Failure Inception of a Spherical Contact Under Slip and Stick Conditions for Various Material Properties

Failure inception of a deformable sphere loaded by a contacting rigid flat is analyzed separately for perfect slip and for full stick conditions and various material properties of the sphere. Ductile yielding and brittle failure inception of the sphere is identified by the critical interference and associated normal loading as well as the location of the first yield or failure occurrence. The analysis is based on the analytical Hertz solution for frictionless slip condition and on a numerical solution for stick condition. Failure inception is determined by using either the von Mises criterion of plastic yield or the maximum tensile stress criterion of brittle failure.