Abstract: The method for making a continuous laminate, in particular suitable as a spar cap or another part of a wind energy turbine rotor blade comprises the steps of providing a plurality of parallel fibers, embedding the fibers in a curable matrix material, curing the matrix material so as to obtain a fiber reinforced laminate having upper and lower major surfaces, and forming channels into at least one of the upper and lower major surfaces of the laminate wherein the channels on the upper and/or lower major surfaces are angled with respect to the direction of the fibers.

Abstract: The present invention discloses a method of producing and application for a projectile resistant matrix that allows for manufacture of low weight projectile resistant armor trauma shields without metal or ceramic plates using projectile resistant textiles encapsulated in a composite matrix through use of injection molding process or spray-on technique as constituents of the projectile resistant trauma shield without metal or ceramic plates of the present invention.

Abstract: A metal matrix composite lightweight compressor airfoil. The airfoil comprises a braided fabric embedded in a lightweight aluminum-lithium alloy. The airfoils are fabricated by forming a plurality of fiber tows by twisting filaments or fibers. The tows are then braided into a fabric. The fabric may be impregnated with an optional fugitive polymer that temporarily occupies interstices of the fabric to facilitate handling of the pre-formed braided fabric, but which is subsequently removed. The airfoil may then be formed as a MMC by one of two separate methods. In the first method, aluminum-lithium alloy is pressure augmented casting into a die that includes a preform of fabric impregnated with fugitive polymer. In a second method, a preform is formed using a tool and mandrel by impregnating fabric with aluminum-lithium alloy. Then aluminum-lithium alloy is pressure augmented cast into a die that includes the alloy-impregnated preform.

Abstract: In a method of manufacturing a blade shell half of a pre-bent wind turbine blade by means of vacuum-assisted resin transfer moulding (VARTM), a fibre lay-up (16) is placed on a mould surface (14) and a distribution layer (24) is placed above the fibre lay-up (16). At least one segmentation area is provided in the distribution layer by providing at least one transversely extending flow barrier in the distribution layer (24) preventing or restricting longitudinal resin flow to the distribution layer. A longitudinally extending first feed channel (27) is placed above the distribution layer (24). The first feed channel (27) is divided into at least two feed channel sections, a feed channel section being arranged in each distribution layer segment. A vacuum bag (43) is arranged on top of the mould part (13) to define a mould cavity. The mould cavity (44) is evacuated and liquid resin is supplied to each feed channel section through a resin inlet to fill the mould cavity and impregnate the fibre lay-up.

Abstract: A composite repair system and method for assisting in the repair of a cured composite part in which a damaged portion has been cut out and removed, exposing a plurality of composite plies and their corresponding composite ply edges. The composite repair system may comprise a light source to illuminate the ply edges, an image capturing device to obtain an image of the ply edges, and a computing device for processing the image of the ply edges and creating a map of the ply edges based on the image. The map may be used to manufacture filler plies having peripheral edges shaped to correspond with the composite ply edges for replacing the damaged portion of the composite part.

Abstract: The present invention relates to a composite-material turbomachine vane (1) comprising a blade (2), wherein said vane (1) comprises a first resin (4) reinforced with long fiber and a second resin (5) reinforced with short fibers, said first and second resins being chemically compatible or identical, said long fibers (4) serving to stiffen the vane (1) and said short fibers (5) dispersed in the second resin serving to fill in the parts of the vane that are not reinforced by the long fibers (4) and giving the vane (1) its substantially final shape.

Abstract: A vacuum-induced injection molding apparatus is disclosed. The apparatus includes a tool surface having an injection port extending therethrough. A flexible film extends over and is sealingly coupled to the tool surface. The flexible film comprises an outer surface and an inner surface such that the flexible film inner surface and the tool surface define a volume. A vacuum chamber is sealingly coupled to the outer surface of the flexible film. A vacuum port is in fluid communication with the volume. A method of injection molding a polymer matrix composite is also disclosed.

Abstract: A method of making a composite prosthetic device, such as a hernia repair device, includes providing a support layer, juxtaposing a layer of an absorbable material with the support layer, and disposing an absorbable adhesive between the support layer and the layer of an absorbable material. The method includes heating the layers for melting the absorbable adhesive so as to bond the support layer with the layer of the absorbable material. Before the heating step, the moisture content of at least one of the layers is increased for improving thermal conductivity between the layers so as to enhance the strength of the bonds formed between the layers. The moisture content may be increased by exposing at least one of the layers to an environment having elevated relative humidity. In one embodiment, the support layer is polypropylene mesh, the layer of the absorbable material is oxidized regenerated cellulose, and the absorbable adhesive is polydioxanone.

Abstract: A mold and method for vacuum assisted resin transfer molding of a fiber reinforced laminated structure are provided. The mold includes a first mold part and a second mold part. The first mold part defines a negative impression of the laminated structure, being structurally stable and forming a support for fiber reinforcement layers of the laminated structure. The second mold part connectable to the first mold part for closing the mold and defines together with the first mold part an enclosed space which can be evacuated. The mold further includes a flow duct for guiding a liquid polymer which is formed as a recess in the first mold part and/or a recess in the second mold part that is open towards the enclosed space and extends along a section of the periphery of the first mold part and/or the second mold part.

Abstract: The present invention relates to a method for producing profile parts, each having an L-shaped cross-section, or an assembled profile part having, in particular, a T-shaped cross-section. For this purpose a lay-up made of composite fiber material is initially placed on a forming tool. In a further step, the lay-up is deformed by the forming tool to form a profile having a preferably U-shaped cross-section, the profile thus exhibiting the book effect at each opposite end. In a further step, the profile is preferably cut in the longitudinal direction in order to produce two profile parts. The idea on which the invention is based is to allow the layers in the lay-up to shift during the deformation process and subsequently to produce a substantially right-angled chamfered end on the profile parts by means of a cutting process. The disadvantageous formation of corrugations and complex clamping of the lay-up are thus avoided.

Abstract: A first process in which a fiber reinforced base is placed in a cavity of a molding die and then resin is injected into the cavity of the molding die in a state where the molding die is opened by a sum of a distance X1 and a distance at the time of completion of molding; a second process in which the molding die is closed to a state where the molding die is opened by a sum of a distance X2 and the distance at the time of completion of molding while resin in the cavity is being drained; and a third process in which the drain of the resin from the cavity is stopped and then the molding die is closed to the distance at the time of completion of molding while a die clamping pressure is maintained at a predetermined value to cure the resin, are carried out sequentially.

Abstract: A preform, formed with a plurality of reinforcing fiber substrates stacked to each other and each made of at least reinforcing fiber yarns, has a resin material, whose main component is a thermoplastic resin, interlaminated between the layers of the reinforcing fiber substrates in the preform, and has through holes extending through a plurality of the reinforcing fiber substrates in the thickness direction of the preform; an FRP molded using this preform; and processes for producing these. By improving the impregnability in the thickness direction of the preform, an FRP excellent both in various mechanical properties and in matrix resin impregnation and stabler in quality can be produced with high productivity.

Abstract: An apparatus for making fiber-reinforced molded articles having a mold surface with a configuration corresponding to at least a portion of a molded article. An electromagnetic energy production element produces electromagnetic energy required to cure the binder. The element is selected from electroluminescent devices, quantum dots and combinations thereof. The element is positioned on the mold surface so as to contact the electromagnetic energy-curable binder with the produced electromagnetic energy while the reinforcing fibers are on the mold surface.

Abstract: A method of forming, on a strip-shaped laminate of multiple reinforcing fiber sheets superimposed one upon another, two flexures with respect to the cross-section configuration thereof, wherein in the forming of the two flexures with the use of two flexure forming dies independent from each other, respectively, the two flexure forming dies are arranged so that the relative distance of the two flexure forming dies is changeable in the direction perpendicular to the longitudinal direction of the strip-shaped laminate. This method can be effectively utilized in the production of a reinforcing fiber molding with changing of the distance between the two flexures namely, width of web portion or gauge between two flange portions from the strip-shaped laminate, or the production of fiber reinforced resin (FRP) molding therefrom.

Abstract: A method for forming a profile for a hollow component is provided. A first composite fibre layer is laid out on a first surface corresponding to a first profile section of the component. A second composite fibre layer is laid out in a second surface corresponding to a second profile section of the component. A collapsed bag is laid out in onto the first composite fibre layer. The bag and the first composite fibre layer are fixed to the first surface. First and second mould elements are coupled such that the first surface and the second surface correspond to the first and second profiles. The bag is inflated such that the first composite fibre layer is pressed to the first surface and the second composite fibre layer is pressed to the second surface so that the first and second layers are coupled to form the profile.

Abstract: A method for manufacturing of a fiber reinforced laminate is provided that includes building up a part of the laminate to a determined thickness using at least one layer of fiber material placing a laterally extended layer on top of the partially completed laminate, the layer having in a first lateral direction a greater stiffness than in a second lateral direction and having in the first lateral direction a greater stiffness than the other layers constituting the laminate, building up a new part of the laminate to a determined thickness, and in case the thickness of the laminate built up pursuant is not as large as a desired thickness of the completed laminate, repeating steps placing a laterally extended layer and the building up a new part until the thickness of the laminate built up is equal to the desired thickness of the completed laminate.

Abstract: The present invention relates to binders for the preforming process to which textile structures are subjected when structural materials are produced by the RIM or RTM method, where the binder composed of an amorphous polyimide is spray applied in a solvent onto the textile structure or onto the textile, and is used as binder for the preforming process. The present invention further relates to a process for producing moldings made of fiber-reinforced composite materials.

Abstract: A housing shell for electrical measuring, controlling and communication devices, in particular the lower housing part of a cellphone, has very great flexural and torsional rigidity in spite of an extremely small wall thickness if it is formed as a part created by a forming operation from the planar blank of a thermoplastically impregnated long-fibered multi-layered mat. Fine-membered functional elements of likewise thermoplastic material are then molded onto the housing shell in an injection mold.

Abstract: A method of making an abrasive article comprising an abrasive disc (1) of non-woven fibres having a central shaft (3) and a hub (2) securing the shaft (3) to the abrasive disc (1). The method comprising forming the hub (3) by injecting molten thermoplastic material into the abrasive disc (1), and allowing the thermoplastic material to cool and solidify such that the shaft (3) is secured to the abrasive disc (1). The invention provides a simple, economical and effective method of securing a shaft to a disc.

Abstract: A wheel rim comprising a lip formed on the wheel rim, the lip running parallel to the circumference of the rim. A method of forming a lip on a wheel rim, the method comprising: forming fiber layers on an upper and lower portion of a mold; forming fiber layers on an upper and lower portion of a mold; curing the fiber layers; removing the cured rim from the upper and lower portions of the mold; in which the internal surface of the lower portion of the mold comprises an indention that, once the fiber layers are cured, creates a lip on the surface of the rim.

Abstract: A composition for the manufacture of a porous, compressible article, the composition comprising a combination of: a plurality of reinforcing fibers; a plurality of polyimide fibers; and a plurality of polymeric binder fibers; wherein the polymeric binder fibers have a melting point lower than the polyimide fibers; methods for forming the porous, compressible article; and articles containing the porous, compressible article. An article comprising a thermoformed dual matrix composite is also disclosed, wherein the composite exhibits a time to peak release, as measured by FAR 25.853 (OSU test), a 2 minute total heat release, as measured by FAR 25.853 (OSU test), and an NBS optical smoke density of less than 200 at 4 minutes, determined in accordance with ASTM E-662 (FAR/JAR 25.853).

Abstract: The formulation for making plasterboard with paper cover sheets comprises finely divided gypsum, a minor amount by weight of starch and, as crosslinking agent for the starch, a tri-functional reactive s-triazine having substituents at positions 2, 4 and 6 of the triazine ring which are reactive with the starch. A preferred crosslinking agent is 2,4,6-trichloro-s-triazine, which is preferably partially reacted with the starch before further reaction with the paper cover sheets for the plaster board.

Abstract: A process and apparatus for producing perforated composite structures, such as acoustic skins suitable for aircraft engine nacelle and duct components. The process includes placing a mat member, a non-impregnated fabric member, and a resin film on a tool surface so that pins disposed on the mat member project through the fabric member and resin film to define holes therein. The fabric member is between the mat member and resin film, and the fabric member and resin film define a stack that conforms to the mat member and tool surface. A caul member is then placed on the stack so that apertures in the caul member are penetrated by the pins. The stack is heated to melt the resin film and cause molten resin to infuse the fabric member and yield a resin-infused fabric stack, after which the molten resin within the resin-infused fabric stack is at least partially cured.

Abstract: In one step of a method of fabricating a composite tube, layers of uncured composite material may be laid over a surface. In another step, spaced-apart strips of at least one of uncured, partially cured, and completely cured composite material may be laid lengthwise over the laid layers of composite material. In still another step, the spaced-apart strips may be compacted against the layers of uncured composite material. In an additional step, the compacted spaced-apart strips and the layers of uncured composite material may be further consolidated and/or cured to form a composite tube.

Abstract: Tapered layers of pre-cured composite material are integrated into a tapered, highly stressed laminate structure in order to provide improved compressive strength. The pre-cured composite material can advantageously be cured under tension as pultruded material, to further augment compressive strength. The thickness of composite layers can be tapered on their termination edges by mechanically abrading, chemical abrading, or other methods. Especially preferred embodiments include aircraft structural components such as wings, wing spars, wing skins, fuselage skins, rotor blades, propellers, and propeller blades. Preferred laminates can be constructed to have at least 6, 10, 30, 50, or 100 layers of material, and can have a maximum thickness of at least 0.15, 0.25, 0.5, 1.0, or 5.0 inches.

Abstract: An article such as a fan blade of a turbofan engine comprises a core made up of components at least some of which comprise packs of rods embedded in a resin matrix material. The rods extend in the span-wise direction of the blade to resist centrifugal forces imposed on the blade during operation. The core is encased in a skin formed from preforms which may comprise fabric reinforcements.

Abstract: A method for producing a composite construction element is disclosed. In one embodiment, the method includes the steps of: a) providing a composite construction element, which comprises a thermoplastic core layer between two fiber-reinforced thermoplastic cover layers; b) providing one or more interruptions in a fiber-reinforced thermoplastic cover layer of the panel; c) positioning a fiber-reinforced thermoplastic reinforcing layer over and/or near the interruption; d) deforming at least the edges situated along the interruption and, if desired, the thermoplastic reinforcing layer, preferably while simultaneously locally compacting the core layer, so that a thermoplastic construction element having a recess which is delimited by fiber-reinforced thermoplastic walls is obtained.

Abstract: Disclosed is a reinforcement blank, in particular a curved ring frame segment for fuselage cells of aircraft, comprising a synthetic material that is reinforced by at least one fiber laminate. The fiber laminate includes at least one full-area layer with a first fiber direction and at least one full-area layer with a second fiber direction, wherein at least one further layer with a third fiber direction is arranged in a peripheral area of the fiber laminate. This results in an orientation of the fibers in the individual layers of the fiber laminate used to reinforce the reinforcement beam that is overall suitable for the applied load, so that the reinforcement beam withstands high mechanical loads at a minimum weight.

Abstract: Molding material that includes a layer of fibrous reinforcing material having one surface on which a first layer of a resin partially impregnates the fibrous material and a further resin layer located on the opposite surface which retains in position surface fibers of the fibrous material. The further resin layer is of lower weight than the first layer and is formed as an openwork structure with a solid part and spaces through which the fibrous material is exposed.

Abstract: A method for producing an article of composite material. A female molding tool is provided. A form bag is provided. At least one prepreg is placed in the molding tool. A heel shaped hard tool part. A hard tool part is placed at the female tool close to an edge of the laminate being placed in the mold. The form bag is placed in the female tool so that the bag seals towards the heel shaped tool part, in such a way that, at a later air evacuation of the bag, an increased pressure that the bag will apply towards the laminate reaches a radius before the pressure reaches an edge.

Abstract: Structural beam of a wind turbine blade comprising a body-root and a body-trunk in the form of a box with a section decreasing towards the blade tip, comprising various piles each formed by various layers of carbon fiber impregnated with a synthetic resin, located on the upper and lower areas, intercalated between various layers of fiber glass impregnated with synthetic resin arranged along its perimeter, including between two piles, at least one layer of reinforcing material on each of the side areas enveloped by an adhesive resin film. The invention also comprises a procedure for the manufacture of the structural beam which, amongst other stages, includes the application of the layers mentioned onto a mold and the beam curing process.

Abstract: In accordance with the present invention, there is provided a method for the forming or curing of polymer composites, the method including the step of: forming or curing the polymer composite in the presence of water vapor at about atmospheric pressure.

Abstract: A composite structure is made by placing a stiffener preform and a composite structure reinforcement on a tool. The preform and the reinforcement are vacuum bagged processed and co-infused with a thermoset resin to form a stiffened, unitized structure.

Abstract: The present invention relates to an automated method for manufacturing layer by layer a composite part with rotational symmetry and complex cross-section, comprising the following stages: a) a reel or roll comprising a reinforcement is continuously unwound; b) as an option, the reinforcement is impregnated with a liquid resin by passing through a bath; c) the impregnated reinforcement is wound onto a rotating cylindrical mandrel; d) the impregnated reinforcement is completely or partially polymerised in order to obtain a composite material; e) a support and/or support material is deposited on both sides of the composite material forming the part being manufactured in such a way as to fill the gaps surrounding said part.

Abstract: The invention describes a new synthetic fiber material of polyhydroxyether, as well as a melt-spinning method for its production. The new material can be used, in particular, for stabilization of the reinforcement fibers of high-performance fiber composite materials before they are embedded in the matrix material. During this usage, the polyhydroxyether fiber material dissolves at a temperature above its glass transition temperature entirely in the matrix material, so that the reinforcement fibers can be arranged largely free of kinking. In addition, it forms cross-links with the matrix material to form a homogeneous matrix and thus does not constitute a disruptive third phase in the composite material. The compatibility of the matrix and reinforcement fiber is also improved. It was possible to improve the bending strength of test slabs by 12% as compared to that of reference slabs with polyester filament.

Abstract: The invention relates to a method for making a thermoplastic composite part by molding. The method includes making several portions of the part according to a molding method, the molding method including placing, in a mold, a composite material containing fibers embedded in a thermoplastic matrix, while arranging the material so that the fibers contained therein are oriented along one or more preferred directions; submitting the mold to particular pressure and temperature conditions, knowing that for each of the different portions the fibers may be of different natures and dimensions, and may be oriented in different directions, while the thermoplastic matrix and that of the material used for making the first portion are identical or compatible; and assembling the different portions obtained, placing them in a mold, and submitting the latter to particular pressure and temperature conditions.

Abstract: In a moulding process for producing automobile parts, the female part (1) of a two part mould is sprayed with a metal such as stainless steel, tin, nickel-tin, copper or zinc. A thermal expansion compensation layer (3) is laid on the sprayed mould surface (1) and a layer of a resin impregnated fibrous material is applied thereto. The resultant assembly is cured and then removed from the female part of the mould or removed from the mould and then cured. The metal surface (2) of the composite part may be subject to further treatment such as polishing, coating and painting, or a combination of these. “Windows” may be produced by leaving areas of the mould part unsprayed with metal. In this way panels for lights, aerials or proximity sensors may be integrally formed.

Abstract: Fabricating a test blade including defects for calibrating a tomography installation for verifying similar blades. A three-dimensional blank is made by weaving fibers of synthetic material and elements of resin in the solid state are inserted into predetermined locations in said blank prior to coating it in resin.

Abstract: A multilayer ceramic matrix composite structure is disclosed. The ceramic matrix composite structure may include a three-dimensional weave fabric forming a core layer. The ceramic matrix composite structure may also include a two-dimensional weave fabric attached to an outer top surface of the three-dimensional weave fabric such that the two-dimensional weave fabric forms a top layer, and a two-dimensional weave fabric attached to an outer bottom surface of the three-dimensional weave fabric generally opposite to the outer top surface such that the two-dimensional weave fabric forms a bottom layer. The structure may include increased interlaminar shear strength.

Abstract: There is provided a continuous molding method capable of varying a thickness of a prepreg molded article. A molding material 10 is prepared such that three plies, for example, of prepreg 31, 32, 33 are laminated with different end face positions on each face of a prepreg laminate 20 of a carbon fibre or the like, and prepreg peel plies 41, 42, 43 are arranged continuously to the respective plies of the prepreg 31, 32, 33. This molding material 10 is transformed into a sheet and continuously sent out to a hot press for molding, which is then heated in a post-curing oven for a prescribed period of time for thermosetting. After the molding, the prepreg peel ply 40 is peeled and removed so that a product whose sectional thickness varies can be obtained.

Abstract: A three-dimensional filter includes a filter frame having a three-dimensional skeletal structure with a filter media connected to the skeletal structure. The filters are nestable. The skeletal structure may be trimmed and provided with walls to create standard sized filters. Methods for making the three-dimensional filter include injection molding of the skeletal structure onto the filter media, injection molding the filter media and the filter frame together in a single molding process, thermoforming a molded or extruded skeletal structure and the filter media, and needle punching a molded or extruded skeletal structure to create filter media within the skeletal structure.

Abstract: A method is disclosed for high volume production of molded dimensionally accurate polymer composite articles comprising three-dimensional carbon fiber reinforcement in high volume. Carbon fiber cloth infiltrated with a liquid thermosetting polymer precursor is shaped by application of pressure to urge the cloth against the surface of a mold and then heated while under pressure to cure the polymer precursor into a solid polymeric matrix for the carbon fiber article. Mold tooling is formed of suitable iron-nickel alloys and provided with a hard electroless nickel coating on the mold cavity surface. The iron and nickel alloy provides thermal expansion properties generally matched to those of the articles for the molding of dimensionally accurate parts.

Abstract: Low density and acoustically absorbing panels are produced by consolidation in a mold of a heated part of a pre-cut, lofty, semi-finished product containing polypropylene fibers and reinforcing fibers and having an air pore content of 20 to 80 vol.-% wherein overlapping with the periphery of the pre-cut part are heated strips of polypropylene optionally containing up to 60 wt.-% reinforcing fibers, but containing 5 vol.-% or less of air pores.

Abstract: Techniques for manufacturing structures that include composite hat stringers are disclosed. In one embodiment, a method of forming a composite structure includes placing a generally cured composite hat stringer on a tool, the hat stringer having a rigid mold line conformal surface for adjoining a generally uncured skin, positioning the skin adjacent to the rigid mold line conformal surface, coupling the skin to the rigid mold line conformal surface of the composite hat stringer, including applying a pressure to a surface of the skin to urge the skin into engagement with the composite hat stringer, and curing the skin.

Abstract: A method for forming improved composite materials using a thermosetting polyester urethane hybrid resin, a closed cavity mold having an internal heat transfer mechanism used in this method, and the composite materials formed by this method having a hybrid of a carbon fiber layer and a fiberglass layer.

Abstract: A manufacturing method and a manufacturing apparatus of a fiber reinforced composite material are provided, in which the whole fiber-based material is impregnated with a resin and a molding can be performed with high dimensional accuracy. A manufacturing method of a fiber reinforced composite material according to the present invention includes fixing a fiber-based material having a first surface to a first mold to provide an opening for the first surface; setting a second mold having a second surface such that the first surface faces the second surface through a space; filling resin into the space; and relatively moving the second mold and the first mold to bring the second surface closer to the first surface, such that the fiber-based material is impregnated with the resin.

Abstract: Process for producing fiber-reinforced composite materials, by a) molding a textile structure and then spray-applying a binder, or saturating the textile structure with a binder, or b) first spray-applying a binder to a textile structure, or saturating a textile structure with a binder, and then subjecting the material to forming and drying.

Abstract: A method for forming a polyimide composite article utilizes a polyimide resin system including at least a first prepolymer component and a second prepolymer component. A preform structure is tackified with the first prepolymer component. Using resin infusion or resin transfer molding techniques, the tackified preform structure is contacted with the second prepolymer component. The polyimide resin system is cured under suitable cure conditions so that the first and second prepolymer components mix and react to produce the polyimide composite structure.

Abstract: The present invention relates to prepregs, towpregs and preforms made from curable compositions of (a) benzoxazines, (b) a combination of adducts a first of which is prepared from hydroxy-containing compounds, isocyanate-containing compounds and phenolic compounds and the second of which is prepared from the first adduct and epoxy-containing compounds, (c) components reactive with the benzoxazine, such as epoxy resins, episulfide resins and oxetane resins, (d) tougheners, such as polyether sulfones, ATBN and core shell materials and (e) a silica component, where the silica has a mean particle diameter on the order of 10?9 meters.

Abstract: A method of preparing a reinforcing structure for use in manufacture a pultruded part where the reinforcing structure is pulled through a pultrusion die in a continuous longitudinal pull direction. The method includes arranging a plurality of first reinforcing fibers in a transverse direction and attaching a permeable transport web of staple fibers to the first reinforcing fibers such that the portion of the first reinforcing fibers oriented in the direction transverse comprises at least 30% of a volume of materials comprising the reinforcing structure.