A three-way loading test device for the upper joint of the nose landing gear

Abstract

This invention belongs to the technical field of fatigue testing of the upper joint of helicopter nose landing gear, and relates to a three-directional loading test device for the upper joint of nose landing gear. It includes a central shaft assembly, an X-axis loading system, a Z-axis loading system, and a Y-axis loading system. The central shaft assembly passes through the upper joint connection hole, is limited vertically by a limiting step, and is fixed by bolts. The Y-axis loading system is connected to the top of the central shaft assembly to achieve Y-axis loading. The X-axis loading system is connected to the central shaft assembly at symmetrical positions relative to the upper joint connection hole to achieve X-axis loading. The Z-axis loading system is connected to the central shaft assembly at symmetrical positions relative to the upper joint connection hole to achieve Z-axis loading. This invention relates to fatigue testing of the upper joint of helicopter nose landing gear, using actuators to apply test loads, applying loads to the upper joint of the nose landing gear in three directions.

Description

Technical Field

[0001] This invention belongs to the technical field of fatigue testing of the upper joint of helicopter nose landing gear, and relates to a three-way loading test device for the upper joint of nose landing gear. Background Technology

[0002] The nose landing gear upper joint is a crucial component of the helicopter's tricycle landing system. It bears the low and high cycle loads transmitted from the nose landing gear, and its failure can lead to landing system malfunction, thereby affecting the safety of helicopter takeoff and landing. In order to accurately locate the fatigue-prone areas and failure modes of the nose landing gear upper joint and to determine its service life, fatigue life testing must be performed on it.

[0003] After reviewing relevant domestic and international literature, no publicly available fatigue testing device for the nose landing gear upper joint has been found for reference. In order to solve the current problem of fatigue life assessment of the nose landing gear upper joint of helicopters and eliminate potential safety hazards during helicopter takeoff and landing, it is urgent to design a fatigue testing device for the nose landing gear upper joint of helicopters to conduct fatigue life assessment of the nose landing gear upper joint. Summary of the Invention

[0004] This invention proposes a three-directional loading test device for the upper joint of the nose landing gear, which applies loads in three directions to the upper joint of the nose landing gear for fatigue life assessment, thereby determining the fatigue-prone parts and failure modes of the upper joint of the nose landing gear and obtaining its service life.

[0005] The first aspect of this invention provides a fatigue testing device for the nose landing gear upper joint. The nose landing gear upper joint is subjected to directional FX, lateral FY, and vertical FZ flight loads during helicopter takeoff and landing. The test piece includes a support frame, a first support beam 1 and a second support beam 2 symmetrically arranged perpendicular to both sides of the support frame, and an upper joint connection hole provided at the connection between one of the support beams and the support frame. A limiting step is provided in the upper joint connection hole. The upper joint communicates with the upper joint connection hole, one end of which contacts the support beam, and the other end is fixedly connected to the support frame. A rectangular window is also provided on the support frame. The testing apparatus includes a central shaft assembly, an X-axis loading system, a Z-axis loading system, and a Y-axis loading system. The central shaft assembly passes through the machine connector connection hole, is limited vertically by a limiting step, and is fixed by bolts. The Y-axis loading system is connected to the top of the central shaft assembly to achieve Y-axis loading. The X-axis loading system is connected to the central shaft assembly at symmetrical positions relative to the machine connector connection hole to achieve X-axis loading. The Z-axis loading system is connected to the central shaft assembly at symmetrical positions relative to the machine connector connection hole to achieve Z-axis loading.

[0006] In one possible embodiment, a constraint system A is also included. Constraint system A is the most fundamental part of the three-way loading test device for the nose landing gear joint. It is bolted to the factory floor rails and is used to withstand enormous test loads. It includes a test piece fixing unit, an X-axis loading system fixing unit, a Z-axis loading system fixing unit, and a Y-axis loading system fixing unit. The bottom end of the test piece fixing unit is fixedly connected to the ground, and the test piece is fixed inside the test piece fixing unit. The Y-axis loading system fixing unit is fixed to the top end of the test piece fixing unit. The fixing ends of the X-axis loading system, Z-axis loading system, and Y-axis loading system are respectively fixedly connected to the X-axis loading system fixing unit, Z-axis loading system fixing unit, and Y-axis loading system fixing unit fixed to the ground.

[0007] In one possible implementation, the test piece fixing unit includes a base plate A1 and a column A5. The base plate A1 is a rectangular steel plate with a certain thickness. The base plate A1 has two sets of 16 M24 threaded holes each. One set is fixed to the column A5 by connecting bolts. The column A5 has 8 sets of through holes, which are used to fix the 8 brackets B1 of the connecting system B by connecting bolts. The other set is fixed to the gantry B3 of the connecting system B. In addition, the base plate A1 also has 8 φ40 through holes, which are used to fix the base plate A1 to the factory floor rail. In one possible embodiment, the Y-direction loading system fixing unit includes an upper top plate A2, which is used to connect to the fixing end of the Y-direction loading system.

[0008] In one possible embodiment, the X-axis loading system fixing unit includes a stand A3; the Z-axis loading system fixing unit includes a stand A4. Stands A3 and A4 are welded components made of steel plates, shaped steel and square steel, etc., and are used to fix the X-axis loading system and the Z-axis loading system, respectively.

[0009] In one possible embodiment, a connection system B is also included. Connection system B is the force transmission system of the three-way loading test device for the nose landing gear upper joint, acting as a bridge for load transfer, primarily transmitting the test load generated by the loading system to the constraint system A. It includes a bracket B1, a base B2, and a gantry B3. The bracket B1 is a welded component with a triangular front view, formed by welding multiple flat plates. One end has a through hole for fixing to the column A5, and the other end is fixed to the nose landing gear upper joint via connecting bolts. The base B2 consists of two sets of L-shaped steel plates, each set containing two L-shaped steel plates. Each L-shaped steel plate has two types of through holes; one type is used for connection and fixation to the gantry B3, and the other type is used for connection and fixation to the nose landing gear upper joint. One end of one set of L-shaped steel plates of the base B2 is fixed to the gantry B3 via connecting bolts, and the other end is fixed to the nose landing gear upper joint via connecting bolts. The first support beam 1 and the second support beam 2 of the upper joint of the landing gear are fixed. One end of another set of L-shaped steel plates is fixed to the gantry B3 by connecting bolts, and the other end is fixed to the support frame of the upper joint of the front landing gear by connecting bolts. At the same time, the L-shaped steel plate of the base B2 is provided with an obstacle avoidance through hole structure. The gantry B3 structure is mainly welded from flat plates and square steel. The front view is a gate structure, and the left view is a right triangle. A steel plate is welded on the gate structure. The steel plate is provided with multiple through holes for connection and fixation with the base B2. At the same time, the steel plate is also provided with two sets of irregular through holes to make room for the Fz loading mechanism C3 of the loading system C.

[0010] In one possible embodiment, the X-axis loading system is a double-fork structure, including a spherical bearing C1-1 with a handle, a double fork lug C1-2, a single fork lug C1-3, a double rod C1-4, and a connecting joint C1-5; the double fork lug end of the X-axis loading system is connected to an actuator for loading loads in the Fx direction.

[0011] In one possible embodiment, the shank bearing end of the X-axis loading system is fixed to the Y-axis loading system. The overall layout of the Y-axis loading system is based on a central shaft as the core component. On the central shaft C2-1, a single fork lug C2-2, a double fork lug C2-3, a spacer sleeve C2-4, a flange C2-5, a fixing bolt C2-6, and a special nut C2-7 are installed. The central shaft of the Y-axis loading system is a stepped shaft with a higher center and lower sides. Threads are provided on both ends of the shaft. The outer surface of the raised cylinder in the middle mates with the inner cylindrical surface of the front landing gear upper connector. The flange C2-5 is provided with countersunk square holes for fixing the connecting bolts. At the same time, the raised cylinder in the middle of the Y-axis loading system is provided with 8 through holes for connecting the central shaft and the flange to the front landing gear upper connector through fixing bolts.

[0012] In one possible embodiment, the loading ends of the X-axis loading system and the Z-axis loading system are fixed to the central shaft C2-1 of the Y-axis loading system by spacer sleeves and special nuts. The connection end between the Z-axis loading system and the actuator is a hinged structure composed of double fork lugs C3-1, connecting bolts C3-2, and connecting joints C3-3. The loading end of the Z-axis loading system consists of two sets of loading arms, each set of loading arms having a connecting rod C3-4, a double fork lug structure connecting joint C3-5, and a fixing bolt C3-6, forming a coupled double fork arm structure.

[0013] Beneficial technical effects of the present invention: This invention proposes a three-directional loading test device for the upper joint of the nose landing gear, relating to fatigue testing of the upper joint of the helicopter nose landing gear. It employs an actuator to apply test loads through three directions to the upper joint of the nose landing gear, simulating the actual boundary conditions and load characteristics of the upper joint during installation. This provides a realistic and accurate fatigue test environment for the upper joint, allowing for accurate identification of fatigue-prone areas and failure modes, thus providing a test basis for determining its service life. Furthermore, this invention designs the lateral load Fy to be applied vertically and the vertical load Fz to be applied horizontally, achieving… The invention achieves stable loading of the hinged structure in the tensile direction, solving the problem of easy instability in the compressive direction. Regarding the fixing of the upper joint of the nose landing gear, the invention adopts a separate design, using eight brackets B1 for installation and fixing, avoiding the interference problem that the azimuth load Fx cannot be applied, and solving the practical installation engineering difficulties such as the lack of operating space for applying tightening torque. In addition, in order to achieve symmetrical application of the vertical load Fz on the central axis of the Fy loading mechanism C2 and solve the interference problem caused by the structure, the invention innovatively proposes a coupled double fork arm structure design, realizing coordinated loading of the upper joint of the nose landing gear in three directions, overcoming technical difficulties and saving the cost of test equipment.

[0014] The three-way loading test device for the nose landing gear upper joint of this invention has an ingenious structural design, which facilitates installation and disassembly. It solves several technical difficulties in three-way loading of the nose landing gear upper joint and can be used to conduct fatigue tests on the nose landing gear upper joint. At the same time, the design of this device follows the load characteristics and installation boundary requirements of the nose landing gear upper joint on the helicopter, and realistically and accurately simulates the load of the nose landing gear upper joint under the working conditions of helicopter takeoff, landing and ground taxiing. It effectively solves the problem of the lack of domestic nose landing gear upper joint fatigue test devices, fills the technical gap in the field of helicopter fatigue testing in China, and further enhances the level of helicopter strength testing in my country. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the test joint structure of the nose landing gear; Figure 2 This is a schematic diagram of an overall fatigue testing device for the upper joint of a nose landing gear aircraft. Figure 3 This is a schematic diagram showing the connection between the X-axis loading system, Z-axis loading system, Y-axis loading system and the test joint of the nose landing gear; Figure 4 This is a schematic diagram of the gantry B3 structure in connection system B; Figure 5 This is a schematic diagram of the X-axis loading system structure; Figure 6 This is a schematic diagram of the Y-axis loading system structure. Figure 7 This is a schematic diagram of the Z-axis loading system structure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0019] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0021] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] Figure 1 This is a schematic diagram of the structure of the front landing gear upper connector, which is the subject of the research of the device of this invention. Figures 2-7 The following is a schematic diagram of the device structure of the present invention, and the present invention will be further described in detail below.

[0024] The technical solution of this invention relates to a fatigue testing device for the upper joint of a nose landing gear, comprising a constraint system A, a connection system B, and a loading system C. The constraint system A is the most fundamental part of the three-way loading testing device for the upper joint of the nose landing gear. It is fixed to the factory floor rails by bolts and is used to withstand huge test loads. It mainly consists of a base plate A1, a platform A2, a platform A3, and a platform A4. The connection system B is the force transmission system of the three-way loading testing device for the upper joint of the nose landing gear, acting as a bridge for load transfer. It mainly transmits the test load generated by the loading system C to the constraint system A. It mainly consists of a support B1, a base B2, and a gantry B3. The loading system C is the core part of the three-way loading testing device for the upper joint of the nose landing gear. It consists of three loading mechanisms: Fx loading mechanism C1, Fy loading mechanism C2, and Fz loading mechanism C3. These mechanisms apply test loads to the upper joint of the nose landing gear from three directions, thereby achieving fatigue life assessment of the upper joint of the nose landing gear.

[0025] The constraint system A mainly consists of a base plate A1, a frame A2, a frame A3, and a frame A4. The base plate A1 is a rectangular steel plate of a certain thickness. The base plate A1 has two sets of 16 M24 threaded holes each. One set is fixed to the frame A2 by connecting bolts, and the other set is fixed to the gantry B3 of the connection system B. In addition, the base plate A1 also has 8 φ40 through holes, which are used to fix the base plate A1 to the factory floor rail. The frame A2 mainly consists of 4 columns and an upper top plate. The upper top plate is used to connect the fixed end of the Fy loading mechanism C2. The columns have 8 sets of through holes, which are used to fix the 8 supports B1 of the connection system B by connecting bolts. The frames A3 and A4 are welded components made of steel plates, shaped steel, and square steel, and are used to fix the Fx loading mechanism C1 and Fz loading mechanism C3 of the loading system C, respectively.

[0026] The connection system B mainly consists of a bracket B1, a base B2, and a gantry B3. The bracket B1 is a welded component with a triangular front view, formed by welding multiple flat plates. One end has a through hole for fixing to the column of the platform A2, and the other end is fixed to the front landing gear upper connector by connecting bolts. Meanwhile, the L-shaped steel plate of the base B2 has an obstacle avoidance through hole structure. The base B2 is composed of two sets of L-shaped steel plates, each set having two L-shaped steel plates. Each L-shaped steel plate has two types of through holes. One set is fixed to the gantry B3 by connecting bolts, and the other set is connected and fixed to the front landing gear upper connector. The gantry B3 structure is mainly welded from flat plates and square steel. The front view is a gate structure, and the left view is a right-angled triangle. A steel plate is welded on the gate structure. The steel plate has multiple through holes for connecting and fixing to the base B2. At the same time, the steel plate also has two sets of irregular through holes to provide clearance space for the loading system C3.

[0027] The loading system C mainly consists of Fx loading mechanism C1, Fy loading mechanism C2, and Fz loading mechanism C3. Fx loading mechanism C1 is a double-fork arm structure, consisting of a specially designed spherical bearing with a handle, double fork lugs, a single fork lug, double rods, and a connecting joint. One end of the double fork lug is connected to an actuator for loading the load in the Fx direction, and the double rods and the spherical bearing with a handle are fixed to the Fy loading mechanism C2. The overall layout of Fy loading mechanism C2 is centered on a central shaft, on which a single fork lug, double fork lug, spacer sleeve, flange, fixing bolts, and specially designed nuts are installed. The central shaft of the Fy loading mechanism C2 is a stepped shaft with a higher center and lower sides. Threads are installed at both ends of the shaft. The outer surface of the centrally protruding cylinder mates with the inner cylindrical surface of the front landing gear upper connector. Simultaneously, eight through holes on the centrally protruding cylinder of the Fy loading mechanism C2 are used to connect the central shaft and flange to the front landing gear upper connector via fixing bolts. Finally, the loading ends of the Fx loading mechanism C1 and Fz loading mechanism C3 are fixed to the central shaft of the Fy loading mechanism C2 using spacer sleeves and special nuts. The connection end of the Fz loading mechanism C3 to the actuator is a hinged structure composed of double fork lugs, connecting bolts, and connecting joints. The loading end of the Fz loading mechanism C3 consists of two sets of loading arms, each with a connecting rod, a double fork lug structure connecting joint, and fixing bolts, forming a coupled double fork arm structure.

[0028] In summary, the calibration device has an ingenious structural design, is easy to install and disassemble, and provides accurate test loading results, enabling it to complete the fatigue life assessment of the nose landing gear upper joint.

[0029] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A fatigue testing device for the upper joint of a nose landing gear, characterized in that, It includes a central shaft assembly, an X-axis loading system, a Z-axis loading system, and a Y-axis loading system. The central shaft assembly passes through the machine-mounted connector connection hole, is limited vertically by a limiting step, and is fixed by bolts. The Y-axis loading system is connected to the top of the central shaft assembly to achieve Y-axis loading. The X-axis loading systems are connected to the central shaft assembly at symmetrical positions relative to the machine-mounted connector connection hole to achieve X-axis loading. The Z-axis loading systems are connected to the central shaft assembly at symmetrical positions relative to the machine-mounted connector connection hole to achieve Z-axis loading.

2. The fatigue testing device for the upper joint of the nose landing gear according to claim 1, characterized in that, It also includes a constraint system A, comprising a test specimen fixing unit, an X-axis loading system fixing unit, a Z-axis loading system fixing unit, and a Y-axis loading system fixing unit; the bottom end of the test specimen fixing unit is fixedly connected to the ground, and the test specimen is fixed inside the test specimen fixing unit; the Y-axis loading system fixing unit is fixed to the top end of the test specimen fixing unit; the fixing ends of the X-axis loading system, Z-axis loading system, and Y-axis loading system are respectively fixedly connected to the X-axis loading system fixing unit, Z-axis loading system fixing unit, and Y-axis loading system fixing unit fixed to the ground.

3. The fatigue testing device for the upper joint of the nose landing gear according to claim 2, characterized in that, The test piece fixing unit includes a base plate A1 and a column A5. The base plate A1 is a rectangular steel plate with a certain thickness. The base plate A1 has two sets of 16 M24 threaded holes. One set is fixed to the column A5 by connecting bolts. The column A5 has 8 sets of through holes, which are used to fix the 8 brackets B1 of the connection system B by connecting bolts. The other set is fixed to the gantry B3 of the connection system B. In addition, the base plate A1 also has 8 φ40 through holes, which are used to fix the base plate A1 to the factory floor rail.

4. The fatigue testing device for the upper joint of the nose landing gear according to claim 2, characterized in that, The Y-direction loading system fixing unit includes an upper top plate A2, which is used to connect to the fixing end of the Y-direction loading system.

5. The fatigue testing device for the upper joint of the nose landing gear according to claim 2, characterized in that, The X-axis loading system fixing unit includes a frame A3; the Z-axis loading system fixing unit includes a frame A4. Frames A3 and A4 are welded components made of steel plates, shaped steel and square steel, etc., and are used to fix the X-axis loading system and the Z-axis loading system, respectively.

6. The fatigue testing device for the upper joint of the nose landing gear according to claim 1, characterized in that, It also includes a connection system B, comprising a bracket B1, a base B2, and a gantry B3. The bracket B1 is a welded component with a triangular front view, formed by welding multiple flat plates. One end has a through hole for fixing to the column A5, and the other end is fixed to the front landing gear upper connector via connecting bolts. The base B2 consists of two sets of L-shaped steel plates, each set containing two L-shaped steel plates. Each L-shaped steel plate has two types of through holes; one type is used for connection and fixing to the gantry B3, and the other type is used for connection and fixing to the front landing gear upper connector. One end of one set of L-shaped steel plates of the base B2 is fixed to the gantry B3 via connecting bolts, and the other end is fixed to the gantry B3 via connecting bolts. The first support beam 1 and the second support beam 2 of the front landing gear are fixed to the upper joint of the bolt. One end of another set of L-shaped steel plates is fixed to the gantry B3 by connecting bolts, and the other end is fixed to the support frame of the upper joint of the front landing gear by connecting bolts. At the same time, the L-shaped steel plate of the base B2 is provided with an obstacle avoidance through hole structure. The gantry B3 structure is mainly welded from flat plates and square steel. The front view is a gantry structure, and the left view is a right triangle. A steel plate is welded on the gantry structure. The steel plate is provided with multiple through holes for connection and fixation with the base B2. At the same time, the steel plate is also provided with two sets of irregular through holes to make room for the Fz loading mechanism C3 of the loading system C.

7. The fatigue testing device for the upper joint of the nose landing gear according to claim 1, characterized in that, The X-axis loading system is a double-fork arm structure, including a spherical bearing C1-1 with a handle, a double fork lug C1-2, a single fork lug C1-3, a double rod C1-4, and a connecting joint C1-5; the double fork lug end of the X-axis loading system is connected to an actuator for loading loads in the Fx direction.

8. The fatigue testing device for the upper joint of the nose landing gear according to claim 1, characterized in that, The shank bearing end of the X-axis loading system is fixed to the Y-axis loading system. The overall layout of the Y-axis loading system is based on the central shaft as the core component. On the central shaft C2-1, a single fork lug C2-2, a double fork lug C2-3, a spacer sleeve C2-4, a flange C2-5, a fixing bolt C2-6, and a special nut C2-7 are installed. The central shaft of the Y-axis loading system is a stepped shaft with a higher center and lower sides. Threads are provided on both ends of the shaft. The outer surface of the raised cylinder in the middle mates with the inner cylindrical surface of the front landing gear upper connector. The flange C2-5 has countersunk square holes for fixing the connecting bolts. At the same time, the raised cylinder in the middle of the Y-axis loading system has 8 through holes for connecting the central shaft and flange to the front landing gear upper connector through fixing bolts.

9. A fatigue testing device for the upper joint of a nose landing gear according to claim 1, characterized in that, The loading ends of the X-axis loading system and the Z-axis loading system are fixed to the central shaft C2-1 of the Y-axis loading system by spacer sleeves and special nuts. The connection end between the Z-axis loading system and the actuator is a hinged structure composed of double fork lugs C3-1, connecting bolts C3-2 and connecting joints C3-3. The loading end of the Z-axis loading system consists of two sets of loading arms. Each set of loading arms has a connecting rod C3-4, a double fork lug structure connecting joint C3-5 and a fixing bolt C3-6, forming a coupled double fork arm structure.

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