IL195777A

IL195777A - Connecting rod for aircraft construction and mechanism comprising such a connecting rod

Info

Publication number: IL195777A
Application number: IL195777A
Authority: IL
Original assignee: Skf Aerospace France
Priority date: 2007-12-07
Filing date: 2008-12-07
Publication date: 2012-02-29
Also published as: DE602008002130D1; ES2350023T3; FR2924774A1; IL195777A0; EP2067697A1; EP2067697B1; FR2924774B1

Description

195777 i7-n I 453596 WW ΠΤ3 ΠΙΓΠ ϋΙΠ 7713Π ΠΗ3Π1 D"O n 3 ΓΠ3"ΙΠ7 ΠΙΡΠ 01T.

CONNECTING ROD FOR AIRCRAFT CONSTRUCTION AND MECHANISM COMPRISING SUCH A CONNECTING ROD The present invention relates to a connecting rod for aircraft construction withstanding primarily tensile and/or compressive loads and comprising a strain gauge sensor for evaluating these loads, in addition to a safety member for protecting said sensor. The invention further relates to an aircraft mechanism comprising such a connecting rod.

In the field of aircraft construction, it is necessary to evaluate the mechanical stresses sustained by a mechanism and, in particular, by the connecting rod(s) which make up said mechanism. A connecting rod of an aircraft mechanism generally comprises a shaft for transmitting loads exerted primarily in traction and/or in. compression when the connecting rod is in operation. In the aircraft mechanisms of the prior art, the connecting rod generally incorporates a linear spring of which the extension is directly proportional to the loads sustained by the connecting rod, which makes it possible to measure these loads. However, the incorporation of such a linear spring increases the spatial requirement, in particular in the axial direction of the connecting rod.

US-B-6 311 566 discloses a connecting rod with an elastically deformable element and a safety member constituted by different pieces, respectively a spring and a stop nut.

In the field of mechanical engineering, parts subjected to tensile and/or compressive loads exist which comprise an elastically deformable element associated with a strain gauge sensor, so as to measure elastic deformation to evaluate these loads. To carry out an accurate measurement, the amplitude of the elastic deformation has to be relatively high for the loads currently sustained in normal operating mode.

Nevertheless, a connecting rod for an aircraft mechanism is dimensioned to withstand critical loads in a faulty operating mode, which are considerably greater than the loads which are sustained in normal operation. More specifically, such critical loads risk causing plastic deformation ofthe elastically deformable element, which makes it unusable and requires its replacement to be able to carry out load measurements again.

The present invention aims, in particular, to remedy these drawbacks by providing a connecting rod for aircraft construction, making it possible to carry out accurate measurements of loads during normal operation ,at a lower cost and with a reduced number of components, whilst protecting the components of the connecting rod during faulty operation.

To this end, the subject of the present invention is a connecting rod for aircraft construction, comprising at least one first assembly comprising: - at least one shaft for transmitting loads exerted substantially in traction and/or in compression when the connecting rod is in operation; - an elastically deformable element fixed to said shaft so as to absorb said stresses, said element being configured to exhibit elastic deformation under the action of said loads; - at least one strain gauge sensor associated with said element so as to measure said elastic deformation to evaluate said loads; said first assembly further comprising a safety member fixed to said elastically deformable element and remote from the shaft when the connecting rod is at rest, said safety member being configured to limit the movements of the shaft when said elastic deformation exceeds a specific limit, so as to transmit the excess portion of said loads, characterized in that the elastically deformable element is made in one piece with the safety member.

In other words, the safety member defines abutment means for the shaft which are able to absorb the majority of the high loads sustained by the connecting rod.

Such a safety member thus makes it possible to protect the elastically deformable element, by "by-passing" said elastically deformable element when the loads exceed the elastic limit thereof. The element thus protected is able to exhibit an elastic deformation of high amplitude in normal operation, so that accurate loads measurements can be carried out.

According to other advantageous but optional features of the present invention, taken in isolation or in any technically possible combination: - the safety member comprises a first and a second bearing surfaces, the shaft comprises a third and a fourth bearing surfaces arranged respectively opposite the first and second bearing surfaces, and the first and third bearing surfaces, on the one hand, and the second and fourth bearing surfaces, on the other hand ,being separated when the connecting rod is at rest, by distances which are respectively lower than said limit, the first and third bearing surfaces being configured to transmit the loads exerted in compression when said limit is exceeded and the second and fourth bearing surfaces being configured to transmit the loads exerted in traction when said limit is exceeded; - the first and second bearing surfaces are defined by machining from a common reference surface, machined on the safety member; - the shaft extends along an axis generally parallel to the direction of application of said loads and said bearing surfaces are generally planar and perpendicular to said loads; - the element has a form of revolution which is coaxial to the shaft, the safety member has a form of revolution which is coaxial to the shaft, the shaft comprises a collar having opposing axial surfaces defining the third and fourth bearing surfaces, the first bearing surface is perpendicular to the axis, the safety member is provided with a retaining ring defining, the second bearing surface and the safety member and the ring form a housing for the collar and the safety member has a form of revolution which is coaxial to the shaft, the shaft comprises a collar having opposing axial surfaces defining the third and fourth bearing surfaces, the first bearing surface is perpendicular to the axis, the safety member is provided with a retaining ring defining the second bearing surface and the safety member and the ring form a housing for the collar; - the element is a membrane, the membrane having a form generally cylindrical or frustoconical with a half-point angle greater than 45°, preferably than 60°; - the shaft is screwed to the element, the threaded portion being made on the shaft; - the shaft is screwed to the element, the internal threaded portion being made on the shaft; - the connecting rod comprises additional means for fixing the shaft to the element, such as a pin or adhesive arranged on the threaded portion; - the distance separating the shaft and the safety member is between 0.1 mm and 0.4 mm, preferably between 0.2 mm and 0.3 mm, in that said elastic deformation limit is reached for a load between 1000 N and 2000 N and the shaft is configured to transmit loads of up to 12000 N to the safety member; - the element is made of a material with a longitudinal modulus of elasticity greater than 100000 MPa, such as for example TA6V titanium alloy. - the connecting rod further comprises a second assembly similar to the first assembly and in that the two safety members are fixed on both sides of a central flange, the two assemblies being arranged symmetrically relative to said flange.

Furthermore, the subject of the present invention is an aircraft mechanism, characterized in that it comprises a connecting rod as explained above.

Finally, the subject of the invention is a method for manufacturing the above connecting rod, wherein the common reference surface is machined on the safety member and said first and second bearing surfaces are made by machining from said common reference surface.

The invention will be understood clearly and further advantages will also emerge from reading the following description, given solely by way of non-limiting example and made by referring to the accompanying drawings, in which: - Figure 1 is a longitudinal section of a connecting rod according to the invention; - Figure 2 is a view in larger scale of the detail II of Figure 1 ; - Figure 3 is a view in larger scale of the detail III of Figure 2; - Figure 4 is a view in larger scale of the detail IV of Figure 2; and - Figure 5 is a longitudinal section in larger scale, of a variant of the connecting rod of the preceding figures.

Figure 1 illustrates a connecting rod 1 which extends along a longitudinal axis Xj. The ends of the connecting rod 1 are formed by respective end fittings 2 and 3, which are intended to be connected to further components, not shown, of an aircraft mechanism. To this end, each end fitting 2 or 3 is perforated by a through-hole 20 or 30, for receiving a complementary part of a further component.

The connecting rod 1 comprises a first shaft 4 to which is fixed the end fitting 2 by means of a threaded portion 21 and a nut 22. Similarly, the connecting rod 1 comprises a second shaft 5 to which is fixed the end fitting 3 by means of a threaded portion 31 and a nut 32. When the connecting rod is in operation, the shafts 4 and 5 are intended to transmit loads from the end fitting 2 to the end fitting 3 and vice versa. Such loads are exerted substantially in traction or in compression. In the example of Figure 1, the end fittings 2 and 3 are subjected to a tensile force F\ which is exerted along the axis X\.

The first and second shafts 4 and 5 are connected to one another by means of a housing 6 and a cap 10, which are assembled by means of screws 8 and 9. The second shaft 5 is fixed to the cap 10, for example by means of a screw 11. The first shaft 4 extends along the axis Xj which is generally parallel to the direction of application of the tensile force Fj.

The housing 6 is formed by a central part 60 and a peripheral part 61. The adjective "central" qualifies an object which is close to the axis Xls whilst the adjective "peripheral" qualifies an object which is more remote therefrom. The shaft 4 is fixed to the central part 60 by means of an internal threaded portion 604, whilst the shaft 4 may transmit to the housing 6 compressive and/or tensile loads, such as the force Fi.

The housing 6 and the first shaft 4 are in this case coaxial, as they both have a symmetry of revolution about the axis X\ In the example of Figures 1 and 2, the internal threaded portion 604 is produced on the shaft 4.

As Figure 2 shows, the central part 60 and peripheral part 61 of the housing 6 are connected by means of an element 62 which is configured to exhibit elastic deformation when the shaft 4 transmits the force F\ to the central part 60. The element 62 is made in one piece with the central part 60 and peripheral part 61. The element 62 has a generally frustoconical or tapered shape around axis Xi of which the thick part 622 of which is connected to the central part 60 along a fillet 602 and of which the thin part 621 of which is connected to the peripheral part 61. The half-point angle of the cone is about 75°. Usually, the half-point angle is greater than 45°, preferably than 60°. According to a non-shown embodiment, the elastically deformable element has a form generally cylindrical and flattened.

Thus, the element 62 forms a membrane which has a frustoconical form relatively flattened, with a relatively smooth thickness variation from the axis Xj up to its circumference. The element 62 hence has a form similar to a solid disc. This construction is particularly compact both in the axial and radial directions. The membrane formed by the element 62 can be elastically deformed along axis X\.

The element 62 is stuck to, hence associated with, a strain gauge sensor 603 known per se and arranged on an axial surface 601 of the central part 60 which is oriented toward the cap 10. The strain gauges, not shown, of the sensor 603 extend radially from the axis Xi to the peripheral part 61, thus forming a complete strain gauge bridge and permitting a plurality of measurements of the loads applied to be carried out simultaneously. The sensor 603 is of the "diaphragm" type.

Since element 62 has the form of a membrane, it can hold adjacent several strain gauge bridges, e.g. two, to make accurate loads measurements. Usually, the strain gauge bridges are offset around axis Xi with an angle between 30° and 60°. The mounting of the strain gauge bridge(s) directly on element 62 provides a relatively high axial compactness to connecting rod 1.

Moreover, additional means may be provided to fix the shaft 4 to the central part 60 and the element 62, such as a radial pin passing through these two parts or adhesive of the "screw locking" type arranged on the threaded portion 604. The use of a pin provides the advantage that the quality of this fixing is independent of the operations to assemble the shaft 4 and the element 62.

When the connecting rod 1 is in operation in normal operating mode, it is subjected to tensile load Fj of moderate intensity, which is transmitted from the end fitting 2 to the housing 6 via the shaft 4, then from the cap 10 to the end fitting 3 via the shaft 5. In this case, the element 62 is elastically deformed, which is measured by the strain gauge sensor 603 arranged on the element 62 and possibly in the central part 60.

In the area direction of the housing 6, the first shaft 4 comprises a collar 41 which extends radially from the axis Xj toward the peripheral part 61. The collar 41 has a cylindrical shape with an axis X\. A retaining ring 7 is positioned in planar abutment against an axial surface 612 of the housing 6 to which the ring 7 is fixed by means of the screws 8 and 9. The ring 7 has an annular shape with an axis Xi and it extends radially toward the axis Xj beyond the surface 612. The peripheral part 61 of the housing 6 comprises, moreover, a shoulder 61 1 arranged opposite the part of the ring 7 which projects toward the axis X\ A surface in this case is denoted "axial or "radial" according to the orientation of a normal to this surface.

The assembly of the ring 7 with the peripheral part 61 of the housing 6 defines a safety member 617 which surrounds the collar 41 of the shaft 4. The safety member 617 is thus fixed to the elastically deformable element 62. Element 62 is integral with peripheral part 61 hence with safety member 617. Safety member 617 has a form of revolution around axis X\. Safety member 617, as well as element 62, are therefore coaxial with shaft 4.

Since element 62 and peripheral part 61 of safety member 617 are integral, this makes it possible to reduce the number of pieces, necessary to fulfill elasticity and safety functions. Due to this structure, assembling and maintenance of the connecting rod 1 are easy to achieve. 8 195777/2 As Figure 3 shows, when the connecting rod 1 is at rest, i.e. when it is not subjected to any tensile or compressive stress, the peripheral part 61 and the ring 7, which form the safety member 617, are remote from the shaft 4. In other words, the safety mermber 617 and the ring 7 form a housing with clearance for the collar 41, which may not slip out after the assembly of the connecting rod 1. The shaft 4, the element 62, the sensor 603 and the safety member 617 form a first assembly for measuring accurately and in complete safety the loads sustained by the connecting rod.

When the connecting rod is in use and it is subjected to a moderate load Fi the element 62 is elastically deformed which causes an elongation of the strain gauges of the sensor 603, and thus a modification of their electrical resistance which makes it possible to evaluate the load F| .

In abnormal or faulty operation, the intensity of the loads exerted on the connecting rod, in this case the tensile force Fi may become very high, for example in the event of impact. In this case, the elastic deformation of the element 62 reaches, and then exceeds, a predetermined limit.

As soon as this limit is exceeded, the safety member 617 restricts the movement of the shaft 4 in the direction of the force Fj. Thus, the mechanical stresses sustained by the element 62 are limited to the stresses corresponding to this elastic deformation limit. The excess portion of the force Fi is transmitted from the shaft 4 to the safety member 617, whilst the element 62 withstands a limited portion of the force Fi. In other words, the collar 41 plays the role of a mechanical "valve" which "by the element 62 to transmit high loads from the shaft 4 to the housing 6.

As Figure 3 shows, the safety member comprises a first bearing surface 61 1 formed by the shoulder of the peripheral part 61 and a second bearing surface 712 formed by the projecting radial part of the ring 7. The first 611 and second 712 bearing surfaces have an annular shape which is planar and perpendicular to the axis Xi However, these bearing surfaces may take other forms, for example planar and inclined to the axis Xi in an oblique manner.

The collar 41 of the first shaft 4 comprises a third bearing surface 413, and a fourth bearing surface 414 which are respectively arranged ,after assembling the safety member 617, opposite the first 61 1 and the second 712 bearing surfaces. The collar 41 has a cylindrical symmetry and the bearing surfaces 413 and 414 are planar, axial and opposing, i.e. one oriented towards the end fitting 2 and the other oriented towards the end fitting 3.

When the connecting rod is at rest, the first 611 and third 413 bearing surfaces are separated by a distance d6 which is less than the selected elastic deformation limit selected for the element 62. As a result, no stress is transmitted between the bearing surfaces 611 and 413, nor therefore between the housing 6 and the shaft 4, as long as the elastic deformation of the element 62 in the longitudinal direction defined by the axis Xi remains less than this limit. Similarly, the second 712 and fourth bearing surfaces are separated when the connecting rod 1 is at rest, by a distance d7 which is less than this limit. As a result, no stress is transmitted between the bearing surfaces 412 and 414 nor therefore between the housing 6 and the shaft 4, as long as the elongation of the element 62 in the longitudinal direction defined by the axis Xi remains less than this limit.

When the connecting rod 1 operates in traction, the bearing surfaces 712 and 414 are brought together and the distance d7 decreases. Conversely, when the connecting rod 1 operates in compression, the bearing surfaces 61 1 and 413 are brought together and the distance d6 decreases.

When the elastic deformation limit of the element 62 is exceeded in traction, the bearing surfaces 712 and 414 come into contact and transmit the force F| of which the intensity has become too great to effect its transmission by the single element 62, from the shaft 4 to the housing 6.

Conversely, when the elastic deformation limit is exceeded in compression, the bearing surfaces 611 and 413 come into contact and thus transmit the compressive loads, of which the intensity is too great for the single element 62, from the shaft 4 to the housing 6.

Thus the bearing surfaces 611 and 712 form abutment means capable of absorbing the loads transmitted by the surfaces 413 or 414.

The bearing surfaces 611, 712, 413 and 414 thus make it possible to protect the element 62 by avoiding any plastic deformation. Thus the stresses tolerated by the connecting rod 1 in normal operation may be measured, without risking damage to its element 62 in faulty operation.

In practice, the distance d6 is equal to, for example, approximately 0.2 mm and the distance d7 to 0.3 mm. In practice, the distances d6 and d7 may be between 0.1 mm and 0.4 mm and preferably between 0.2 mm and 0.3 mm.

The element 62 is made of a material with a high longitudinal modulus of elasticity (Young's modulus), such as titanium (Ti). By high longitudinal modulus of elasticity is understood a modulus greater than 100000 MPa.

The choice of such a material and the dimensioning of the element 62 makes it possible to obtain a relatively high elastic deformation, which increases the precision of the measurements of the loads sustained by the connecting rod. However, the more the element 62 has to be deformed, the more its deformation risks approaching the plastic zone. However, the collar 41 and the safety member 617 ensure the protection of the element 62 in this case.

The elastic deformation limit of the element 62 is in this case selected in traction and in compression, so as to be reached by a load greater than that of the abutment of the by-pass" cited above. In practice, this load limit may be defined above 2000 N. In the normal operating range of the connecting rod 1, where the loads are between 0 and 500 N, the element 62 permits an accuracy of ±10 N for the measurement of the loads transmitted by the element 62.

Moreover, the dimensioning of the collar 41 and the safety member 617, i.e. the dimensioning of the bearing surfaces 611, 712, 413 and 414, permits them to transmit loads up to 12000 N.

Figure 4 illustrates schematically how to machine the safety member 617 and the collar 41. The direction of machining is denoted by the arrow U on Figure 4. In this case, the shapes of the housing 6, the ring 7 and the collar 41 are relatively simple to obtain, and therefore economical, whilst ensuring the distances d6 and d7. The housing 6 is machined by means of a digitally controlled lathe which permits an accuracy of ±3/100 mm.

Firstly, an axial surface 605 located on the central part 60 and oriented towards the first shaft 4 is machined. The surface 605 is then used as a common reference surface for machining the peripheral part 61 of the housing 6. Thus an annular surface 612 is produced which is planar and axial and which is located at the end of the housing 6 in the direction of the shaft 4. The shoulder 611 is then produced, whilst still taking the surface 605 as a reference. Then the collar 41 is machined by producing the measurement d^. The ring 7 also has to be produced with a good surface evenness of the second bearing surface 712, as said second bearing surface has to be pressed against the surface 612 during the assembly of the safety member 617.

As far as the digital lathing makes it possible to obtain measurements of the surfaces 605, 612 and 611 to an accuracy of ±3/100 mm, it is simple and inexpensive to ensure that the distances d6 and d7 are between 0.2 and 0.3 mm. After this machining, the assembly of the first assembly may be implemented in a simple manner and without any necessary adjustment.

Figure 5 illustrates a variant of the connecting rod 1 of Figures 1 to 4. The elements of Figure 5 which are identical or correspond to those of Figures 1 to 4 bear the same reference numeral increased by 1000. The description of the connecting rod 1 provided above may be transposed to the connecting rod 1000 illustrated in Figure 5.

The connecting rod 1001 extends along a longitudinal axis Xi00i. The connecting rod 1001 or the connecting rod 1 may measure approximately 23 cm in length and weigh approximately 1 kg. The connecting rod 1001 comprises a first assembly consisting of a first shaft 1004, a housing 1006 and a ring 1007. The shaft 1004 comprises a collar 1041 and the housing 1006 comprises a central part 1060, a peripheral part 1061 and an elastically deformable element 1062. The peripheral part 1061 and the ring 1007 form a safety member 1617. Moreover, the housing 1006 is provided with a strain gauge sensor 1603 which is stuck to, hence associated with, the element 1062.

The connecting rod 1001, of which the end fittings are not shown in Figure 5, is distinguished from the connecting rod 1 in that it comprises, in place of the cap 10 and the shaft 5, a second assembly similar to the first assembly of the connecting rod 1 , and which is mounted symmetrically relative to the plane of the central section of the connecting rod 1001. In other words, the second assembly shown to the left in Figure 5 is mounted head-to-tail relative to the first assembly shown to the right in Figure 5. This second assembly thus comprises a shaft 1005, a housing 1016, a ring 1017 and a strain gauge sensor 1613 respectively similar to the shaft 1004, the housing 1006, the ring 1007 and the sensor 1603. The ring 1017 forms, with a peripheral part 1161 of the housing 1016, a safety member 1761 similar to the member 1617.

The housings 1006 and 1007 are fixed on both sides of a central flange 1050, for example by means of screws 1008 and 1009, shown by their axial lines in Figure 5. The two assemblies, from the right and from the left, are thus arranged symmetrically relative to the central flange 1050. As the connecting rod 1001 is provided with two sensors 1603 and 1613, it is possible to carry out two separate series of measurements, whilst having a relatively compact assembly. The measurements carried out by the sensor 1603 may be used to adjust the aircraft mechanism provided with the connecting rod 1001, whilst the measurements carried out by the sensors 1613 are used to verify the compliance of the measurements carried out by the sensor 1603 Thus, if one of the sensors 1603 and 1613 no longer functions, for example if the element 1062 is plastically deformed, the difference in measurement between the sensors 1613 and 1603 thus indicates the failure of the sensor.

Moreover, the connecting rod 1001 is distinguished from the connecting rod 1 in that the shaft 1004 bears a threaded portion ,1604 whilst the shaft 4 bears an internal threaded portion 604. This configuration of the shaft 1004 has the advantage of ensuring that the safety member 1617 absorbs the loads transmitted by the shaft 1004, in the event of the connection between the shaft 1004 and the central part 1060 being ruptured. Indeed, in the case of the connecting rod 1001, there is the risk that the rupture is produced on the annular section of the central part 1060 in the region of the end of the internal threaded portion. The shaft 1004 remains in one piece so that it may transmit loads to the safety member 1617.

Moreover, the simplicity of the geometry of the components of the connecting rod 1 or of the connecting rod 1001 permits a simple adaptation of the range of stress measurement, if it is desired to produce mechanisms of different dimensions.

Claims

14 195777/2 Claims

1. Connecting rod (1; 1001) for aircraft construction comprising at least one first assembly comprising: - at least one shaft (4; 1004) for transmitting loads (Fj) exerted substantially in traction and/or in compression when the connecting rod (1; 1001) is in operation; - an elastically deformable element (62; 1062) fixed to said shaft (4; 1004) so as to absorb said loads (F\), said elastically deformable element (62; 1062) being configured to exhibit elastic deformation under the action of said loads (F\); - at least one strain gauge sensor (603; 1603) associated with said elastically deformable element (62; 1062) so as to measure said elastic deformation to evaluate said loads (Fj); said first assembly further comprising a safety member (617; 1617) fixed to said elastically deformable element (62; 1062) and remote from the shaft (4; 1004) when the connecting rod (1; 1001) is at rest, said safety member (617; 1617) being configured to limiting the movements of the shaft (4; 1004)when said elastic deformation exceeds a specific limit, so as to transmit the excess portion of said loads characterized in that the elastically deformable element (62; 1062) is made in one piece with the safety member (617; 1617).

2. Connecting rod (1; 1001) according to Claim 1, characterized in that said safety member (617; 1617) comprises a first (611) and a second (712) bearing surfaces, in that the shaft (4; 1004) comprises a third (413) and a fourth (414) bearing surfaces arranged respectively opposite the first (611) and second (712) bearing surfaces, and the first (611) and third (413) bearing surfaces, on the one hand, and the second (712) and fourth (414) bearing surfaces, on the other hand, being separated when the connecting rod (1; 1001) is at rest, by distances (d6, d7) which are respectively less than said limit, the first (611) and third (413) bearing surfaces being configured to transmit the loads exerted in compression when said limit is exceeded 15 195777/2 and the second (712) and fourth (414) bearing surfaces being configured to transmit the loads exerted in traction (Fi) when said limit is exceeded.

3. Connecting rod (1; 1001) according to Claim 2, characterized in that the first (611) and second (712) bearing surfaces are defined by machining from a co reference surface (605), machined on the safety member (1617 ;617).

4. Connecting rod (1; 1001) according to Claim 2 or 3, characterized in that said shaft (4; 1004) extends along an axis (Xi; X10oi) generally parallel to the direction of application of said loads (F and in that said bearing surfaces (611, 712, 413, 414) are generally planar and perpendicular to said loads (F\).

5. Connecting rod (1; 1001) according to Claim 4, characterized in that the elastically deformable element (62; 1062) has a form of revolution which is coaxial to the shaft (4; 1004), in that the safety member (617; 1617) has a form of revolution which is coaxial to the shaft (4; 1004) in that the shaft (4; 1004) comprises a collar (41 ; 1041) having opposing axial surfaces defining the third (413) and fourth (414) bearing surfaces, in that the first bearing surface (61 1) is perpendicular to the axis (Xi; Xiooi) in that the safety member (617; 1617) is provided with a retaining ring (7; 1007) defining the second bearing surface (712) and in that the safety member (617; 1617) and the ring (7; 1007) form a housing for the collar (41; 1041).

6. Connecting rod (1 ; 1001) according to claim 5, characterized in that the elastically deformable element (62 ; 1062) is a membrane, the membrane having a form generally cylindrical or frustoconical with a half-point angle greater than 45°, preferably than 60°.

7. Connecting rod (1001) according to one of the preceding claims, characterized in that the shaft (1004) is screwed to the elastically deformable element (1062), the threaded portion (1604) being made on the shaft (1004).

8. Connecting rod (1) according to one of Claims 1 to 7, characterized in that the shaft (4) is screwed to the elastically deformable element (62), the internal threaded portion (604) being made on the shaft (4). 16 195777/2

9. Connecting rod (1; 1001) according to one of Claims 8 or 9, characterized in that it comprises additional means for fixing the shaft to the elastically deformable element (62; 1062), such as a pin or adhesive arranged on the threaded portion (604; 1604).

10. Connecting rod (1 ; 1001) according to one of the preceding claims, characterized in that the distance (d , d7) separating the shaft (4; 1004) and the safety member (617; 1617) is between 0.1 mm and 0.4 mm, preferably between 0.2 mm and 0.3 mm, in that said elastic deformation limit is reached for a load (Fj) between 1000 N and 2000 N and in that the shaft (4; 1004)is configured to transmit loads of up to 12000 N to the safety member (617; 1617).

11. Connecting rod (1 ; 1001) according to one of the preceding claims, characterized in that the elastically deformable element (62; 1062) is made from a material with a longitudinal modulus of elasticity greater than 100000 MPa, such as for example TA6V titanium alloy.

12. Connecting rod (1001) according to one of the preceding claims, characterized in that it further comprises a second assembly similar to the first assembly and in that the two safety members (1617, 1761) are fixed on both sides of a central flange (1050) the two assemblies being arranged symmetrically relative to said flange (1050).

13. Aircraft mechanism, characterized in that it comprises a connecting rod (1 ; 1001) according to one of the preceding claims.

14. Method for manufacturing a connecting rod according to one of Claims 3 to 12, wherein the common reference surface (605) is machined on the safety member (617; 1617) and said first (611) and second (712) bearing surfaces are made by machining from said common reference surface. LUZZATTO & LUZZATTO