

1. An acoustic insert (18; ... 68) for a honeycomb (10) for absorbing sound waves, wherein... - The insert (18; ... 68) has a main axis (H) and can be mounted into a cellular cell (16) such that the main axis (H) extends in the depth (T) direction of the cellular cell (16), and - The insert (18; ... 68) includes a continuous surface (25; ... 65) and has a first end (21; ... 61) and a second end (22; ... 62) in the direction of the main axis (H). Its features are, The coherent surfaces (25; ... 65) of the embedding (18; ... 68) have mutually spaced surface regions (25a, 25b; ... 65a, 65b) in the direction of the main axis (H), the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis (H), so that a channel (20; ... 60) for sound waves is defined between the surface regions (25a, 25b; ... 65a, 65b) in the direction of the main axis (H). The continuous surface (25; ... 65) extends from the first end (21; ... 61) through the surface region (25a, 25b; ... 65a, 65b) and to the second end (22; ... 62) around the main axis (H) and / or crosses the main axis multiple times.

2. An acoustic insert (18; 78; 88) for a honeycomb (10) for absorbing sound waves, wherein - The insert (18; 78; 88) has a main axis (H) and can be mounted into a cellular cell (16) such that the main axis (H) extends in the direction of the depth (T) of the cellular cell (16), and - The insert (18; 78; 88) includes a continuous surface (25; 75; 85) and has a first end (21; 81) and a second end (22; 82) in the direction of the main axis (H). Its features are, The coherent surfaces (25; 75; 85) of the embeddings (18; 78; 88) have mutually spaced surface regions (25a, 25b; 75a, 75b; 85a, 85b) in the direction of the main axis (H), the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis (H), so as to limit the channels (20; ... 80) for sound waves between the surface regions (25a, 25b; 75a, 75b; 85a, 85b) in the direction of the main axis (H) and divide the cellular unit (16) into a plurality of cavities (29), the plurality of cavities being limited in the direction of the main axis (H) by the mutually facing surface regions (25a, 25b; 75a, 75b; 85a, 85b).

3. The acoustic embedding according to claim 1 or 2, characterized in that, The honeycomb structure is used to absorb the operating noise of the aircraft.

4. The acoustic embedding according to claim 1 or 2, characterized in that, The insert can be installed into a hexagonal cellular cell.

5. The acoustic embedding according to claim 1 or 2, characterized in that, The surface region is aligned in its projection onto a plane perpendicular to the principal axis (H).

6. The acoustic embedding according to claim 1 or 2, characterized in that, The coherent surface covers the cross-section of the cellular cell (16) in its projection onto a plane perpendicular to the main axis (H), and the insert can be mounted or installed into the cellular cell.

7. The acoustic embedding according to claim 1 or 2, characterized in that, The insert has a trunk (36; 46) that extends through the direction of the main axis (H).

8. The acoustic embedding according to claim 7, characterized in that, The main trunk extends through the first end (31; 41; 81) of the insert to the second end (32; 42; 82) of the insert.

9. The acoustic embedding according to claim 1 or 2, characterized in that, The coherent surfaces (25; ... 65) include helical surfaces and / or unfoldable surfaces.

10. The acoustic embedding according to claim 9, characterized in that, The helical surface has a helical axis that extends in the direction of the main axis (H) of the insert, wherein the helical surface has a radially inward edge and a radially outward edge.

11. The acoustic embedding according to claim 10, characterized in that, The spiral axis coincides with the main axis (H).

12. The acoustic embedding according to claim 10, characterized in that, The insert has a trunk (36; 46) that extends through the direction of the main axis (H), and the radially built-in edges (37; 47) are supported by the trunk (36; 46).

13. The acoustic embedding according to claim 10, characterized in that, The radially built-in edge is suspended.

14. The acoustic embedding according to claim 1 or 2, characterized in that, The orientation of the coherent surface surrounds the main axis (H) at least 360°.

15. The acoustic embedding according to claim 14, characterized in that, The orientation of the connecting surface is greater than 360° around the main axis (H).

16. The acoustic embedding according to claim 14, characterized in that, The orientation of the coherent surface surrounds the main axis (H) by at least 720°.

17. The acoustic embedding according to claim 1, characterized in that, The insert (18) is configured to divide the cellular cell (16) into cavities (29) such that the connecting surface (25) limits the cavities (29).

18. The acoustic embedding according to claim 17, characterized in that, The connecting surface (25) defines the cavity (29) such that every two cavities (29) are acoustically connected to each other.

19. The acoustic embedding according to claim 18, characterized in that, Each pair of cavities (29) is acoustically connected to each other through at least one channel opening (26).

20. The acoustic embedding according to claim 1 or 2, characterized in that, At least some surface regions (25b, 25a; 75a, 75b; 85a, 85b) extend obliquely relative to the direction of the main axis (H).

21. The acoustic embedding according to claim 20, characterized in that, At least some of the face regions (25b, 25a; 75a, 75b) facing each other extend at an angle relative to each other.

22. The acoustic embedding according to claim 1 or 2, characterized in that, The insert (88) has at least two pyramidal or funnel-shaped body segments (83) for dividing the cellular unit (16) into cavities (29), wherein the pyramidal or funnel-shaped body segments (83) are arranged offset from each other in the direction of the main axis (H) and provide face regions (85a, 85b) facing each other.

23. The acoustic embedding according to claim 22, characterized in that, The pyramidal or funnel-shaped body segment (83) is arranged coaxially with the main axis (H).

24. The acoustic embedding according to claim 22, characterized in that, The pyramidal or funnel-shaped body segments (83) are interconnected by at least one connecting segment.

25. The acoustic embedding according to claim 24, characterized in that, The at least one connecting section is a trunk (86) that is centrally arranged and extends in the direction of the main axis (H).

26. The acoustic embedding according to claim 1 or 2, characterized in that, The connecting surface of the insert includes a ruled surface, and / or the connecting surface of the insert has convex and / or concave surface regions (45a, 45b).

27. The acoustic embedding according to claim 1 or 2, characterized in that, The coherent surface of the embedding includes a trapezoidal and / or corrugated surface.

28. The acoustic embedding according to claim 1 or 2, characterized in that, The inserts (18; ... 88) are manufactured in one piece and / or with uniform materials.

29. The acoustic embedding according to claim 1 or 2, characterized in that, The inserts (18; ... 88) are manufactured using an additive manufacturing process, or The inserts (18; 78) are manufactured using folding and / or embossing techniques.

30. The acoustic embedding according to claim 29, characterized in that, The inserts (18; ... 88) are manufactured by 3D printing.

31. The acoustic embedding according to claim 1 or 2, characterized in that, The connecting surfaces (25; ... 85) are at least partially composed of strips (33) made of plastic, and / or of fibrous material and / or of metal.

32. The acoustic embedding according to claim 31, characterized in that, The plastic is a thermoplastic or a thermosetting plastic.

33. The acoustic embedding according to claim 31, characterized in that, The fiber-containing material is glass fiber or carbon fiber.

34. The acoustic embedding according to claim 1 or 2, characterized in that, The insert (18; ... 88) comprises a breathable material.

35. A composite component (1) for absorbing sound waves, comprising at least one honeycomb (10), said at least one honeycomb having honeycomb cells (16) and having a number of acoustic inserts (18; ... 68), wherein, At least one acoustic embedding (18; ... 68) according to any one of claims 1 to 34 is arranged in at least some of the cellular units (16), wherein, - The embeddings (18; ... 68) are arranged in the respective cellular cells (16) such that the main axis (H) of the embeddings extends in the depth (T) direction of these cellular cells (16).

36. The composite component (1) according to claim 35, wherein, The embedding divides the cellular cell (16) into a plurality of cavities (29) in the direction of the main axis (H) by the surface regions (25a, 25b; 75a, 75b; 85a, 85b) facing each other.

37. The composite member (1) according to claim 35 or 36, comprising at least one covering and / or intermediate layer (12, 14) connected to the honeycomb (10), wherein - The cover and / or intermediate layer (12, 14) is made of plastic, composite material, metal and / or ceramic; and / or - The honeycomb (10) is made of plastic, composite material, metal or ceramic; and / or - The insert (18; ... 88) is bonded to the adjacent wall (17) of the corresponding cellular cell (16) and / or to the cover or intermediate layer (12, 14) and / or locked by thermal process material.

38. A method for manufacturing a composite component (1) for absorbing sound waves, the method comprising: - Provides a cellular structure (10), and - The acoustic inlays (18; ... 88) are embedded into the cellular cells (16) of the cellular structure (10). The characteristic feature is that the inserts (18; ... 88) are manufactured by an additive manufacturing process, such that the inserts (18; ... 88) each have a continuous surface (25; ... 85), and the continuous surface (25; ... 65) of the inserts (18; ... 68) has mutually spaced surface regions (25a, 25b; ... 65a, 65b) in the direction of the main axis (H) of the inserts (18; ... 68), the surface regions facing each other and overlapping in projection onto a plane perpendicular to the main axis (H), so that a channel (20; ... 60) for sound waves is defined between the surface regions (25a, 25b; ... 65a, 65b) in the direction of the main axis (H). The connecting surface (25; ... 65) extends from the first end (21; ... 61) of the insert (18; ... 68) through the surface region (25a, 25b; ... 65a, 65b) and to the second end (22; ... 62) of the insert (18; ... 68) around the main axis (H) and / or crosses the main axis multiple times.

39. The method according to claim 38, characterized in that, The surface regions are aligned with each other in their projection onto a plane perpendicular to the principal axis (H).

40. The method according to claim 38, characterized in that, In one step, the provision of the honeycomb (10) and the embedding of the acoustic inserts (18; ... 88) into the cellular cells (16) of the honeycomb (10) are performed by an additive manufacturing process.

41. The method according to any one of claims 38 to 40, characterized in that, The additive manufacturing process is a 3D printing process.

42. The method according to any one of claims 38 to 40, characterized in that, The insert (18; ... 88) is bonded to the adjacent wall (17) of the corresponding cellular cell (16) and / or to the cover or intermediate layer (12, 14) and / or locked by thermal process material.

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