In situ indentation testing of elastomers

The development of the contact is crucial in indentation testing, yet only limited knowledge exists on the true contact size for compliant materials. In this investigation the contact evolution and the deformation behavior of polydimethylsiloxane was studied during indentation in situ inside a scanning electron microscope and by observation in a light microscope. Since detailed information on the true contact area and the amount of sink-in can be acquired from finite element analysis, simulations on the indentation process have been performed in order to complement the in situ testing. Comparison of results revealed that the contact areas calculated according to the standard Oliver–Pharr procedure deviated from the real contact size by approximately 10% for the elastomeric PDMS material.