A calibration device and method for a flexible beam of a helicopter tail rotor

Abstract

The application provides a helicopter tail rotor flexible beam calibration device, the device comprises: a calibration platform fixed on the ground; a connecting block arranged on the calibration platform; wherein the connecting block comprises a first surface and a second surface, the first surface and the second surface are adjacent; a clamping tool for assembling a flexible beam test piece; wherein the assembled flexible beam test piece is fixed in the connecting block together with the clamping tool; meanwhile, the application also provides a helicopter tail rotor flexible beam calibration method; the calibration method provided by the application realizes the calibration of three kinds of loads of the flexible beam test piece, that is, the edgewise bending moment, the flapwise bending moment and the torsion moment, obtains the calibration coefficient of the corresponding load of the flexible beam test piece, and can be used for measuring and debugging the test load in the fatigue test process of the flexible beam test piece, and calculating the rigidity and deformation of the flexible beam; the calibration device provided by the application adopts the overall structure design of the test platform, is stable in rigidity, has a wide application range, is convenient to install and disassemble, and has no redundant structure.

Description

Technical Field

[0001] This application belongs to the field of fatigue testing technology for the strength of flexible beams of helicopter tail rotors, and particularly relates to a calibration device and calibration method for a flexible beam of a helicopter tail rotor. Background Technology

[0002] As a key component of helicopter tail rotors, flexible beams require fatigue verification tests to assess their fatigue performance stability. In the swing fatigue test of flexible beams, in order to measure the swing bending moment, oscillation bending moment, and torque values ​​using strain gauges, calibration coefficients for different cross-sections of the flexible beam are needed to measure the stiffness and deformation of the flexible beam during the test.

[0003] The methods used in this technology are designed for components such as blades and wings, but cannot be used to calibrate the flexible beam of the helicopter tail rotor, including the calibration process for three test loads: flapping moment, oscillation moment, and torque.

[0004] Therefore, this application proposes a flexible beam calibration device and calibration method. Strain gauges are attached to different cross-sectional positions of the flexible beam. A certain swing moment, oscillation moment, and torque value are applied to the flexible beam through the calibration device. The strain values ​​are collected and recorded, and the calibration coefficients for each cross-section are calculated using a formula. Summary of the Invention

[0005] To address the aforementioned technical problems, in a first aspect, this application provides a helicopter tail rotor flexible beam calibration device, the device comprising:

[0006] The calibration platform is fixed to the ground.

[0007] A connecting block is disposed on the calibration platform; wherein the connecting block includes a first surface and a second surface, the first surface and the second surface being adjacent to each other;

[0008] A clamping fixture is used to assemble a flexible beam specimen; wherein the assembled flexible beam specimen is fixed together with the clamping fixture to the connecting block.

[0009] Preferably, the device further includes:

[0010] The small shaft is calibrated and connected to the metal clamps at both ends of the flexible beam specimen.

[0011] A suspension hook is connected to the calibration shaft;

[0012] Weights are set on the suspension hook; wherein, weights are applied in stages to calibrate the swing moment and oscillation moment.

[0013] Preferably, the assembled flexible beam specimen is fixed together with the clamping fixture on the first surface of the connecting block, and weights are applied in stages to calibrate the swing moment.

[0014] Preferably, the assembled flexible beam specimen is fixed together with the clamping fixture on the second side of the connecting block, and weights are applied in stages to calibrate the pendulum bending moment.

[0015] Preferably, the calibration platform is welded from square steel.

[0016] Preferably, the clamping fixture includes:

[0017] Upper clamping fixture;

[0018] The lower clamping fixture is connected to the upper clamping fixture by bolts and nuts.

[0019] Preferably, the device further includes:

[0020] The calibration shaft is connected to the metal clamps at both ends of the flexible beam specimen.

[0021] The calibration frame is set up on the ground;

[0022] A calibration disk is fixed on the calibration frame; wherein the calibration disk is connected to the calibration shaft via a flat key.

[0023] The steel cable is mounted on the calibration plate;

[0024] A hook is attached to the steel cable;

[0025] Weights are placed on the hook; wherein, the assembled flexible beam specimen is fixed together with the clamping fixture on the first side of the connecting block, and weights are applied in stages to achieve torque calibration.

[0026] Secondly, this application also provides a method for calibrating a flexible beam for a helicopter tail rotor, the method comprising:

[0027] Strain gauges were attached to different cross-sectional positions on the flexible beam specimen and connected to a dynamic data acquisition system via wires to measure the deformation generated by the specimen during calibration.

[0028] Check the function of the strain gauges and adjust their positions as needed to balance and eliminate the coupling of swinging moment and oscillation moment;

[0029] The flexible beam specimen was installed on a clamping fixture, which consisted of upper and lower parts connected by bolts and tightened with nuts.

[0030] The connecting block is fixed to the calibration table with bolts, and then the flexible beam specimen and the clamping fixture are installed together on the connecting block;

[0031] Waving moment calibration: Connect the metal clamps at both ends of the flexible beam specimen to the calibration shaft, suspend hooks on the calibration shafts on both sides, load weights in stages on the hooks, and collect the corresponding strain values ​​at the same time;

[0032] Vibration moment calibration: The flexible beam specimen and clamping fixture are installed on the side of the connecting block. Then, the metal clamps at both ends of the specimen are connected to the calibration shaft, and the hook is suspended. Weights are applied to the hook in stages, and the corresponding strain values ​​are collected at the same time.

[0033] Torque calibration: The calibration frame is connected to the metal clamp of the flexible beam specimen via the calibration shaft. The calibration disc is fixed on the calibration frame and connected to the calibration shaft via a flat key. Steel cables and hooks are suspended on the calibration disc, and weights are added in stages to apply a torque load.

[0034] This application has the following technical effects:

[0035] The calibration method provided in this application calibrates three types of loads on flexible beam specimens: swing moment, oscillation moment, and torque. It obtains the calibration coefficients for the corresponding loads on the flexible beam specimens, which can be used to measure and adjust the test loads during fatigue testing of flexible beam specimens, and to calculate the stiffness and deformation of the flexible beam. The calibration device provided in this application adopts an integrated test bench structure design, ensuring stable stiffness, wide applicability, easy installation and disassembly, and no redundant structures. Attached Figure Description

[0036] Figure 1 A schematic diagram of a flexible beam swing deformation segment swing moment calibration device provided in this application embodiment;

[0037] Figure 2 A schematic diagram of a flexible beam swing deformation segment swing vibration bending moment calibration device provided in this application embodiment;

[0038] Figure 3 This is a schematic diagram of a flexible beam swing deformation segment torque calibration device provided in an embodiment of this application. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-3 The present application will be further described in detail with reference to specific embodiments:

[0040] The flexible beam calibration device provided in this application is a test bench, which includes a calibration table, calibration frame, connecting block, clamping fixture, calibration plate, calibration shaft, calibration small shaft, hook and weights, etc., and can realize the calibration of three test loads: swing moment, oscillation moment and torque.

[0041] In this embodiment, the swing moment and oscillation moment calibration schemes are as follows: Before calibration, strain gauges are attached to different cross-sectional positions of the flexible beam specimen. Then, the specimen is connected to the clamping fixture and fixed together on the connecting block, which is then fixed to the calibration platform with bolts. Metal clamps at both ends of the flexible beam specimen are connected to the calibration shaft, and hooks are suspended on the calibration shafts on both sides. Weights are applied to the hooks in stages, and the corresponding strain values ​​are collected simultaneously using a dynamic data acquisition system. The torque calibration scheme is as follows: Before calibration, strain gauges are attached to different cross-sectional positions of the flexible beam specimen. Then, the specimen is connected to the clamping fixture and fixed together on the connecting block, which is then fixed to the calibration platform with bolts. Metal clamps at both ends of the flexible beam swing are connected to the calibration shaft, which is connected to the calibration plate via a flat key and fixed together on the calibration frame. Steel cables and hooks are suspended on the calibration plate, and weights are applied to the hooks in stages. The corresponding strain values ​​are collected simultaneously using a dynamic data acquisition system.

[0042] In other embodiments of this application, the flexible beam calibration method described in this application includes the following steps:

[0043] 1. Strain gauges are attached to different cross-sectional positions on the flexible beam specimen and connected to a dynamic data acquisition system via wires to measure the deformation generated by the specimen during calibration.

[0044] 2. Check the function of the strain gauges and adjust their positions as needed to balance and eliminate the coupling of swinging moment and oscillation moment;

[0045] 3. Install the flexible beam specimen on the clamping fixture, which consists of upper and lower parts connected by bolts and tightened with nuts;

[0046] 4. Fix the connecting block to the calibration table with bolts, and then install the flexible beam specimen and clamping fixture together on the connecting block;

[0047] 5. Waving moment calibration: Connect the metal clamps at both ends of the flexible beam specimen to the calibration shaft, suspend hooks on the calibration shafts on both sides, load weights in stages on the hooks, and collect the corresponding strain values ​​at the same time;

[0048] 6. Vibration moment calibration: Install the flexible beam specimen and clamping fixture on the side of the connecting block, then connect the calibration shaft to the metal clamps at both ends of the specimen, suspend the hook, load weights in stages on the hook, and collect the corresponding strain values ​​at the same time.

[0049] 7. Torque Calibration: The calibration frame is connected to the metal clamp of the flexible beam specimen via the calibration shaft. The calibration disc is fixed on the calibration frame and connected to the calibration shaft via a flat key. Steel cables and hooks are suspended on the calibration disc, and weights are added in stages to apply a torque load.

[0050] The calibration method provided in this application calibrates three types of loads on flexible beam specimens: swing moment, oscillation moment, and torque. It obtains calibration coefficients for the corresponding loads on the flexible beam specimens, which can be used to measure and adjust the test loads during fatigue testing of flexible beam specimens, and to calculate the stiffness and deformation of the flexible beam. The calibration device of this invention adopts an integrated test bench structure design, ensuring stable stiffness, wide application range, easy installation and disassembly, and no redundant structures. This invention has high practical value and has already been applied to actual scientific research and production projects. This application has been applied to the swing fatigue test of a flexible beam for a helicopter tail rotor.

[0051] For other embodiments in this application, please refer to Figures 1 to 3 The flexible beam calibration device includes a calibration platform 1, a clamping fixture 2, a connecting block 3, a calibration shaft 4, a hook 5, a weight 6, a calibration shaft, a steel cable, a calibration plate, and a calibration frame.

[0052] The flexible beam calibration device can calibrate three test loads: swing moment, oscillation moment, and torque. First, a calibration platform 1 is designed, welded from square steel and fixed to the ground. Connecting blocks 3 are fixed to the calibration platform with bolts. The flexible beam specimen 0 is assembled with the upper and lower clamping fixtures 2, and fixed and locked with connecting bolts and nuts. The assembled flexible beam specimen 0 and clamping fixtures 2 are then fixed together on the connecting blocks 3. Metal clamps at both ends of the flexible beam specimen 0 are connected to calibration shafts 4, and hooks 5 are suspended. Then, weights 6 are applied in stages to calibrate the swing moment and oscillation moment. A metal clamp at one end of the flexible beam specimen 0 is connected to a calibration shaft, which is connected to a calibration plate via a flat key and fixed together on the calibration frame. Hooks 5 are suspended from the calibration plate by steel cables, and then weights 6 are applied in stages to calibrate the torque.

[0053] For other embodiments in this application, please refer to Figures 1 to 3 The flexible beam calibration method provided in this application includes the following steps:

[0054] 1. Strain gauges were attached to different cross-sectional positions on the flexible beam specimen 0 and connected to the dynamic data acquisition system via wires to measure the deformation of the specimen under swinging moment, oscillation moment and torque load during calibration.

[0055] 2. Check the function of the strain gauges and adjust their positions as needed to balance and eliminate the coupling of swinging and oscillating moments;

[0056] 3. Install the flexible beam specimen 0 on the clamping fixture 2. The clamping fixture 2 consists of two parts, upper and lower, which are connected by bolts and tightened with nuts to the specified torque.

[0057] 4. Fix the calibration platform 1 to the ground, fix the connecting block 3 to the calibration platform 1 with bolts, and then install the flexible beam specimen 0 and the clamping fixture 2 together on the connecting block 3;

[0058] 5. Swinging Moment Calibration: Zero the strain gauges, connect the metal clamps at both ends of the flexible beam specimen 0 to the calibration shaft 4, suspend hooks 5 on both sides of the calibration shaft 4, and simultaneously apply weights 6 in stages on the hooks 5 at both ends. The specimen will deform in the swing load direction. At this time, the strain values ​​generated by the strain gauges are collected according to the loading stages. Repeat the loading three times, process the data, and obtain the swing calibration coefficient of the flexible beam specimen 0.

[0059] 6. Bending Moment Calibration: The flexible beam specimen 0 and clamping fixture 2 are mounted together on the side of the connecting block 3. The strain gauges are zeroed. The flexible beam specimen 0 is connected to the calibration shaft 4 via metal clamps at both ends. Hooks 5 are suspended on the calibration shaft 4 on both sides. Weights 6 are simultaneously applied in stages on the hooks 5 at both ends. The specimen deforms in the direction of the bending load. The strain values ​​generated by the strain gauges are then collected according to the loading stages. The loading is repeated three times, and the data is processed to obtain the bending moment calibration coefficient of the flexible beam specimen 0.

[0060] 7. Torque Calibration: Install the flexible beam specimen 0 and clamping fixture 2 together on the connecting block 3, and zero the strain gauges. Connect the metal clamps at both ends of the flexible beam specimen 0 to the calibration shaft. Fix the calibration disk on the calibration frame and connect it to the calibration shaft via a flat key. Adjust the leveling bolts at the bottom of the calibration frame to ensure the strain gauge values ​​are consistent with those before installation. Suspend the steel cable and hook 5 on the calibration disk, and apply weights in stages to apply a torque load. The specimen will deform in the torsional direction. At this time, collect the strain values ​​generated by the strain gauges according to the loading stages. Repeat the loading three times clockwise and three times counterclockwise, process the data, and obtain the torque calibration coefficient of the flexible beam swing deformation section specimen 0.

Claims

1. A calibration device for a flexible beam of a helicopter tail rotor, characterized in that, The device includes: The calibration platform is fixed to the ground. A connecting block is disposed on the calibration platform; wherein the connecting block includes a first surface and a second surface, the first surface and the second surface being adjacent to each other; A clamping fixture is used to assemble a flexible beam specimen; wherein, the assembled flexible beam specimen is fixed together with the clamping fixture to the connecting block; The device further includes: The small shaft is calibrated and connected to the metal clamps at both ends of the flexible beam specimen. A suspension hook is connected to the calibration shaft; Weights are set on the suspension hook; wherein, weights are applied in stages to calibrate the swinging moment and oscillation moment; The device further includes: The calibration shaft is connected to the metal clamps at both ends of the flexible beam specimen. The calibration frame is set up on the ground; A calibration disk is fixed on the calibration frame; wherein the calibration disk is connected to the calibration shaft via a flat key; The steel cable is mounted on the calibration plate; A hook is attached to the steel cable; Weights are placed on the hook; wherein, the assembled flexible beam specimen is fixed together with the clamping fixture on the second side of the connecting block, and weights are applied in stages to achieve torque calibration.

2. The apparatus according to claim 1, characterized in that, The assembled flexible beam specimen is fixed together with the clamping fixture to the first surface of the connecting block, and weights are applied in stages to calibrate the swing moment.

3. The apparatus according to claim 1, characterized in that, The assembled flexible beam specimen is fixed together with the clamping fixture to the first surface of the connecting block, and weights are applied in stages to calibrate the pendulum bending moment.

4. The apparatus according to claim 1, characterized in that, The calibration platform is made of square steel welded together.

5. The apparatus according to claim 1, characterized in that, The clamping fixture includes: Upper clamping fixture; The lower clamping fixture is connected to the upper clamping fixture by bolts and nuts.

6. A method for calibrating a flexible beam for a helicopter tail rotor, characterized in that, The method uses the helicopter tail rotor flexible beam calibration device as described in any one of claims 1-5, and the method includes: Strain gauges were attached to different cross-sectional positions on the flexible beam specimen and connected to a dynamic data acquisition system via wires to measure the deformation generated by the specimen during calibration. Check the function of the strain gauges and adjust their positions as needed to balance and eliminate the coupling of swinging moment and oscillation moment; The flexible beam specimen was installed on a clamping fixture, which consisted of upper and lower parts connected by bolts and tightened with nuts. The connecting block is fixed to the calibration table with bolts, and then the flexible beam specimen and the clamping fixture are installed together on the connecting block; Waving moment calibration: Connect the metal clamps at both ends of the flexible beam specimen to the calibration shaft, suspend hooks on the calibration shafts on both sides, load weights in stages on the hooks, and collect the corresponding strain values ​​at the same time; Vibration moment calibration: The flexible beam specimen and clamping fixture are installed on the first side of the connecting block. Then, the metal clamps at both ends of the specimen are connected to the calibration shaft, and the hook is suspended. Weights are loaded in stages on the hook, and the corresponding strain values ​​are collected at the same time. Torque calibration: The calibration frame is connected to the metal clamp of the flexible beam specimen via the calibration shaft. The calibration plate is fixed on the calibration frame and connected to the calibration shaft via a flat key. Steel cables and hooks are suspended on the calibration plate, and weights are applied in stages to apply torque load.

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