Vibration amplifier and testing method for simulating high-order nonlinear vibration fatigue of blade

Abstract

The invention discloses a vibration amplifier and a testing method for simulating the high-order nonlinear vibration fatigue of a blade. The vibration amplifier comprises a base, a fixed shell, an upper cushion block, a lower cushion block, first fixing screws, a second fixing screw, an amplification arm and a clamping block; the upper cushion block and the lower cushion block are located in the fixed shell; one end of the amplification arm sequentially passes through one side surface of the fixed shell, a space between the upper cushion block and the lower cushion block, and the other side surface of the fixed shell, and then extends out from the fixed shell; the clamping block is located on the upper surface of the other end of the amplification arm; the first fixing screws pass through the clamping block and the amplification arm, so that the clamping block can be connected with the amplification arm; and the second fixing screw passes through the top of the fixed shell, extends into the fixed shell and contacts with the upper surface of the upper cushion block, so that the upper cushion block, the lower cushion block and the amplification arm can be fixedly connected with one another. With the amplifier and the method adopted, detection on the fatigue strength of the blade can be realized based on a fatigue testing process of resonance frequency and amplitude.

Description

technical field [0001] The invention belongs to the field of material fatigue fracture and high-cycle fatigue test methods, and relates to a vibration amplifier and a test method for simulating high-order nonlinear vibration fatigue of blades. Background technique [0002] Aeroengines, ground gas turbines and other high-speed rotating machinery have variable working conditions and are always under a complex and harsh working condition. High-cycle fatigue fracture of rotor blades is the most common and serious failure problem, and vibration fatigue is the main fatigue form. . [0003] At present, the fatigue performance assessment method of blades still mainly adopts the first-order bending vibration fatigue test, and the main assessment is the fatigue performance of the blade root (one-pitch line). have been effectively avoided. However, fatigue failures such as blade drop-off and cracks caused by high-order vibrations are still very serious, especially after the blades ar...

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Problems solved by technology

[0004] In the design of high-order vibration fatigue test method, there are mainly problems of excitation difficulty: on the one hand, because the excitation requires a larger vibration acceleration, on the other hand, because the reaction force on the vibration table during resonance will reduce the vibration of the vibration table. output vibration acceleration

The existing technology proposes to set up a fixture support body, protruding symmetrical shafts on both sides of the support body, and generate high acceleration through the resonance of the shaft body, but it does not solve the problem of suppressing vibration caused by the reaction force caused by resonance

In addition, the shaft in this patent is fixed, and the resonant frequency is adjusted by moving the specimen fixture. This method has a small frequency adjustment range, and the cross-section of the shaft is circular, which is prone to torsional vibration. At the same time, the shaft and the fixture Fixed connection is prone to torsion

[0005] In the process of high-order vibration fatigue experiments, due to factors such as material properties and mode shape geometric properties, stiffness nonlinear phenomena will be caused, resulting in changes in its natural frequency, making it difficult for the vibration control system to track the resonance peak

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