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DLC-coatings are commonly used in industry as a wear protective layer and as a solid lubricant for highly loaded tribological contacts. In order to evaluate the wear performance of different DLC-coatings under unlubricated oscillating sliding wear conditions and to validate the reliability of coated components, many wear-tests with simple model-geometries as well as expensive endurance-tests with the real application conditions have to be performed. This is because the transfer of the wear results to different contact conditions (variation of load, application geometry) is not yet possible. In an earlier paper a novel unified dissipated energy model for the ball-on-plate-geometry was developed and its transferability to different types of coatings was verified. In this paper the model was applied to different load steps and a piston-cylinder-geometry in order to verify its generality. The analytical wear calculation tool-the Global Incremental Wear Model (GIWM)-was revised by considering different load steps and by implementing a new approach for the calculation of wear in the piston-cylindercontact. Based on the good agreement between the experimental results and both wear and friction simulations, the validity of the unified wear model regarding its transferability to different loading histories and geometries was successfully proven.

Finite-element (FE) simulations, based on a phenomenological nonlinear constitutive model, were carried out to show the impact of ferroelastic switching on compressive and tensile loading of a soft and hard ferroelastic polycrystalline lead zirconate titanate ceramic (PbZr1-xTixO3, PZT). Hereby, a model assembly is used that simulates mechanical stresses generated by the contact of a ceramic element with a concave counterpart. In order to parameterize the constitutive model, the elastic and piezoelectric tensors are determined by the small signal resonance method and by the direct measurement under compressive/tensile loads. In addition, the large field ferroelectric and ferroelastic behavior of polarization and strain were characterized. The simulations show that the tensile stress level within the piezoceramic is much lower compared to a linear elastic model, which is related to ferroelastic switching. This is demonstrated to have a significant influence on mechanical lifetime predictions. To validate the parametrized FE model, a four-point bending experiment was used. The comparison of the calculated and measured strain on the compressive and tensile sides of the sample showed very good correlation.

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