Viscoelastic modeling of nanoindentation experiments: A multicurve method

Significance statement

   Nanoindentation is becoming an important technique for characterization of material properties especially at small sizes and for small quantities of material. However the time dependent characteristics of viscoelastic materials make the application of indentation on, e.g., polymeric materials, problematic. The significance of the described work is that it provides improvements to conventional methods of extracting viscoelastic properties from indentation results. The new method, based on a viscoelastic contact mechanics analysis of multiple indentation curves obtained at different loading rates, provides a more complete and accurate description of the viscoelastic response.     

 

 

Viscoelastic modeling of nanoindentation experiments

Journal Reference

Journal of Polymer Science Part B: Polymer Physics, Volume 52, Issue 9, pages 633–639,  2014.

Meiyu Zhai , Gregory B. McKenna*

Department of Chemical Engineering, Texas Tech University, Lubbock, Texas.

 

Abstract

Nanoindentation is an increasingly used method of extracting surface mechanical properties of viscoelastic materials, especially polymers. Recently, Hutcheson and McKenna used a viscoelastic contact mechanics model to analyze the contact problem between a nanosphere and polystyrene surface. In nanoindentation experiments, the ramp loading test is a similar problem to the particle embedment experiment except that the indentation load function differs. The motivation in this work is to expand the Hutcheson and McKenna analysis to the nanoindentation problem. In particular, we illustrate the limitations of analyzing only a single load-indentation curve, which does not provide enough information to determine the full range of the viscoelastic response of a polymer, and we show that performing a test sequence that includes multiple loading rates or indentation rates spanning two or more orders of magnitude greatly improves the extracted viscoelastic properties.

© 2014 Wiley Periodicals, Inc.

 

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