Estimation Of Structural Vibration Fatigue Life With Temperature Involved

In the practical engineering, structural fatigue failure often occurs under thermal vibration environment, especially to the structure of hypersonic aircraft. One problem is the thermal vibration fatigue which is caused by the high temperature gradient exist in the skin of the supersonic aircraft, another aspect is the vibration fatigue which is induced by thermo-mechanical coupling environment in supersonic aircraft structure. Therefore, the typical structure in the aircraft (such as plates and stiffened plates) is employed as the object that is studied on the problem of vibration fatigue life with temperature involved. An analytical method for vibration fatigue life with temperature is proposed, which pays attention to the impacts of high temperature on vibration and fatigue life. The research results are very important to the structure design and to guarantee the safety reliability of supersonic aircraft. The main work of this paper is listed as follows:Firstly, the theory of thermal stress, and theory of elastic thin plate vibration and fatigue life analysis method are used as basic theory, and an elastic plate is used as the study object, the temperature field and thermal stress response for the elastic plate is analyzed and the vibration mode and vibration fatigue life under high temperature are calculated. Therefore, a one-way double-stiffen plate is modeled with FEM and vibration analysis is conducted. On this basis, the effect of temperature on vibration fatigue life is studied. Finally, based on the stress results and the structure fatigue life S-N curve, combined thermal stress and vibration stress, the impact of temperature on the structure fatigue life is discussed.Results indicate that temperature is very sensitivity to vibration mode and stress response. The impact of temperature on fatigue life is very obvious. All the results of this study are very important to structure design of aircraft.