Effect Of Uniformly Distributed Pressurized Load On Fatigue Performance Of Fuselage Skin Connection Structure

Aluminum alloy is widely used in aerospace and other fields due to its low density,good corrosion resistance,high flexural ratio,good weldability and ease of processing and forming,etc.People have put forward higher and higher requirements for the anti-fatigue performance of aluminum alloy.In this paper,2B06-T4 and 6061 aluminum alloy are taken as the research objects,and the fatigue performance of these two kinds of aluminum alloy prefabricated square plates with initial cracks along the perforated edges is systematically studied under the load of uniformly distributed supercharging under the limited test times by using the self-made aircraft body skin uniformly distributed supercharging fatigue simulation device.It mainly includes crack growth rate and fatigue life.Fatigue tests were carried out for each group at the same maximum uniform pressure Max =7.8psi(0.0538MPa).The fatigue crack propagation path and fatigue crack propagation rate of the fuselage skin structure were studied.Finally,in order to further understand the fatigue failure mechanism of the skin structure caused by crack penetration and to analyze the reasons for the differences in fatigue life of each group,the morphology characteristics of the fatigue fracture section of each group were observed by scanning electron microscopy(sem)in this experiment,and the fatigue crack propagation mechanism was analyzed.Besides,the elements in the fracture characteristic area were studied by energy spectrum analysis,and the reasons for the difference in fatigue life of the three groups of specimens were compared and analyzed.The following results are mainly obtained: through the analysis of the fatigue fracture morphology of the three groups of specimens,it is found that the fatigue failure mechanism of the three groups of specimens is basically the same,and the characteristics of the bending fatigue fracture are very obvious.Among them,the fatigue crack propagation life of 2B06-T4 aluminum alloy is longer,and the strain value of the characteristic point hardly changes with the crack propagation,indicating that the aluminum alloy has better crack propagation resistance and fatigue resistance performance.Through the analysis of fatigue life data and fracture mechanism,this paper provides a certain test basis for ensuring the reliability and application of 2B06-T4 and 6061 aluminum alloy connectors as the materials of airplane fuselage skin.