Spherical indentation of a finite poroelastic coating

Indentation testing of a finite poroelastic layer is considered. Finite element modeling was used to investigate spherical contact creep tests, with emphasis on the influence of layer thickness and of finite rise time on the time-dependent deformation. Thin layers are stiffened by the substrate constraint even at very small relative indenter penetrations and reach steady state more quickly than thick layers. The degree of consolidation following loading is affected by the interaction of layer thickness and rise time and cannot be predicted from either alone. These results provide guidance for micro- and nanoindentation testings of hydrogel coatings for biomedical applications.