@article{WolfRichter2003,
  author    = {Wolf, Bodo and Richter, Asta},
  title     = {The concept of differential hardness in depth sensing indentation},
  journal   = {New Journal of Physics},
  volume    = {5},
  number    = {15},
  issn      = {1367-2630},
  url       = {https://nbn-resolving.org/urn:nbn:de:kobv:526-opus4-5657},
  institution = {Fachbereich Ingenieurwesen / Wirtschaftsingenieurwesen (bis 8/2014)},
  pages     = {15.1 -- 15.17},
  year      = {2003},
  abstract  = {Since in-depth sensing indentation load-depth data of the entire loading-unloading cycle are available, more information than a single hardness value and an elastic modulus can be extracted from the experimental data. The conventional hardness H (h) = F (h)/Ac(h) and the differential hardness Hd(h)=dF/dAc are calculated as continuous functions of depth h and compared to each other in this paper (F: load, Ac: contact area). It turns out that Hd describes the momentary material resistance to deformation, whereas H integrates over deformation states from first tip-sample contact to current penetration h. This difference is particularly important for materials not homogeneous in depth (e.g. layer systems), and for situations where time-dependent external factors influence the momentary deformation resistance. Photoplasticity is considered as an example for the latter.},
  language  = {en}
}