Difference between Creep and Strain Rate Sensitivity

[phgw]

Hello,

recently I became interested in some basics of material science and there was one thing that I did not really understand.

What is the difference (or what are things in common) between creep and strain rate sensitivity?
I read about it in connection with indentation.

- To measure the creep of a material using nanoindentation, the load is applied to the sample and then held constant for a given time. If the indenter continues to penetrate the sample during this time, creep occurs.
- To measure strain rate sensitivity, the load is applied to the sample within different times. If there's a difference between applying the load slowly or fast, the material shows strain rate sensitive behavior.

For me, these two things seem to be quite similar. Or are these phenomena two totally different things? If not, are there equations that show the similarities?

I am sorry, I know that this is probably really basic stuff, but maybe somebody can explain it to me.

Thanks a lot,

phgw

 

[Dr. Courtney]

The time scales for rate sensitivity range from 1/s to 10^8/s (ballistics and blast). The time scales for creep are much slower.

 

[dipstik]

creep is constant load, looking at the strain versus time.
strain rate sensitivity looks at how the performance (typically yield) of a material changes depending on how quickly/slowly you strain the material.

they are very different.