Material elastic-plastic property characterization by nanoindentation testing coupled with computer modeling

In this paper, an innovative approach through nanoindentation testing using a Berkovich sharp-tip and a cylindrical flat-tip, respectively, and coupled with computer modeling is proposed as a means of characterizing the elastic-plastic properties of materials within micro/nanoscale. Low carbon steel was selected as a case study material. Nanoindentation tests were carried out to obtain load-depth graphs. For cylindrical flat-tip indentation, a mechanical model was proposed for directly extracting yield strength of the testing material from the corresponding load points, considering a modifier k. Young's modulus was derived from the indentation tests using both tips. The final indentation sites were measured and analyzed using a 3D laser scanning microscope. The nanoindentation solid models were developed, and computer modeling based on finite element analysis was conducted to find the effects of indentation depth, yield strength and strain hardening coefficient on the load-depth graph and the final indentation pileup profiles, taking into account the effects of friction on nanoindentation. The computer modeling nanoindentation data was compared with and validated by the nanoindentation tests.