What is thermal drift and what are its causes ? I did nanoindentation of a polymer nanocomposite. To know the thermal drift, at the end of unloading, low load of 0.01 mN was held constant for 70 seconds. There was not any pattern, the depth increased and decreased and at the end the depth was same as it was in the beginning. How to correct for thermal drift in such a case ? If there was only increase or decrease, i could have fit a line or curve to it and correct the displacement readings accordingly. But since there is no any pattern to it what shall I do ?
Thermal drift is used to define any evolution of the displacement of the tip while maintaining a constant force. Of course, for time dependent materials, such as polymers, it can be tricky to separate the effect of creep from the effect of thermal drifts (that are cause by slight local temperature changes). But if you have signifiant displacements (for a material with a very low stiffness for example), then the thermal drift shall be not be a problem.
It is usually better to measure this thermal drift before the test by maintaining a very low load for a given amount of time. A drift rate can then be evaluated and used to extrapolate the thermal drift during the test. The drift free displacement can then be evaluated after the test is over (your software may perform that correction automatically).
The thermal drift shall be evaluated prior to any measurement as it may vary from one test to another. It is very dependent on your device, your testing conditions, your material, etc. And last be not least, the shorter the test, the better it is (regarding thermal drifts issues).
In your case, if you do not have any trend, then you should not be influenced by thermal drifts. You may check that by performing your drift evaluation prior to your test.
https://www.set-transducer.com/Article-ThermalDrift.html
hello
this Article may be useful for you.
Thermal drift is a variation in the force or depth signal arising from thermal expansion or contraction of the specimen. To some extent, thermal drift may also be caused by the electronics unit having not reached a stable temperature
Vincent Le Saux I totally agree with you. Furthermore, a possible solution to measure thermal drift could be a reference (e.g. a ring) between the indenter and the sample's surface: https://www.anton-paar.com/corp-en/products/details/nanoindentation-tester-nht3/
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