Asperity creep under constant force boundary conditions

This work presents an analysis of the transient creep deformation of a hemisphere in contact with a rigid flat, loaded by a constant force. The analysis is based on extensive finite element simulations, using a Garofalo creep law. Motivated by the simulations, an analytical framework is derived. Starting from the trivial case of a cylinder, the analytical framework can be generalized by exchanging a few functionals; this will describe the spherical geometry under analysis. The necessary functionals are derived by using a combination of analytical and empirical models. The resulting model accurately predicts the creep evolution of arbitrary asperities for a wide parameter range, requiring only the bulk material parameters. The results are interpreted in view of transient friction effects with creep as their possible cause.