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Graduate Student Seminar by Angela Brickler |
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Date: July 6, 2006
Time: 10:00am
Location: NIA, Rm 137
Structural Evaluation of Electron Beam Freeform Fabrication of Stiffened Panels
Angela Brickler, University of Maryland
The goal of this study is to validate advanced fabrication techniques for aircraft components. The test specimens are aluminum alloy blade-stiffened panels which represent a component of skin-stiffener compression panels used in the design of aircraft fuselage and wings. The three different methods tested and compared are a stiffener riveted onto the skin, an integral stiffener machined from plate, and a stiffener built by electron beam freeform fabrication (EBF3). To validate the fabrication techniques, first the buckling characteristics are determined with compression tests and analysis. Then the results for the panels made with the new technique of EBF3 are compared with the results for the panels made with the more proven manufacturing methods. The integrally stiffened and riveted specimens both failed in global buckling. The results show that the integrally stiffened panels carried a 7% higher compression load than the riveted panels and a 16% higher compression load than the EBF3 panels. Three test panels were manufactured using the EBF3 process to apply stiffeners. Different procedures were used for each panel to remove residual stresses from thermal gradients that were introduced during the process. Test results show that the EBF3 process has potential as a manufacturing technique for aerospace structures, but that more work needs to be done to understand and reduce the residual stresses in the panel.
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