Airplane structure fatigue test buffering and restraining device

Abstract

The invention belongs to the technical field of airplane structure strength tests, and particularly relates to a buffering and restraining device for an airplane structure fatigue test. In a test, a course load unbalance amount enables the tester to have a trend of moving along the course, at the moment, the buffer restraint device is compressed or stretched, the disc located on the piston rod pushes the metal spring to move along the course, oil in the compressed cavity flows into the other cavity through the throttle valve, and the metal spring moves gently under the action of oil damping; and after the displacement matched with the current load is reached, the metal spring is not compressed any more, the test load reaches new balance, and the current working condition is completed. Along with the next working condition of the test, after a new unbalanced load appears, the buffer restraint device enters the next motion state, or releases displacement or continues to be compressed. And when the load of the whole aircraft is balanced, the buffer restraint device is driven by the metal spring to slowly recover to the initial state. Structural displacement caused by load imbalance can be effectively released.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft structure strength testing, and in particular relates to a buffer restraint device for aircraft structure fatigue testing. Background Art

[0002] Six-degree-of-freedom (DOF) static constraints are commonly used in full-aircraft fatigue testing. These constraints are located in non-test areas of the test aircraft with high stiffness and low displacement. Typically, the restraint method is a combined landing gear-fuselage six-degree-of-freedom static constraint, with vertical constraints applied to the nose and main landing gear, and directional and lateral constraints applied to the fuselage. Load sensors are installed at each restraint point to monitor the load at that point during the test. The accuracy of the applied load on the entire aircraft is determined by the load error at that point.

[0003] During full-aircraft fatigue testing, continuous loads of different conditions are applied in a certain sequence to simulate the loads of various conditions during actual flight, such as ground control, takeoff, departure, climb, cruise, descent, approach, and landing. The entire aircraft is balanced under each load condition. However, during actual testing, factors such as aircraft attitude and structural deformation and uncoordinated loading at various loading points during the test cause unbalanced loads on the entire aircraft. These unbalanced loads are balanced by the restraints, which adds additional load burdens to the restraints. In particular, during fatigue tests with continuous switching of load conditions and long-term operation, the restraints are subjected to long-term dynamic impact loads, causing the structures near the restraints to be subjected to fatigue cycle loads that are not experienced in actual service, leading to unexpected fatigue damage in these parts. To mitigate the impact of unexpected dynamic impact loads on the restraints, one method is to appropriately release the displacement of the restraints, thereby reducing the impact load magnitude through displacement changes and thus reducing its impact on the fatigue life of the structure.

[0004] Therefore, there is an urgent need for a technical solution to overcome or alleviate at least one of the above-mentioned defects of the prior art. Summary of the Invention

[0005] The purpose of this application is to provide an aircraft structure fatigue test buffer restraint device to solve the problem that the existing technology uses a landing gear-fuselage combined static restraint method, which causes unbalanced loads during test operation and causes the structure to be easily damaged, thereby affecting the test safety.

[0006] The technical solution of this application is:

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

[0008] A connecting base connected to the test load-bearing frame;

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

[0010] The buffer cylinder comprises an inner sleeve and an outer sleeve, wherein a cavity is formed between the outer sleeve and the inner sleeve;

[0011] A cover plate, comprising a front end cover and a rear end cover, wherein the front end cover and the rear end cover are respectively mounted on both ends of the outer sleeve;

[0012] Connecting rods, including a plurality of connecting rods, connecting the front end cover, the rear end cover and the connecting base through the plurality of connecting rods;

[0013] A piston rod, wherein four discs are mounted on the piston rod, wherein the two middle discs are fixed discs fixedly connected to the piston rod, and the two discs on both sides are movable discs movably connected to the piston rod, the piston rod is arranged in the cavity, the fixed disc divides the cavity into a front cavity and a rear cavity, the inner sleeves are respectively sleeved on the piston rod between the two discs in the front cavity and the rear cavity, one end of the piston rod is provided with a threaded section extending from the front end cover, and the other end extends from the rear end cover to abut against the connecting base;

[0014] Two metal springs, one of which is sleeved on the inner sleeve of the front cavity, and the other is sleeved on the inner sleeve of the rear cavity;

[0015] a connecting screw connected to the threaded section of the piston rod;

[0016] a throttle valve pipeline, through which the front cavity and the rear cavity are connected, 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 joint.

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

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

[0020] In at least one embodiment of the present application, the number of the connecting rods is four.

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

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

[0023] In at least one embodiment of the present 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 structure fatigue test buffer restraint device of the present application can effectively release the structural displacement caused by load imbalance while ensuring test safety and load application accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of a buffer restraint device for fatigue testing of an aircraft structure according to one embodiment of the present application;

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

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

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

[0030] Figure 5 This is a schematic diagram of the layout of the nose heading and lateral restraint points of a full-aircraft fatigue testing machine according to one embodiment of the present 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 joint. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0034] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.

[0035] The following is combined with Figures 1 to 5 This application is described in further detail.

[0036] The present application provides a buffer constraint device for aircraft structure fatigue test, which provides a buffer constraint, 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 load-bearing frame, and the test load-bearing frame preferably adopts a steel skeleton 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, and the force sensor 3 is connected to the aircraft constraint point through the connecting joint 4. The connecting joint 4 can be a double-ear joint or a single-ear 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 mounted on both ends of the outer sleeve 22. A plurality of connecting rods 25 are provided, connecting the front cover 23 and the rear cover 24 to the connection base 1. In this embodiment, the front cover 23 and the rear cover 24 are both square, and there are four connecting rods 25.

[0040] Four discs are mounted on the piston rod 26, wherein the two middle discs are fixed discs (such as Figure 4As shown, it is fixedly connected to the piston rod 26. The two discs on either side are movable discs, movably connected to the piston rod 26. The piston rod 26 is set in the cavity. The fixed disc divides the cavity into a front cavity and a rear cavity. The piston rod 26 between the two discs in the front cavity and the rear cavity is respectively sleeved with an inner sleeve 21. One end of the piston rod 26 extends from the front end cover 23 and is provided with a threaded section. The other end extends from the rear end cover 24 and abuts against the connection base 1. There are two metal springs 27, one metal spring 27 sleeved on the inner sleeve 21 of the front cavity, and the other metal spring 27 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. The front cavity and the rear cavity are connected by a throttle valve pipe 29, which is provided with a throttle valve 210. In this embodiment, a sealing ring is provided between the disc and the outer sleeve 22. When not in operation, a set gap is reserved between the inner sleeve 21 and the two discs.

[0041] In the preferred embodiment of the present application, a constraint mode is provided for the fatigue test of the whole aircraft. The aircraft constraint points include the nose heading constraint point and the nose lateral constraint point. The specific constraint form is as follows: Figure 5 shown.

[0042] In the aircraft structure fatigue test buffer constraint device of the present application, the piston rod 26 of the spring damper buffer module 2 is designed with two disc groups, each disc group includes a fixed disc and a movable disc, and a filling seal ring is used between the disc and the outer sleeve 22 to improve the sealing performance. The two fixed discs in the middle separate the cavity into a front cavity and a rear cavity, and the front and rear cavities are connected through a throttle valve pipe 29. One end of the piston 26 protruding from the front cavity is designed with a threaded section to match the connecting screw 28, and the other end slides in the confined space in the rear cavity. The parts of the piston rod 26 located in the front and rear cavities are both installed with an inner sleeve 21, and a certain gap is left between the inner sleeve 21 and the disc group and the end cover. This gap 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 via a throttle valve pipe 29. Hydraulic oil is injected into the front and rear cavities through a reserved hole above the throttle valve pipe 29 and then sealed. This allows the metal spring 27 to be placed in the cavity oil, which acts as a damper for the movement of the metal spring 27. The throttle valve 210 adjusts the oil flow in the front and rear cavities to control the movement speed of the metal spring 27, ensuring stable and safe release of the displacement of the restraint part.

[0043] In the aircraft structure fatigue test buffer constraint device of the present application, the model of the metal spring 27 of the spring damper buffer module 2 is designed according to the buffer force and buffer displacement; oil is filled into the two cavities through the throttle pipe 29 and the throttle valve 210, and the oil flow rate is adjusted by the throttle valve 210 to apply damping to the movement of the metal spring 27, and the contraction speed of the metal spring 27 is controlled to ensure the stability and safety of the release of the constraint part displacement, while absorbing the energy in the displacement change process; during the test, after the constraint part is subjected to the unbalanced load of the whole aircraft, the load is transmitted to the buffer constraint device through the joint connected to the aircraft, and the compression buffer constraint device releases part of the displacement to reduce the load on the constraint part; an appropriate maximum compression amount is set for the metal spring 27. When the unbalanced load of the whole aircraft is transmitted to the buffer constraint device to the maximum compression amount, the buffer constraint device can be regarded as a rigid body to effectively constrain the aircraft attitude, ensuring that the aircraft attitude meets the test requirements.

[0044] The aircraft structure fatigue test buffer restraint device of the present application is initially assembled, with the front and rear chamber metal springs 27 set to an initial compression amount. During the test, after the metal spring 27 at one end is compressed, the metal spring 27 at the other end releases its original compression amount. The initial compression amount is set based on calculation and analysis of different test requirements. During the test, the unbalanced heading load causes the test aircraft to tend to move along the heading. At this time, the buffer restraint device is compressed or stretched (the total compression amount is not greater than the reserved gap between the sleeve 21 in the rear chamber, and the total stretching amount is not greater than the reserved gap between the sleeve 21 in the front chamber, and the total compression or stretching amount is equal to the reserved gap). The disc on the piston rod 26 pushes the metal spring 27 along the heading. At the same time, the oil in the compressed chamber flows into the other chamber through the throttle valve 210. Under the action of the oil damping, the metal spring 27 moves smoothly. After reaching the displacement matching the current load, the metal spring 27 is no longer compressed, the test load reaches a new balance, 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 of the entire machine reaches equilibrium, the buffer restraint device slowly returns to its initial state under the drive of the metal spring 27.

[0045] The aircraft structure fatigue test buffer constraint device of the present application is suitable for the heading and lateral buffer constraints of full-size aircraft fatigue strength tests. It can reasonably release the displacement of the restraint parts during fatigue tests, reduce the additional damage caused by dynamic loads, ensure structural safety, and has strong versatility and easy installation.

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

Claims

1. A buffer restraint device for aircraft structure fatigue test, characterized in that: include: A connecting base (1), wherein the connecting base (1) is connected to the test bearing frame; A spring damper buffer module (2), the spring damper buffer module (2) comprising: The buffer cylinder comprises an inner sleeve (21) and an outer sleeve (22), wherein a cavity is formed between the outer sleeve (22) and the inner sleeve (21); A cover plate, comprising a front end cover (23) and a rear end cover (24), wherein the front end cover (23) and the rear end cover (24) are respectively mounted on two ends of the outer sleeve (22); Connecting rods (25), including a plurality of connecting rods (25), connecting the front end cover (23), the rear end cover (24) and the connecting base (1) via the plurality of connecting rods (25); A piston rod (26), wherein four discs are mounted on the piston rod (26), wherein the two middle discs are fixed discs fixedly connected to the piston rod (26), and the two discs on both sides are movable discs movably connected to the piston rod (26), the piston rod (26) is arranged in the cavity, the fixed discs divide the cavity into a front cavity and a rear cavity, the inner sleeve (21) is respectively sleeved 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 at the portion extending from the front end cover (23), and the other end is extended from the rear end cover (24) to abut against the connecting base (1); The metal springs (27) include two metal springs (27), 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), the connecting screw (28) being connected to the threaded section of the piston rod (26); a throttle valve pipe (29), communicating the front cavity with the rear cavity through the throttle valve pipe (29), and a throttle valve (210) is provided on the throttle valve pipe (29); A force sensor (3) is provided, one end of which is connected to the connecting screw (28), and the other end of which is connected to the aircraft restraint point via a connecting joint (4).

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

3. The aircraft structure fatigue test buffer restraint device according to claim 1, characterized in that: The front end cover (23) and the rear end cover (24) are both square.

4. The aircraft structure fatigue test buffer restraint device according to claim 1, characterized in that: The connecting rods (25) include four.

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

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

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

Images