Volume 30, Issue 1 (January 2002)
Evaluation of Sharp Indentation Testing of Thin Films and Ribbons on Hard Substrates
A numerical investigation of sharp indentation of thin films and ribbons has been conducted using the finite element method. For a wide variety of material behavior, the critical ratio of indentation depth to thin film thickness is determined for the case of indentation of thin films or ribbons perfectly clamped on hard substrates. The critical ratio is defined as the ratio at which the indentation response can no longer be considered closely acceptable to the corresponding response at indentation of bulk materials. The indentation parameters investigated are hardness (average contact pressure), the size of the contact area between indenter and material, and the initial unloading slope of the indentation load-indentation depth curve. The implications of the results for material characterization of thin films and ribbons by indentation are discussed in some detail.