Cyclic friction tests of ballast stones interfaces under varying vertical load

This data set contains results from cyclic ballast-ballast friction tests under varying load.
Two types of railway ballast were tested: “Calcite” (stems from Croatia) and “Kieselkalk”, also known as Helvetic Siliceous Limestone, (stems from Switzerland).
In each friction test, a stone with a distictive tip was sheared over a flat (stone) surface under a given normal load.
The applied normal load was increased from 10 N to 100 N in several load steps in each test.
For each applied load, a given number of cycles were conducted.
In total, 7 tests were conducted for Calcite  and 8 for Kieselkalk.
The test results are provided in .csv files and contain (among other values) the measured coefficient of friction (CoF) values.
The test were organised in three test series. In all conducted test, the angular tip stones were 3D scanned before and after the tests.
Test series 1 and 2, involved a 3D scanning before each load increase.
The data of these tip scans are also provided (in .ply file format). From the 3D scans the contact areas were calculated (using an alogorithm described in the paper below).
A detailed description of the tests and discussion of measurements can be found in:

B. Suhr, T.A. Butcher, R. Lewis, K. Six
"Friction and wear in railway ballast stone interfaces"
 Tribology International 2020
https://doi.org/10.1016/j.triboint.2020.106498

This data set is organised as follows:

Folder FrictionTests: contains measured data from friction tests in .csv file format.
Folder TipScans: contains data from scans of ballast tip stones before/in between/after cyclic friction tests. Meshes are provided in .ply file format.
Folder TipScans: contains two files with detail information on the contact area calculation (for the two types of ballast tested)

Each folder contains three subfolder: Series1, Series2, Series3, which contains the data of the corresponding test series,
see paper above for a more detailed description.

Check the README.txt file for more information on the technical aspects

The investigated ballast types are the same, as  previously investigated

1) in uniaxial compression tests and direct shear tests:
Suhr, Bettina, & Six, Klaus. (2018).
"Compression tests and direct shear test of two types of railway ballast [Data set]"
Zenodo. http://doi.org/10.5281/zenodo.1423742

2) in shape analysis including 3D scans:
Suhr, Bettina, Six, Klaus, Skipper, William A., & Lewis, Roger. (2020).
"3D scans of two types of railway ballast including shape analysis information [Data set]".
Zenodo. http://doi.org/10.5281/zenodo.3689592