Helge Klaas

EVALUATION OF THE STRESS SITUATION OF COATED TRIBOSYSTEMS WITH CONTACT MECHANICS SIMULATION

For the realization of environmental compatible tribosystems within the special research centre SFB 442 PVD coated systems are developed, which improve the tribological characteristics together in interaction with compatible lubricants. For the evaluation of coated substrate systems employed in tribosystems, it is significant to characterize the mechanical stress collective within the systems by means of their mechanical properties. Subject of the presented investigations is an analysis about the properties of the systems that have significant effects on the system stress collective. Differences to the well-known surface stress of solid materials are pointed out and mathematical models for the description are developed to describe the influence of coated substrates. The aim of these investigations is to draw a connection between these stresses occurring in tribosystems (e.g. industrial applications bearings) and the loads applied in test methods e.g. microindentation (Rockwell Hardness Tests) and nanoindentation. To evaluate the stresses applied in real tribosystems the theory of micro contact mechanics of Greenwood and Williamson is used and is found to be appropriate. Since, only with this connection it is possible to consult the results gained in the coating test methods for the evaluation of a coated system. Essential aid in here is the simulation of the mechanical surface stresses by means of FEM (finite element method). At this point it is possible to take the anisotropic and inhomogeneous material properties of the coating material and the substrate into account.Copyright