# Explicit Dynamic Limitations

**URL:** <https://prepomax.discourse.group/t/explicit-dynamic-limitations/1615>\
**Category:** General Questions\
**Tags:** dynamic\
**Created:** [March 18, 2024, 5:14pm UTC](https://prepomax.discourse.group/t/explicit-dynamic-limitations/1615 "2024-03-18T17:14:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![SashaTheWhite](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@SashaTheWhite](https://prepomax.discourse.group/u/SashaTheWhite)\
**Post date:** [March 18, 2024, 5:14pm UTC](https://prepomax.discourse.group/t/explicit-dynamic-limitations/1615/1 "2024-03-18T17:14:03Z")

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I have an explicit dynamic analysis (crash test scenario with 20 bodies) I need to run and I’ve recently fallen in love with how easy PrePoMax is to use vs Salome Meca. I’m trying to argue the case for PrePoMax to my company, but I’ve read in a few places that PrePoMax (and Calculix by extension) are not ideal for explicit dynamics, but I haven’t come across an explanation as to why.  
Can someone shed some light on this? I’m very new to dynamic analysis in general.

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [March 18, 2024, 5:20pm UTC](https://prepomax.discourse.group/t/explicit-dynamic-limitations/1615/2 "2024-03-18T17:20:06Z")

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Yeah, explicit dynamics simulations in CalculiX can be really annoying with all those limitations. I stumbled upon them some time ago: [Can't get simple explicit dynamics impact analysis to work - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).](https://calculix.discourse.group/t/cant-get-simple-explicit-dynamics-impact-analysis-to-work/1910)

and mentioned some of them in this tutorial: [https://www.youtube.com/watch?v=-X0Shj7UXE0](https://www.youtube.com/watch?v=-X0Shj7UXE0)

IMO the worst one (apart from painfully slow calculations) is that rigid bodies don’t work with 2D elements: [Rigid body constraint doesn't work with shell, axisymmetric and plane stress/strain elements in explicit dynamics · Issue #59 · Dhondtguido/CalculiX · GitHub](https://github.com/Dhondtguido/CalculiX/issues/59)  
Hopefully, Guido will fix it in the next version of CalculiX.