Vibration Fatigue Life Analysis Based On Strain Mapping Technology

With the rapid development of modern industrial technology, all kinds of mechanical equipment,mechanical and electrical products, transportation and military hardware are moving into the direction of high pressure, high speed, high temperature, which makes the vibration environment of structure become complex increasingly so that the structural failure is also more and more. Besides that,vibration fatigue damage is one of the main forms of the structural failure. Therefore, it is of great importance for both theoretical research and engineering practice to study and modify the method of vibration fatigue life analysis and improve the accuracy of fatigue life prediction of structure in vibration environment.The study of the method of vibration fatigue life prediction is always in the direction of more convenient and reliable. In this paper, further research is done in the time and frequency domain by the method of considering the influence of the loading sequence and mapping the strain response to improve the precision of vibration fatigue life.In time domain, a method of calculating the minimum and maximum values of the structural fatigue life under two extreme cases is proposed in this paper, according to the damage curve method which considering the loading sequence. Then, a strain response mapping technique based on the modal superposition method is proposed to solve the problem of collecting the response signal of dangerous position difficultly. Firstly, the strain time-domain signal of dangerous position is obtained by mapping the strain time history of strain gauge. Secondly, the fatigue life of the structure is estimated by the strain signal of dangerous position. And the ideal life prediction results can be get.In the frequency domain, with the help of the cumulative damage model of the damage curve method in time domain, a method of modifying the life by using a three curves is proposed. And this method is used to modify the fatigue life by several traditional frequency domain algorithm and the relatively accurate and safe fatigue life is get.In addition, several methods proposed in this paper are verified by doing the random vibration fatigue test of 2024-O aluminum alloy and taking a certain aerial institute as the engineering example.