Papers by Author: Otmar Vöhringer

Abstract: In a three-dimensional Finite-Element-Simulation of shot peening, a combined isotropickinematic viscoplastic material description was introduced in order to describe the cyclic softening effects during peening. After verifying the model in the simulation of push-pull tests at different strain amplitudes it could be used for the shot peening simulation. The simulated residual stress profile is compared with experimental results determined by X-ray diffraction and with simulated results of a simpler isotropic viscoplastic material model.

Abstract: In the work presented here the residual stress states of sintered iron (ASC 100.29) were studied after mechanical surface treatments. This included the investigation of the stability of compressive residual stresses of deep rolled sintered iron at different angles relative to the rolling direction at quasistatic and cyclic bending loading. An increase of the compressive residual stress in the transversal deep rolling direction at fatigue loading was found and will be discussed in this presentation.

Abstract: Al2O3 ceramic plates of diameter 166 mm and thickness 5 mm were subjected to frictional loading regimes. The resultant residual stress effect in the material was analyzed using the sin2y and AP methods based on a modified measurement condition for the pole angle y and the azimuth angle F on a 4 cycle goniometer. Furthermore, the frictional loading of the Al2O3 plates lead to clear differences in the residual stress state near the surface. An underlying correlation was observed between the residual stress state of the Al2O3 material and its residual strength with this effect being ascribed to the magnitude of frictional load applied.