A contact model for a creeping sphere and a rigid flat

The creep of a polymer sphere in contact with a rigid flat under a constant normal load is investigated numerically by a finite element method. A simplified form of the modified time hardening is used for the constitutive material model. A new dimensionless form of the creep displacement is suggested, which enables a universal solution of the problem for any contact time based on a conveniently selected reference time. The model may be applicable to other materials which can be described by the modified time hardening model including biological materials.