Nanoindentation of soft viscoelastic materials

By Taha Goudarzi

University of Illinois at Urbana-Champaign

Finds viscoelastic parameters of Standard Linear Solid models from experimental data

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Version 1.0i - published on 19 Jul 2016

doi:10.4231/D35M6280K cite this

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Abstract

This tool provides users with viscoelastic parameters for the standard linear solid model to define the viscoelastic behavior of indented materials based on time-displacement results of load-controlled viscoelastic nanoindentation experiments with spherical indenters. Time-displacement data needs to be uploaded in a text file with two columns separated by spaces -- users need to select the units of displacement and time for the input data. To approximate the viscoelastic behavior of indented materials, this tool utilizes closed-form expressions for time-dependent displacement of indenters -- indenting on a material with the standard linear solid model representing its viscoelastic behavior -- under ramp and creep following a ramp loadings. After uploading time-displacement experimental data for ramp loadings, by pressing the simulate button an algorithm searches for the viscoelastic parameters that provide the best fit (based on nonlinear least squares method) between the closed-form expressions and the experimental data. Since the algorithm only provides local minima users need to input initial values for the viscoelastic parameters of the standard linear solid model. Once the viscoelastic parameters are defined users can use the closed-form expressions for other types of loading (e.g. creep). For more information see the User’s manual.

References

1. E.H. Lee, J.R.M. Radok, 1960. The contact problem for viscoelastic bodies. Journal of Applied Mechanics 30, 438 – 444.

2. K.L. Johnson, 1987, Contact Mechanics, Cambridge University Press, Cambridge, UK.

3. L. Cheng, X. Xia, L.E. Scriven, W.W. Gerberich, 2005. Spherical-tip indentation of viscoelastic materials, Mechanics of Materials 37, 213 – 226. 

4. M. Oyen, 2005, PhD Dissertation, University of Minnesota, Twin City, MI, USA.

Cite this work

Researchers should cite this work as follows:

  • Taha Goudarzi (2016), "Nanoindentation of soft viscoelastic materials," http://nanohub.org/resources/viscoindent. (DOI: 10.4231/D35M6280K).

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