Method, device and computer program for manufacturing a composite material component from recycled material chips

Abstract

The invention relates in particular to a method for manufacturing a composite material component from chips of at least one first recycled component, said chips being grouped into families according to chip types. After obtaining (125) a plurality of desired characteristics of said composite material component and after obtaining, from the desired characteristics, using a knowledge base (135) comprising a set of composition rules, each composition rule associating characteristics of a sample formed from chips of at least one second recycled component with at least one type of chips forming said sample and an arrangement of chips forming said sample, at least one composition rule of said set, at least one type and arrangement of chips to be used to manufacture said composite material component are estimated (130) using said at least one rule obtained. (Shorthand figure: Figure 1)

Description

Title of the invention: Method, device and computer program for manufacturing a composite material component from recycled material chips

[0001] The present invention relates to the field of recycling composite materials, in particular composite materials containing carbon fibers. It relates specifically to a process, a device, and a computer program for manufacturing a composite material component from recycled material chips.

[0002] Carbon fiber-based composite materials are used in many technical fields for their mechanical properties, in particular strength and lightness, for example in the aeronautical, automotive, and nautical fields, but also in the fields of construction, energy, etc.

[0003] Carbon fiber-based composite materials generally comprise carbon fibers included in a matrix.

[0004] Several methods can be used to manufacture carbon fibers, the principle being a deposition of carbon at very high temperature, either from paper or viscose (fibres "ex-cellulose"), or from polyacrylonitrile (fibres "ex-PAN"), or from petroleum or coal residues (fibre "ex-pitch").

[0005] Carbon fibers are included in the matrix in a given orientation, for example unidirectionally, or in the form of woven fiber sheets.

[0006] Regarding the matrix, it is generally made of a polymer or consists essentially of a polymer. The matrix may also be called an "adhesive" or even a "resin" (the matrix generally being a polymer). As is well known, the matrix may be thermoplastic or thermosetting.

[0007] Thermosetting polymers undergo a chemical reaction (crosslinking) during the shaping of the composite material, which generates chemical bonds and is irreversible. The most effective thermosetting polymers for forming a carbon fiber-based composite material are polyepoxides (also known as "epoxies").

[0008] Thermoplastic polymers are polymers which, above a certain temperature, called the "phase transition temperature," which is lower than their thermal degradation temperature, become viscous and can thus be shaped. When the temperature drops below this phase transition temperature, the polymer hardens and regains its initial stiffness. The transition from the viscous to the solid state is reversible.

[0009] The most common thermoplastic polymers are polyethylene (PE), the poly(ethylene terephthalate) (PET) or polycaprolactam (PA-6). For certain applications, special thermoplastic polymers may be used, such as poly(phenylene ether-ether-ketone) (PEEK), poly(phenylene sulfide) (PPS), or polyetherimide (PEI).

[0010] Given the numerous and increasingly widespread applications of carbon fiber-based composite materials, the question of recycling these materials arises. Recycling can involve end-of-life or damaged composite material components, manufactured components that no longer meet certain standards required for their intended use, or, more rarely, components that have not been used by a certain date.

[0011] To recycle composite materials reinforced with carbon fibers, three main categories of methods have been developed: so-called mechanical recycling, so-called chemical recycling and so-called thermal recycling.

[0012] Mechanical recycling, in principle, consists of fractionating and grinding existing composite material parts to at least partially separate the fibers from the resin, so as to obtain fibers of varying lengths that can be reused as reinforcement in new resin. The low-fiber particles resulting from grinding, which are in powder form, can be mixed with resin during the formation of a new composite material component.

[0013] The ground composite fragments are used as fillers or reinforcements in molded parts, but are not actually intended to replace virgin carbon fibers such as those used in conventional manufacturing processes for composite parts (based on non-recycled materials). It is generally accepted that the mechanical properties (flexural strength or flexural stiffness) of a part obtained by a prior art mechanical recycling process are at least four times lower than those of a similar new part.

[0014] Chemical recycling consists of chemically degrading the hardened resin of a composite material in order to recover carbon fibers present in that material. The recovered fibers are then generally aligned and / or spun to create a yarn from several thousand recovered fibers. The mechanical properties of parts formed from composite materials containing these recycled fibers are significantly lower than those of composite materials containing new, non-recycled carbon fibers.

[0015] Finally, thermal recycling, in principle, consists of thermally degrading the resin of a composite material to recover the carbon fibers. The heat can be supplied by a pyrolysis process, which essentially involves burning the resin in a furnace, by a fluidized bed process that uses the combined action of a solvent and high temperature, and finally by microwaves.

[0016] Although these processes are being optimized, the recovered fibers have significantly degraded mechanical properties compared to virgin fibers. The recovered fibers are generally short; they must be aligned and spun to be reused in applications requiring adequate mechanical characteristics. Otherwise, they are used as fillers, as is the case, for example, with the powders obtained in the mechanical recycling processes mentioned above.

[0017] The present invention aims to provide a method, a device and a computer program to improve the manufacture of a part made of composite material from chips of recycled elements, the part made of composite material having high mechanical properties, at a controlled economic and environmental cost. Description of the invention

[0018] The invention relates to the manufacture of a composite material part comprising chips of different types, at least partially embedded in a matrix, arranged to obtain predetermined technical characteristics. Each chip has a substantially constant thickness defined between two parallel opposite faces of the chip, each chip comprising carbon fibers at least partially embedded in an adhesive cured during a first curing step prior to the formation of said part. At least a majority of the fibers of the chip extend substantially parallel to the opposite faces of the chip. The matrix in which each chip is at least partially embedded is formed from an adhesive cured during a second curing step. Thus, a bonding interface is formed between the matrix and each chip of the part.

[0019] A first aspect of the invention relates to a method for manufacturing a composite material element from chips of at least one first recycled element, said chips being grouped into families according to chip types, the method comprising,

[0020] - obtaining a plurality of desired characteristics of said element in composite material,

[0021] - obtaining, from the desired characteristics, using a basis of knowledge comprising a set of composition rules, each composition rule associating characteristics of a sample formed from chips of at least one second recycled element with at least one type of chips forming said sample and an arrangement of chips forming said sample, of at least one composition rule of said set, and

[0022] - the estimation, using said at least one rule obtained, of at least one type and of a chip arrangement to be used to manufacture said element from composite material,

[0023] said elements being elements based on synthetic fibers.

[0024] Thus, from the desired characteristics of an element to be manufactured, it is possible to obtain a composition of chips having different characteristics and an arrangement of these allowing to reach or tend towards the desired characteristics.

[0025] According to a particular embodiment, the desired characteristics include at least a flexural modulus of elasticity, a flexural strength, a tensile modulus of elasticity, a tensile strength, an interlaminar shear strength, a yield strength, light polarization properties, heat dissipation properties, acoustic behavior and / or electromagnetic wave behavior.

[0026] According to a particular embodiment, the types of chips are determined according to parameters including at least one armor, one linear or surface mass, one chip mass, one thickness, one shape, one roughness, one porosity, one surface chemistry, one thermal dissipation characteristics, one electromagnetic properties and / or one light polarization properties.

[0027] According to a particular embodiment, the estimation of at least one type of chips includes the determination of a ratio of chips from different families of chips.

[0028] According to a particular embodiment, the process further comprises obtaining several composition rules, the estimation comprising an extrapolation or an interpolation from the composition rules obtained.

[0029] According to a particular embodiment, the synthetic fibers comprise carbon fibers and / or para-aramid synthetic fibers.

[0030] A second aspect of the invention relates to a method for constructing a knowledge base for manufacturing a composite material element from chips of at least one first recycled element, the method comprising,

[0031] - obtaining a plurality of parameters characterizing each of the chips of minus a second recycled element,

[0032] - the determination of chip families according to said plurality of parameters,

[0033] - the estimation of characteristics of a sample comprising chips of said at minus a second recycled element,

[0034] - the determination of at least one composition rule associating the characteristics estimated with at least one type of chips included in said sample and an arrangement of chips included in said sample, a chip type corresponding to a chip family and

[0035] - memorizing said at least one composition rule determined in said knowledge base.

[0036] The method according to the invention thus allows the establishment of rules enabling the fa manufacturing of composite material elements having particular characteristics, from recycled elements, for example according to the manufacturing process described above.

[0037] According to a particular embodiment, the characteristics of said sample include at least a flexural modulus of elasticity, a flexural strength, a tensile modulus of elasticity, a tensile strength, an interlaminar shear strength, a yield strength, light polarization properties, heat dissipation properties, acoustic behavior and / or electromagnetic wave behavior.

[0038] According to a particular embodiment, the types of chips are determined according to parameters including at least one reinforcement, a linear or surface mass, a chip mass, a thickness, a shape, a roughness, a porosity, a surface chemistry, and / or thermal dissipation characteristics, electromagnetic properties and / or light polarization properties.

[0039] According to a particular embodiment, the composition rule associates the characteristics with a ratio of chip types forming said sample and an arrangement of the chips forming said sample.

[0040] According to a particular embodiment, said estimation of characteristics of a sample includes a simulation of said sample.

[0041] In another particular embodiment, the estimation of the characteristics of a sample includes manufacturing the sample and at least one measurement (435) of the manufactured sample. The sample may be a composite material element manufactured according to the manufacturing process described above.

[0042] According to a particular embodiment, the process further comprises a repetition, for different samples, of the steps of estimating characteristics, determining at least one composition rule and memorizing said at least one rule.

[0043] According to a particular embodiment, the process further comprises a repetition, for different samples, of the characteristic estimation step and comprising a modification of at least one previously memorized composition rule.

[0044] A third aspect of the invention relates to a device configured to implement the processes described above. The advantages provided by this device are similar to those described previously with regard to the processes.

[0045] A computer program, implementing all or part of the process described above, installed on pre-existing equipment, is in itself advantageous, since it allows easy and quick access to and selection of an event likely to be of interest to a user.

[0046] Thus, the present invention also relates to a computer program comprising instructions for implementing the process described above, when this program is executed by a processor.

[0047] This program may use any programming language (for example, an object-oriented language or other) and may be in the form of interpretable source code, partially compiled code or fully compiled code.

[0048] Another aspect relates to a non-transient storage medium for a computer-executable program, comprising a set of data representing one or more programs, said one or more programs comprising instructions for, when said one or more programs are executed by a computer comprising a processing unit operationally coupled to memory means and an input / output interface module, to execute all or part of the process described above. Brief description of the drawings

[0049] Other features, details, and advantages of the invention will become apparent from the detailed description below. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0050] [Fig.1] schematically illustrates an example of steps in a process for manufacturing a composite material element from recycled element chips, according to embodiments of the invention;

[0051] [Fig.2] schematically illustrates an example of steps for the preparation of chips from recycled elements, according to embodiments of the invention;

[0052] [Fig.3] illustrates examples of chip arrangements having different characteristics, including different sizes;

[0053] Figure 4 illustrates an example of steps for constructing and updating a rule base for defining manufacturing parameters, for example chip types and their arrangement, based on characteristics of a part to be manufactured; and

[0054] [Fig.5] illustrates an example of a device that can be used to implement, at least partially, embodiments of the invention, in particular steps described with reference to Figures 1, 2 and 4. Detailed description

[0055] In general, the invention relates to the manufacture of a part made of composite material comprising different types of chips at least partially included in a matrix, arranged in a particular way during the manufacture of the part such that the types of chips and their arrangement make it possible to obtain the desired characteristics for the part, in particular partial mechanical characteristics. culières.

[0056] According to certain embodiments, each chip has a substantially constant thickness defined between two parallel opposite faces of the chip, each chip comprising carbon fibers at least partially embedded in an adhesive cured during a first curing step prior to the formation of said part. At least a majority of the chip fibers extend substantially parallel to the opposite faces of the chip. The matrix in which each chip is at least partially embedded may be formed from a thermosetting adhesive cross-linked during a second curing step, or from a cured thermoplastic adhesive. In this case, a bonding interface is formed between the matrix and each chip of the part.Alternatively, if each chip contains carbon fibers at least partially embedded in a thermoplastic adhesive cured during an initial curing prior to the formation of said part, no adhesive is added and the matrix is ​​formed from the thermoplastic adhesive of each chip of the part.

[0057] The bonding interface may essentially comprise mechanical adhesion bonds (mechanical anchoring such as physical anchoring of the adhesive in the asperities of the solid surface of the chips), as well as possibly a diffusion bond (diffusion of the adhesive in the chip) and / or a thermodynamic bond, in particular of the "Van der Waals" type.

[0058] Throughout this document, the term "substantially" refers conventionally to the perception of this characteristic according to the system used for its measurement or manufacture. If a characteristic is observed with the naked eye, the term "substantially" therefore refers to an observer's perception of that characteristic. An expression containing the term "substantially" should be interpreted as a technical characteristic produced within the tolerance range of its manufacturing method. In particular, the "substantially parallel" characteristic between two elements can be understood to be within 10° of an angle. If the fiber in question is included in a fabric (typically taffeta, twill, or satin), the direction of fiber extension is considered by neglecting any fiber undulations related to the weaving process.

[0059] By "chips at least partially embedded in a matrix," it is specified that each chip is embedded in the matrix, with the possible exception of some chips that may emerge on the surface of the part. Similarly, by "carbon fibers at least partially embedded in an adhesive cured during an initial curing," it is specified that the carbon fibers are embedded in the adhesive of a chip, with the possible exception of some fibers that may emerge on the surface of the chip.

[0060] Suitable adhesives for composite materials can be chosen from the group consisting of thermosetting resins such as epoxy resins, cyanate ester resins, and phenolic resins. Suitable epoxy resins include ethers diglycidyl bisphenol A, diglycidyl bisphenol F ethers, novolac epoxy resins and N-glycidyl ethers, glycidyl esters, aliphatic and cycloaliphatic glycidyl ethers, aminophenol glycidyl ethers, glycidyl ethers of any substituted phenols, and mixtures thereof. Also included are modified mixtures of the aforementioned thermosetting polymers. "Modified mixture" refers to a polymer that has been modified, typically, by the addition of rubber or thermoplastic.

[0061] Any suitable catalyst (or “hardener”) may be used. The catalyst will be chosen to match the resin used. The catalyst may be accelerated. For example, when a dicyandiamide catalyst is used, a substituted urea may be used as an accelerator.

[0062] The curing agent with an epoxy resin can also be chosen from Dapsone (DDS), Diamino-diphenyl methane (DDM), BF3-amine complex, substituted imidazoles, accelerated anhydrides, metaphenylene diamine, diamino-diphenyl ether, aromatic polyetheramines, aliphatic amine addition products, aliphatic amine salts, aromatic amine, aromatic amine addition products and salts.

[0063] Suitable accelerators include Diuron, Monuron, Fenuron, Chlortoluron, toluenediisocyanate bis-urea and other substituted homologues.

[0064] Suitable adhesives for composite materials can also be chosen from the group consisting of thermoplastic resins. Among thermoplastics, a distinction can be made between high-performance plastics, engineering plastics, and standard plastics. Most thermoplastics used in composite materials are high-performance or engineering plastics. These plastics are distinguished from standard plastics, in particular, by their greater wear resistance and chemical resistance. However, standard thermoplastics can offer advantages, such as glass fiber reinforced polypropylene (GF / PP) or SrPP and SrPET (self-reinforced polypropylene and self-reinforced polyethylene terephthalate), because their glass transition temperature is not very high.

[0065] Thermoplastics, depending on their nature, can be hard in amorphous or crystalline form. Among the amorphous thermoplastics commonly used in composite materials are polyetherimides (PEI), polyethersulfone (PES), polysulfones (PSU), polycarbonates (PC), and polycarbonate / acrylonitrile butadiene styrene (PC / ABS). Among the crystalline thermoplastics commonly used in composite materials are polyamides (PA), polyethylene (PE), poly(ethylene terephthalate), polyphthalamide (PPA), poly(phenylene sulfide) (PPS), and polyetheretherketone (PEEK).

[0066] Each chip is formed such that the majority of its fibers are oriented parallel to the chip faces. This allows the fibers to have a significant length and a controlled orientation within the chip. Ultimately, the length and orientation of the fibers in the chips, and the arrangement of the chips in the workpiece, give it high mechanical properties.

[0067] The chips can in particular be obtained by cutting elements made of carbon fiber-based composite material to be recycled, as explained in more detail below. The formation of a part according to the invention thus allows the recycling of such elements, using a low-polluting mechanical process, while offering good mechanical performance to the formed part.

[0068] The faces of each chip can have a surface area, referred to as the chip surface, of at least 10 mm². These values, given by way of example, are understood to be minimums. Depending on the parts considered, the chips can have a much larger surface area, for example, on the order of 3 cm², 5 cm², 10 cm², or 20 cm², 100 cm².

[0069] The chips formed and used here thus have a large surface area, allowing the inclusion of long carbon fibers since the latter extend substantially parallel to the opposite faces of the chip.

[0070] Each chip advantageously has a small thickness (e) compared to its other dimensions. Since a chip is thus an essentially two-dimensional part of small thickness, its other dimensions typically correspond to the largest dimension (d) measurable on the chip's surface and the dimension measured perpendicularly, also on the chip's surface. The ratio (e) / (d) is, for example, between 0.2 and 0.0001 and preferably between 0.06 and 0.0005. It should be noted that, unless otherwise specified, the ranges are inclusive.

[0071] In the composite material part, the carbon fibers advantageously extend predominantly in parallel planes. Furthermore, the chips can exhibit a unidirectional arrangement of carbon fibers, along two distinct directions, for example, a first direction and a second direction forming a 90° angle between them, or along multiple directions, it being observed that a controlled orientation of the chips, and therefore of the fibers, within the part allows for obtaining the desired mechanical properties. In addition, the chips can be arranged in the part according to a repeating pattern, corresponding to a particular relative arrangement of several chips.

[0072] The carbon fibers present in each chip can be arranged into sheets, each having a weave of carbon fibers.

[0073] In the composite material part, the shape and dimensions of the chips used are chosen to obtain the desired mechanical properties. By way of illustration, each chip can be substantially rectangular in shape. (that is, the faces of each chip are essentially rectangular) with several different sizes.

[0074] The thickness of the chips can for example be between 100 µm and 1 mm.

[0075] The composite material may comprise fibrous zones, formed by the chips and representing between 20% and 85% by volume of the part, and non-fibrous zones, consisting of the adhesive applied and hardened during the second curing, forming the remainder of the part. A part made of composite material may comprise:

[0076] - a plurality of zones comprising carbon fibers and a first adhesive, the carbon fibers exhibiting a non-random orientation within the same zone, and all the carbon fibers in said zones being oriented along substantially parallel planes, and

[0077] - at least one area devoid of carbon fibers, comprising a second adhesive,

[0078] the plurality of zones comprising carbon fibers and a first adhesive being at less partly included in at least one carbon fiber-free area comprising a second adhesive, that is to say that the second adhesive of the at least one carbon fiber-free area encompasses at least 75%, preferably at least 80%, even more preferably at least 85% such as for example 90%, of the surface of the plurality of areas comprising carbon fibers and the first adhesive.

[0079] Areas containing carbon fibers can also be distributed in the composite material part according to a pattern.

[0080] The first adhesive may be identical to the second adhesive, the first adhesive having been hardened before the second adhesive, or different.

[0081] The composite material part can, for example, be a flat or curved panel.

[0082] Fig. 1 schematically illustrates an example of steps in a process for manufacturing a composite material element from recycled element chips according to embodiments of the invention.

[0083] As illustrated, the process here comprises three phases: a phase 100 of cutting the elements to be recycled into chips, a phase 105 of manufacturing preparation to determine in particular the chips to be used and their arrangement and a phase 110 of manufacturing.

[0084] According to the illustrated example, the preparation phase for the chips to be used in manufacturing a component includes a step of cutting the components to be recycled into chips (step 115) and a step of classifying the resulting chips into families (step 120). The components to be recycled are components based on synthetic fibers, for example, components based on carbon fibers and / or para-aramid synthetic fibers such as Kevlar fibers (Kevlar is a brand name). By way of illustration, the examples described primarily concern carbon fibers.

[0085] The chips are obtained by cutting the elements to be recycled (step 115), by For example, mechanical cutting. Chip cutting can be carried out using a cutting machine such as a blade device, for example, a planer-type device, with a blade that separates thin slices of uniform thickness from the surface of the element it passes over. The material to be cut is positioned in the cutting machine according to the arrangement of its carbon fibers.

[0086] If the fibers in the material to be cut are unidirectional, that is, included in a matrix substantially parallel to each other in a single direction, then the fibers can be positioned parallel to the direction of travel of the cutting device. If the fibers are included in the form of woven sheets, the workpiece is preferably positioned so that the weft or warp yarns are substantially parallel to the direction of travel of the cutting device. The fibers can also be arranged in a succession of layers, each layer containing unidirectional fibers, but the layers having different fiber orientations. This is, for example, the case for so-called "four-way" materials, whose layers can have the following successive relative orientations: 0° (reference layer), 90°, 45°, -45°.The blade device can then be adjusted so that its blade attacks the element between two layers of fibers, whether they are two layers of unidirectional fibers or two woven plies.

[0087] The slices obtained may in particular have a thickness of between 200 pm and 1 mm, preferably between 200 pm and 500 pm.

[0088] The items to be recycled can be cut to the desired length for the chips before being sliced ​​by the cutting machine, so that the chips of the desired length are obtained directly at the output of the cutting machine.

[0089] Alternatively, the slices are then cut again to obtain chips. Typically, they are cut transversely by any suitable cutting means, for example by sawing, in order to form thin rectangular chips of uniform length. Other chip shapes can obviously be cut from the slices obtained.

[0090] For example, for the production of flat panels, chips 10 cm to 20 cm long can be obtained, resulting in very good mechanical performance. Longer lengths, such as 50 cm or even 1 m, can also be used.

[0091] Obviously, the cutting process described above can be adapted according to the application considered and the quantities to be produced.

[0092] When the material to be recycled is a pre-coated, but uncured, carbon fiber fabric, this material can first be cured (polymerized for a material coated with a thermosetting resin) and then cut to the desired chip shape. Alternatively, it can be cut to the desired chip shape and then hardened. Alternatively still, it can be cut to the desired chip shape without subsequent hardening. Since such a fabric generally has a thickness between 200 µm and 500 µm, the resulting chip has a thickness perfectly suited for use according to the present invention in forming a part, particularly a molded part, from composite material.

[0093] Once formed, the chips are in the form of thin elements comprising carbon fibers embedded, at least partially, in a resin. The chips are therefore substantially two-dimensional (in that their thickness is very small compared to their other dimensions). The surface area of ​​the chips is advantageously at least 10 mm², and preferably greater than 3 cm², on the order of 10 cm², or even greater, for example up to approximately 100 cm².

[0094] When the hardening of the chip matrix is ​​prior to the formation of the final part by molding, it is referred to as first hardening (in order to distinguish it from the hardening of the part matrix, which aims to bind the chips, and which will be carried out during the molding of the part).

[0095] The carbon fibers are oriented in the resin of the chips. Preferably, they are substantially parallel, orthogonal to each other, and / or oriented at 45° to each other.

[0096] Since the fibers of the chips have a substantially constant thickness, they comprise two opposite faces (between which the thickness is defined). The chip cutting is carried out in such a way as to preserve as many of the carbon fibers as possible. To this end, the chips are cut so that the fibers (mostly, or even almost all, or all) extend parallel to the opposite faces of the chips. The fibers thus extend in planes parallel to the general plane of extension of the chip, and can therefore be quite long despite the thinness of the chips.

[0097] By "majority" we mean more than 50% by number and by "almost all" we mean more than 90% by number.

[0098] Several cutting machines or several settings of the same cutting machine can be used to cut parts to be recycled into chips of varying dimensions and shapes. Therefore, as illustrated in [Fig. 2], several types of cutting can be implemented, for example, n types of cutting referenced herein 115-1 to 115-n. Combined with different parts to be recycled and different fiber arrangements in these parts, this results in chips with different characteristics in terms of size, fiber arrangement, etc. and therefore in terms of mechanical characteristics.

[0099] To improve the use of the resulting chips, they are grouped into categories or families, for example into p families as illustrated in [Fig. 2] (referenced 200-1 to 200-p), according to their characteristics, for example their thickness, dimensions, shape, mass, linear or surface density, fiber orientation (e.g., unidirectional or woven), weave (e.g., twill, plain weave, satin, etc.), roughness, porosity, surface chemical properties, heat dissipation characteristics, electromagnetic properties, light polarization properties, etc. By way of illustration, the chips can be grouped into the following families: Family parameters values ​​1 Fiber orientation unidirectional dimensions 100 x 10 x [0.3 - 0.5] mm 2 Fiber orientation woven Young's modulus E1 thickness 0.5 mm 3 Fiber orientation woven Young's modulus E2 thickness 0.5 mm 4 Fiber orientation woven Young's modulus E1 thickness 1 mm 5 Fiber orientation woven Young's modulus E2 thickness 1 mm

[0100] where the value of the parameter El is greater than that of the parameter E2.

[0101] Other parameters may be taken into account. Furthermore, the number of families is not necessarily equal to 5. It can be less than or greater than this value.

[0102] According to other embodiments, the chips are divided into families and subfamilies, according to two or more levels of depth, the families being linked to one or more first criteria, for example the orientation of the fibers, the subfamilies being linked to one or more second criteria, for example the dimensions of the chips, and so on.

[0103] Returning to [Fig. 1] and in a subsequent phase (phase 105), the characteristics, by For example, the mechanical characteristics of the composite material element to be manufactured from recycled material chips are obtained (step 125) and an analysis is carried out to identify manufacturing parameters (step 130), for example the types of chips to be used and their distribution.

[0104] Characteristics of the composite material element to be manufactured (step 125) can be obtained directly from the element's technical specifications, for example, a file from an application such as a computer-aided design application, and / or can be provided by a user, for example, via a graphical interface. They can also be determined from other characteristics of the element to be manufactured. Such characteristics of the element to be manufactured include, for example, a flexural modulus of elasticity, flexural strength, tensile modulus of elasticity, tensile strength, interlaminar shear strength, yield strength, dimensions, light polarization properties, heat dissipation properties, acoustic behavior, electromagnetic wave behavior, etc.

[0105] These characteristics are then used to determine manufacturing parameters (step 130). In particular embodiments, a rule engine or an artificial intelligence engine is used. By way of illustration, a rule engine containing rules associating characteristics of parts to be manufactured from chips with manufacturing parameters such as the types of chips to be used and their distribution, stored for example in a database 135, can be used to select one or more rules and identify manufacturing parameters, for example by applying the closest rule or by extrapolating from two (or more) closest rules.

[0106] Such rules are, for example, the following: Rule, Characteristics, Element, Manufacturing Parameters: 1 - Mechanical requirement: orthotropic material (same properties in the longitudinal and transverse directions) - Aesthetic requirement: unidirectional appearance on the outside, outer layers with family 1 and core of the material with family 2 —> 80% family 2 / 20% family 1 2 - Mechanical requirement: material stressed in only one longitudinal direction - Aesthetic requirement: woven appearance on the outside, outer layers with family 2, core of the material with family 1. —> 80% family 1 / 20% family 2 3 - Dimensional requirement: two layers of family 5 and one laminate thickness of 2.5 mm - manufacturing requirement: very short manufacturing time (e.g., high-volume production) - mechanical requirement: intermediate performance family 3 layer (alternatively five family 3 layers, but shorter manufacturing time with sufficient mechanical performance) —> 66.7% family 5 / 33.3% family 3 (or —> 100% family 3) 4 - mechanical requirement: formation of a laminate with Young's modulus E3 - manufacturing requirement: need for a lot of "raw material", high-volume production association of families 2 and 3 to form a laminate with modulus E3 following the mixture law: E3 = xEl + yE2.Association of two families to expand the stock of material —> x% family 2 / y% family 3 5 - mechanical requirement: high stress on one part of the part, and medium on the other - manufacturing requirement: short manufacturing time use of family 4 for the part with high stress (module El) and of family 5 for the part with medium stress (E2) —> 50% family 4 / 50% family 5.

[0107] These rules, or some of them, can be defined by specialists and / or users. They can also be automatically populated in the database from measurements or simulation, as described below with reference to [Fig.4].

[0108] Figure 3 illustrates examples of chip arrangements with different characteristics, including different sizes. Of course, many other arrangements are possible, and other chip sizes or shapes can be used. It is observed here that the chips can be positioned relative to each other precisely or randomly or pseudo-randomly, for example, according to given directions and / or densities. It is thus possible to ensure that all chips of the same type are placed on the same layer, for example, an outer surface of the part to be manufactured, in the same direction (which can be defined relative to the part to be manufactured or to a direction of other chips), with certain densities in some regions of the part to be manufactured and other densities in other regions of the part to be manufactured.

[0109] Returning to [Fig.1] and at the end of manufacturing preparation phase 105, manufacturing phase 110 can begin.

[0110] As illustrated, this phase includes a first step of adhesive preparation and, optionally, coating (step 140).

[0111] In this step, after obtaining the chips corresponding to the manufacturing parameters determined previously, the chips can be mixed with a liquid adhesive to coat them for molding (it being noted that the adhesive can be applied in different ways, for example as a spray, by pouring, etc.). In this case, if chips from several families are used, they are preferably mixed with the liquid adhesive by family so that they can be arranged in a mold according to the determined manufacturing parameters, for example in layers.

[0112] This step can be carried out before the chips are placed in the mold intended to form the desired part, or during, or even after, placement in the mold. By way of illustration, the following describes how to obtain parts conforming to embodiments of the invention at a pilot or prototype scale. In this example, the chips are mixed with an adhesive before being placed in a mold. At the prototype scale, the mixing can be done manually in a suitable container, for example, made of aluminum. The mixing is preferably vigorous or mechanized in order to homogenize the thickness of the adhesive on each chip.

[0113] The chips can first be weighed in the container, then the adhesive (e.g., a resin / hardener system, see below) is prepared and added. The coating is complete when each chip is evenly covered with adhesive. The addition of the adhesive and the mixing of the chips and adhesive can be automated. An automatic mixer can be used to mix the chips and adhesive.

[0114] The amount of adhesive to be added to the chips is determined according to the characteristics of the part (e.g., the panel) to be produced. The amount of adhesive to be added depends, for example, on the desired volume or mass percentage of chips in the final material to obtain the desired mechanical properties, and on the adhesive used, particularly its density. The applied masses can also be determined by the desired panel thicknesses.

[0115] For many applications where high mechanical performance is required, it is necessary to maximize the proportion of chips in the material. The inventors have produced parts containing up to 80% chips by mass and believe that parts containing up to 85% chips by mass, or even slightly more, can be successfully produced.

[0116] Various adhesives can be used. Generally, all adhesives known to be used as a matrix in composite materials containing carbon fibers can be used, with the possible exception of adhesives that would be incompatible with the cured adhesive present in the chips. By incompatible, it is understood that the adhesive used would cause an undesired chemical reaction with The hardened adhesive present in the chips would be poorly suited to forming mechanical bonds with the chips. For example, two-component epoxy system adhesives can be used. Such two-component epoxy systems consist of an epoxy resin and a hardener. When the resin and hardener come into contact, polymerization begins. The polymerization time varies depending on the nature of the system used.

[0117] A first two-component epoxy system mentioned as an example is the system marketed by SIKA under the name ADEKIT H9011 (ADEKIT is a registered trademark). The transparency of the adhesive once cured allows the chips to be seen in the final part. A second two-component epoxy system mentioned as an example is a system marketed by SICOMIN under the name "SR 1700 EPOXY RESIN + SD 2803 STANDARD HARDENER".

[0118] As indicated above, numerous adhesives can be used for forming parts according to various embodiments of the invention. These include systems designed for composite production applications (infusion, injection, and lamination resins), as well as systems designed for structural applications as adhesives. These systems may have a density ranging from 1.03 to 1.38 at 25°C. Their dynamic viscosity may range from 0.4 to 80 Pa·s. They may have a modulus of elasticity (once cured) ranging from 2 GPa to 4 GPa. The polymerization of these adhesives can take place at room temperature or at higher temperatures, on the order of 70°C. Since polymerization times vary considerably depending on the thermosetting adhesive system, the choice of system may also depend on this time, according to the desired mechanical properties and cycle times.

[0119] The additive(s) may also contain fillers. Fillers refer to all particulate elements that can be added to the adhesive to modify its properties and / or to reduce its cost per unit volume. The fillers envisaged include, in particular, mineral or organic particles capable of improving certain properties of the final part, especially its scratch or abrasion resistance.

[0120] These fillers are most often of a mineral nature (aluminum, calcium, etc. fillers) in the form of particles whose size is on the order of nanometers or micrometers.

[0121] The adhesive may also include glass microbeads.

[0122] The charge used may also contain carbon dust, for example from the operations of preparing and cutting the elements to be recycled. In this case, it is therefore an organic charge.

[0123] Such additives may be provided for in the rules used to determine certain manufacturing parameters such as chip types and their positioning.

[0124] The mixture of chips and adhesive is then molded.

[0125] Alternatively, according to specific embodiments, the chips and adhesive are deposited into the mold without prior mixing. A first layer of resin is deposited into the mold manually or automatically. A layer of chips is then laid down, in a predefined pattern, manually or automatically. The layers of adhesive and chips are thus alternated until the desired thickness is achieved. One method of depositing the resin into the mold is to use a pouring method. The resin and hardener are contained in two separate tanks and pumped to a mixing head. The two products then meet at the end of the mixing head, in a static mixer, to be deposited into the mold as a bead. Another method of depositing the resin into the mold is the spraying method.The principle is the same as the casting method, but compressed air is applied through a nozzle at the end of a static mixer to atomize the adhesive bead formed into droplets that will be deposited in the mold.

[0126] Overmolding can be performed. To do this, at the end of polymerization, resin is injected into the mold to coat the molded part and obtain a specific surface finish. The high injection pressure during overmolding can allow the addition of functional features to the surface of the molded part (grooves, notches, rails, etc.) or the creation of the desired surface appearance. Overmolding can also be performed on another mold of the "insert molding" type. As an alternative or in addition to overmolding, a gel coat can be applied to the mold, or a top coat can be applied to the part after it has been molded.

[0127] By way of illustration, it is assumed here that the composite material element to be manufactured is a flat panel. The mold used comprises a concave part, called the female cavity, and a part forming a corresponding male cavity.

[0128] Before the chips are placed, a release agent can be applied to the internal surface of the mold to facilitate the extraction of the part once it has been formed.

[0129] When the chips have been mixed with the adhesive, they should be placed in the female cavity of the mold (step 145), for example according to the manufacturing parameters determined in step 130, and then the molding should be completed under pressure (steps 150 and 155).

[0130] Depending on the scale of production envisaged, the placement of the chips can be carried out manually, using templates or visual markers (for example, guides formed by a laser), or automatically.

[0131] The adhesive-coated chips are arranged in the female cavity of the mold, on an extraction plate. The extraction plate allows the panel to be extracted from the The mold is formed after the pressing action. It can also be used to adjust the thickness of the panel being formed (multiple thicknesses can be produced in the same mold by varying the thickness of the extraction plate). If an extraction plate is used, it forms the internal surface of the mold, and it is the extraction plate that will be coated with release agent, if necessary.

[0132] The chip placement step in the mold is important, particularly to enable the manufactured part to have the desired mechanical properties. It must be carried out according to the determined manufacturing parameters.

[0133] Assuming that the chips have unidirectional carbon fibers, the chips can be arranged in the mold randomly, unidirectionally (the chips are all arranged in the same direction, with a certain tolerance, for example on the order of plus or minus 10° or with less than 10% of the chips not conforming to the desired orientation and angle tolerance), or multidirectionally (with, where applicable, similar tolerances). Figure 3 illustrates examples of multidirectional fiber arrangements.

[0134] A multidirectional arrangement can consist of creating several plies (each comprising one or more layers of chips) with different chip orientations between adjacent plies. For example, with rectangular chips, it is possible to alternate the plies, with the chips of one plie arranged at 90° to the chips of the adjacent plies. According to certain embodiments, a multidirectional arrangement can therefore be defined as a stacking of unidirectional layers as described above. The example located at the top left of [Fig.[Fig. 3] partially represents three plies (only some chips from each plie are shown to illustrate the stacking of the chips), namely an upper plie in which the chips are oriented along a first direction (x), an inner plie in which the chips are oriented along a direction (y) orthogonal to the direction (x), and a lower plie in which the chips are oriented along the first direction (x). The chips of the flat panel taken here as an example are positioned parallel to the (x,y) plane. In other embodiments, the chips are nested within each other, not forming a stack of unidirectional layers, as in the example located at the bottom left of [Fig. 3].

[0135] The arrangements described above concern a thin, flat panel. For forming a part with a significant thickness (for example, a cube) or a complex three-dimensional shape, it is also possible to position chips orthogonally to the planes of chip extension for molding, forming a random, unidirectional, or multidirectional configuration as described above. These chips, which extend through the thickness of the part, increase the mechanical properties of the part in their direction of extension. Considering an orthogonal coordinate system (x,y,z), as represented in [Fig.3], with the majority of chips oriented in planes parallel to the (x,y) plane, chips positioned orthogonally in the z direction (for example parallel to the (x,z) or (y,z) plane) mechanically reinforce the part in the z direction.

[0136] In general, the arrangement of the chips, provided that it is not purely random, can be such that the chips form a particular pattern which is repeated to form the panel (or more generally a part).

[0137] A pattern corresponds to a particular arrangement of several chips relative to each other in three dimensions. Thus, with the exception of a purely random arrangement, the other arrangements considered (unidirectional, bidirectional, multidirectional, with, where applicable, a three-dimensional arrangement of the chips, etc.) can be considered as the repetition of a chip pattern.

[0138] The arrangement, geometry, chip size, and ply thickness can be adapted according to the intended application and thus, according to the characteristics of the part to be manufactured. The arrangement, geometry, and chip size can also be determined, particularly for an external ply and at least in part, according to aesthetic criteria. Thus, for example, the arrangement, geometry, and chip size of an external ply can be chosen to form a particular geometric pattern such as a logo.

[0139] To a certain extent, the longer the chips, the better the mechanical properties. However, in practice, the length of chips that can be formed and used depends on the recycled and manufactured components, and in particular on their geometric complexity (it is clearly easier to integrate long chips into a large, flat panel than into a curved part with complex geometry and / or numerous geometric details). Generally speaking, it is advantageous to use chips whose longest dimension is between 3 and 20 cm.

[0140] Once the chips are placed in the female cavity of the mold, the mold is closed by positioning the male cavity. The mold is then installed in a press, which is activated to pressurize the mold contents (step 150). Panel prototypes were produced by applying a pressure of between 1 and 50 bar.

[0141] When a thermosetting resin is used, polymerization can take place at room temperature. However, the mold can be heated to accelerate polymerization. To obtain efficient and homogeneous heating (a temperature of around 70°C may be desired), two heating plates can be used, one on each side of the mold. To regulate the heating, and to take into account the exo nature thermal polymerization of the adhesive, a closed-loop control, for example of the PID (proportional, integral, derivative) type, can be used.

[0142] A first curing step preferably takes place when the mold is under pressure (step 150). Some adhesives, depending on their nature, require a second curing step in open air (step 160), also known as post-curing.

[0143] For the ADEKIT H9011 system, the polymerization time is 16 hours at 70°C. By comparison, complete polymerization of this adhesive takes approximately one week at room temperature.

[0144] The process described above thus enables the manufacture of molded parts in composite material formed from elements in composite material based on synthetic fibers, for example carbon fibers or para-aramid fibers, to be recycled.

[0145] The process described above involves molding the part. Alternatively, other forming techniques can be used. For example, a pultrusion process or a calendering process can be used.

[0146] Fig. 4 illustrates an example of steps for constructing and updating a rule base to define manufacturing parameters, for example chip types and their arrangement, from characteristics of an element to be manufactured.

[0147] As illustrated, the first step here is a step of obtaining characteristics of an element to be manufactured, in particular technical characteristics such as mechanical characteristics, for example identical or similar to step 125 described with reference to [Fig.1].

[0148] A test is then performed to determine whether manufacturing parameters are imposed or not (step 400), for example, entered by a user, for example via a graphical interface. If manufacturing parameters are not imposed, a test is performed to determine whether the characteristics obtained from the part to be manufactured are close to the characteristics of at least one rule stored in the rule base 135 described with reference to [Fig. 1]. To determine whether the characteristics obtained from the part to be manufactured are close to the characteristics of at least one stored rule, the difference can be compared, parameter by parameter, with thresholds, the characteristics obtained from the part to be manufactured being considered not close to the characteristics of at least one stored rule if at least one difference is greater than the corresponding threshold.Alternatively, the differences are cumulative, possibly with weighting, and compared against a single threshold. Other criteria can be used to estimate the proximity of the characteristics obtained concerning the element to be manufactured and the characteristics of the rules.

[0149] If manufacturing parameters are imposed or if the characteristics obtained from If the part to be manufactured does not closely match the characteristics of at least one stored rule, a subsequent step is to obtain the manufacturing parameters (step 410). As described previously, these parameters can be entered by a user, for example, through a graphical interface. These parameters include, for example, one or more types of chips to be used and their arrangement, or information enabling the determination of these chip types and their arrangement.

[0150] If, on the contrary, manufacturing parameters are not imposed and if the characteristics obtained from the element to be manufactured are close to characteristics of at least one stored rule, a subsequent step consists of obtaining manufacturing parameters (step 415), for example from the rule associated with the closest characteristics or by extrapolation from values ​​provided by rules (for example 2 or 3 rules) associated with the closest characteristics.

[0151] By way of illustration, if the characteristics of an element to be manufactured include significant resistance to mechanical stress exerted in a single longitudinal direction and a woven appearance on the outside, it can be determined that these characteristics are close to those referred to in rule 2 of the table provided previously comprising an example of rules, to which are associated manufacturing parameters indicating types of chips to be used and their proportions, here 80% chips of family 1 and 20% chips of family 2, the chips of family 2 being for example placed on the outer layers and the chips of family 1 being for example arranged in an inner layer.

[0152] After obtaining the manufacturing parameters and if these do not include types of chips to be used and their arrangement, the type(s) of chips to be used and their arrangement are determined from the parameters obtained (step 420).

[0153] A test is then performed to determine whether the item to be manufactured should actually be manufactured or whether it should be simulated (step 425). This choice can be made automatically, for example, according to the context, or made by a user, for example, via a graphical interface. When the choice is made automatically, it may nevertheless be necessary for it to be validated by a user. According to some embodiments, an item to be manufactured is both manufactured and simulated.

[0154] After the element has been manufactured (step 430), if it is to be manufactured, some of its characteristics are measured (step 435), for example its flexural modulus of elasticity, its flexural strength, its tensile modulus of elasticity, its tensile strength, its interlaminar shear strength, its yield strength, its dimensions, etc., to allow the establishment of a link between these characteristics and the manufacturing parameters of this element.

[0155] Similarly, if the element to be manufactured is to be simulated, some of its characteristics are estimated (step 440), typically the same as those measured on a manufactured element, to, again, allow the establishment of a link between these characteristics and the manufacturing parameters of this element.

[0156] In a subsequent step (step 445), the rule base, for example rule base 135, is updated. This step may involve modifying an existing rule, for example, to add one or more parameters or one or more features, or to adjust a range of values ​​for one or more parameters or one or more features. This update may also involve adding a rule. These modifications or additions may be made automatically, optionally after validation by a user. Alternatively, these modifications or additions may be made by a user based on the manufacturing parameters of the component and the measured or simulated features. These parameters and features may be presented to a user via a graphical interface, which the user can also use to modify a rule that the user has selected or that has been automatically selected, or to add a new rule..

[0157] According to other embodiments, the rules engine is replaced or used in conjunction with an artificial intelligence engine, for example an artificial neural network whose inputs are the characteristics of the item to be manufactured and whose outputs are the manufacturing parameters. Such an engine can be trained with measured or simulated characteristics and corresponding manufacturing parameters.

[0158] This rule base and / or artificial intelligence engine constitutes a knowledge base which makes it possible to estimate manufacturing parameters of a composite material element from recycled element chips according to characteristics of the element to be manufactured.

[0159] Figure 5 illustrates an example of a device that can be used to implement, at least partially, embodiments of the invention, in particular steps described with reference to Figures 1, 2 and 4.

[0160] Device 500 is for example a server, a computer, a terminal or a personal device such as a smartphone or tablet.

[0161] The device 500 preferably includes a communication bus 502 to which the following are connected:

[0162] - a central processing unit or microprocessor 504 (CPU, abbreviation for Central Processing Unit (in Anglo-Saxon terminology);

[0163] - a 506-bit read-only memory (ROM) Anglo-Saxon) which may include an operating system and programs such as "Prog";

[0164] - a random access memory or cache memory 508 (RAM, acronym for Random Access Memory (in Anglo-Saxon terminology) comprising registers adapted to store variables and parameters created and modified during program execution as mentioned above; and

[0165] - a communication interface 526 connected to a distributed communication network 528, for example a wireless communication network and / or a local communication network, the interface being capable of transmitting and receiving data, including to and from a user's device.

[0166] Optionally, device 500 may also include the following elements:

[0167] - a 520 hard drive capable of containing the aforementioned "Prog" programs and data processed or to be processed according to the invention;

[0168] - a keyboard 522 and a mouse 524 or any other pointing device such as a optical pencil, a touch screen or a remote control allowing the user to interact with the programs according to the invention;

[0169] - a 510 removable storage media reader 512 such as a memory card or a disc, for example a DVD disc; and

[0170] - a graphics card 514 connected to a screen 516.

[0171] The communication bus enables communication and interoperability between the various elements included in or connected to the device 500. The bus representation is not limiting and, in particular, the central unit is capable of communicating instructions to any element of the device 500 directly or via another element of the device 500.

[0172] The executable code of each program enabling the programmable device to implement the processes according to the invention can be stored, for example, in the hard disk 520 or in read-only memory 506.

[0173] According to one variant, the executable code of the programs can be received via the communication network 528, via interface 526, to be stored in the same way as described above.

[0174] More generally, the program(s) may be loaded into one of the storage means of device 500 before being executed.

[0175] The central processing unit 504 will command and direct the execution of the instructions or portions of software code of the program(s) according to the invention, instructions which are stored in the hard drive 520 or in the read-only memory 506 or in the other aforementioned storage elements. Upon power-up, the program(s) stored in non-volatile memory, for example the hard drive 520 or the read-only memory 506, are transferred to the random access memory 508, which then contains the executable code of the program(s) according to the invention, as well as registers for storing the variables and parameters necessary for the implementation of the invention.

[0176] Depending on the embodiment chosen, certain acts, actions, events or functions of each of the methods described in this document may be performed or occur in a different order than that in which they have been described, or may be added, merged, or not performed or not occur, as the case may be. Furthermore, in some embodiments, certain acts, actions, or events are performed or occur concurrently and not successively.

[0177] Although described through a number of detailed embodiment examples, the proposed method and the equipment for carrying out the method include various variants, modifications, and improvements that will be obvious to those skilled in the art, it being understood that these various variants, modifications, and improvements form part of the scope of the invention, as defined by the following claims.In particular, if the examples presented are related to items to be recycled and manufactured from synthetic fibers, the invention can be implemented with other types of fibers, including natural fibers such as flax fibers and / or mineral fibers such as glass or basalt fibers.

[0178] Furthermore, the various aspects and features described above can be implemented together, separately, or substituted for one another, and all the different combinations and subcombinations of the aspects and features form part of the scope of the invention. In addition, some of the systems and equipment described above may not incorporate all of the modules and functions described for the preferred embodiments.

Claims

Claims

1. A method of manufacturing a composite material element from chips of at least one first recycled element, said chips being grouped into families according to chip types, the method comprising, - obtaining (125) a plurality of desired characteristics of said composite material element, - obtaining, from the desired characteristics, using a knowledge base (135) comprising a set of composition rules, each composition rule associating characteristics of a sample formed from chips of at least one second recycled element with at least one type of chips forming said sample and an arrangement of chips forming said sample, at least one composition rule of said set, and - estimating (130), using said at least one rule obtained, at least one type and arrangement of chips to be used to manufacture said composite material element,said elements being elements based on synthetic fibers.,

2. The method of claim 1, wherein the desired characteristics include at least one of flexural modulus, flexural strength, tensile modulus, tensile strength, interlaminar shear strength, yield strength, light polarization properties, heat dissipation properties, acoustic behavior, and / or electromagnetic wave behavior.

3. A method according to claim 1 or claim 2, wherein the chip types are determined according to parameters including at least one of armor, linear or surface density, chip mass, thickness, shape, roughness, porosity, surface chemistry, heat dissipation characteristics, electromagnetic properties and / or light polarization properties.

4. A method according to any one of claims 1 or 3, wherein estimating at least one type of chips comprises determining a ratio of chips from different chip families.

5. A method according to any one of claims 1 or 4, the method further comprising obtaining a plurality of composition rules, the estimation comprising extrapolation or interpolation from the obtained composition rules.

6. A method according to any one of claims 1 or 5, wherein the synthetic fibers comprise carbon fibers and / or para-aramid synthetic fibers.

7. Method for constructing a knowledge base for manufacturing a composite material element from chips of at least one first recycled element, the method comprising, - obtaining a plurality of parameters characterizing each of the chips of at least one second recycled element, - determining (120) chip families according to said plurality of parameters, - estimating (435, 440) characteristics of a sample comprising chips of said at least one second recycled element, - determining (445) at least one composition rule associating the estimated characteristics with at least one type of chips included in said sample and an arrangement of chips included in said sample, a type of chips corresponding to a chip family and - storing said at least one determined composition rule in said knowledge base.

8. The method of claim 7, wherein the characteristics of said sample include at least one of flexural modulus, flexural strength, tensile modulus, tensile strength, interlaminar shear strength, yield strength, light polarization properties, heat dissipation properties, acoustic behavior and / or electromagnetic wave behavior.

9. A method according to claim 7 or claim 8, wherein the chip types are determined according to parameters comprising at least one of reinforcement, linear or surface density, chip mass, thickness, shape, roughness, porosity, surface chemistry, and / or heat dissipation characteristics, electromagnetic properties and / or light polarization properties.

10. A method according to any one of claims 7 to 9, wherein the composition rule associates the characteristics with a ratio of chip types forming said sample and an arrangement of the chips forming said sample.

11. A method according to any one of claims 7 to 10, wherein said estimation of characteristics of a sample comprises a simulation (440) of said sample.

12. A method according to any one of claims 7 to 11, wherein said estimation of characteristics of a sample comprises a fabrication (430) of said sample and at least one measurement (435) of said fabricated sample.

13. The method of claim 12, wherein said sample is a composite material element manufactured according to the method of any one of claims 1 to 6.

14. Method according to any one of claims 7 to 13, the method further comprising a repetition, for different samples, of the steps of estimating characteristics, of determining at least one composition rule and of storing said at least one rule.

15. Method according to any one of claims 7 to 13, the method further comprising a repetition, for different samples, of the step of estimating characteristics and comprising a modification of at least one previously stored composition rule.

16. Computer program comprising instructions for implementing each of the steps of the method according to one of claims 1 to 11, when this program is executed by a processor.

17. Device comprising a processing unit configured to execute each of the steps of the method according to one of claims 1 to 15.

Images