TRIBOLOGY CHALLENGE
Part A is open!
Harmonization of Reciprocating Friction Testing Practices
The Challenge
Every tribology lab is equipped with a reciprocating tribometer, which measures the tangential force (N) between the fixed and moving samples, as well as the position (m) of the moving sample. However, when the same system is tested in different labs, significant variations in the results are often reported, undermining the credibility of the research and making it harder to draw meaningful conclusions or develop universally accepted standards. The Tribology Challenge aims to remedy that.
The Tribology Challenge consists of two parts: PART A and PART B:
PART A
Data Evaluation
The value of the CoF can vary depending on the method used to evaluate the signals. It’s time to align our practices!
PART A focuses on harmonizing the post-processing of the tribometer measurements.
- If we have measured the same signals, shouldn’t we all reach the same CoF?
A guideline for calculating the different parameters that result from a reciprocating friction test will be developed based on the results of Part A.
PART B
Experimental Round Robin Test
PART B will be launched after PART A.
In PART B, the participants will receive two samples to be tested on their own reciprocating tribometers. The testing conditions will also be specified.
The participants will be asked to provide the results of the tests.
PART A: Data Evaluation
We provide the signals resulting from three reciprocating friction tests (namely System A, B, and C). Participants of the challenge must post-process the signals and fill out the questionnaire provided below.
To simplify Part A, the signals from the systems A, B, and C will be released at different times. Several aspects must be harmonized, and we will address them one by one. Part A focuses on the analysis at the CYCLE-level, Part B addresses the TEST-level, and Part C examines the entire system (see the three levels of evaluation).
| System A | Test A (download) | Questionnaire System A (download) | CLOSED (evaluating results) |
| System B | Test B | (not released yet) | COMING SOON |
| System C | Test C1, Test C2, Test C3 | (not released yet) |
Send your replies in .pdf format to office@i-tribomat.eu.
We will process the answers as we receive them, and an online workshop will be organized to harmonize and discuss the results. A scientific publication summarizing the results of Part A of the Tribology Challenge is expected.
NOTE: Part A of the Tribology Challenge does not involve conducting experiments; it focuses solely on data processing. Your task is to analyze friction data from a reciprocating test. An example of the provided data is shown below:
A guideline for calculating the different parameters that outcome from a reciprocating friction test will result from PART A.
Register to stay up to date with the Tribology Challenge.
Disclaimer
- Your data will be treated anonymously and in accordance with GDPR.
- The results will be evaluated by a committee of volunteer tribologists from institutes supporting the challenge.
- Anonymized data might be published after the challenge. Participants will have the option to choose whether they want to be acknowledged for their contribution..
Join the Challenge & Stay informed
Supporters
Why is this Tribology Challenge necessary?
- It is not clear which parameters are relevant in reciprocating friction results.
- It is not clear how these parameters are calculated.
- Every scientist evaluates reciprocating data in a different way (which they usually do not tell).
Result: We end up comparing apples and oranges/pears.
Objectives of the Tribology Challenge
- Make our results comparable.
- Stop reinventing the wheel every time we test.
- Open the door to reusing past results, big data, and AI.
- Make tribology greater, or at least a little bit more reliable.
What about the current norms?
- ASTM G133: It does not explain how to calculate the Coefficient of Friction (CoF) per cycle.
- ASTM G203: It only shows one way to calculate the CoF (i.e., the Energy CoF). It is not clear whether the stroke length or the slip distance must be considered.
- ASTM G115: There is no calculation method. It explains how reciprocating friction results should be reported. It is a good starting point but it is not enough.
- ISO 19291: The “peak-to-peak” CoF is mentioned, but no formula is given. The peak-to-peak CoF relies on just two measurement points per cycle.
- ASTM D6425 & DIN 51834-2: The “peak value” CoF is mentioned, but no formula is given. The peak value CoF presumably relies on just one measurement point per cycle.
Even if a norm would unequivocally specify a CoF per cycle (e.g., peak-to-peak), it is not clear what to do for the entire duration of the test, or for the whole tribological system. See the three levels of evaluation that require normalization.
Three different levels of evaluation
CoF per cycle: parameters that can be extracted from each friction-loop (e.g., maximum, average, peak-to-peak, peak-value (Spitzenwerte), etc.).
CoF per test: once we have the CoFs of each cycle for the entire test, what information can we get from them?
COF per system: we usually do repetitions (“one test is no test”). How to unify the results? At the end, we aim for the Coefficient of Friction (CoF) of a tribological system.