# Shear strains in 3DEC v5.2 **URL:** \ **Category:** 3DEC\ **Created:** [August 2, 2023, 10:21pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107 "2023-08-02T22:21:46Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\ **Post date:** [August 2, 2023, 10:21pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/1 "2023-08-02T22:21:46Z")
Greetings to all! I’m curious about how to obtain shear strains from particular zones by utilizing specified grid points. Can this be accomplished using LIST commands? Furthermore, with over 30 strain commands available in 3DEC, which one allows us to obtain the Shear strain (%) and Maximum shear strain (%)? Additionally, could you explain the difference between “increment” and “rate” in this context? - **ssi2** second strain increment invariant - **ssideterm** inant strain increment determinant - **ssid** eviatoric deviatoric strain increment - **ssij2** second deviatoric strain increment invariant - **ssimax** maximum principal strain increment - **ssimid** intermediate principal strain increment - **ssimin** minimum principal strain increment - **ssin** orm norm of strain increment - **ssio** ctahedral octahedral strain increment - **ssiv** olumetric volumetric strain increment - **ssiv** onmises von Mises strain increment - **ssixx** _xx_ -strain increment - **ssixy** _xy_ -strain increment - **ssixz** _xz_ -strain increment - **ssiyy** _yy_ -strain increment - **ssiyz** _yz_ -strain increment - **ssizz** _zz_ -strain increment - **ssrd** eterminant strain rate determinant - **ssrd** eviatoric deviatoric strain rate - **ssri2** second strain rate invariant - **ssrj2** second deviatoric strain rate invariant - **ssrmax** maximum principal strain rate - **ssrmid** intermediate principal strain rate - **ssrmin** minimum principal strain rate - **ssrn** orm norm of strain rate - **ssro** ctahedral octahedral strain rate - **ssrv** olumetric volumetric strain rate - **ssrv** onmises von Mises strain rate - **ssrxx** _xx_ -strain rate - **ssrxy** _xy_ -strain rate - **ssrxz** _xz_ -strain rate - **ssryy** _yy_ -strain rate - **ssryz** _yz_ -strain rate - **ssrzz** _zz_ -strain rate ---
**Author:** ![Huy](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Huy](https://forum.itascainternational.com/u/Huy)\ **Post date:** [August 3, 2023, 2:14pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/2 "2023-08-03T14:14:22Z")
Hello, The strain increment is calculated based on the displacement while the strain rate is based on the velocity. In your case, it should be the strain increment. And you can get the maximun shear from the principal strain increments ---
**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\ **Post date:** [August 3, 2023, 2:39pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/3 "2023-08-03T14:39:02Z")
Greetings, @Huy ! I appreciate your quick reply. Among the options listed earlier, could you kindly specify which one is more suitable for achieving maximum shear strain? ---
**Author:** ![Huy](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Huy](https://forum.itascainternational.com/u/Huy)\ **Post date:** [August 3, 2023, 2:56pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/4 "2023-08-03T14:56:14Z")
Hello, As mentionned earlier, you can get from the principal strain increment. The maxinum shear strain is the difference between maximun and minimun principal strain increment. So you need **ssimax** and **ssimin** Huy ---
**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\ **Post date:** [August 3, 2023, 3:16pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/5 "2023-08-03T15:16:18Z")
Understood, Huy! Thank you very much. ---
**Author:** ![VijayKiranKota](https://avatars.discourse-cdn.com/v4/letter/v/c4cdca/32.png) [@VijayKiranKota](https://forum.itascainternational.com/u/VijayKiranKota)\ **Post date:** [August 16, 2023, 7:20pm UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/7 "2023-08-16T19:20:00Z")
Hi @Huy I appreciate your previous response. Following your advice, I aimed to acquire **ssi** values. I’ve written two simple FISH scripts to record strains during loading, with the goal of plotting shear strain against time. Regrettably, neither of these scripts is yielding the expected results. I have validated the accurate extraction of variables gp1, bi1, and z1, except for the **ssi** value, which stubbornly stays at zero. Your assistance in resolving this issue would be immensely valued. ;-------------------------; Code: 1 ;--------------------------------------------------- def \_ssi gp1 = gp\_near(x, y, z) bi1 = gp\_block(gp1) z1 = b\_zone(bi1) ssi1 = z\_ssi(z1) end @\_ssi hist @ssi1 ;----------------------; Code: 2 ;------------------------------------------------------ def \_ssi z1 = z\_near(x, y, z) ssi1 = z\_ssi(z1) end @\_ssi hist @ssi1 ;---------------------------------------------------------------------------- ---
**Author:** ![Huy](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Huy](https://forum.itascainternational.com/u/Huy)\ **Post date:** [August 17, 2023, 7:44am UTC](https://forum.itascainternational.com/t/shear-strains-in-3dec-v5-2/1107/8 "2023-08-17T07:44:09Z")
Hi, I’ve replied in your other topic.