Best Abaqus strain metric for comparison with strain gage data

[jball1]

I using Abaqus/Explicit to correlate with strain gage test data for a dynamic test of a composite component. Peak strains measured in the test are ~0.005 in/in, so definitely elastic.

I am trying to understand the difference between my two options for strain output, "Nominal Strain" and "Logarithmic Strain", in order to determine which I should choose for my correlation. I have read the documentation and have also done some googling.

Am I correct in saying that "Nominal Strain" is something like "Engineering Strain" and "Logarithmic Strain" is something like "True Strain"? If that is true, am I right in saying that I should use "Nominal Strain", because that likely most closely approximates the strains recorded by the strain gages?

Since the strains are relatively low, perhaps there won't be much difference.

Also note that since the data is from 30 years ago - all I have are the strain time histories and gage locations, there is no info on the gages themselves, etc.

Thanks for the help.

 

[FEA way]

Yes, logarithmic strain is true strain. This is often described in literature using a simple 1D example. Check the video "Understanding True Stress and Strain" on The Efficient Engineer YouTube channel for very good explanation.

True strain will be much more accurate for large deformations.