The Study on the Substrate Effect in the Nanoindentation Experiment of the Hybrid Material

The nanoindentation (NI) experiment is an effective method to evaluate the micromechanical property of materials. The substrate effect is a nonnegligible factor which could influence the accuracy of the NI experiment result. Large numbers of previous studies have focused on the substrate effect based on the coating/substrate model, whereas the substrate effect in the testing of the hybrid material was rarely involved. The real NI experiment and the numerical simulation method were adopted to reveal the characteristics of the substrate effect in the NI experiment of the hybrid material in this paper, such as the rock or cement material. The peak displacement h_peakand the residual displacement h_residualof the indenter, which could obtain directly from the NI experiment and were usually considered as key basic variables to calculated other parameters, were selected as evaluation indexes of the substrate effect. The results indicated that there was a significant difference of the NI experiment result between the coating/substrate and the hybrid material under the same condition. The lateral boundary stiffness and discontinuous face were considered as main factors that induced this difference, and their effect were analysed, respectively. Young’s modulus E_sand Poisson’s ratio μ_sof the substrate were selected as the variables in the parametric study, and the relationship between them and the NI experiment result were discussed.

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