Indentation fatigue, where a cyclic load is applied on the sample via an indenter, emerges as an alternative approach for measuring the fatigue properties of materials. We have carried out indentation fatigue tests on a poly(vinyl chloride) (PVC) bulk material, as well as on TiN and NiP films/coatings deposited on SUS304 steel substrates, and demonstrate that a simple power-law relationship can be established between the indentation load amplitude and number of cycles to failure. Such a law is very similar to the conventional fatigue strength law obtained from uniaxial tests. The agreement between the fatigue stress exponents obtained by uniaxial and indentation fatigue tests suggests the potential applicability of the indentation fatigue technique for extracting the fatigue properties of materials.
The work is supported by National Science Foundation (NSF Grant No. CMMI-0643726), by World Class University (WCU) program through the National Research Foundation of Korea (Grant No. R32-2008-000-20042-0), and by National Natural Science Foundation of China (NSFC Grant No. 50928601).
- Acoustic emission
- Fatigue strength
- Indentation fatigue
- Thin films