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Sankt Stefan ob Leoben, Austria

Grun F.,University of Leoben | Godor I.,University of Leoben | Javidi A.,University of Leoben | Pondicherry K.,Material Center Leoben Forschungs GmbH
Tribologie und Schmierungstechnik | Year: 2010

Current study describes a methodology to in-situ visualize the formation of tribofilms for large area contacts. The test configuration is based on the system ring-on-disc. The methodology consists of a closed loop test- and analysis chain consisting of different analysis methods (light microscopy, SEM/EDX, C-AFM, XPS). We benchmarked the performance of the proposed method by applying it on three different material systems: a) pure iron system (steel against EN-GJL250), b) two mixed systems (steel against Al and steel against CuPb22Sn2). For the experiments we employed three different lubricants (OU A = base oil, Oil B = oil with ZnPbased additives and Oil C = oil with Pbased additives).

Reiser J.,University of Leoben | Maier B.,University of Leoben | Ganser H.-P.,Material Center Leoben Forschungs GmbH | Guster C.,University of Leoben | Pippan R.,Austrian Academy of Sciences
19th European Conference on Fracture: Fracture Mechanics for Durability, Reliability and Safety, ECF 2012 | Year: 2012

The aim of this work is the investigation of damage evolution of materials under single step and variable amplitude loading in tests and corresponding simulations. Approaches for fatigue lifetime and fatigue limit prediction at the mesoscopic scale incorporate microstructure and grain features. This micromechanical approach coupled with polycrystalline plasticity should be able to take into account the contribution of grain orientation, grain shape, crystallographic orientation, as well as the influence of material defects. For the purpose of studying local plastic strain accumulation and therefore fatigue behavior at higher load cycles a new test rig for SEM in-situ tension-compression testing was developed by using finite element simulation coupled with topology optimization. Oxygen free high conductivity (OFHC) polycrystalline copper material with nearly uniform grain size distribution and no preferred grain orientation was chosen for the experimental investigations within this work. For investigation of local strain evolution during the test run digital image correlation was used. A simulation model of the chosen OFHC polycrystalline copper was set up. The model incorporates crystal plasticity with randomly distributed grain orientation and nearly uniform grain size distribution to match the properties of the tested specimens. Due to the high purity of OFHC copper the influence of grain boundaries can be neglected in the first phase of simulation. First test and simulation results are shown.

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