This repository is written with a specific work-flow in mind. Before diving into your analysis, take a day to read the code and check that used logic applies to your problem. Once you feel comfortable, a good way to start is to run the code with ctrl.verbose = 1, as this will activate extensive plotting of what is happening.
Once it seems like everything is working, I recommend you spend some time with the structure diagnostics, which contains various low-level output. An alternative is to simply step through the code in the debugger, but diagnostics allows you to collect and plot low-level outputs for all samples. This can help you spot strange results if you are postprocessing a large set of indentations.
The repository contains the code to calculate indentation moduli and hardness values of indentation tests. It assumes the material response is a combination of elastic, plastic and linearly viscoelastic mechanisms.
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The repository is missing the function readIBW.m. This function reads the binary files output by an Asylum Research/Oxford Instruments Atomic Force Microscopy (AFM) machine. I do not own the rights to this file, so I cannot share it freely. There are alternative codes out there, e.g.
- https://se.mathworks.com/matlabcentral/fileexchange/42679-igor-pro-file-format-ibw-to-matlab-variable
- https://cran.r-project.org/web/packages/IgorR/
but I did not attempt to use them. I did try the first link and the results were equivalent (although stored differently).
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The repository has been designed to be possible to run from both MATLAB and Octave. Although this is the intention, I do not guarantee that this will always work, as I develop on MATLAB.
If you have access to the file, you can clone or download this repository. The code here is the "functional" part of the program, but typically we use a script to specify links to the data and to plot the outputs.
The basics of nano-indentation testing is the theory of Hertzian contact. All developments share this fundamental base. Beyond a general understanding of Hertz contact theory, I recommend the following articles to understand this repository:
[1] Oliver, W. C., & Pharr, G. M. (1992).
An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments.
Journal of Materials Research, 7(6), 1564–1583. https://doi.org/10.1557/JMR.1992.1564
[2] Oliver, W. C., & Pharr, G. M. (2004).
Measurement of hardness and elastic modulus by instrumented indentation: Advances in understanding and refinements to methodology.
Journal of Materials Research, 19(1), 3–20. https://doi.org/10.1557/jmr.2004.19.1.3
[3] Feng, G., & Ngan, A. H. W. (2002).
Effects of creep and thermal drift on modulus measurement using depth-sensing indentation.
Journal of Materials Research, 17(3), 660–668. https://doi.org/10.1557/JMR.2002.0094
[4] Tang, B., & Ngan, A. H. W. (2003).
Accurate measurement of tip - Sample contact size during nanoindentation of viscoelastic materials.
Journal of Materials Research, 18(5), 1141–1148. https://doi.org/10.1557/JMR.2003.0156
[5] Cheng, Y. T., & Cheng, C. M. (2005).
Relationships between initial unloading slope, contact depth, and mechanical properties for conical indentation in linear viscoelastic solids.
Journal of Materials Research, 20(4), 1046–1053. https://doi.org/10.1557/JMR.2005.0141
[6] Cheng, Y. T., & Cheng, C. M. (2005).
Relationships between initial unloading slope, contact depth, and mechanical properties for spherical indentation in linear viscoelastic solids.
Materials Science and Engineering A, 409(1–2), 93–99. https://doi.org/10.1016/j.msea.2005.05.118
In the code, three methods are implemented, called "Ganser", "Feng" and "Oliver-Pharr". The method controls which of the equations
- "Feng" fits the equation from [3].
- "Oliver-Pharr" fits the equation from [1].
- "Ganser" is a hold-over kept for legacy compatibility and gives similar performance to "Feng".
If you have a suggestion I propose that you contact me directly and I will try to accomodate you.
- August Brandberg augustbr at k t h . s e.