FR2501579A1 - Composite fibre reinforced profiles for sail-board masts - with longitudinal reinforcement of differing lengths for progress stiffness variation overall - Google Patents

Abstract

A tubular structure offering a progressive reduction in flexural stiffness is made from two concentric layers of cross braided resin impregnated fabric enclosing a series of intermediate layers of successively shorter lengths and comprised of longitudinally reinforced fabric. Esp. suitable for fabrication of masts for sailing surfboards, where consistently high stiffness for at least the lower third of the mast is less advantageous than for a mast for a conventional large yacht. Alternate reinforcing filaments in the intermediate layers may be shorter than the full length of that layer, esp. where relatively steep taper ratios are reqd., e.g. a reduction from 106 mm diam. to 50 mm diam. over 9.5 m length. These longitudinal ties are pref. filaments of carbon, boron, aramid, etc. located angularly by relatively fine, low-tensile annular or diagonal threads.

Description

UTII TUBULAR STRUCTURE, ISABLE IN PARTICULAR FOR REALIZATION
OF MATS OF SAILING YACHTS.

 The present invention relates to a new type of laminated tubular structure consisting of superimposed textile sheaths and impregnated with a suitable resin. It relates more particularly to a new type of tubular structure having a variable flexibility over its length and which, in particular, is particularly suitable for the production of masts of sailing yachts.

 In the following description, the invention will be described more particularly for this application, but it is obvious that this is not limiting and that such a structure could possibly be used in other fields, for example for making poles. , polls...

 For a very long time, the material used to make sailboat masts was wood. For a number of years, metal masts have been produced, in particular in alumi sium and quite recently it has been proposed to use the techniques used for the production of laminates, that is to say materials made of a reinforced polymerizable resin. by a textile structure.

 Thus, it has been proposed to produce masts by winding a mixed fabric, glass fiber / carbon, reinforced longitudinally with unidirectional carbon fibers, the assembly being impregnated with polymerizable resin. This type of mast makes it possible to obtain a certain flexibility in the longitudinal direction, which improves the performance of the wing and allows the use of a two-ply sail which surrounds the mast and is held in place by a "Wishbone" .

 Furthermore, in its French patent application No. 79/12 533, the Applicant has proposed a composite multilayer tubular structure which can be used to make windsurf masts. However, the material which is the subject of this request is not suitable for the manufacture of masts for conventional sailboats since, for such an application, the mast must be practically rigid up to a third of its height whereas it must present progressive flexibility to the top. In contrast, a windsurf mast should be able to flex practically from its base to its end and has no rigid part.

 Now we have found, and this is what is the subject of the present invention, a new type of tubular structure which not only is simple and economical to produce but which, moreover, makes it possible to obtain masts of all dimensions. , these masts also having progressive flexibility from their base to their top, a first part of the mast extending from the base over a relatively large length, generally equal to 1/3 of the total length of the mast, being practically rigid while the remaining part of said mast has variable flexibility along its length.

 In general, the invention therefore relates to a tubular structure of the type comprising a plurality of superposed textile layers, at least the internal layer and the external layer being constituted by bidirectional braided sheaths, extending over the entire length of the material. and this structure being characterized by the fact that between the two extreme layers are arranged a plurality of intermediate cheeks, constituted at least in the majority of longitudinal wires, extending from one end of the structure over increasingly short lengths when we go from the inner layer to the outer layer.

 These different textile layers are conventionally impregnated with a polymerizable resin.

 As textile material which can enter into the constitution both of bidirectional braided sheaths and of intermediate layers based on longitudinal threads, it is possible to use glass threads, threads with a high modulus of elasticity such as those based on boron, carbon, aramid ...

 In the following description, the invention will be described for a material entirely based on glass strands but, of course, this is not limiting and one could, as in any laminate, use various combinations of materials for example making the internal and external layers of glass and the intermediate layers of carbon or other or having in the same layer an alternation of different threads, for example an alternation of glass threads and carbon threads.

 Furthermore, within the meaning of the present invention, by "bidirectional braided sheaths" means a ti-esse consisting of two series or groups of son of identical pi-éference, crisscrossed and arranged at a determined angle relative to the generatrices of said sheath, the inclination of the wires being generally, before placing the material, close to 45 °. Such braids have the characteristic of being able to deform both in the longitudinal direction and in the lateral direction and as a result of being able to take a shape other than cylindrical, frustoconical for example.

 Furthermore, if the intermediate textile sheaths can consist only of longitudinal threads, parallel to each other, comprising no connecting element, in a preferred form of the invention the longitudinal threads will be held together by braided binding threads, these tying threads being relatively fine compared to the longitudinal threads and constituting only a minority part of the whole.

 In addition, if in each intermediate layer the longitudinal wires can have identical lengths, in some cases it can be envisaged to have wires of different lengths. Thus, in each intermediate layer, it is possible to envisage having alternately longer and shorter wires. It is an embodiment which favors the obtaining of a tubular structure of frustoconical shape having a relatively large slope. If in general, the inner layer and the outer layer of said tubular structures are constituted by a single bidirectional braided sheath, it may be envisaged, for certain applications, to have, for example, an external layer constituted by two superimposed bidirectional braided sheaths.

The invention and the advantages which it brings will however be better understood thanks to the example of embodiment given below by way of indication but not limitation and which is illustrated by the attached diagrams in which
FIG. 1 illustrates in perspective, schematically, a tubular structure produced in accordance with the invention,
- Figures 2, 3 and 4 are also schematic perspective views showing in more detail the different types of materials that can enter the realization of such a tubular structure.

 In accordance with the invention, a frustoconical tubular structure is produced having a total length of 9.50 m, an internal diameter D of 106 mm at the base and d of 50 mm at the top.

 To make such a part, a frusto-conical mandrel 1 made of steel (or any other material) having the aforementioned dimensions is used and which is mounted in port # e-à-faux to allow the establishment of the various textile layers. On this mandrel, previously coated with a layer of a conventional release agent, a first bidirectional braided sheath, threaded over the entire length, having a structure such as that illustrated in FIG. 4, is threaded. series or groups of crisscrossed wires 3-4 which form an angle of approx. 400 between them. Given the possibilities of deformation of such a structure, it is possible to perfectly adapt the sheath around the mandrel 1.

In this case, this bidirectional braided sheath has, before installation, a nominal diameter of 110 mm and is made up of two groups of interlaced glass strands, each group comprising 48 glass strands each having an overall titer of 52,000 Tex .

Given the possibilities of deformation of such a textile structure, this sheath perfectly matches the surface of the mandrel. This sheath being put in place, the ends of it are fixed on the mandrel for example by means of an adhesive tape,
Once this operation has been carried out, four unidirectional textile sheaths 5, 6, 7, 8 are superimposed on this first layer, consisting mainly of longitudinal threads.

These sheaths extend from the base of the mandrel of diameter D over increasingly shorter lengths when one goes from the inner layer 2 to the outer layer. In the present case, these four sheaths respectively have the following lengths
- duct 5: 9.50 m
- duct 6: 8.55 m
- duct 7: 6.50 m
- duct 8: 3.50 m
These sheaths are made up, as illustrated in FIG. 2, of parallel threads 9 linked together by loose braided binding threads 10. In the present case, the threads 9 have an overall titer of 187,000 Tex and the threads binding 10, also in glass, have an overall titer of 13,000 Tex.

 In the present case, the sheaths 5 and 6 have, before installation, a diameter of 105 mm and have 156 longitudinal wires 9. The sheaths 7 and 8 have an internal diameter of 110 mm and are each made up of 156 longitudinal wires 9 .

 For certain applications, it could be envisaged, as illustrated in FIG. 3, to use intermediate sheaths in which the longitudinal wires 9 would have two different lengths. This solution can be envisaged when the taper of the tubular structure which it is envisaged to produce is large, which would make it possible to obtain better progressiveness and a more homogeneous distribution of the filaments.

 In the present example, only intermediate sheaths of the type illustrated in FIG. 2 are used.

 After each of these sheaths has been put in place, the assembly is covered by means of two bidirectional braided sheaths 10-11 extending over the entire length of the structure.

(Figure 1). Only part of the length of the sheaths has been shown to allow the internal complementary textile sheaths to be shown. These braided sheaths 10-11 have the same constitution as the internal sheath 2 and, taking into account their deformation possibilities, come to be applied by fact around the layers previously put in place and trap the intermediate sheaths 5, 6, 7 and 8.

 On this complex textile structure thus produced, a hot or cold polymerizable resin (of the polyester, vinylester or epoxy type) is then deposited in a conventional manner. After polymerization, the mandrel is then removed.

 These operations being conventional will not be described in detail for the sake of simplification.

 Such a tabular structure can be used as a mast for pleasure yachts and it has been found that it has, compared to previous masts, the advantage of having adjustable flexibility from the base of said mast to its top. Thus, for example, we can make a mast whose lower part has, over a relatively large length, for example on 1/3 of the total height of the mast, good rigidity while the remaining part has a variable flexibility up to at the top.

 By # ai11eurs, the peripheral surface of this structure being perfectly smooth, this mast can be used in combination with a two-ply sail held in place by a wishbone.

 Of course, the invention is not limited to the embodiment cited above, but it covers all the variants produced in the same spirit. Thus, depending on the desired performance, it could be envisaged to produce a structure comprising a more or less large number of intermediate layers made up mainly of longitudinal wires. Similarly, if in the example given, two external layers 10-11 are provided, it could be envisaged to have only one.

 Compared to previous masts, such a tubular structure has the advantage of being able to be produced very easily and economically, over significant lengths, and above all to have variable flexibility over its length. In addition, this flexibility can easily be adapted by modifying the number of intermediate layers and / or the length of these different layers together.

Claims (6)

 1 - Tubular structure of the type comprising a plurality of superimposed textile layers, of which at least the internal layer 2 and the external layer 11 are constituted by bidirectional braided sheaths extending over the entire length of the material, characterized by the fact of these layers 11-2 are arranged a plurality of intermediate textile sheaths (5, 6, 7, 8) consisting at least in the majority of longitudinal threads 9, extending from one end of the structure over increasingly short lengths when going from the textile layer (2) to the outer layer (11).  2 - Tubular structure according to claim 1 characterized in that in each intermediate textile sheath 5, 6, 7, 8, the longitudinal son 9 have identical lengths.  3 - Tubular structure according to claim 1 characterized in that in each intermediate textile sheath 5, 6, 7, 8 the longitudinal son 9 are alternately longer and shorter.  4 - Tubular structure according to one of claims 1 to 3 characterized in that in each intermediate textile sheath 5, 6, 7, 8, the longitudinal son 9 are held together by braided binding son 10, these son binding 10 being relatively fine compared to the longitudinal son 9 and constituting only a minority part of the whole.  5 - Tubular structure according to one of claims 1 to 4 characterized in that the son forming part of both bi-directional braided sleeving 2-11 que'des intermediate layers 5,6,7,8 based on longitudinal son 9 , the yarns chosen from glass yarns, yarns with a high modulus of elasticity such as those based on boron, carbon, aramid, are used.  6 - Masts for sailboats made from a tubular structure according to one of claims 1 to 5