Study On The Stress-Fatigue Life Of Flat Steel Bar Base On Finite Element Method

The fatigue life is an important target of modern product quality. In order to improve the competition status of product in the market, the product fatigue life analysis is becoming more and more important to the manufacturers. The flat steel bar studied in this article has the very important status in an accelerating device, once the flat steel bar expires, it will cause the entire accelerating device destroyed. So this article attempts to carry on the stress fatigue life forecast of the flat steel bar.The flat steel bar system is composed of the flat steel bar, the top-board and the pre-tight installment. The stress fatigue life of the dangerous spot in the flat steel bar under different pretightening force added by the pre-tight installment is computed mainly in this article. In order to obtain its stress fatigue life, Must know the dynamic response of the structure, this article uses the finite element method to obtain the structure dynamic response, also this is the most important method for structure mechanical analysis presently. These following researches and methods are contained in this article.The dynamic load is exerted on the flat steel bar from the top-board through the contact with the flat steel bar, because the top-board is the high speed movement, stress whose amplitude is changed over time is exerted on the flat steel bar.. According to the actual work condition of the flat steel bar, using finite element method, and then carried on dynamics analysis of the flat steel bar, Calculated the pressure, the shearing force and so on, obtains the stress with time change.According to the flat steel bar dynamic response analysis result, the type of fatigue of flat steel bar is mechanical fatigue with huge period and changed amplitude. Using linear damage cumulative rules, according to its type of fatigue, selects the limited-life-design method to carry on the fatigue analysis and design of the flat steel bar. Studied the influence of the mean stress to the material S-N must be considered, and revises the mean stress the influence. Then the programs, with the approach of nominal stress and the theory of linear damage cumulative is compile to calculate the fatigue life of flat steel bar in the danger point.