Viscoelastic modeling of nanoindentation experiments: A multicurve method

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.

On couple-stress elasto-plastic constitutive frameworks for glassy polymers

“…As length scale dependent deformations in the considered glassy polymers are mainly of elastic nature, a different approach should be pursued in polymers. Although rate dependent deformation is much more pronounced in polymers (see, e.g., Sperling, 1993;Zhai & McKenna, 2014;Krairi & Doghri, 2014) than in metals, the rate effects for the following material description is neglected assuming that during the deformation process the deformation M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 8 rates remain within a similar range (changes in the deformation due to rate differences are negligible). Furthermore, we assume that the considered polymers exhibit isotropic deformation behavior.…”

“…While the mechanical response of polymeric materials are clearly known to be time dependent (Oyen & Cook, 2003;Zhai & McKenna, 2014;Anand & Ames, 2006;Gudmundson, 2006;Sperling, 1993), for simplicity we restrict our attention to length scale dependent elasto-plastic deformation in glassy polymers under conditions where rate effects are assumed to be negligible.…”

Mechanical and viscoelastic properties of confined amorphous polymers

“…Nanoindentation provides a semi-classical approach to measure the mechanical response of films and can be applied to the deformation of rubbery materials (generally crosslinked), but additional care must be taken to account fully for the tip shape and the time-dependent response. 161,162 For polymer melts, the deformation by the tip induces flow and this requires computational models to interpret the results. 163 The surface viscosity of PS thin films appears to be unchanged from the bulk when using of a scanning probe tip.…”

Thermal kinetics and thermo‐mechanical properties of graphene integrated fluoroelastomer

“…Although the elastomers reinforced by fillers have been studied for decades, it is still the focus of current and future researches because of its profound influence of the elastomer's properties . The concurrent enhancing effect of elastic modulus mainly relies on the hydrodynamic effect and filler–polymer interaction.…”

“…INTRODUCTION Although the elastomers reinforced by fillers have been studied for decades, it is still the focus of current and future researches because of its profound influence of the elastomer's properties. [1][2][3][4][5] The concurrent enhancing effect of elastic modulus mainly relies on the hydrodynamic effect and filler-polymer interaction. In this effect, the modulus is mainly dependent on the volume fraction as well as the specific surface area and aspect ratio of the filler.…”