# Calculate local strain tensor in a deforming 3D mesh

**URL:** https://discourse.paraview.org/t/calculate-local-strain-tensor-in-a-deforming-3d-mesh/11372
**Category:** ParaView Support
**Tags:** vtk
**Created:** [February 10, 2023, 7:50pm UTC](https://discourse.paraview.org/t/calculate-local-strain-tensor-in-a-deforming-3d-mesh/11372 "2023-02-10T19:50:18Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Gening\_Dong](https://discourse.paraview.org/user_avatar/discourse.paraview.org/gening_dong/32/10295_2.png) [@Gening\_Dong](https://discourse.paraview.org/u/Gening_Dong)
#### Post date: [February 10, 2023, 7:50pm UTC](https://discourse.paraview.org/t/calculate-local-strain-tensor-in-a-deforming-3d-mesh/11372/1 "2023-02-10T19:50:18Z")

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Hi,

I’m trying to display local strain field in a deforming 3D mesh. My steps were as follows:

1. Open .vtk files - Apply
2. WrapByVector - Vectors: MeshDisplacement - Apply
3. ComputeDerivatives - Settings as follows

And then I got this. I was wondering what those 0-8 options refer to. Is Strain0 eta\_xx and Strain1 eta\_xy? If so, I think it’s the result of global coordinates. Is there a way to compute the strain tensor in local coordinates (in the normal and tangent directions of each cell)?

 ![Screenshot 2023-02-10 143812](https://discourse.paraview.org/uploads/default/original/2X/7/794849312ef8348dad370e8db8674268b228ac66.jpeg)  
 ![20230210144338](https://discourse.paraview.org/uploads/default/original/2X/b/b8dbc72d313bbf66a56880e3740797d8c1cd83d1.jpeg)

Many Thanks,  
Gening

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 13, 2023, 10:37am UTC](https://discourse.paraview.org/t/calculate-local-strain-tensor-in-a-deforming-3d-mesh/11372/2 "2023-02-13T10:37:13Z")

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> [@Gening\_Dong](#):
>
> I was wondering what those 0-8 options refer to.

That are the 9 components of a tensor

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### Author: ![FEngineer](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/f/5f8ce5/32.png) [@FEngineer](https://discourse.paraview.org/u/FEngineer)
#### Post date: [February 13, 2023, 1:50pm UTC](https://discourse.paraview.org/t/calculate-local-strain-tensor-in-a-deforming-3d-mesh/11372/3 "2023-02-13T13:50:27Z")

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> [@mwestphal](#):
>
> That are the 9 components of a tensor

That’s right but for stress and strain tensors they are typically reduced to 6 components since σ\_xy = σ\_yx and so on. However, it’s possible that some software doesn’t do this, it all depends on the source of the data.