Microstructures on polymer surfaces are known to reduce friction and thevisibility of scratches. Due to the complex interaction of multiple surface areas in contactwith each other the prediction of coefficient of friction (COF) or wear is difficult and dependson an empirical solution. This article deals with possibilities of calculating the deformingpart of friction via an analytical solution and a FE-model. In a first step the modelling ofsingle contacts is demonstrated. The analytical calculation based on the Hertzian contactequations is extended regarding viscoelastic material parameters. The basic approach ofFE-modelling is explained including calibration of the material model using the softwareMCalibration®. The article introduces the different procedures of simulating and modellingCOF and wear taking into account the area of contact and resulting stress distribution.

he conveying velocity achievable with vibratory conveyors depends largely on the conveying pan movement. For the specific simulation of these systems using the discrete element method (DEM), it is necessary to connect the geometric reproductions of conveying pans to practical relevant movement functions. The article describes the integration of movement functions in the open source DEM software LIGGGHTS. A movement of meshed CAD during the simulation process is enabled by trigonometric series. [Keywords: vibratory conveyor, vibratory movement, discrete element method] 1 EINLEITUNG

The paper presents analytical approaches for calculating the effective contact area of the sphere-plane contact, which allow conclusions to be drawn about the coefficient of friction of thermoplastics with manageable effort. These approaches are verified experimentally utilizing friction and wear tests using the example of a steel sphere against PE-UHMW. The friction area of the sphere was varied using a self-constructed adjustment unit and a spherical wedge. With the help of parametric experiments regarding the angular position of the spherical wedge, a limiting contact angle was detected. This limiting angle allows the calculation of the deformative and adhesive friction. FE models are being developed for the simulative verification of the analytical approaches and further investigations of structures for friction reduction. These require specific material models as a basis for the representation of the stress-strain behavior in contact. The different FEM material models are calibrated and compared against each other based on experimental tests. The materials POM, PP, PMMA, and PE-UHMW were considered.

The paper presents analytical approaches for calculating the effective contact area of the sphere-plane contact, which allow conclusions to be drawn about the coefficient of friction of thermoplastics with manageable effort. These approaches are verified experimentally utilizing friction and wear tests using the example of a steel sphere against PE-UHMW. The friction area of the sphere was varied using a self-constructed adjustment unit and a spherical wedge. With the help of parametric experiments regarding the angular position of the spherical wedge, a limiting contact angle was detected. This limiting angle allows the calculation of the deformative and adhesive friction. FE models are being developed for the simulative verification of the analytical approaches and further investigations of structures for friction reduction. These require specific material models as a basis for the representation of the stress-strain behavior in contact. The different FEM material models are calibrated and compared against each other based on experimental tests. The materials POM, PP, PMMA, and PE-UHMW were considered.