indentASME2009 - Long Ge e-mail: ccdel@u.edu Nam H. Kim1...

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Long Ge e-mail: ccdel@uf.edu Nam H. Kim 1 Associate ProFessor e-mail: nkim@uf.edu Gerald R. Bourne Research ±aculty e-mail: grb@uf.edu W. Gregory Sawyer ProFessor e-mail: wgsawyer@uf.edu Department oF Mechanical and Aerospace Engineering, University oF ±lorida, Gainesville, ±L 32611 Material Property Identifcation and Sensitivity Analysis Using Micro-Indentation Mechanical properties of materials in small-scale applications, such as thin coatings, are often different from those of bulk materials due to the difference in the manufacturing process. Indentation has been a convenient tool to study the mechanical properties in such applications. In this paper, a numerical technique is proposed that can identify the mechanical properties using optimization and evaluate the robustness of identiFed mate- rial properties using sensitivity analysis. ±irst, two response surfaces are constructed for loading and unloading curves from the indentation experiment of a gold Flm on the silicon substrate. Unessential coefFcients of the response surface are then removed based on the test statistics. Unlike the traditional methods of identiFcation, the tip geometry of the indenter is included because its uncertainty signiFcantly affects the results. In order to validate the accuracy and stability of the method, the sensitivity of the identiFed material properties with respect to each coefFcient is analyzed. It turns out that the plastic hardening parameter is the most sensitive to the experimental data. In addition, all material parameters are sensitive to the coefFcients of higher-order bases. However, their effects are diminished because the magnitudes of these coefFcients are small. f DOI: 10.1115/1.3142902 g Keywords: indentation, material property identiFcation, regression, sensitivity analysis, elastoplasticity, contact, tip geometry 1 Introduction Microscale materials show different properties from those of bulk materials f 1 g . Recent advances in technology allow experi- ments to be carried out on such a small scale. Indentation is a powerful tool to study mechanical properties. It is widely used in the automotive, semiconductor, biomedical, and magnetic record- ing industries, and in the academics f 2–4 g . Extensive reviews of indentation techniques are available in the literature f 5–7 g . In this paper, a numerical method is presented that can identify the ma- terial properties using the data obtained from indentation experi- ments and evaluate the sensitivity of identiFed material properties with respect to experimental data. Recently, numerical studies emerged to catch up with the ex- perimental research on microscales. Numerical methods can de- termine properties or parameters that are difFcult to obtain from experiments. They are able to elucidate physical mechanisms or procedures that are difFcult in experiments. They can also provide suggestions and give a guide for experiments.
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indentASME2009 - Long Ge e-mail: ccdel@u.edu Nam H. Kim1...

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