Elastic deformation of a fixture and turbine blades system based on finite element analysis

Finite element analysis (FEA) has been used to recapitulate the interactions between fixtures and components over the last decade. Most of the researches were focussed on the 3-2-1 fixture for components with regular geometry using point-to-point contact elements, where the fixture element is represented by a point-contacting component. Due to predicable behaviour of the fixture–component pair, such a point-to-point contact representation may be sufficient. However, when components with complex geometry, e.g. B-spline surfaces, which are widely used in the automotive and aero-engine industries, are of interest, the point-to-point method can no longer be satisfactory. This paper proposes a method of FEA on a system of a fixture and turbine blades by considering the complex contact geometry and complicated contact status of fixture–component pairs using surface-to-surface contact elements. A complete procedure of FEA modelling including geometry simplification, contact modelling, stiffness of locators, mesh generation, boundary condition and loading sequence is explained in detail. Having verified the FEA prediction of the elastic deformation with the displacement of the workpiece measured by coordinate measurement machines (CMMs), the influential factors of deformation, such as friction and machining directions, are analysed.