Study on Size Effect in Indentation Tests

The depth dependence of the indentation hardness, i.e., size effect (ISE), was manifested as an increase or decrease in hardness when penetration decreases, which observed by previous experiments. Most scholars believe it is generated strain gradient. However, additional opinions argue that other factors, similar to gradient, can also contribute ISE. Importantly, if such ISE occurs experiment, one needs distinguish its causes. In this study, two external factors were considered, specimen surface defect and indenter tip irregularity, lead hardness–depth-dependent relationships Moreover, a theoretical model established interpret dependent validated via finite element simulations. simulation results showed both significant hardness–depth dependences, great agreement with derivations. demonstrated irregularity have unified influence on ISE, attributed sole deviation δ. Lastly, based eliminated real obtained. Based this, appears, be distinguished whether caused