Numerical and experimental analysis of stiffened aluminum panels used in aerospace industry under compression

Reducing the weight of primary structures in the aviation industry is an important and challenging issue in terms of decreasing operating costs. Significant weight gains can be achieved by allowing localized buckling of the stiffened panels considered as one of the basic structure of an airframe during operational conditions. In this thesis study, the load carrying ability and buckling behavior of a stiffened aluminum panel designed by adopting current design application and 'Post-Buckling Design' approach were investigated experimentally and numerically. The test specimen that is reinforced by 'Z' type stiffeners and manufactured from Aluminum 2024 T3 Clad material was tested under compressive load. Buckling behavior was observed by means of 3 –Dimensional Digital Image Correlation (DIC) analyzes and strain gauge pairs. The experimental study was followed by developing an efficient and reliable finite element model whose ability to predict the behavior of the stiffened panel that is used in this project is verified. While finite element model is being prepared, all nonlinearities about material behavior and geometrical imperfections of stiffened panel are considered. Panel designs were produced for different number of stiffeners and panel thickness values using the numerical model according to the 'Post-Buckling Design' technique. A comparison of the weight saving of a panel designed according to the 'Buckling Resistant Design' technique, which will carry the same load safely with these panels, has been evaluated through the concept of 'Structural Efficiency'.