Connecting rod device with damping capabilities

Abstract

Title. Connecting rod device with damping capabilities. The invention relates to a connecting rod device with damping capabilities, of the type comprising a body (30) equipped with two distant attachment means (31). The body (30) has, in the longitudinal direction, at least one weakened zone in the transverse direction, designed to generate, during axial compression or tension, a deformation in the transverse direction, and in that said weakened zone is associated with damping means (37) designed to attenuate said deformation. Figure for the abstract: Fig. 4

Description

Title of the invention: Connecting rod device having damping capabilities

[0001] The present invention relates to a connecting rod device having damping capabilities, and in particular, but not limited to, a connecting rod device made of composite material.

[0002] Connecting rods are structural elements found in lattices of all kinds, serving as structural connecting elements, in particular, but not limited to, in the aeronautics and space fields. Connecting rods made of composite material have the qualities of lightness, while being strong and rigid.

[0003] Usually, such a connecting rod comprises a body provided with two distant attachment means, which may consist of articulation means, and intended for fixing the connecting rod between two points of a structure. The composite body, which is intended for compressive and tensile stresses, may have different aspects; in most cases, it is of elongated shape, and it may be solid or hollow, i.e. tubular, or made up of one or more elements such as more or less parallel members joined by their ends.

[0004] If these connecting rods show great qualities, they can also present drawbacks or defects, such as for example a transmission of parasitic movements resulting from excitations on the structure, a transmission of noise in the structures, fatigue of the structures and therefore a limited lifespan of these, in particular when they are made of composite material.

[0005] The present invention aims to eliminate the various aforementioned drawbacks, or at least reduce their effects, by proposing a connecting rod device which has damping capabilities, in order to attenuate the dynamic movements of the structures, and which may in particular, but not exclusively, relate to connecting rod devices made of composite material.

[0006] The connecting rod device having damping capacities according to the invention is of the type comprising a body provided with two distant attachment means, it is characterized in that said body comprises in the longitudinal direction at least one weakening zone in the transverse direction, designed to be capable of generating, during an axial compressive or tensile stress, a deformation in the transverse direction, and in that said weakening zone is associated with damping means designed to be capable of attenuating said deformation.

[0007] Due to the weakening of the body in the transverse direction, an axial compressive stress tends to cause swelling of the transverse section, while an axial compressive stress axial tension tends to narrow the cross-section. By combining means of damping the deformation in the transverse direction, i.e. attenuating swelling or shrinkage, we act on the damping of the axial deformation of the connecting rod, without altering its tensile or compressive strength.

[0008] According to an additional characteristic of the damping connecting rod device according to the invention, the weakening zone consists of at least one slot extending in the longitudinal direction, while the damping means consist of at least one means of connecting the two longitudinal edges of said slot, joined to said two edges by elements made of elastically deformable material.

[0009] According to a first embodiment of the connecting rod device according to the invention, the body is of generally tubular shape, and it comprises at least one longitudinal slot constituting the weakening in the transverse direction, while the damping means consist, for each slot, of a reinforcing piece covering all or part of said slot from the outside of said body, after interposition and securing of an element made of damping material.

[0010] The geometry of the part is adapted to allow the transformation of transverse movements of the body of the connecting rod, in the cutting zone, into shearing of the damping link.

[0011] The dynamic behavior of the connecting rod device is as follows: during compression, the slot tends to widen, and the area comprising it to swell, and this swelling induces shearing of the damping link while limiting the amplitude of the swelling, while during traction, the slot tends to close, and the area comprising it to shrink, the shear resistance of the link made of damping material limiting the shrinking deformation.

[0012] An alternating stress on the structure in which the connecting rod is arranged may result from a shock or vibratory excitation on the structure, which causes an alternating tensile-compressive stress in the connecting rod, and therefore an alternating shearing of the link(s) made of damping material.

[0013] The viscoelastic nature of the damping material constituting the links blocks deformations all the more as the deformation speed is high, this property allows the energy absorption specific to attenuating the dynamic movements of the connecting rod.

[0014] The nature and hardness of the damping material will be adapted to the nature of the dynamic disturbances to be controlled. It may be made of elastomer, elastomer foam or any other material promoting the damping of parasitic movements.

[0015] It should be noted that the transverse deformations of the cutting zone are very large compared to the longitudinal deformations of the connecting rod: the evolution of the length of the connecting rod is a consequence of its longitudinal rigidity and the longitudinal force acting on the connecting rod.

[0016] The fact that the cut(s) are longitudinal only very slightly affects the rigidity of the connecting rod while allowing significant local transverse deformations, which gives a multiplicative effect between longitudinal and local transverse deformation.

[0017] This property of maintaining a high level of rigidity makes it possible to have very rigid behavior of the structure in which the connecting rod is integrated while providing a beneficial damping capacity to said structure.

[0018] For example, the presence of a few connecting rods of this type in the central box of an aircraft will make it possible to provide structural damping without modifying the aircraft's natural modes in terms of their frequencies while reducing their amplitudes.

[0019] In another field of use, the presence of damping connecting rods judiciously placed between the walls of wind turbine blades can reduce dynamic disturbances, which results in a significant increase in the lifespan of these blades.

[0020] According to a second embodiment of the connecting rod device according to the invention, the body consists of an I-beam, that is to say it comprises a web inserted between two members, said web having a longitudinal slot, while the damping means consist of a reinforcing piece covering all or part of said slot on at least one side of said web, after interposition of an element made of damping material.

[0021] The strength and rigidity of the connecting rod are ensured by the members while the web ensures the cohesion of the two members between them. The longitudinal weakening of the web allows local deformations of the members in approach or separation when the connecting rod is stressed, respectively in tension or in compression. These transverse deformation movements of the members will be controlled by the reinforcing part(s), in association with the element(s) made of damping material.

[0022] The transverse deformations of the members will induce shear deformations of the damping element(s) which will allow the connecting rod to have damping properties during dynamic stresses which may be superimposed on the nominal stress of the connecting rod.

[0023] According to another additional characteristic of the damping connecting rod device according to the invention, the reinforcing part(s) are made of a material identical to that from which the body is made.

[0024] According to a third embodiment of the connecting rod device according to the invention, the body is made up of two members kept at a distance from each other through at least one spacer, which at least one spacer is made up of two independent segments, each secured to one member and projecting towards the other member, the free end parts of which are juxtaposed and face each other and are secured to each other by means of an element made of damping material.

[0025] This embodiment also allows the buckling of connecting rods having a significant elongation to be controlled. The members of the connecting rod have a shape adapted so as to cause the members to buckle outwards, said buckling being blocked by the spacer.

[0026] According to another additional characteristic of the damping connecting rod device according to the invention, it is made entirely or partly of composite material.

[0027] The connecting rod device can be made of metal, but preferably it is made of composite material, in particular the body.

[0028] According to another additional characteristic of the damping connecting rod device according to the invention, the securing of the element(s) made of damping material to the body is carried out by gluing and / or polymerization.

[0029] The advantages and characteristics of the connecting rod device according to the invention will emerge more clearly from the description which follows and which refers to the appended drawing, which represents several non-limiting embodiments thereof.

[0030] In the attached drawing:

[0031] [Fig-1] represents a schematic perspective view of a first mode of rea use of a damping connecting rod device according to the invention,

[0032] [Fig.2] represents a cross-sectional view of the same connecting rod device weaving,

[0033] [Fig.3] represents a cross-sectional view of a second embodiment of the damping connecting rod device according to the invention,

[0034] [Fig.4] represents a schematic perspective view of a third mode of rea use of the damping connecting rod device according to the invention,

[0035] [Fig.5] represents a schematic perspective and cross-sectional view of the same damping rod device.

[0036] With reference to Figures 1 and 2, a first embodiment of a damping connecting rod device 1 according to the invention can be seen, in this case made of composite material.

[0037] This connecting rod device 1 is of the type comprising a body 10 provided with two distant attachment means 11. The body 10 is of tubular design, in this case spindle-shaped, while the attachment points 11 each consist of an eyelet.

[0038] According to the invention, the body 10 comprises two longitudinal slots 12, only one of which is visible in [Fig.l], diametrically opposite and located, preferably in the middle portion of the body 10. Still according to the invention, the slots 12 are re covered from the outside, in this case not entirely but in the middle zone, each with a reinforcing piece 13, after having inserted a damping element 14 made of damping material, preferably an elastomer.

[0039] It will be understood that axial stresses of the connecting rod device 1, in compression and in traction, generate deformations of the slots 12, respectively in widening or narrowing, deformations limited and damped by the damping elements 14 made of elastomer material, which work in shear with the reinforcing pieces 13.

[0040] Consequently, the connecting rod device 1 is damped in the longitudinal direction, without loss of rigidity.

[0041] Variants are possible, thus, without limitation, in addition to the characteristics of the material chosen for the production of the damping elements 14, it is possible for example to vary the number of slots 12, as well as their width.

[0042] Referring now to [Fig. 3], a second embodiment of a damping connecting rod device 2 according to the invention can be seen. This connecting rod device 2 is of the type comprising a body 20 consisting of an I-beam, comprising a web 21 bordered by two members 22.

[0043] According to the invention, the core 21 is provided longitudinally with a cutout 23, covered, in this case on either side, by two reinforcing pieces 24, linked to the core 21 through elastomer elements 25.

[0044] During axial stresses in compression or in traction, the cutout 23 tends to, respectively, shrink or widen, the elastomer elements 25 which work in shear between the core 22 and the reinforcing pieces 24, ensure the damping of these transverse deformations, and consequently also dampen the axial deformations.

[0045] According to variants, it is possible to vary the width of the cutout 23, as well as the distance over which it extends.

[0046] Referring now to Figures 4 and 5, a third embodiment of a damping connecting rod device 3 according to the invention can be seen. As can be seen in [Fig.l], the connecting rod device 3 is of the type comprising a body 30 and two distant attachment means 31, the body 30 being made up of two spindle-shaped members 32, connected two by two on the one hand by their ends and on the other hand in the middle part by a spacer 33.

[0047] With particular reference to [Fig. 5], it can be seen that the spacer 33 is made up of the bringing together of two segments 34, each secured to a member 32 from which it projects towards the other member 32, the end parts 35 of these segments 34 which face each other, being separated by a space 36 in which is inserted an element 37 which is secured to them.

[0048] The axial tensile or compressive stresses of the connecting rod device 3 induce, respectively, the bringing together or the separation of the members 32, while the shear work of the element 36 makes it possible to achieve damping.

[0049] Whatever the embodiment considered, a damping composite connecting rod device 1, 2 or 3 has a damping capacity allowing the attenuation of dynamic movements of the structures, without altering its resistance capacities.

[0050] This attenuation has the following advantages: - reduction of parasitic movements resulting from excitations on the structure, - modification of the behavior of the structure in the natural modes of vibration, - improvement of the fatigue resistance of structures, - increase in the lifespan of structures, - reduction of noise transmission in structures, - improvement of the comfort of vehicles or objects in which such shock-absorbing connecting rod devices are installed.

Claims

Claims

1. Connecting rod device having damping capabilities, of the type comprising a body (10; 20; 30) provided with two distant attachment means (11; 31), characterized in that said body (10; 20; 30) comprises in the longitudinal direction at least one weakening zone in the transverse direction (12; 23; 36), designed to be capable of generating, during an axial compressive or tensile stress, a deformation in the transverse direction, and in that said weakening zone (12; 23; 36) is associated with damping means (14; 25; 37) designed to be capable of attenuating said deformation; and in that said weakening zone consists of at least one slot (12; 23; 36) extending in the longitudinal direction, while the damping means consist of at least one connecting means (14; 25; 37) of the two longitudinal edges of said slot (12; 23; 36), joined to said two edges by elements (14; 25; 37) made of elastically deformable material.

2. Connecting rod device according to claim 1, characterized in that the body (10) is of generally tubular shape, and it comprises at least one longitudinal slot (12) constituting the weakening in the transverse direction, while the damping means consist for each slot (12), of a reinforcing piece (13) covering all or part of said slot (12) from the outside of said body (10), after interposition and securing of an element made of damping material (14).

3. Connecting rod device according to claim 1, characterized in that the body (20) consists of an I-beam, that is to say that it comprises a web (21) interposed between two members (22), said web (20) having a longitudinal slot (23), while the damping means consist of a reinforcing piece (24) covering all or part of said slot (23) on at least one side of said web (21), after interposition of an element (25) made of damping material.

4. Connecting rod device according to any one of claims 1 to 3, characterized in that the reinforcing part(s) (13; 24) are made of a material identical to that from which the body (10; 20) is made.

5. Connecting rod device according to claim 1, characterized in that the body (30) consists of two members (32) held at a distance from each other through at least one spacer (33), which at least one spacer (33) consists of two independent segments (34), each integral with a member (32) and projecting towards the other member (32), the free end parts (35) of which are juxtaposed and face each other and are secured to each other by means of an element (37) made of damping material.

6. A connecting rod device made of composite material according to any one of claims 1 to 5, characterized in that it is made entirely or partly of composite material.

7. Connecting rod device made of composite material according to any one of claims 1 to 6, characterized in that the securing of the element(s) (14; 25; 37) made of damping material to the body (10; 20; 30) is carried out by bonding and / or polymerization.

8. A connecting rod device made of composite material according to any one of claims 1 to 7, characterized in that the damping material consists of an elastomer or an elastomer foam.

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