Fish joint device having an improved mechanical hold

Abstract

The invention relates to a fish joint device intended to attach securely first and second structural elements of an aircraft to one another, having two fishplates positioned either side of the structural elements, and attached to them by a set of fishplate through fastenings. According to the invention, the fish joint device includes at least one intermediate fish joint plate which is positioned between one of said fishplates and said structural elements which said intermediate plate partly covers, and which is attached to these elements by a set of intermediate plate through fastenings which includes the set of fishplate through fastenings.

Claims

1. A fish joint device configured to securely attach first and second structural elements of an aircraft to one another, the fish joint device comprising: a first fishplate disposed on either side of the first and second structural elements; a second fishplate disposed on a side of the first and second structural elements opposite the first fishplate, the second fishplate including a first attachment branch, a second attachment branch, and a third attachment branch; a set of through fastenings configured to attach the first and second fishplates to the first and second structural elements, the second fishplate being attached to the first and second structural elements by the first and second attachment branches, respectively, and to a third structural element by the third attachment branch; and at least one intermediate fish joint plate disposed between and in contact with one of the first or second fishplates and the first and second structural elements, respectively, wherein the intermediate fish joint plate at least partly covers and is attached to the first and second structural elements by at least some of the through fastenings, wherein the at least one intermediate fish joint plate has a flexural rigidity greater than the first or second fishplate located on a same side as the at least one intermediate fish joint plate, relative to the first and second structural elements, and wherein the first and second fishplates and the at least one intermediate fish joint plate are configured to transmit forces experienced by the first and second structural elements into the first and second fishplates and the at least one intermediate fish joint plate.

2. The fish joint device according to claim 1, wherein at least 50% of the through fastenings passing through the at least one intermediate fish joint plate also pass through the first or second fishplate on the same side of the first and second structural elements as the at least one intermediate fish joint plate.

3. The fish joint device according to claim 2, wherein the through fastenings passing through the at least one intermediate fish joint plate are distributed in several rows which extend in parallel to a joining direction of the first and second structural elements, each of which has a same number of the through fastenings.

4. The fish joint device according to claim 1, wherein each fishplate and each of the at least one intermediate fish joint plate is dimensioned and configured to transmit, between the first and second structural elements, a level of forces greater than or equal to 50% of a reference level equal to a quotient of a predefined maximum level of forces, divided by a number of fishplates and intermediate fish joint plate(s) of the fish joint device.

5. The fish joint device according to claim 1, wherein the at least one intermediate fish joint plate comprises at least two intermediate fish joint plates, at least one second intermediate fish joint plate being disposed between the first or second fishplate and a first intermediate fish joint plate which is in contact with the first and second structural elements, the at least one second intermediate fish joint plate having a rigidity less than or equal to that of the first intermediate fish joint plate.

6. The fish joint device according to claim 1, wherein the at least one intermediate fish joint plate comprises a local thickness of between 50% and 80% of a combined local thickness of the first or second fishplate and each of the at least one intermediate fish joint plate between the first or second fishplate and the first and second structural elements.

7. The fish joint device according to claim 6, wherein the at least one intermediate fish joint plate in contact with the first and second structural elements has a local thickness strictly greater than a local thickness of the first or second fishplate.

8. The fish joint device according to claim 6, wherein the first or second fishplate on a same side of the first and second structural elements as the at least one intermediate fish joint plate has a local thickness of between 20% and 50% of the combined local thickness of the first or second fishplate and each of the at least one intermediate fish joint plate.

9. The fish joint device according to claim 1, wherein the first or second fishplates comprises a metal material, wherein another of the first or second fishplates comprises a metal material or a composite material, and wherein each of the at least one intermediate fish joint plate comprises a composite material.

10. An aircraft structure comprising an aircraft wing surface including a wing surface element, forming the first structural element, a fuselage box including a lower panel, forming the second structural element, and the fish joint device according to claim 1 to securely attach the wing surface element and the lower panel of the fuselage box.

11. The fish joint device according to claim 1, wherein more than 66% of the through fastenings passing through the intermediate fish joint plates also pass through the first or second fishplate on a same side of the first and second structural elements as the at least one intermediate fish joint plate.

12. The fish joint device according to claim 1, wherein more than 75% of the through fastenings passing through the intermediate fish joint plates also pass through the first or second fishplate on a same side of the first and second structural elements as the at least one intermediate fish joint plate.

13. The fish joint device according to claim 1, wherein 100% of the through fastenings passing through the intermediate fish joint plates also pass through the first or second fishplate on a same side of the first and second structural elements as the at least one intermediate fish joint plate.

14. The fish joint device according to claim 1, wherein each fishplate and each of the at least one intermediate fish joint plate is dimensioned and configured to transmit, between the first and second structural elements, a level of forces greater than or equal to 100% of a reference level equal to a quotient of a predefined maximum level of forces, divided by a number of fishplates and intermediate fish joint plate(s) of the fish joint device.

15. The fish joint device according to claim 1, wherein each fishplate and each of the at least one intermediate fish joint plate is dimensioned and configured to transmit, between the first and second structural elements, a level of forces greater than or equal to 150% of a reference level equal to a quotient of a predefined maximum level of forces, divided by a number of fishplates and intermediate fish joint plate(s) of the fish joint device.

16. A method for fishplating first and second structural elements of an aircraft together, the method comprising: providing a fish joint device comprising: a first fishplate disposed on either side of the first and second structural elements; a second fishplate disposed on a side of the first and second structural elements opposite the first fishplate, the second fishplate including a first attachment branch, a second attachment branch, and a third attachment branch; a set of through fastenings configured to attach the first and second fishplates to the first and second structural elements, the second fishplate being attached to the first and second structural elements by the first and second attachment branches, respectively, and to a third structural element by the third attachment branch; and at least one intermediate fish joint plate disposed between and in contact with one of the first or second fishplates and the first and second structural elements, respectively, wherein the intermediate fish joint plate at least partly covers and is attached to the and second structural elements by at least some of the through fastenings, wherein the at least one intermediate fish joint plate has a flexural rigidity greater than the first or second fishplate located on the same side as the at least one intermediate fish joint plate, relative to the first and second structural elements, and wherein the first and second fishplates and the at least one intermediate fish joint plate are configured to transmit forces experienced by the first and second structural elements into the first and second fishplate and the at least one intermediate fish joint plate; positioning the first and second fishplates, together with each of the at least one intermediate fish joint plate of the device between the first or second fishplate and the first and second structural elements, on either side of the first and second structural elements; attaching the first and second fishplates and each of the at least one intermediate fish joint plate to the first and second structural elements by the through fastenings; and transmitting, by each fishplate and the at least one intermediate fish joint plate, forces experienced by the first and second structural elements into the first and second fishplate and the at least one intermediate fish joint plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, as non-restrictive examples, with reference to the appended illustrations, in which:

(2) Previously described FIG. 1 is a schematic lengthways section view of a fish joint device according to an example of the prior art;

(3) FIGS. 2A and 2B are schematic transverse section views of fish joint devices according to two first embodiments of the invention;

(4) FIG. 3 is a schematic transverse section view of a fish joint device according to a third embodiment of the invention;

(5) FIG. 4 is a schematic transverse section view of a fish joint device according to a fourth embodiment of the invention.

(6) In all these figures, identical references can designate identical or comparable elements.

DETAILED DESCRIPTION

(7) FIG. 2A shows schematically, as a transverse section, a fish joint device 10 according to a first embodiment of the invention.

(8) It should be noted that the illustration is not to scale, to improve its clarity.

(9) Fish joint device 10 according to the invention is intended to attach securely together structural elements 1, 2 of an aircraft.

(10) It includes a T-shaped fishplate 20 including a first, a second and a third attachment branches 21, 22, 23.

(11) First and second attachment branches 21, 22 are roughly an extension of one another, to the dihedral angle.

(12) Third attachment branch 23 is inclined relative to first and second branches 21, 22 of fishplate 20. In particular, third branch 23 extends roughly orthogonally to second branch 22.

(13) Fish joint device 10 also includes a second fishplate 30, called a backing plate in what follows, which is attached to said structural elements 1, 2.

(14) Backing plate 30 takes the form of a plate designed to come into contact with structural elements 1, 2, and is positioned on the side opposite that of fishplate 20.

(15) In the illustrated example, structural element 1 is a lower element of a wing surface of an aircraft, whereas element 2 is a lower panel of a central box of the aircraft, and element 3 is a side panel of this central box. Such a central box is, indeed, formed from lower, side and upper panels assembled together with one another.

(16) As shown by FIG. 2A, fishplate 20 and backing plate 30 are attached to structural elements 1, 2 by means of fishplate through fastenings 11.

(17) First and second structural elements 1, 2, are said to be adjacent or consecutive, if they are positioned roughly as extensions to one another.

(18) These two elements have respective edges which are facing one another, and which extend in a joining direction X.

(19) More specifically, first branch 21 of fishplate 20 is attached to first structural element 1, and second branch 22 of the fishplate is attached to second structural element 2.

(20) They are attached by means of through fastenings 11 which traverse fishplate 20, structural element 1, 2 in question, and backing plate 30.

(21) Fastenings 11 are rod-based devices, for example of the rivet, screw and bolt, rod and crimping ring type, or of the lock bolt type.

(22) Clearance holes are thus present in fishplate 20, backing plate 30 and structural elements 1, 2, to receive fastenings 11.

(23) In the first embodiment of the invention illustrated in FIG. 2A, fish joint device 10 includes an intermediate fish joint plate 40 positioned between fishplate 20 and structural elements 1, 2.

(24) There may be a single intermediate fish joint plate 40, as illustrated in FIG. 2, or several intermediate plates superposed on one another, for example two, three, four, five or more such plates.

(25) Intermediate fish joint plate 40 is thus sandwiched between structural elements 1, 2, firstly, and fishplate 20, secondly.

(26) It has a shape which is designed to come into full contact with first and second attachment branches 21, 22 of fishplate 20.

(27) Intermediate fish joint plate 40 includes clearance holes aligned with those of structural elements 1, 2, those of fishplate 20, and those of backing plate 30, so as to receive fishplate through fastenings 11.

(28) Each fishplate through fastening 11 thus traverses both corresponding structural element 1 or 2, intermediate fish joint plate 40 and fishplate 20 and/or backing plate 30. Each fishplate through fastening 11 thus also an intermediate plate through fastening in the terminology used in the present invention.

(29) Fishplate 20, backing plate 30 and intermediate fish joint plate(s) 40 have clearance holes for fastenings 11. The diameter of each of the clearance holes traversed by a given fastening 11 is roughly identical, and roughly equal to the diameter of said fastening 11, such that the latter is in contact with the side wall of the holes which it occupies almost without any clearance.

(30) In accordance with a preferential characteristic of the invention, intermediate fish joint plate 40, which is in contact with structural elements 1, 2, has a local thickness which is strictly 50% greater than the combined local thickness, whilst being less than 80% of it. The combined local thickness is the sum of the local thickness of intermediate plate 40 and of the local thickness of attachment branch 21, 22 in question of corresponding fishplate 20.

(31) This intermediate fish joint plate 40 thus has a rigidity greater than that of fishplate 20, which is located on the same side as said intermediate plate 40 relative to said structural elements 1, 2.

(32) Attachment branch 21, 22 in question of fishplate 20 has a local thickness of between 20% and 50% of the combined local thickness.

(33) Fishplate 20 is monolithic and manufactured as a single piece from a metal material, for example aluminium, steel, or titanium.

(34) Backing plate 30 is monolithic and produced from a metal material, for example aluminium, steel or titanium, or from a composite material including a blend of fibres and resin. Backing plate 30 is preferably manufactured from a composite material.

(35) Intermediate plate 40 is monolithic and produced from a metal material, for example aluminium, steel or titanium, or from a composite material including a blend of fibres and resin. The intermediate plate is preferably made from a composite material.

(36) It should be noted that each of fishplate 20, backing plate 30 and intermediate plate 40 is dimensioned such that it is capable of transferring more than one third of the maximum level of forces which may be imposed on the fish joint device. This value of one third is equal to 50% of the quotient of the abovementioned maximum level of forces divided by the number of fishplates and intermediate fish joint plate(s), which in this case is equal to three.

(37) Device 10 according to the invention has a large number of force transfer pathways from structural element 1, 2 in question in the fish joint device.

(38) Indeed, the forces experienced by first (respectively second) structural element 1, 2 are transferred into first (respectively second) attachment branch 21, 22 of fishplate 20, into backing plate 30, and into intermediate fish joint plate(s) 40, via the set of intermediate plate fastenings 11, which include the fastenings of fishplates 20, 30.

(39) This results in a greater discretisation of the transfer of the forces compared to the fish joint device according to the prior art, which enables the maximum stresses present in the stress concentration zones of the fish joint device, namely the zones surrounding the clearance holes of fastenings 11, to be reduced.

(40) FIG. 2B illustrates a fish joint device according to a second embodiment of the invention, in which fishplate 20 takes the form of a simple plate similar to intermediate fish joint plate 40, and is surmounted by a joining piece with a T-shaped section having two branches attached to fishplate 20, each by means of a row of through fastenings 11, and also a third branch 23 for attachment to third structural element 3.

(41) In this case also, each of fishplate 20, backing plate 30 and intermediate plate 40 is dimensioned so as to be capable of transferring more than 33% of a maximum level of forces admissible within the fish joint device.

(42) FIG. 3 illustrates a fish joint device according to a third embodiment of the invention, which differs from the one described in reference to FIG. 2A essentially in that it includes an intermediate fish joint plate 50 positioned not on the side of fishplate 20, but on the side of backing plate 30.

(43) The above explanations relative to intermediate fish joint plate 40 of FIG. 2A naturally apply to intermediate fish joint plate 50 of FIG. 3.

(44) FIG. 4 illustrates a fish joint device according to a third embodiment of the invention, which includes an intermediate fish joint plate 40 positioned between fishplate 20 and structural elements 1, 2, and an intermediate fish joint plate 50 positioned between backing plate 30 and structural elements 1, 2.

(45) Intermediate fish joint plates 40, 50 are similar to those described above.

(46) Assembly by fishplating of structural elements 1, 2 according to any one of the invention's embodiments may be accomplished in the following manner: a fishplate 20 and a backing plate 30, and also at least one intermediate fish joint plate 40 positioned between said fishplate 20 and said structural elements 1, 2, and/or at least one intermediate fish joint plate 50 positioned between said backing plate 30 and said structural elements 1, 2, are positioned either side of said structural elements 1, 2; and then said fishplate 20, said backing plate 30, and each intermediate fish joint plate 40, 50, are attached to said structural elements 1, 2 by means of intermediate plate through fastenings 11.