Main differences when using a spherical vs cylindrical indenters

Main differences when using a spherical vs cylindrical indenters

Here are the main differences when using a spherical vs cylindrical indenter:

Spherical Shaped Indenter

Cylindrical Shaped Indenter
  • A model should be used to fit to this data (Hayes, Hertz, Sneddon). See Mach-1 Analysis User Manual for more information on Hayes/Hertz models.
  • The area of contact is changing over the course of the indentation.
  • The area of contact is constant.
  • The analysis must be done from the start of the indentation.
  • Any part of the curve can be analyzed, as the results should be linear.
  • The Mach-1’s Normal Indentation function can be used to create a diagonal or “normal” contact with the surface of the sample.

  • The test can also be performed on a flat sample.
  • The sample must be flat, as the indentation is purely in the Z-axis.
  • If the sample is angled, only multiple-axis load cells or a 1.5N single-axis should be used if the contact is diagonal.
  • Otherwise, any load cell can be used if the sample is flat.
  • Any load cell can be used and only on a flat sample.
  • Appropriate for samples where the transition from air/liquid to sample is clear in the data.
  • Data is difficult to analyse if sample is very soft or very sticky (<1kPa).
  • Appropriate for samples where the transition from air/liquid to sample is clear in the data.
  • More appropriate than spherical for very soft and sticky samples (<1kPa), such as brain, spinal disk, iris, ovary, etc.

 Here are some resources for training on this topic: 

Mapping of cartilage tutorial: https://www.youtube.com/playlist?list=PLNlS2DfX2uD_39H2fu6Fs9nI8btKxoJIh

Indentation Testing of Soft Hydrogel: https://www.youtube.com/watch?v=-zLGT5Stt7Y

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