A Method for Determining the Surface Contact Stresses Resulting From Interference Fits

Abstract

A method is presented whereby the pressures, which are generated at the contact surfaces of two axisymmetrical components assembled together with an interference fit, can be determined. The approach of this method is to set up a series of influence coefficients for discrete matching nodal positions on the mating surfaces of the two components and to relate these by means of a matrix formulation, to the local nodal pressure and interference. Solution of the resulting set of linear simultaneous equations is readily performed by digital computer. The finite element approach for the determination of stresses and displacements in axisymmetrical components is used, in a somewhat modified form, to establish the influence coefficients at the surface of the outer component. While this same approach could be used for the inner component, in this present work, in order to emphasize the scope of the method, the inner component has been considered to be a solid shaft of infinite length for which influence coefficients derived from a “classical elasticity” approach can be used. Results are given for the pressure distribution along the contacting surface of a solid shaft when it is filled with axisymmetrical sleeves of various configurations—including rectangular, triangular, and stepped forms. The effect of using materials of different stiffness for the shaft and sleeve is analyzed, and the results obtained for the cases where the ratio of the material stiffness is very high and very low are compared with previously known solutions for these cases. The effect of using a varying interference is also considered. Full sets of computer programs, written in Fortran language, for each of the stages of the computation, together with detailed instructions for the compilation of input data, are presented.