阅读说明：本技术 复合材料制成的部件的破裂或变形的风险预警方法以及如此得到的部件 (Method for the risk early warning of cracking or deformation of a part made of composite material and part thus obtained ) 是由 居伊·瓦莱姆布瓦 伯特兰·弗洛伦兹 尼古拉-让·费舍尔 于 2019-06-04 设计创作，主要内容包括：本发明涉及一种用于复合材料制成的部件(1)在受力时破裂或变形的风险预警方法,所述部件包括纤维增强的热塑性或可热硬化的基质。所述方法包括：将所述纤维布置成通过缠绕纤维形成在节点(20)处连接在一起或相交的条(21)而制成的晶格结构(2)；设计所述晶格的至少一个条(21)和/或在所述部件中并入具有确定的位置和抗拉强度的至少一个附加条(3)；将传感器装置(4)在部件内与至少一个条相关联,该传感器装置(4)设计为检测其破裂；以及将装置(5)与传感器装置(4)相关联,装置(5)用于在部件外发射有关破裂的信号。(The invention relates to a method for warning the risk of a part (1) made of a composite material breaking or deforming when subjected to a force, said part comprising a fibre-reinforced thermoplastic or thermohardenable matrix. The method comprises the following steps: arranging the fibres into a lattice structure (2) made by winding fibres to form strips (21) joined together or intersecting at nodes (20); designing at least one strip (21) of the lattice and/or incorporating at least one additional strip (3) having a determined position and tensile strength in the component; associating a sensor device (4) with at least one strip within the component, the sensor device (4) being designed to detect a breakage thereof; and associating means (5) with the sensor means (4), the means (5) being intended to emit a signal relating to the breakage outside the component.)

1. Method for early warning of the risk of rupture or deformation of a structural component (1) made of composite material when subjected to a force, wherein the component consists of a fibre-reinforced thermoplastic or thermosetting matrix, wherein the component comprises:

-arranging the fibres in a net structure (2) obtained by winding fibres, whether or not impregnated with resin, onto struts or the like, so as to stretch the fibres between the struts to form strips (21) connected or intersecting in nodes (20), wherein the strips (21) are oriented to withstand tensile or compressive stresses,

-configuring at least one strip (21) of the mesh and/or incorporating in said component at least one additional strip (3) created from an additional node (30) and/or one or more nodes (201,202,203) of the mesh (2), the position and resistance to rupture of which are determined: on the one hand, its rupture does not compromise the integrity of the use of the mesh (2) and therefore of the component at its location; on the other hand, the resistance to cracking is calibrated to a value higher than the value that allows to withstand the optimum stresses when the component is used, but lower than the maximum stress of the component,

-associating a sensor device (4) with said at least one strip, said sensor device (4) being designed to detect, within said component, a breakage thereof,

-associating with said sensor means (4) means (5) for transmitting a signal relating to the breakage outside said component.

2. The method of claim 1, wherein the intensity of the at least one additional bar is calibrated by: by reducing its cross-section relative to the cross-section of the other strips, or by using less efficient materials than those used for the other strips, or by creating shape discontinuities in the strips that can cause excessive stress, or by adding undersize of nodes.

3. A method as claimed in claim 1 or 2, wherein a second sensor means for detecting rupture of a component associated with a component of the structure is incorporated into the mesh structure.

4. Structural component made of a composite material, comprising a system for early warning of the risk of rupture or deformation when subjected to a force, said component being made of a composite material consisting of a fibre-reinforced thermoplastic or thermosetting matrix, wherein the fibers are arranged in a net structure obtained by winding the fibers, whether or not impregnated with a resin, around a support post or the like, so that the fibers progress between the struts to form strips connected or intersecting at nodes, the strips being oriented to withstand tensile or compressive stresses, the composite part further comprises at least one bar created from additional nodes and/or one or more nodes of the mesh, the position and the resistance to rupture thereof being determined such that, on the one hand, the resistance to rupture is calibrated to be less than the resistance to rupture which the component must have but higher than the resistance to rupture which allows it to withstand the optimal stresses when the component is in use; on the other hand, its breakage does not compromise the integrity of the part in operation; and in that said at least one strip is associated with sensor means designed to be able to detect its breakage; and in that the sensor means are associated with means for transmitting a signal relating to the rupture.

5. A composite part according to claim 4 wherein the sensor means is in the form of an electrical wire or optical fibre arranged in at least one of the additional strips, dedicated to measurement, designed to be ruptured simultaneously with at least one of the strips.

6. A composite part according to claim 4 wherein the sensor means is in the form of a gauge for measuring strain caused by elongation of a strip of coils or electrically conductive wires whose length change during deformation affects the strength of the wires.

7. A composite part according to any of claims 4 to 6, wherein the means for transmitting a signal comprises a wired connection through the matrix.

8. A composite part according to any of claims 4-6, wherein the means for transmitting a signal comprises communications electronics embedded in a matrix.

9. A composite part according to any one of claims 4 to 6 wherein the means for transmitting a signal comprises light transmitting means when the matrix is transparent.

10. A composite part as claimed in any one of claims 4 to 6, wherein the detection transmission means is embedded in or printed on the resin and includes an RF antenna capable of remote interrogation.

11. Method for warning of the risk of cracking or deformation of a structural component (1) made of composite material when subjected to a force, said component consisting of a fibre-reinforced thermoplastic or thermosetting matrix (10) comprising:

-arranging the fibres in a net structure (2) obtained by winding fibres, whether or not impregnated with resin, onto struts or the like (20) so as to stretch the fibres between the struts to form strips (21) connected in nodes, wherein the strips (21) are oriented to withstand tensile or compressive stresses,

-designing at least a portion (7) of said component by means of at least one strip of said mesh and/or at least one additional strip (23; 23) created from additional nodes (24) and/or one or more nodes of said mesh, the position and resistance to cracking of which are determined: on the one hand, in its position, when the component is subjected to a force up to or exceeding the nominal force, it is subjected to a force that causes it to break, the breaking of which does not compromise the mesh and therefore the integrity of the component in use; on the other hand, the resistance to cracking is calibrated to a value higher than the value that allows to withstand the optimum stresses when the component is used, but lower than the maximum stress of the component,

and in that said portion (7) of said component (1) comprises an externally distinguishable portion designed to be capable of undergoing deformation upon rupture of said at least one strip.

12. Structural component made of composite material, comprising means for early warning of the risk of rupture or deformation when subjected to a force, said component being made of a composite material consisting of a fibre-reinforced thermoplastic or thermosetting matrix (10), wherein the fibres are arranged in a network (2) obtained by winding fibres, whether or not impregnated with resin, onto struts or the like (20) so as to stretch the fibres between the struts (20) to form strips connected in nodes, wherein the strips are oriented to withstand tensile or compressive stresses,

in that said component (1) comprises at least one portion (7), said at least one portion (7) incorporating at least one strip of said mesh (2) and/or at least one additional strip (22; 23) created from additional nodes (24) and/or one or more nodes (20) of said mesh, called measuring strips, the position and resistance to rupture of which are determined so that: on the one hand, in its position, when the component is subjected to a force up to or exceeding the nominal force, it is subjected to a force that causes it to break, and its breaking does not compromise the mesh and therefore the integrity of the component in use; on the other hand, the resistance to cracking is calibrated to a value higher than the value that allows to withstand the optimum stresses when the component is used, but lower than the maximum stress of the component,

and in that said part (7) comprises an externally distinguishable portion designed to be deformed upon breakage of said at least one strip.

13. A composite part according to claim 12, wherein the measuring strip (22; 23) has a reduced cross-section compared to the other strip (20) of the network (2).

14. A composite part according to claim 12, wherein the measuring strip (22; 23) has an embrittlement zone.

15. The composite component of claim 14, wherein said embrittlement zone comprises a winding on a coil (24) of limited strength.

16. A composite part as claimed in claim 12, wherein the measuring strip (22; 23) comprises drawn fibres and looser fibres, the looser fibres being capable of allowing increased movement of the part after the drawn fibres have ruptured.

17. The composite component of claim 12, wherein the portion of the component for identifying a fracture comprises a primary tubular structure made of reinforcing fibers having a high modulus and a low elongation at break, the primary structure being associated with a secondary structure, whether or not concurrent with the primary structure, and the secondary structure being made of reinforcing fibers having a lower modulus, a higher elongation at break, and/or a higher tensile stress than the fibers of the primary structure.

Technical Field

The present invention relates to the field of structural components made of composite materials comprising a fibre-reinforced thermoplastic or thermosetting matrix, such as fittings.

The present invention relates to a process for pre-warning the risk of cracking or deformation of such structural components according to their use, and to a composite component comprising a system for pre-warning the risk of cracking or deformation.

Background

It should be noted that the term "fiber" is understood to mean all the forms in which the reinforcing fibers can be present, i.e. but not limited to, strands, bands or cords of reinforcing fibers.

Composite parts used as structural parts have the drawback of having an inevitable risk of breakage, since they deform little before breaking, and these parts are nowadays oversized so that they break beyond a limit force that is much higher than the maximum operating force. In addition, they are also oversized to withstand the ultimate working loads and fatigue (even after damage) as sometimes they are accidentally damaged but not seen.

However, in terms of weight and economy, it is preferable to make damage to these composite components more clearly discernible by being able to detect the risk of cracking preventively.

Objects are also known from US 2007/037462, FR 2865539, FR 2980574, DE 102007032351, WO 2007/003883, WO 2009/044191, or also JP 3344805, EP 2500706 and EP 2112374, which incorporate components having a calibrated fragility associated with the sensor device, with the disadvantage that they are not part of the structural components, they are at best only connecting structural components, and therefore they may be subjected to other causes than stress from the force of the object (e.g. electric shock).

Disclosure of Invention

It is therefore an object of the present invention to provide a method for manufacturing a composite structural component and a composite structural component thus obtained, which by incorporating means for early warning of risks in the assembly, cause resistance to loads, allowing to avoid the risk of breakage.

According to the invention, a method for warning of the risk of rupture or deformation of a structural component made of composite material when subjected to a force, wherein said component consists of a fibre-reinforced thermoplastic or thermosetting matrix, is characterized in that it comprises:

-arranging the fibres in a net-like structure obtained by winding fibres, whether or not impregnated with resin, onto struts (studs) or the like, so as to stretch the fibres between the struts to form strips connected or intersecting in nodes, wherein the strips are oriented to withstand tensile or compressive stresses,

-configuring at least one strip of the mesh and/or incorporating in the component at least one additional strip created from additional nodes and/or one or more nodes of the mesh, the location and resistance to rupture of which are determined such that, on the one hand, at its location, its rupture does not compromise the integrity of the use of the mesh and therefore of the component; on the other hand, the resistance to cracking is calibrated to a value higher than the value that allows to withstand the optimum stresses when the component is used, but lower than the maximum stress of the component,

-associating said at least one strip, inside said part, sensor means designed to detect the breakage thereof,

-associating said sensor means for transmitting a signal relating to the breakage outside said component.

The invention thus exploits the properties of the mesh structure to create secondary cells within it that extend between the nodes of the primary cells, and at least one strip of the secondary cells is dedicated to the measurement.

According to another characteristic of the method of the invention, the intensity of the at least one additional strip is calibrated by: by reducing its cross section with respect to that of the other strips, or by using a material less resistant than that used for the other strips, or by creating shape discontinuities (accidents) on the strips that can cause excessive stresses, or by adding nodes of too small a size.

According to another additional feature of the method according to the invention, a second sensor device is incorporated in the reticular structure, the second sensor device being intended to detect a rupture of one of the components associated with the components of the structure.

Under important stress, in addition to the secondary mesh structure dedicated to detection, the primary mesh structure deterioration may also be undetectable or invisible in the representation of the composite part or object comprising said part, and therefore the second sensor means are intended to target early warning in order to make a quick decision.

The invention also relates to a structural component made of composite material, comprising a system for early warning of the risk of rupture or deformation when subjected to a force, said component being made of a composite material consisting of a fibre-reinforced thermoplastic or thermosetting matrix, characterised in that the fibres are arranged in a net-like structure obtained by winding the fibres (whether or not impregnated with resin) onto a support or the like, so that the fibers progress (progress) between the struts to form strips that connect or intersect at nodes, wherein the strips are oriented to withstand tensile or compressive stress, the composite component further comprising at least one strip created from additional nodes and/or one or more nodes of the mesh, the position and the resistance to cracking thereof being determined such that, on the one hand, the resistance to cracking is calibrated to be less than the resistance to cracking that the component must have and to be higher than the resistance to cracking that the component should withstand the optimum stress when it is in use; on the other hand, its breakage does not compromise the integrity of the part in operation; characterized in that said at least one strip is associated with sensor means designed to be able to detect the breakage thereof; and, characterized in that said sensor means are associated with means for transmitting a signal relating to the rupture.

Thus, a rupture of the at least one strip dedicated to the measurement constitutes the first visible damage to the component, which maintains its integrity during normal operation.

The observed cracking of the strip dedicated to the measurement is an indication of overload compared to the nominal load when the part is stressed. Exceeding the pre-alarm threshold may trigger a pre-alarm or maintenance action.

The sensor device may be of different forms, i.e. without limitation:

-an electrical wire or optical fiber arranged in a strip dedicated for measurement, which is broken simultaneously with the strip,

measuring instruments for measuring strains caused by elongation of a strip, for example consisting of coils or wires, the length change of which during deformation directly affects the strength of the wire,

or any other system allowing to measure deformations or stresses.

It should be noted that the inclusion of a resin in the mesh allows to place the sensor in the vicinity of the strip dedicated to the measurement, since the local deformations in the vicinity of the strip dedicated to the measurement are similar to those of the strip in the resin, since the resin constituting the matrix with negligible rigidity is located before this composite material constituting the mesh.

The means for transmitting the signal can be implemented in different ways, namely, without limitation:

-through the substrate, by wired connection to the sensor,

-communication electronics directly embedded in or printed on the substrate via a wireless link,

-using a transparent matrix by means of light transmission means,

or by using as a sensor an RFID antenna that can be remotely interrogated by an active source capable of detecting its breakage or deformation.

The invention also relates to a variant of the method for warning of the risk of cracking or deformation of a structural component made of composite material when subjected to a force, said component consisting of a fibre-reinforced thermoplastic or thermosetting matrix, the process being characterized in that it comprises:

arranging the fibres in a net-like structure obtained by winding the fibres (whether or not impregnated with resin) onto struts or the like, so as to stretch the fibres between the struts to form strips connected in nodes, wherein the strips are oriented to withstand tensile or compressive stresses,

-designing at least a part of the component by means of at least one strip of the mesh and/or at least one additional strip created from additional nodes and/or one or more nodes of the mesh, the position and the resistance to rupture of which are determined in such a way that, on the one hand, when the component is subjected to a force that reaches or exceeds a nominal force, it is subjected to a force that causes it to rupture, the rupture of which does not compromise the integrity of the mesh and thus of the component in use; in another aspect, the resistance to rupture is calibrated to a value that is higher than the value that allows it to withstand the optimum stress when the component is in use, but lower than the maximum stress of the component, and in that the portion of the component comprises an externally distinguishable portion designed to be able to undergo deformation when the at least one strip ruptures.

Thus, according to this variant, a composite part of the type having a reticular structure is produced, which is intended to withstand the stresses and comprises a portion that also withstands said stresses, the reticular structure of which portion has a resistance to rupture that is less than that of the rest of the mesh, but higher than the required strength of the composite part and lower than the maximum strength of the composite part. Furthermore, this part of the composite part is discernible whose structural rupture produces an externally visible change, for example a deformation.

Thus, the deformation of the portion comprising the at least one strip dedicated to the measurement constitutes a first visible damage to the component, which maintains its integrity in normal operation.

It is thus possible to detect that the composite part has been subjected to a force higher than the nominal force before the risk of its breaking.

The observed cracking of the strip dedicated to the measurement is an indication of overload compared to the nominal load when the part is stressed. Exceeding the pre-alarm threshold may trigger a preventative or maintenance action.

The invention also relates to a structural component made of composite material, comprising means for early warning of the risk of breakage or deformation when subjected to forces, said component being made of a composite material consisting of a fibre-reinforced thermoplastic or thermosetting matrix, characterized in that the fibres are arranged in a network obtained by winding the fibres (whether or not impregnated with resin) onto struts or the like, so as to stretch the fibres between the struts to form strips connected in nodes, wherein the strips are oriented to withstand tensile or compressive stresses,

in that said component comprises at least one portion incorporating at least one strip of said mesh and/or at least one additional strip created from additional nodes and/or from one or more nodes of said mesh, called measuring strip, the position and the resistance to rupture of which are determined such that, on the one hand, in its position, when the component is subjected to a force that reaches or exceeds the nominal force, it is subjected to a force that causes it to rupture and its rupture does not compromise the integrity of said mesh and therefore of said component in use; on the other hand, the resistance to cracking is calibrated to a value higher than the value that allows to withstand the optimum stresses when the component is used, but lower than the maximum stress of the component,

and in that said component comprises an externally distinguishable portion designed to be deformed upon rupture of said at least one strip.

The strip dedicated to the measurement may be given a lower resistance to fracture in different ways, for example, without limitation, with a reduced cross section compared to another strip of mesh, an embrittlement zone, giving the strip an initial shape to reduce its resistance to buckling by passing the winding through a specific transit point, for example, incorporating an intermediate coil in the strip, the strength of which is limited, so that a determined force exerted on the strip exceeds its breaking.

According to a particular embodiment, the measuring strip comprises drawn fibres and looser fibres, the looser fibres enabling an increased movement of the component after breaking of said drawn fibres.

According to a particular embodiment of the component made of composite material according to the invention, the portion of the component for identifying a break comprises a primary tubular structure made of reinforcing fibres having a high modulus and a low elongation at break, said primary structure being associated with a secondary structure, whether or not present simultaneously with the primary structure and made of reinforcing fibres having a lower modulus, a higher elongation at break and/or a higher tensile stress than the fibres of the primary structure.

The primary structure ruptures under a force determined by the dimensions of the component resulting in a transfer of the force path to the secondary structure. This change in force path results in a change in overall stiffness, detectable elongation and/or visible cracking, allowing detection of the component's sustained damage.

Advantageously, the secondary structure is able to withstand a greater final load before breaking than the primary structure, so as to ensure correct functioning of the component even if damaged.

Thus, for example, in a web structure made of HM (high modulus) carbon fibers, so-called measuring tapes or tapes are lined with (HR) (high strength) carbon fibers, resulting in a reduction of stiffness after the HM fibers break, using HR fibers with higher elongation at break and higher allowable values than HM fibers, the final highest force is greater than the first force at break.

It should be noted that the lining may also be implemented with S-type glass fibers.

Drawings

The effects and characteristics of the method of the invention and of the parts made of composite material thus produced will be clearer from the following description, made with reference to the attached drawings, which represent a non-limiting, identical embodiment.

In the drawings:

fig. 1 shows a schematic front view of a part made of composite material relating to the field of the invention.

Figure 2 shows the same component made of composite material equipped with a system for warning of the risk of breakage or deformation according to the invention.

Fig. 3 shows the same part made of composite material equipped with another system for warning of the risk of rupture or deformation according to the invention.

Fig. 4 shows a schematic front view of a part made of composite material, relating to the field of the invention, equipped with a device for early warning of the risk of rupture or deformation according to the invention.

Fig. 5 shows the same part made of composite material equipped with a variant of the device for warning of the risk of rupture or deformation according to the invention.

Detailed Description

With reference to fig. 1, a part 1 made of a composite material according to the invention is visible. The composite part 1 used to illustrate the invention comprises, without limitation, a pillar (pole) suitable to be subjected to mechanical stress S when in use.

The composite part 1 comprises a fibre-reinforced thermoplastic or thermosetting matrix 10, the fibres being arranged in a network 2 made up of filament windings according to a carefully selected path around a coil or pulley to form nodes 20 of the mesh 2, while the rectilinear portions extending between the nodes 20 constitute strips 21. The fibers may be pre-coated with a thermoplastic or thermoset resin.

The preform constituted by the meshes 2 is then incorporated into the matrix 10 so as to prevent the transverse deformation of the fibres, or is immersed in the material constituting the matrix at a temperature that allows a viscosity sufficient to cover the meshes of the fibres 2, or is moulded in a mould, injecting the filling volume of the part in addition to the meshes 2 previously placed in the mould.

With reference to fig. 2, it can be seen that mesh 2 according to the invention comprises an additional strip 3 obtained by winding between node 201 of mesh 2 and an additional node 30, which in turn results from winding with two nodes 202 and 203 of mesh 2.

On the other hand, the additional strip 3 does not contribute to the nominal strength of the composite part 1, it being subjected to tensile or compressive stresses when the composite part 1 is subjected to stresses.

The additional strips 3 are configured to provide less resistance than the other strips 21, without limitation through a smaller cross-section, or using less efficient materials, or the presence at any location, or abrupt shape changes resulting in excessive stress, or undersize the nodes 30, or some combination of these.

Furthermore, according to the invention, the additional strip 3 is associated with a sensor device 4, which sensor device 4 is intended to be integrated into the substrate 10 and is capable of measuring the deformation or rupture of the additional strip 3. In the embodiment shown, the sensor device 4 is connected to means 5 for transmitting signals arranged outside the component 1 and is connected to the sensor device 4 by a wired link 50.

The sensor means 4 are able to detect the deformation or rupture of the additional strip 3 and send this information to the means 5 for transmitting a signal.

Referring now to fig. 3, a specific embodiment of the early warning system according to the present invention can be seen.

In this embodiment, the additional strip 6 dedicated to pre-warning is made by winding the wire 60 around two additional nodes 61 and 62, each of these two additional nodes 61 and 62 resulting from the creation of two additional strips 63 and 64 and 65 and 66 respectively by winding with the nodes 204 and 205 and 206 and 207 respectively of the mesh 2.

The additional strips 6, 63, 64, 65 and 66, and the additional nodes 61 and 62, form a secondary mesh extending internally to the mesh 2 between the nodes 204, 205, 206 and 207, and the strips 6 constitute strain gauges subjected to stresses.

It will be appreciated that changes in the length of the strip 6, and hence the wire (conductor)60, directly affect the strength of the wire.

Referring now to fig. 4, a part 1 made of composite material according to the invention is seen, comprising a vertical component 11 and a horizontal component 12.

According to this variant of the invention, the composite part 1 comprises an externally discernible portion 7, this portion 7 comprising strips 22 of meshes 2, which are arched like a stay (stay) between the nodes 20 of the vertical assemblies 11 and the nodes 20 of the horizontal assemblies 12.

The so-called measuring strip 22 is positioned so as not to participate in the strength of the component 1 when the component 1 is subjected to forces, so that in the event of a fracture the integrity of the component 1 is not compromised. It is configured with a value of the resistance to rupture higher than that which allows the part 1 to withstand the optimum stresses when it is used, and lower than that of the maximum stress of the part 1.

Thus, the rupture of the strip 22, visible from the outside, causes a deformation or rupture of the portion 7 of the component 1, allowing to detect that the component 1 has been subjected or withstood a force greater than the nominal force required.

As can be seen when referring to fig. 5, in a variant, the part 7 of the component 1 passes through a portion of the meshed net 2, which comprises a strip 23 extending between the nodes 20 of the vertical assemblies 11 and the nodes 20 of the horizontal assemblies 12, and has, in the intermediate portion, a winding on a coil 24, the crush resistance of the winding on the coil 24 under traction being calibrated to break when the component 1 is subjected to a force greater than the nominal force required.