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he object of the research are short, thin-walled columns with open channel cross section. The profiles were made of carbon-epoxy symmetrical composite prepared with a pre-preg technology using 8 layers of unidirectional band. The material used was a composite of epoxy matrix reinforced with carbon fiber (system HexPly M12, Hexcel). The M12 system is used above all in aircraft structures. It exhibits high fatigue durability and good maintenance properties at relatively low specific gravity. The research was lead as the FEM numerical analyses and experimental tests in buckling and post-buckling states, as well. The study involves solving the problem of eigenvalue and the non-linear problem of stability of the structure. The numerical analysis was performed with the commercial FEM simulation software ABAQUS®. During the experiments the test parameters were registered (axial load, deflections of a profile’s walls and its strains) in order to plot the post-critical equilibrium paths for real structure. The basic aim of the research was determination of the load eccentricity effect on the value of critical load, as well as the post-critical equilibrium paths. During the whole compression process the Vallen’s “AMSY-5” Acoustic Emission (AE) acquisition system was collecting the elastic wave propagation data. These signals contained information on defect initiation and propagation within the composite columns, even though the damage was not visible nor could be heard. The piezoelectric sensor registered the motion of the specimen’s surface as a result of damage processes. The signal was next multiplied and registered by the “AMSY-5” AE equipment. Thanks to this, the load – deflection curve could be enriched with additional data, such as the number of AE counts. The experimental outcomes enabled elaboration of adequate numerical models for the tested structures. The study was conducted under the project UMO-2015/19/B/ST8/02800 financed by the National Science Centre Poland.
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