A method for improving the damage tolerance performance of connector lugs

Abstract

A method for improving the damage tolerance performance of a joint ear piece, wherein a bushing is provided in a hole of the joint ear piece, and two anti-wear grooves are provided on an outer surface of the bushing, wherein the anti-wear grooves are located in the middle of the width of the bushing, and a center line connecting the two anti-wear grooves passes through the center of the bushing; when installing the bushing, the anti-wear grooves of the bushing are positioned corresponding to a severely stressed area of ​​the joint ear piece hole, and the anti-wear grooves can improve the micro-motion wear phenomenon of the severely stressed area between the bushing and the ear piece hole.

Description

Technical Field

[0001] The invention belongs to the related technology of aircraft damage tolerance design, in particular to a method for improving the damage tolerance performance of a joint ear. Background Art

[0002] During the design process of aircraft connection joints (e.g., fuselage-wing connection joints, fuselage-landing gear connection joints), bushings are usually provided at the joint ear holes to reduce the wear of the ear holes.

[0003] During the use of an aircraft, the load on the connecting joint changes continuously over time, resulting in extremely small relative movement of the contact surface between the joint ear and the bushing, which can easily cause damage to the mating surface, form a fatigue source, and cause fatigue cracks.

[0004] To ensure safe use of aircraft, it is necessary to establish appropriate inspection intervals for the joint lug structure so that cracks can be detected and replaced before the lug breaks.

[0005] In the initial stage of crack expansion, since the ear crack is inside the structure, effective inspection cannot be carried out. Only when the crack expands to the outer surface of the ear can it be inspected.

[0006] When using traditional bushings (ring type), cracks in the lugs usually start and expand in the middle area of ​​the lug thickness direction. Therefore, when the cracks are detectable on the outer surface of the lug, they have already expanded to a large area inside the lug structure. The aircraft service life from the time when the cracks are detectable to the lug breaking is short, resulting in a short inspection interval for the joint lugs.

[0007] The existing solution is: to ensure that cracks in the joint ear are discovered in time before the ear breaks, the joint ear needs to be inspected more frequently (i.e., the inspection frequency is increased) during the use of the aircraft.

[0008] There are problems with existing solutions: there are many joint ear structures in the aircraft structure, and high-frequency inspections will lead to high field operation costs and poor economy. Summary of the invention

[0009] The object of the present invention is to provide a method for improving the damage tolerance performance of a joint lug, thereby extending the inspection interval at the joint lug while reducing the weight of the structure and reducing the inspection and maintenance cost of such a structure.

[0010] The technical solution of the present invention is:

[0011] A method for improving the damage tolerance performance of a joint ear, wherein a bushing is provided in a hole of the joint ear, and the method is characterized by comprising the following contents: 1) two anti-wear grooves are provided on the outer surface of the bushing, the anti-wear grooves are located in the middle of the width of the bushing, and the center line of the two anti-wear grooves passes through the center of the bushing; 2) when installing the bushing, the anti-wear grooves of the bushing are positioned corresponding to the severely stressed area of ​​the joint ear hole.

[0012] The beneficial effects of the present invention are: proposing a method for improving the damage tolerance performance of a joint ear, by adopting a bushing with an anti-wear groove, changing the fatigue crack initiation site, thereby reducing the crack expansion area inside the ear structure, so that the crack can be detected on the outer surface of the ear at the beginning of expansion, and extending the inspection interval at the aircraft joint ear while reducing the structural weight, thereby reducing the inspection and maintenance costs of such structures.

[0013] The present application is further described in detail below in conjunction with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the joint ear hole structure with a bushing.

[0015] Figure 2 The figure shows a bushing structure with anti-wear grooves.

[0016] Figure 3 It is a schematic diagram of the angle between the upper and lower boundaries of the anti-wear groove and the center line of the bushing.

[0017] Figure 4 It is a schematic diagram of the corresponding assembly relationship between the anti-wear groove of the bushing and the severely stressed area of ​​the ear hole of the joint.

[0018] Explanation of numbers in the figure: 1 joint ear, 2 bushing, 3 anti-wear groove, 4 severe stress area. DETAILED DESCRIPTION

[0019] Referring to the attached drawings, the method for improving the damage tolerance performance of the joint ear piece of the present application is that a bushing 2 is provided in the hole of the joint ear piece 1, and in particular, two anti-wear grooves 3 are provided on the outer surface of the bushing 2, and the anti-wear grooves 3 are located in the middle of the width of the bushing, and the center line of the two anti-wear grooves 3 passes through the center of the bushing; when installing the bushing 2, the anti-wear grooves 3 of the bushing 2 are installed correspondingly on the severely stressed area 4 of the connecting hole of the joint ear piece 1. The severely stressed area of ​​the connecting hole of the joint ear piece generally refers to: the area where the normal of the inner side wall of the ear piece hole is perpendicular to the load direction is the severely stressed area, Figure 4 The direction indicated by the arrow in is the load direction borne by the inner wall of the ear hole. The severely stressed area 4 is located on the inner walls on both sides of the ear hole, and the normal of the severely stressed area 4 is perpendicular to the load direction indicated by the arrow.

[0020] In implementation, the anti-wear groove 3 is an elongated arc-shaped groove, the depth of the anti-wear groove 3 is less than 1 / 3 of the bushing wall thickness, the major axis of the anti-wear groove 3 is less than 1 / 2 of the bushing width, and the angle between the upper and lower side boundaries of the anti-wear groove 3 and the center line of the bushing is between 25 degrees and 35 degrees.

[0021] The area of ​​the anti-wear groove 3 corresponds to the severely stressed area 4 of the ear hole, which is also the area with the greatest stress. The anti-wear groove 3 can improve the micro-wear phenomenon of the severely stressed area 4 between the bushing and the ear hole, thereby moving the fatigue crack initiation position toward the direction close to the outer surface of the ear. When the crack is detectable on the outer surface of the ear, the expansion area inside the ear is smaller, thereby extending the service life of the aircraft from the time when the crack can be detected to the time when the ear breaks, and significantly improving the structural inspection interval without increasing the structural weight.

Claims

1. A method for improving the damage tolerance performance of a joint ear, wherein a bushing is provided in a hole of the joint ear, characterized in that It includes the following contents: 1) Two anti-wear grooves are provided on the outer surface of the bushing, the anti-wear grooves are located in the middle of the width of the bushing, and the center line of the two anti-wear grooves passes through the center of the bushing; 2) When installing the bushing, the position of the anti-wear groove of the bushing is aligned with the severe stress area of ​​the joint ear hole, and the anti-wear groove is an elongated arc groove, the depth of the anti-wear groove is less than 1 / 3 of the bushing wall thickness, the major axis of the anti-wear groove is less than 1 / 2 of the bushing width, and the angle between the upper and lower boundaries of the anti-wear groove and the center line of the bushing is between 25 and 35 degrees.

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