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Bestimmung des zyklischen Langzeitverhaltens ausgewählter Aluminiumschaumverbunde

: Schröder, T.

Freiberg, 2010, 121 pp.
Freiberg, TU Bergakademie, Dipl.-Arb., 2010
Fraunhofer IWU ()
Stahl-Aluminiumschaum-Sandwich; Ermüdung; Vierpunkt-Biegeversuch; Wechselverformung; Kernscherversagen; aluminium foam sandwich; steel sheet layer; fatigue four-point bending test; core shear failure

In this thesis the cyclic behaviour of selected powder metallurgical fabricated aluminium foam sandwiches with steel sheet layers was investigated, using methods of DoE (Design of Experiments) to get information about the effect of several factors. Static four-point bending tests were realised to define the test load for fatigue experiments. Almost all specimens consisting of X5CrNi18-10 sheet layers failed by local delaminating of the sheet layer from the foamed core, which results in relative low testing loads. Higher loads were measured on sandwiches with low alloyed steel sheets DC01, where failure occurred in the foam core by core shear. The load controlled cyclic four-point bending experiments with fully reversed load (R = -1) were done until 105 load cycles. Nearly all specimens exceeded this limit at the selected load level. In spite of the low bending forces, many specimens showed a progressive separation of the stainless steel sheet layers, however not leading to a complete miss of the sandwiches composite action or rather failure. Sandwiches with DC01-sheet layers partly exhibited a decrease of deflection until 104 load cycles, which probably results from an increasing bending stiffness due to cyclic hardening of the face sheets. On higher loaded specimens or such with very low core density fatigue crack propagation in the foam core leaded to core shear failure.
The results of the experiments realised in this thesis serve as first step stone for further investigations. These should concern with the fatigue behaviour on higher load cycles and finally determine characteristic values for cyclic loaded steel-aluminium-sandwiches.