Measurement nonlinearity interpreted as material behavior in dynamic nanoindentation

This paper explores the errors that may arise in when interpreting dynamic nanoindentation measurements with a linear oscillator model. The work was motivated by an experimental observation that the system's primary resonance can be dramatically altered by changes in loading conditions. Investigations elucidate that different sources of nonlinearity can interact to alter the identified contact stiffness which will manifest itself as a change in the system's primary and secondary resonances.The errors associated with interpreting dynamic indentation measurements with a linear model are investigated through modeling, analysis, and numerical study. Theoretical efforts show that measurement nonlinearity can be falsely interpreted as material behavior. Hence, the common practice of applying a linear oscillator model is expected to sometimes lead to significant errors. These finding suggest that a nonlinear analysis may often be required to improve measurement interpretations.