Experiences with ANSYS in Ultimate-Load Analyses of Aircraft Fuselage Panels

Wider parts of the fuselage of a commercial aircraft are subject to shear and compression loads in such a way that this is relevant for dimensioning. First elastic, later plastic buckling can appear. The ultimate load is reached when a combined buckling of skin and longitudinal reinforcements (stringers) leads to failure of a panel. This behavior is tested physically, but over years CAD-FEM and Airbus Deutschland worked together to simulate the test and analyze further configurations under aircraft-like conditions with ANSYS. The paper describes which difficulties had to be overcome to achieve convergence and obtain reliable ultimate loads. The advantages and disadvantages of different load and solution control features such as force or displacement control, arc-length method, different ways of incrementing are lined out as well as different kinds of imperfections. Furthermore, the use of linear buckling and eigenvalue extraction at some stages of non-linear analysis is considered. It is shown that ANSYS is an appropriate tool for such kind of analysis, but the importance of some missing features becomes evident.

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