Aircraft structure fatigue test buffer restraint device

Abstract

The application belongs to the technical field of aircraft structure strength test, and particularly relates to a buffer constraint device for aircraft structure fatigue test. In the test, the heading load imbalance makes the test machine have a tendency to move along the heading direction, at this time, the buffer constraint device is compressed or stretched, the disc located on the piston rod drives the metal spring to move along the heading direction, and the oil in the compressed cavity flows into another cavity through the throttle valve, the metal spring moves slowly under the action of the oil damping, and after reaching the displacement amount matched with the current load, the metal spring is no longer compressed, the test load reaches a new balance, and the current working condition is completed. With the test entering the next working condition, the new unbalanced load appears, the buffer constraint device enters the next movement state, or releases the displacement or continues to compress. When the full machine load reaches the balance, the buffer constraint device slowly recovers to the initial state under the drive of the metal spring. The application can effectively release the structural displacement caused by the load imbalance.

Description

Technical Field

[0001] This application belongs to the field of aircraft structural strength testing technology, and specifically relates to a buffer constraint device for aircraft structural fatigue testing. Background Technology

[0002] Six-degree-of-freedom statically determinate constraints are commonly used in full-aircraft fatigue testing. The constraint locations are selected from non-test areas on the testing aircraft that have high stiffness and small displacement. The typical constraint method is a landing gear-fuselage combined six-degree-of-freedom statically determinate constraint, where vertical constraints are applied to the nose and main landing gear, and directional and lateral constraints are applied to the fuselage. Load sensors are installed at each constraint point to monitor the load during the test, and the accuracy of the applied load on the entire aircraft is determined from the load error at the constraint points.

[0003] In full-aircraft fatigue testing, different load conditions are applied sequentially to simulate the loads experienced during actual flight, including ground control, takeoff, departure, climb, cruise, descent, approach, and landing. Under each load condition, the entire aircraft is balanced. However, in actual testing, factors such as aircraft attitude and structural deformation, and uncoordinated loading at various points cause load imbalances. These imbalances are balanced by constraint points, increasing their additional load burden. Especially in fatigue tests with continuous load switching and long-term operation, constraint points endure prolonged dynamic impact loads, leading to fatigue cyclic loads not present in actual service, and consequently, unexpected fatigue damage in these areas. To mitigate the impact of unexpected dynamic impact loads on constraint points, one method is to appropriately release the displacement of the constraint points, reducing the impact load value through displacement changes, thereby reducing its impact on structural fatigue life.

[0004] Therefore, there is an urgent need for a technical solution to overcome or mitigate at least one of the aforementioned defects in the existing technology. Summary of the Invention

[0005] The purpose of this application is to provide a buffer constraint device for aircraft structural fatigue testing, in order to solve the problem that the unbalanced load in the existing landing gear-fuselage combined statically determinate constraint method can easily cause structural damage during test operation, thus affecting test safety.

[0006] The technical solution of this application is:

[0007] A fatigue testing buffer restraint device for aircraft structures, comprising:

[0008] A connecting base is connected to the test support frame;

[0009] Spring damper buffer module, the spring damper buffer module comprising:

[0010] A buffer cylinder includes an inner sleeve and an outer sleeve, with a cavity formed between the outer sleeve and the inner sleeve;

[0011] The cover plate includes a front cover and a rear cover, wherein the front cover and the rear cover are respectively installed at both ends of the outer sleeve;

[0012] A plurality of connecting rods are used to connect the front end cover, the rear end cover and the connecting base.

[0013] A piston rod is provided, on which four discs are mounted. The two middle discs are fixed discs and are fixedly connected to the piston rod, while the two discs on both sides are movable discs and are movably connected to the piston rod. The piston rod is disposed in the cavity, and the fixed discs divide the cavity into a front cavity and a rear cavity. The inner sleeves are respectively fitted onto the piston rod between the two discs in the front cavity and the rear cavity. One end of the piston rod, which extends from the front end cover, is provided with a threaded section, and the other end extends from the rear end cover and abuts against the connecting base.

[0014] The metal spring comprises two springs, one of which is sleeved on the inner sleeve of the front cavity, and the other of which is sleeved on the inner sleeve of the rear cavity.

[0015] A connecting screw, wherein the connecting screw is connected to the threaded section of the piston rod;

[0016] A throttle valve pipeline connects the front chamber and the rear chamber, and a throttle valve is provided on the throttle valve pipeline;

[0017] A force sensor, one end of which is connected to the connecting screw, and the other end of which is connected to the aircraft constraint point through a connecting connector.

[0018] In at least one embodiment of this application, the test load-bearing frame adopts a steel frame structure.

[0019] In at least one embodiment of this application, both the front cover and the rear cover are square.

[0020] In at least one embodiment of this application, the connecting rods comprise four.

[0021] In at least one embodiment of this application, a sealing ring is provided between the disk and the outer sleeve.

[0022] In at least one embodiment of this application, in the non-working state, a predetermined gap is reserved between the inner sleeve and the two disks.

[0023] In at least one embodiment of this application, the aircraft constraint points include a nose heading constraint point and a nose lateral constraint point.

[0024] The invention has at least the following beneficial technical effects:

[0025] The aircraft structural fatigue test buffer constraint device of this application can effectively release structural displacement caused by load imbalance, while ensuring test safety and load application accuracy. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an aircraft structural fatigue test buffer restraint device according to one embodiment of this application;

[0027] Figure 2 This is a schematic diagram of a spring damper buffer module according to one embodiment of this application;

[0028] Figure 3 This is a cross-sectional view of a spring damper buffer module according to one embodiment of this application;

[0029] Figure 4 This is a schematic diagram of a piston rod according to one embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the nose heading and lateral constraint point layout of a full-machine fatigue testing machine according to one embodiment of this application;

[0031] in:

[0032] 1-Connecting base; 2-Spring damper buffer module; 21-Inner sleeve; 22-Outer sleeve; 23-Front end cover; 24-Rear end cover; 25-Connecting rod; 26-Piston rod; 27-Metal spring; 28-Connecting screw; 29-Throttle valve pipe; 210-Throttle valve; 3-Force sensor; 4-Connecting connector. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0034] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0035] The following is in conjunction with the appendix Figures 1 to 5 This application will be described in further detail.

[0036] This application provides a buffer constraint device for aircraft structural fatigue testing, providing buffer constraints, such as... Figure 1 As shown, it includes: a connecting base 1, a spring damper buffer module 2, and a force sensor 3.

[0037] Specifically, the connecting base 1 is connected to the test bearing frame, which preferably adopts a steel frame structure; one end of the spring damper buffer module 2 is connected to the connecting base 1, and the other end is connected to the force sensor 3. The force sensor 3 is connected to the aircraft constraint point through the connecting joint 4, which can be a double-eared joint or a single-eared joint.

[0038] like Figure 2-3 As shown, the spring damper buffer module 2 includes: a buffer cylinder, a cover plate, a connecting rod 25, a piston rod 26, a metal spring 27, a connecting screw 28, and a throttle valve pipe 29.

[0039] The buffer cylinder includes an inner sleeve 21 and an outer sleeve 22, with a cavity formed between the outer sleeve 22 and the inner sleeve 21; the cover plate includes a front cover 23 and a rear cover 24, which are respectively installed at both ends of the outer sleeve 22; multiple connecting rods 25 are included, which connect the front cover 23, the rear cover 24 and the connecting base 1. In this embodiment, both the front cover 23 and the rear cover 24 are square, and there are four connecting rods 25.

[0040] Four discs are mounted on the piston rod 26, of which the two middle discs are fixed discs (e.g., Figure 4As shown, the piston rod 26 is fixedly connected to the piston rod 26. Two movable discs on either side are movably connected to the piston rod 26. The piston rod 26 is disposed within the cavity. The fixed discs divide the cavity into a front cavity and a rear cavity. Inner sleeves 21 are fitted onto the piston rod 26 between the two discs in the front and rear cavities. One end of the piston rod 26, extending from the front end cover 23, has a threaded section, and the other end extends from the rear end cover 24 and abuts against the connecting base 1. Two metal springs 27 are included: one metal spring 27 is fitted onto the inner sleeve 21 in the front cavity, and the other metal spring 27 is fitted onto the inner sleeve 21 in the rear cavity. A connecting screw 28 is connected to the threaded section of the piston rod 26. The front cavity and rear cavity are connected through a throttle valve pipe 29, on which a throttle valve 210 is installed. In this embodiment, a sealing ring is provided between the discs and the outer sleeve 22. In the non-working state, a predetermined gap is reserved between the inner sleeve 21 and the two discs.

[0041] In a preferred embodiment of this application, a constraint method is provided for full-aircraft fatigue testing. The aircraft constraint points include a nose heading constraint point and a nose lateral constraint point, and the specific constraint forms are as follows: Figure 5 As shown.

[0042] The aircraft structural fatigue testing buffer restraint device of this application features a piston rod 26 of the spring damper buffer module 2 with two disc assemblies. Each disc assembly includes a fixed disc and a movable disc. A filler seal ring is used between the discs and the outer sleeve 22 to improve sealing performance. The two fixed discs in the middle divide the cavity into a front cavity and a rear cavity, which are connected by a throttle valve pipe 29. One end of the piston 26 extending out of the front cavity has a threaded section to match the connecting screw 28, while the other end slides within a defined space in the rear cavity. Inner sleeves 21 are installed on the portions of the piston rod 26 located in both the front and rear cavities. A certain gap is left between the inner sleeve 21 and the disc assembly and end cap, which is the maximum compression or tension value of the spring damper buffer module 2. The front and rear cavities of the spring damper buffer module 2 are connected by a throttle valve pipe 29. Hydraulic oil is injected into the front and rear cavities through a pre-drilled hole at the top of the throttle valve pipe 29 and then sealed, so that the metal spring 27 is placed in the hydraulic fluid in the cavity, and the hydraulic fluid acts as a damper for the movement of the metal spring 27. The flow rate of the hydraulic fluid in the front and rear cavities is adjusted by the throttle valve 210 to control the movement speed of the metal spring 27, ensuring the stability and safety of the displacement release of the restrained part.

[0043] The aircraft structural fatigue test buffer restraint device of this application uses a metal spring 27 of the spring damper buffer module 2, designed according to the buffer force and buffer displacement. Oil is injected into the two chambers through the throttle valve pipe 29 and the throttle valve 210. The flow rate of the oil is adjusted by the throttle valve 210 to apply damping to the movement of the metal spring 27, controlling the contraction speed of the metal spring 27 to ensure the stability and safety of the displacement release of the restrained part, while absorbing energy during the displacement change process. During the test, after the restrained part bears the unbalanced load of the entire aircraft, this load is transmitted to the buffer restraint device through the joint connected to the aircraft, compressing the buffer restraint device to release part of the displacement and reduce the load on the restrained part. An appropriate maximum compression is set for the metal spring 27. When the unbalanced load of the entire aircraft is transmitted to the buffer restraint device to the maximum compression, the buffer restraint device can be regarded as a rigid body, thus effectively restraining the aircraft attitude and ensuring that the aircraft attitude meets the test requirements.

[0044] The aircraft structural fatigue test buffer restraint device of this application has an initial compression amount set for the front and rear chamber metal springs 27 during initial assembly. During the test, after one end of the metal spring 27 is compressed, the other end of the metal spring 27 releases its original compression amount. The initial compression amount is calculated and analyzed based on different test requirements. During the test, the unbalanced yaw load causes the test aircraft to tend to move along the yaw direction. At this time, the buffer restraint device is compressed or stretched (the total compression amount is not greater than the reserved gap in the sleeve 21 of the rear chamber, the total stretching amount is not greater than the reserved gap in the sleeve 21 of the front chamber, and the total compression amount or stretching amount is equal to the reserved gap). The disc located on the piston rod 26 pushes the metal spring 27 to move along the yaw direction. At the same time, the oil in the compressed chamber flows into another chamber through the throttle valve 210. Under the action of oil damping, the metal spring 27 moves smoothly. After reaching the displacement amount that matches the current load, the metal spring 27 stops compressing, the test load reaches a new equilibrium, and the current working condition is completed. As the test enters the next working condition, after a new unbalanced load appears, the buffer restraint device enters the next motion state, either releasing the displacement or continuing to compress. When the load on the entire machine reaches equilibrium, the buffer constraint device slowly returns to its initial state under the drive of the metal spring 27.

[0045] The aircraft structural fatigue test buffer constraint device of this application is applicable to the heading and lateral buffer constraints of full-size aircraft fatigue strength tests. It can reasonably release the displacement of the constraint parts during fatigue tests, reduce the additional damage caused by dynamic loads, ensure structural safety, and is highly versatile and easy to install.

[0046] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A buffer constraint device for aircraft structural fatigue testing, characterized in that, include: A connecting base (1) is connected to the test support frame; A spring damper buffer module (2), the spring damper buffer module (2) comprising: The buffer cylinder includes an inner sleeve (21) and an outer sleeve (22), and a cavity is formed between the outer sleeve (22) and the inner sleeve (21); The cover plate includes a front cover (23) and a rear cover (24), wherein the front cover (23) and the rear cover (24) are respectively installed at both ends of the outer sleeve (22); Connecting rods (25), including multiple ones, connect the front end cover (23), the rear end cover (24) and the connecting base (1) through multiple connecting rods (25); A piston rod (26) is provided with four discs, of which the two middle discs are fixed discs and are fixedly connected to the piston rod (26), and the two discs on both sides are movable discs and are movably connected to the piston rod (26). The piston rod (26) is located in the cavity. The fixed discs divide the cavity into a front cavity and a rear cavity. The inner sleeve (21) is respectively fitted on the piston rod (26) between the two discs in the front cavity and the rear cavity. One end of the piston rod (26) is provided with a threaded section extending from the front end cover (23), and the other end extends from the rear end cover (24) and abuts against the connecting base (1). The metal spring (27) includes two springs, one of which is sleeved on the inner sleeve (21) of the front cavity, and the other of which is sleeved on the inner sleeve (21) of the rear cavity. A connecting screw (28) is connected to the threaded section of the piston rod (26); A throttle valve pipe (29) connects the front chamber and the rear chamber, and a throttle valve (210) is provided on the throttle valve pipe (29); Force sensor (3), one end of which is connected to the connecting screw (28), and the other end is connected to the aircraft constraint point through the connecting connector (4).

2. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, The test load-bearing frame adopts a steel skeleton structure.

3. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, Both the front cover (23) and the rear cover (24) are square.

4. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, The connecting rod (25) comprises four.

5. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, A sealing ring is provided between the disc and the outer sleeve (22).

6. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, In the non-working state, a set gap is reserved between the inner sleeve (21) and the two disks.

7. The aircraft structural fatigue test buffer constraint device according to claim 1, characterized in that, The aircraft constraint points include the nose heading constraint point and the nose lateral constraint point.

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