Using a variety of depth-sensing indentation techniques, the creep response of high-purity indium, from room temperature to 75 ЊC, was measured. The dependence of the hardness on the variables of indentation strain rate (stress exponent for creep (n)) and temperature (apparent activation energy for creep (Q)) and the existence of a steady-state behavior in an indentation test with a Berkovich indenter were investigated. It was shown for the first time that the indentation strain rate ( /h) could ⅐ h be held constant during an experiment using a Berkovich indenter, by maintaining the loading rate divided by the load ( /P) constant. The apparent activation energy for indentation creep was found ⅐ P to be 78 kJ/mol, in accord with the activation energy for self-diffusion in the material. Finally, by performing /P change experiments, it was shown that a steady-state path independent of hardness ⅐ P could be reached in an indentation test with a geometrically similar indenter.

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This paper describes experimental measurements of the linear viscoelastic behavior of the surface of low-density (LD) polyethylene in contact with a pyramidal Berkovich diamond indenter. The experiments were carried out at two different temperatures, 15.9 and 27.2 °C, between frequencies of 0.1 and 800 Hz. Using the shift of the loss tangent between the two temperatures at frequencies lower than 20 Hz and an Arrhenius equation, an activation energy of 105 ± 2 kJ/mol was obtained. This value is in good agreement with the bulk value of the a relaxation of LD polyethylene reported in the literature.

Depth-sensing indentation involves applying a specific force-time history on a rigid indenter while continuously monitoring the displacement of the indenter into the surface. Frequency specific depth-sensing indentation testing entails adding a small harmonic force on the indenter and measuring the harmonic response of the indenter at the excitation frequency. While often taken for granted, understanding the dynamics behind these frequency specific measurements is of vital importance in the determination of quantitative mechanical properties. This paper will focus on the dynamics of a variety of depth-sensing indentation systems and how these dynamics affect such parameters as detecting the point of surface contact, environmental sensitivity, dynamic frequency range, and the range over which contact stiffnesses and moduli can be accurately measured.