Theoretical-Experimental Approach to Determining the Mechanical Characteristics of Thin Polymer Composite Coatings

A method is proposed for determining the mechanical characteristics of thin polymer composite coatings by comparing the results of a numerical modeling and an indentation experiment. An elastoplastic axisymmetric problem for a two-layered foundation modeling the indentation process of thin coatings is considered. To solve it, the finite-element method and the ANSYS software package were used. A cone with special parameters of the taper angle and rounding radius at the vertex was used as an indenter. Such an indenter has the same function of area and depth projection as the standard Berkovich indenter used during the experiments. The resulting model allows one to build “loading-unloading” curves similar to those obtained in an instrumental indentation. The main idea of this work was to obtain the yield strength of thin polymer composite coatings by comparing and approximating experimental and calculated curves for a set of known input parameters. In the future, the value obtained in this way can be taken as an approximate yield strength of the material. It is shown that, by applying an optimization algorithm to adjust the yield strength of the coating, it is possible to achieve a good agreement between the results of modeling and experiment.