Method for testing vibration fatigue performance of metal in axial resonance state

Abstract

The invention provides a method for testing the vibration fatigue performance of metal in an axial resonance state. The method comprises steps: selecting a test piece, pasting a strain gauge, and measuring a response acceleration-strain / stress relationship of the test piece in a resonance state; in combination with the planned stress level, calculating the response acceleration of the test piece during formal test; carrying out the modal test on the test piece to obtain an inherent frequency point and a response amplitude ratio of axial vibration; setting the excitation frequency according tothe inherent frequency point, and calculating an excitation acceleration according to the response amplitude ratio measured by the test; finely adjusting a real-time excitation acceleration value in the test so that target response acceleration change is + / -2%; setting a resonance search and resonance residence program to keep the test piece in a resonance state in the test process, and stopping the test when the response acceleration of the test piece is suddenly reduced or the test piece is broken; and obtaining the cycles of the vibration system when the test is stopped. The method is advantaged in that the axial fatigue test is carried out on a metal material in a vibration mode, and the test period can be greatly shortened.

Description

technical field [0001] The invention belongs to the technical field of resonance fatigue, and in particular relates to a method for testing the vibration fatigue performance of a metal in an axial resonance state. Background technique [0002] During ground operations and air flight, some parts of the aircraft are always in the environment of aerodynamic load and noise. Due to the excitation of noise and aerodynamic load, random vibration stress is generated in these parts. Some structures, such as rudder surface, flat tail, vertical tail, ventral fins and external pylons, etc., will also generate vibration stress due to the effect of turbulence. The fatigue phenomenon caused by the action of this vibration stress is vibration fatigue. [0003] There are many problems involved in solving structural dynamic fatigue, and dynamic fatigue analysis is one of the important problems. In order to perform a dynamic fatigue analysis on a structure, a dynamic fatigue SN curve is requ...

AI Technical Summary

Problems solved by technology

Most parts will bear higher frequency loads during work, and ordinary fatigue testing machines often cannot reach such high frequency output, so there may be some differences between the test results and the actual working life, so it is necessary to change the original fatigue testing machine. Performance test method, increase the loading frequency, so that the fatigue performance measured by the material can be directly used in the actual working conditions

[0006] In addition, assuming that the test frequency is 50Hz, in order to complete 10 7 cycle, the total test time takes about two and a half days; if the ultra-high cycle fatigue test is carried out, it will take longer time. From this point of view, the time cost of ordinary fatigue test is relatively high

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