# Crushable Foam Model in CalculiX **URL:** \ **Category:** Uncategorized\ **Created:** [June 12, 2021, 6:25am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617 "2021-06-12T06:25:24Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\ **Post date:** [June 12, 2021, 6:25am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/1 "2021-06-12T06:25:24Z")
Hi Has anyone used Crushable foam model in CalculiX? (Also called as Deshpande Fleck model) I found that CalculiX does not have this material model inbuilt in it like ABAQUS. I plan to write a UMAT for it and implement it in CalculiX. Any suggestions on how to start? I am not looking for the complete UMAT code itself, rather I’d like to discuss/get help on how to write it from scratch. Thanks ---
**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\ **Post date:** [June 12, 2021, 6:45pm UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/2 "2021-06-12T18:45:47Z")
I haven’t used the crushable foam model. You could start with the UMAT subroutines for the card \*HYPERFOAM - I think that would give you a good start. ---
**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\ **Post date:** [June 12, 2021, 10:24pm UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/3 "2021-06-12T22:24:01Z")
Thanks. This is for rubber-type materials I believe. Anyway, let me see how it goes. ---
**Author:** ![suzuki\_h](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@suzuki\_h](https://calculix.discourse.group/u/suzuki_h)\ **Post date:** [June 19, 2021, 2:08am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/4 "2021-06-19T02:08:35Z")
I think it would be a good idea to create a UMAT subroutine based on \*HYPERFOAM, but if ABAQUS has a “Crushable foam model” or “Deshpan de Fleck model”, I think it is better to create a UMAT subroutine based on them, if we can read the source code of them. ---
**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\ **Post date:** [June 20, 2021, 6:44am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/5 "2021-06-20T06:44:22Z")
Thanks for this. Unfortunately, we don’t have the access to ABAQUS source files (except the documentation/theory manual). Bhanu ---
**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\ **Post date:** [February 3, 2022, 5:51am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/6 "2022-02-03T05:51:12Z")
Hi I feel this is a silly question, but anyway, let me post it: Can anyone clarify whether the Deshpande Fleck Model (\*CEUSHABLE FOAM) in ABAQUS, accounts for rate effects or not? (As per ABAQUS documentation, there is an option of including rate effects using a separate card \*RATE DEPENDENT, but the crushable foam model as such does not ask for any other inputs other than the quasi-static cauchy-stress–true-strain hardening data.) Another question, does CalculiX have any way of including rate effects? Bhanu ---
**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:** [February 3, 2022, 10:53am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/7 "2022-02-03T10:53:39Z")
As you said, in Abaqus you have to add the \*RATE DEPENDENT keyword to account for strain rate dependence. Constants for it are specified under this keyword, not under the material model keyword. From what I know, CalculiX doesn’t have built-in strain rate dependence and you would need UMAT to include it. ---
**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\ **Post date:** [February 3, 2022, 11:34am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/8 "2022-02-03T11:34:51Z")
Does it make the Crushable Foam model a rate-independent model as such? I mean the constitutive model itself. (I am a little confused here) > [@Calc\_em](#): > > you have to add the \*RATE DEPENDENT keyword to account for strain rate dependence ---
**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:** [February 3, 2022, 11:58am UTC](https://calculix.discourse.group/t/crushable-foam-model-in-calculix/617/9 "2022-02-03T11:58:04Z")
Yes, that’s right. Check the Abaqus documentation chapters “Crushable foam plasticity models” and “Models for crushable foams”. They discuss this material model in detail, including equations.