I have seen some articles that do measurements of hardness and elastic modulus by instrumented indentation (nanoindentation) in different directions of the material (for example: rolling direction, transverse direction and normal direction). Despite some articles discuss these measurements according to the direction tested, they do not make clear if the technique is really directional. Although the intenter moves in a single direction, from my view point, the material during the test will be deformed in 3 dimensions. Hence, the value we obtain is not the value of hardness or elastic modulus in the direction the indenter is moving, but a 3 dimensional response.
Does someone know where I could get a theory that explains this?
I hope I have made myself clear.
Thank you in advance.
Prezado Leonardo,
Yes, the response is a deformation in 3 dimensions. However, the 3D response is not the same for each orientation, and from those differences you can infer particular properties for each direction/orientation.
See for instance my publication
http://www.sciencedirect.com/science/article/pii/S0921509314008466
You can check the references to gain more insights into the basics.
I will be visiting IFI-UNICAMP next week if you want to discuss more about this.
Hope it helps,
Best regards,
Carlos
Thank you Carlos, I am going to read it!
Unfortunately I can not meet you in Brazil because I am in Spain doing part o my thesis. But maybe some other time! Thanks.
Of course, during indentation tests we have 3D stress state. Values obtained are differ from values of elastic modulus which measured in standard uniaxial compression test. Best regards
Hi Gleb, Thanks for your response. I'm studying a cold rolled titanium alloy with crystallographic texture. I wanted to evaluate young's modulus on different directions. As my samples are too small to do stress-strain tests, I would like to use nanoindentation. But it seems it's not straightforward to get a directional value after the test. Have you ever done something similar? I have here available a Berkovich indenter and a spherical indenter.
Depending on the type of indenter and type of material, the state of stress varies. For example. Berkovich indenter on the typical flat sample gives 3D state of stress. Cylindrical indenter on micro and nanopillars give the 1D state of stress.
Thanks Mallikarjunachari,
I've heard about this technique with micro and nanopilars. I'm considering to try to do this. I'm talking to a profesor I know who work with this.
Thanks!
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