A phenomenological model for predicting local creep and thermal drift of polymers from micro-indentation test data.

Polymers have emerged as a novel class of engineered materials that find application in several domains, such as structural components, fittings, couplings, and more. Due to their viscoelastic nature, these materials experience a deformation dependent on time when subjected to an applied load. This paper presents a novel approach to address this research gap by introducing simplified and practical models for predicting creep and back creep displacement utilizing a non-destructive technique, specifically micro-indentation. A comprehensive experimental investigation of multi-cycle indentation testing has been conducted. The creep and back creep models that have been developed are expressed as nonlinear exponential equations, which include variables such as material properties determined using micro-indentation techniques, as well as experimental parameters like maximum load, loading and unloading rates, and the indenter's hold time. The relationships discussed significantly influence the holding time at maximum and minimum loading conditions. One advantage of these exponential models is their ability to provide a simple mathematical representation. By utilizing this approach, there is no longer a requirement to conduct multiple single-cycle indentations or to depend only on conventional creep tests. [ABSTRACT FROM AUTHOR]