A flexible beam fatigue test loading device

Abstract

The present application belongs to the technical field of fatigue test, and discloses a flexible beam fatigue test loading device, which comprises a flexible beam joint, an actuating cylinder and a centrifugal force loading structure. The front end of the flexible beam joint is connected with a flexible beam so that the flexible beam is fixed relative to the flexible beam joint. The rear end of the flexible beam joint is provided with an eccentric shaft. The front end of the actuating cylinder is a joint with a knuckle bearing. The joint is rotatably connected to the eccentric shaft of the flexible beam joint. The eccentric structure is used to apply a pendulum force and a flapping force to the flexible beam. The centrifugal force loading structure is indirectly connected to the flexible beam joint and applies a simulated centrifugal force to the flexible beam. The present application has a simple structure and is convenient to disassemble and assemble. The flapping force and the pendulum force for the helicopter flexible beam can be simulated simultaneously by using one actuating cylinder, and the real working condition of the helicopter flexible beam can be simulated.

Description

Technical Field

[0001] This invention belongs to the field of fatigue testing technology and relates to a fatigue testing device, specifically a fatigue testing loading device for a flexible beam of a helicopter. Background Technology

[0002] Flexible beams are crucial load-bearing components in helicopters, subjected to complex stress environments. To understand their strength and fatigue life, it is essential to conduct tests to determine their fatigue characteristics and ultimately their lifespan. During testing, the stress state of the flexible beam on a helicopter must be simulated.

[0003] Currently, my country uses the three-point bending test method for fatigue testing of flexible beams. This method cannot apply swaying loads according to the actual load conditions of the flexible beam, and the test frequency is relatively low, which cannot simulate the actual working conditions of high-frequency vibration of the flexible beam. Summary of the Invention

[0004] The purpose of this invention is to solve the above problems by providing a loading device for fatigue testing of flexible beams, which can meet the requirements of complex load loading of flexible beams and achieve the purpose of evaluating the fatigue performance of flexible beams.

[0005] The technical solution of the present invention:

[0006] A loading device for fatigue testing of a flexible beam includes a flexible beam joint, an actuating cylinder, and a centrifugal loading structure. The front end of the flexible beam joint is connected to a flexible beam, fixing the flexible beam relative to the joint. An eccentric shaft is provided at the rear end of the joint. The front end of the actuating cylinder is a joint with a spherical bearing. The joint is rotatably connected to the eccentric shaft of the joint. The eccentric structure applies a swinging force and a flapping force to the flexible beam. The centrifugal loading structure is indirectly connected to the joint and applies a simulated centrifugal force to the beam.

[0007] Furthermore, it also includes a connecting shaft, an upper connecting plate, and a lower connecting plate. The connecting shaft passes through the flexible beam joint from top to bottom. One end of the upper connecting plate is connected to the upper end of the shaft, and the other end of the upper connecting plate is connected to the centrifugal loading structure. One end of the lower connecting plate is connected to the lower end of the shaft, and the other end of the lower connecting plate is connected to the centrifugal loading structure.

[0008] Furthermore, the connecting shaft can rotate within the flexible beam joint.

[0009] Furthermore, the centrifugal force loading structure includes a disc connecting shaft and a disc. The disc connecting shaft is located between the upper connecting plate and the lower connecting plate. The disc is rotatably mounted on the disc connecting shaft. The outer edge of the disc has a groove. The force loading machine provides tension to the disc by a steel wire rope wound in the groove of the disc to simulate centrifugal force.

[0010] Furthermore, the upper and lower connecting plates are connected to the connecting shaft and the disc connecting shaft via spherical bearings.

[0011] Furthermore, the flexible beam joint is connected to the connecting shaft via bearings, and the discs are connected to each other via bearings.

[0012] Furthermore, the center plane of the flexible beam joint is on the same plane as the center plane between the upper and lower connecting plates, and the wire rope is also located on the center plane between the upper and lower connecting plates; the eccentric shaft is eccentrically positioned upwards or downwards at a certain distance relative to the center plane of the flexible beam joint.

[0013] Furthermore, the flexible beam joint cannot move up or down relative to the connecting shaft, and the disc cannot move up or down relative to the disc connecting shaft.

[0014] The beneficial effects of this invention are:

[0015] 1. The present invention has a simple structure, is easy to assemble and disassemble, and can meet the load loading requirements during fatigue testing of flexible beams.

[0016] 2. This invention can simultaneously simulate the flapping force and oscillation force of a helicopter's flexible beam using a single actuator. Compared to the method of applying force using two actuators, this invention can prevent mutual interference that may occur when different actuators move, the input control parameters are simpler, and the simulation accuracy is higher.

[0017] 3. This invention can automatically adjust the interference of deformation caused by the changes in the flexible beam during its movement on the loading lever arm, thereby further improving the accuracy of the simulation. Attached Figure Description

[0018] Figure 1 This is a front view of the structure of the present invention;

[0019] Figure 2 This is a top view of the structure of the present invention;

[0020] Among them, 1—flexible beam joint, 2—connecting shaft, 3—upper connecting plate, 4—upper left nut, 5—upper right nut, 6—disc connecting shaft, 7—disc, 8—wire rope, 9—lower connecting plate, 10—lower right nut, 11—lower left nut. Detailed Implementation

[0021] 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, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] A loading device for fatigue testing of a flexible beam includes a flexible beam joint 1, an actuating cylinder, and a centrifugal loading structure. The front end of the flexible beam joint 1 is connected to a flexible beam, making the flexible beam fixed relative to the flexible beam joint 1. The rear end of the flexible beam joint 1 is provided with an eccentric shaft a. The front end of the actuating cylinder is a joint with a joint bearing. The joint is rotatably connected to the eccentric shaft a of the flexible beam joint 1. The eccentric structure applies a swinging force and a flapping force to the flexible beam. The centrifugal loading structure is indirectly connected to the flexible beam joint 1 and applies a simulated centrifugal force to the flexible beam.

[0023] It also includes a connecting shaft 2, an upper connecting plate 3 and a lower connecting plate 9. The connecting shaft 2 passes through the flexible beam joint 1 vertically. One end of the upper connecting plate 3 is connected to the upper end of the shaft 2, and the other end of the upper connecting plate 3 is connected to the centrifugal loading structure. One end of the lower connecting plate 9 is connected to the lower end of the shaft 2, and the other end of the lower connecting plate 9 is connected to the centrifugal loading structure.

[0024] The connecting shaft 2 can rotate within the flexible beam joint 1. This design is intended to allow the flexible beam joint 1 to self-adjust its angle when the flexible beam deforms due to the oscillation force, so that the flexible beam joint 1 and the actuator cylinder do not generate a new lever arm, thus eliminating the need to consider the deformation effect when inputting oscillation simulation parameters.

[0025] The centrifugal force loading structure includes a disc connecting shaft 6 and a disc 7. The disc connecting shaft 6 is located between the upper connecting plate 3 and the lower connecting plate 9. The disc 7 is rotatably mounted on the disc connecting shaft 6. The outer edge of the disc 7 is provided with a groove. The force loading machine provides tension to the disc 7 by means of a steel wire rope 8 wound in the groove of the disc 7 to simulate centrifugal force.

[0026] The upper connecting plate 3 and the lower connecting plate 9 are connected to the connecting shaft 2 and the disc connecting shaft 6 via spherical bearings.

[0027] The flexible beam joint 1 is connected to the connecting shaft 2 by bearings, and the disc 7 is connected to the disc connecting shaft 6 by bearings.

[0028] The center plane of the flexible beam joint 1 is on the same plane as the center plane between the upper connecting plate 3 and the lower connecting plate 9. The wire rope 8 is also located on the center plane between the upper connecting plate 3 and the lower connecting plate 9. The eccentric shaft a is eccentrically positioned upwards or downwards relative to the center plane of the flexible beam joint 1 by a certain distance. The magnitude of the eccentric bending moment is controlled by the eccentric distance of the eccentric shaft a.

[0029] The flexible beam joint 1 cannot move up or down relative to the connecting shaft 2, and the disc 7 cannot move up or down relative to the disc connecting shaft 6.

[0030] Another embodiment of the present invention will now be described with reference to the accompanying drawings.

[0031] To achieve the above-mentioned objective, a flexible beam fatigue test loading device is provided, characterized in that it includes a flexible beam joint 1, a connecting shaft 2, an upper connecting plate 3, an upper left nut 4, an upper right nut 5, a disc connecting shaft 6, a disc 7, a wire rope 8, a lower connecting plate 9, a lower right nut 10, and a lower left nut 11.

[0032] The flexible beam joint 1 has a hole in the middle, and the connecting shaft 2 is inserted into the hole of the flexible beam joint 1 and fixed. The upper connecting plate 3 has holes at both ends, which are connected to the connecting shaft 2 and the disc connecting shaft 6 respectively, and fixed by the upper left nut 4 and the upper right nut 5. The disc 7 has a hole in the center, and the disc connecting shaft 6 is inserted into the hole on the disc 7 and fixed. The outer edge of the disc 7 has a groove, through which the wire rope 8 is connected to the disc 7. The lower connecting plate 9 has holes at both ends, which are connected to the connecting shaft 2 and the disc connecting shaft 6 respectively, and fixed by the lower left nut 11 and the lower right nut 10.

[0033] In one possible embodiment, spherical bearings are fitted onto the upper connecting plate 3 and the lower connecting plate 9, respectively, and the spherical bearings are installed in the holes at both ends of the upper connecting plate 3 and the lower connecting plate 9, in order to make the rotation more flexible and smooth.

[0034] In one possible embodiment, a bearing is installed in the intermediate hole of the flexible beam joint 1 to make the rotation more flexible and smooth.

[0035] In one possible embodiment, the central hole of the disk 7 is fitted with a bearing, which enables more flexible and smooth movement.

[0036] In one possible embodiment, the upper connecting plate 3 and the lower connecting plate 9 are symmetrical, with the symmetry plane being the center of the wire rope 8, in order to reduce the eccentric torque.

[0037] In one possible embodiment, the wire rope 8 can be replaced with a chain.

[0038] In one possible embodiment, the flexible beam joint 1 and the eccentric shaft (a) can be connected by means of threaded connection, welding or the like.

[0039] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A loading device for fatigue testing of a flexible beam, characterized in that, The device includes a flexible beam joint (1), an actuator cylinder, and a centrifugal loading structure. The front end of the flexible beam joint (1) is connected to the flexible beam so that the flexible beam is fixed relative to the flexible beam joint (1). The rear end of the flexible beam joint (1) is provided with an eccentric shaft (a). The front end of the actuator cylinder is a joint with a joint bearing. The joint is rotatably connected to the eccentric shaft (a) of the flexible beam joint (1). The eccentric structure applies a swinging force and a flapping force to the flexible beam. The eccentric shaft (a) is eccentrically positioned upward or downward relative to the center surface of the flexible beam joint (1) by a certain distance. The magnitude of the eccentric bending moment is controlled by the eccentric distance of the eccentric shaft (a). The centrifugal loading structure is indirectly connected to the flexible beam joint (1) and applies a simulated centrifugal force to the flexible beam. It also includes a connecting shaft (2), an upper connecting plate (3) and a lower connecting plate (9). The connecting shaft (2) passes through the flexible beam joint (1) from top to bottom. One end of the upper connecting plate (3) is connected to the upper end of the shaft (2), and the other end of the upper connecting plate (3) is connected to the centrifugal loading structure. One end of the lower connecting plate (9) is connected to the lower end of the shaft (2), and the other end of the lower connecting plate (9) is connected to the centrifugal loading structure. The connecting shaft (2) can rotate within the flexible beam joint (1).

2. The loading device for fatigue testing of a flexible beam according to claim 1, characterized in that, The centrifugal loading structure includes a disc connecting shaft (6) and a disc (7). The disc connecting shaft (6) is located between the upper connecting plate (3) and the lower connecting plate (9). The disc (7) is rotatably mounted on the disc connecting shaft (6). The outer edge of the disc (7) is provided with a groove. The force loading machine provides tension to the disc (7) through a steel wire rope (8) wound in the groove of the disc (7) to simulate centrifugal force.

3. The loading device for fatigue testing of a flexible beam according to claim 2, characterized in that, The upper connecting plate (3) and the lower connecting plate (9) are connected to the connecting shaft (2) and the disc connecting shaft (6) through spherical bearings.

4. The loading device for fatigue testing of a flexible beam according to claim 2, characterized in that, The flexible beam joint (1) is connected to the connecting shaft (2) by a bearing, and the disc (7) is connected to the disc connecting shaft (6) by a bearing.

5. The loading device for fatigue testing of a flexible beam according to claim 2, characterized in that, The center plane of the flexible beam joint (1) is the same plane as the center plane between the upper connecting plate (3) and the lower connecting plate (9). The wire rope (8) is also located on the center plane between the upper connecting plate (3) and the lower connecting plate (9). The eccentric shaft (a) is eccentrically positioned upward or downward relative to the center plane of the flexible beam joint (1) by a certain distance.

6. The loading device for fatigue testing of a flexible beam according to claim 2, characterized in that, The flexible beam joint (1) cannot move up or down relative to the connecting shaft (2), and the disc (7) cannot move up or down relative to the disc connecting shaft (6).

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