Depth-sensing indentation of an epoxy-based polymeric material

In a typical depth sensing indentation test, load and displacement beneath an indenter are continuously recorded to determine a wide range of mechanical properties. In spite of the wide practical and scientific applications of DSI to a variety of materials, analysis of DSI data from materials exhibiting viscoelastic (VE)/viscoplastic (VP) behaviour is still not fully understood. The specific aim of the present research was to investigate the indentation behaviour of a polymeric material in order to generate meaningful mechanical properties at a micron scale under different loading and environmental conditions. The material investigated in this work was an epoxy-based thermosetting polymeric material (SL 7580) manufactured by a stereo lithography (SL) process. Information regarding the mechanical properties of SL materials, which can vary across a component and on ageing, is currently rather limited. Additionally, typical bulk property measurements are unable to provide the spatial resolution necessary to characterise the variations in mechanical properties observed in SL parts. The influence of the ageing and post processing techniques used in stereo lithography process were studied using DSI and their influence on the mechanical properties determined. [Continues.]