# Can user materials be used in a dynamic explicit step? **URL:** \ **Category:** Uncategorized\ **Created:** [August 27, 2024, 1:39pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388 "2024-08-27T13:39:05Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![flani](https://avatars.discourse-cdn.com/v4/letter/f/ea5d25/32.png) [@flani](https://calculix.discourse.group/u/flani)\ **Post date:** [August 27, 2024, 1:39pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/1 "2024-08-27T13:39:06Z")
Hello i created a user material of a composite that is working fine in static steps, however, to be able to model progressive damage, i’d like to use it in a dynamic step… Now i would like to use it in Dynamic explicit steps, is there any known limitation for user materials with dynamic explicit steps ? Thank you for your help ! ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [August 27, 2024, 2:23pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/2 "2024-08-27T14:23:20Z")
I don’t think it’s mentioned in the documentation and I haven’t seen any working analyses like that. Abaqus has separate subroutines for implicit and explicit solver (e.g. UMAT and VUMAT). But give it a try and let us know, it would be nice to have a confirmation if it’s possible in CalculiX. > [@Using Abaqus VUMAT files in CalculiX](https://calculix.discourse.group/t/using-abaqus-vumat-files-in-calculix/1027): > > Hello Everyone, Does anyone have experience using Abaqus VUMAT files in CalculiX? I am looking for example files to get going. Many thanks, JW ---
**Author:** ![flani](https://avatars.discourse-cdn.com/v4/letter/f/ea5d25/32.png) [@flani](https://calculix.discourse.group/u/flani)\ **Post date:** [August 27, 2024, 3:09pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/3 "2024-08-27T15:09:00Z")
Thank you for the link, i already went through that one. I am trying to find out just by using a umat containing linear elasticity. Actually what is stopping the calculation of moving forward is the calculation of the stable time increment. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [August 27, 2024, 5:08pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/4 "2024-08-27T17:08:48Z")
What if you add dummy element(s) with built-in elasticity ? Or even use direct incrementation (normally not recommended) ? ---
**Author:** ![flani](https://avatars.discourse-cdn.com/v4/letter/f/ea5d25/32.png) [@flani](https://calculix.discourse.group/u/flani)\ **Post date:** [August 27, 2024, 7:11pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/5 "2024-08-27T19:11:26Z")
Hello @Calc_em , thank you for those hints. Indeed i used the DIRECT keyword & the stable time increment computed with the built-in linear elastic orthotropic material, and it the simulation runs. I agree with you that putting somewhere a built in linear elastic element should do the trick, i’ll try it as well and post the outcome here. Note that I could not find in the source code where the increment is computed based on the density and elastic properties. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [August 27, 2024, 7:24pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/6 "2024-08-27T19:24:49Z")
> [@flani](#): > > Note that I could not find in the source code where the increment is computed based on the density and elastic properties. It seems to be this file: [CalculiX/src/calcstabletimeincvol.f at master · Dhondtguido/CalculiX · GitHub](https://github.com/Dhondtguido/CalculiX/blob/master/src/calcstabletimeincvol.f) ---
**Author:** ![flani](https://avatars.discourse-cdn.com/v4/letter/f/ea5d25/32.png) [@flani](https://calculix.discourse.group/u/flani)\ **Post date:** [August 27, 2024, 8:02pm UTC](https://calculix.discourse.group/t/can-user-materials-be-used-in-a-dynamic-explicit-step/2388/7 "2024-08-27T20:02:05Z")
oh thanks, indeed with that name i should have found it 🙂 i’ll have a look !