Modelling the behaviour of a contact layer between the workpiece and a locator

The assurance of high precision alignment of workpieces with low stiffness requires thorough knowledge about the phenomena taking place in the contact area under the influence of forces exerted by actuators. It is indispensable to utilise the model of a contact and deformations taking place in it. In order to solve the problem of contact, the contact geometry was modelled by means of a flat and rough surface model based on stereometric measurements, as well as by means of the finite element method (FEM). In a FEM method, a spherical structure of the surface layer was assumed and only one zone was taken into consideration, i.e. 0.4.Rt (maximum surface roughness). Zone structure allows easy changing of mechanical properties of material during the introduction of data defined by a strengthening curve in the plastic region. The possibility of expanding the model by consecutive zones allows taking into consideration the physical properties in complex analyses of the surface layer. This paper presents the problem of contact related to the alignment and fixing process, a model of contact deformations between a flat and a rough surface, as well as the algorithm for determining the model of a surface profile according to the bearing ratio curve.