Materials Gateway
Resource Center
Login button
 Open/CloseSend Us Your Feedback

Indentation responses of time-dependent films on stiff substrates

Author(s):
Michelle L. Oyen, Robert F. Cook, John A. Emerson, Neville R. Moody

A viscous-elastic-plastic indentation model was extended to a thin-film system, including the effect of stiffening due to a substrate of greater modulus. The system model includes a total of five material parameters: three for the film response (modulus, hardness, and time constant), one for the substrate response (modulus), and one representing the length-scale associated with the film-substrate interface. The substrate influence is incorporated into the elastic response of the film through a depth-weighted elastic modulus (based on a series sum of film and substrate contributions). Constant loading- and unloading-rate depth-sensing indentation tests were performed on polymer films on glass or metal substrates. Evidence of substrate influence was examined by normalization of the load-displacement traces. Comparisons were made between the model and experiments for indentation tests at different peak load levels and with varying degrees of substrate influence. A single set of five parameters was sufficient to characterize and predict the experimental load-displacement data over a large range of peak load levels and corresponding degrees of substrate influence.

Member Price: $25.00; Non-Member Price: $25.00
Volume: 19
#: 8
Pages: 2487-2497
DOI: 10.1557/JMR.2004.0308