An indentation study of an elastoviscoplastic material

Indentation measurements are described where Plasticine, a commercial dispersion of clay particles in a mineral oil, is used as a model elastoviscoplastic material. The data reported were obtained by indenting in plane strain with steel wedges for a range of included angles and measuring the reaction force as a function of the indentation velocity. The interface friction was varied by changing the temperature of the wedges. It is shown that an extension of existing slip-line held solutions provides a constitutive description of the deformation and flow behaviour for the Plasticine which is consistent with tensile and orifice flow measurements. This study also demonstrates that slip-line field solutions correctly predict the influence of interface friction on the indentation hardness.