# Deformation plasticity strain output

**URL:** <https://calculix.discourse.group/t/deformation-plasticity-strain-output/3836>\
**Category:** Model setup\
**Created:** [March 23, 2026, 1:47am UTC](https://calculix.discourse.group/t/deformation-plasticity-strain-output/3836 "2026-03-23T01:47:11Z")\
**Posts on this page:** 1\
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**Author:** ![shah](https://avatars.discourse-cdn.com/v4/letter/s/f4b2a3/32.png) [@shah](https://calculix.discourse.group/u/shah)\
**Post date:** [March 23, 2026, 5:26pm UTC](https://calculix.discourse.group/t/deformation-plasticity-strain-output/3836/3 "2026-03-23T17:26:40Z")

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Thank you Victor, this clarifies things for me. Interestingly, I could not find any reference to a v2.21 switch-over to Lagrangian strain for deformation plasticity outputs. The Table 18 entry describing the output variable E as Lagrangian strain appears to have remained unchaged since a while ago (I traced it back to the manual for v2.17).

The most relevant record I found was Guido’s plan to switch the strain output from Eulerian to logarithmic strain in the following post, which coincides with v2.21 release period. Perhaps Guido decided to use Lagrangian after that discussion:

> [@Deformation Plasticity. Eulerian strain](https://calculix.discourse.group/t/deformation-plasticity-eulerian-strain/1511/15):
>
> Hi, the formula for the Eulerian strain in the manual is unfortunately wrong, the second term should have -3/2 instead of -1/2. So the Eulerian strain is not as close to the logarithmic strain as I had hoped for. I took this opportunity to change the formulation in CalculiX for deformation plasticity from Eulerian strain to logarithmic strain, as in Abaqus. Will be available in the next CalculiX version (summer 2023). Best Greetings, Guido

Either way, good to know this detail.

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