Abstract: In this paper a linearized and unified yield crierion of metals is presented, which is in a form of a set of linear functions with two pararneters. The parameters are ex- pressed in terms of tension yield stress and so-called "shear-stretch ratio" and can bereadily determined from experimental data. It is shown that in stress space the set of yield functions is a set of polygons with twelve edges located between the Tresca’s hexagon and twin-shear-stress hexagon^[1]. In this paper the present yield function isused to analyse the prestressiap loose running fit cylinders.

Key words: mechanical system, contact problem, planet gear drive, ratio of shear-stretch, yield criterion, linearized and unified form