The aim of the presented study was to perform a global sensitivity analysis of various design parameters affecting the lost motion of the harmonic drive. A detailed virtual model of a harmonic drive was developed, including the wave generator, the flexible ball bearing, the flexible spline and the circular spline. Finite element analyses were performed to observe which parameter from the harmonic drive geometry parameter group affects the lost motion value most. The analyses were carried out using 4% of the rated harmonic drive output torque by the locked wave generator and fixed circular spline according the requirements for the high accuracy harmonic drive units. The described approach was applied to two harmonic drive units with the same ratio, but various dimensions and rated power were used to generalize and interpret the global sensitivity analysis results properly. The most important variable was for both harmonic drives the offset from the nominal tooth shape.

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This article deals with an optimisation procedure of inner geometry of rolling elements designed for spherical roller bearings. A process of selection of the most appropriate solution to increase spherical roller bearing durability is understood under the term optimisation in this case. The aim of this article is to examine the impact of a change of inner geometry on the durability and reliability of spherical roller bearings regarding production technology and competitiveness. Contact strain along with a spherical roller by means of Finite Element Method (FEM) in contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of inner geometry of a bearing from the standpoint of calculated durability will be determined based on the results of analyses.

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