Research On Vibration Fatigue Of Stiffened Aluminum Alloy Panel

Fatigue failure is the main destroy mode in engineering pratice for most of the components when they work under compexed vibration environments, especially to aircraft, spaceflight, ship industry and prtroleum chemical industry, etc. Therefore, how to properly evaluate the fatigue life of structure under forced vibration becomes a hot research topic now.For obtaining a definite understanding of the mechanism of vibration fatigue, the stiffened structure which is widely used in modern aircraft was employed as a study object. Based on the fatigue life experiment and CAE simulation technology such as finite element analysis and fatigue simulation analysis, the vibration fatigue life of stiffened structure was analyzed systematically combined with damage mechanics and modal analysis theory. For the above purpose, some works were done as follows:Firstly, three finite element models were created for stiffened structure with different type of connection through the FEA soft such as Msc.Patran and Nastran. Modal experiment was carried out for the stiffened structure with free boundary to update the finite model. Finite element analysis was done for the preparation of the future fatigue simulation analysis.In addition, in order to reveal the influence factors on life of structural vibration fatigue profoundly, fatigue life experiments of stiffened structure were done used vibration exciter exerts load on the structure directly. Results indicate that fatigue life of stiffened with rolling weld connection is the longest among the different test piece under the same loading.What is more, structural fatigue life was analyzed used Msc.Fatigue soft with different loading mode and the simulation results were compared with test results. The general rule of structural fatigue life was summarized for different connection mode under different exciting.Finally, the crack propagation of stiffened was simulated through the method of finite element analysis based on fracture mechanics, and the dynamic stress intensity factor was calculated during crack propagation so as to improve the precision of life prediction. A more realistic and accurate calculation method for fatigue crack growth was proposed in the end.