Method for designing ultrasonic torsion fatigue testing specimen with uniform section

Abstract

The invention proposes a design method for ultrasonic torsional fatigue samples of equal cross-section. First, according to the sample material parameters and geometric design dimensions, the resonance length of the torsional fatigue sample is obtained through the analytical formula of the resonance length of the torsional fatigue sample, and then the resonant length of the torsional fatigue sample is obtained by using the finite element The method analyzes the natural frequency corresponding to the torsional vibration mode of the sample, and corrects the resonant length of the torsional sample according to the analysis results, so that the actual natural frequency of the sample is close to the design frequency within the range of F±0.5kHz, and the equal maximum torsion is obtained in the gauge length section The stress meets the requirements of the ultrasonic torsional fatigue test and improves the accuracy of the test data. The invention enriches the sample types of the ultrasonic fatigue test, expands the application range of the ultrasonic fatigue test method, improves the accuracy of the ultrasonic fatigue test, and lays a foundation for the research on the ultra-high cycle torsional fatigue performance of metal materials.

Description

technical field [0001] The invention relates to the field of torsional fatigue performance and durability testing of metal materials, in particular to a design method for ultrasonic torsional fatigue samples of equal cross-section. Background technique [0002] Fatigue is the permanent damage of a certain point or part of a material under the repeated action of stress or strain. After a certain cycle of loading, cracks are formed, and the cracks further expand to complete fracture. This kind of material performance change caused by repeated stress and strain, The phenomenon that causes a material to fail is called fatigue of the material. Fatigue failure is the main failure mode of structural parts under the action of cyclic alternating loads, such as shafts, cranks, blades, gears, etc., and the main failure mode of pressure vessels, pipelines, vehicles, aircraft and other components is fatigue damage. Production practice development, it was found that according to the numb...

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Problems solved by technology

[0004] In order to solve the problem in the prior art that it is difficult to obtain accurate ultra-high-cycle torsional fatigue test data due to the lack of design methods for ultrasonic torsional fatigue specimens with equal cross-sections, the present invention proposes a design method for ultrasonic torsional fatigue specimens with equal cross-sections suitable for different materials , obtain equal maximum torque in the equal cross-section area (gauge length section) in the middle of the sample, increase the maximum torsional stress area, and make the natural frequency corresponding to the torsional mode shape near the operating frequency of the ultrasonic torsional fatigue testing machine, which can be used in ultrasonic torsional fatigue testing Realized torsional resonance loading on the testing machine

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