Nonlinear Dynamic + contact

disla

Hi ,
I have a red warning in the contat BC which says contact cannot be used with Nonlinear Dynamic solver.
I have pushed the run button just for fun and it has completed the analysis.
Is it a bug on the warning or may I consider the results wrong? Is it a new feature in ccx v2.19?
I have read in the forum that Nonlinear Dynamics and contact do not work but senns it was only for plastic materials ¿isn’t it?.

disla

JohnM

We use dynamics with contact. Works fine. Keep contact stiffness values reasonable, set time step small, be smart about mesh size!

JohnM

sample dynamic with contact

disla

Hi ,

I think this should be just a bug in the UI. There is a red colour in the "contact" text for the Dynamic Response and it disappears when I switch to Nonlinear Dynamic Response. Contact seems available for both analyses.

Thanks for the example file, JohnM. Very cool. Seems like you are checking the resistance of some internal component when it falls. I will play some different options later. I don't have any practical experience with dynamics.

kennethfugate

Here is an update to to the ball.inp Calculix example modified to run in Mecway. It adds a CCX model definition to add an initial velocity. At the end of the run, there is a dent in the panel and the energy absorbed by the plastic deformation reduces the return velocity.

I tried adding EXPLICIT to the *DYNAMIC keyword. Calculix didn't complain and ran but produced erroneous results. Ran fine without the EXPLICIT keyword, i.e. implicit solution.

disla

Which version of ccx are you using?. When I try to run it, exits the solver without any message.

kennethfugate

2.18

Try restarting it a few times. For some reason, it sometimes doesn't run on the first try hitting the run button.

disla

It doesn't respond. ¿Is it just me?. I would appreciate if someone else can give it a try.
I have tried v.17.1, v.18, v.19 on a WIN10 machine and the one coming with Mecway.
¿Could you post your ccx executable?

JohnM

@disla there are times the "red" can be ignored. You will get that same warning if you use self-contact in a nonlinear static run (master/slave surfaces the same). But it works!

disla

Thanks, JohnM,

I was lucky to press the button but it would be a pity if someone needs it and do not give it a try just for seeing that red alert.

I'm still trying to run the Ball file with Nonlinear and Plasticity and it is not responding to me. I have tried some different versions (maybe a dozen) . ¿What could be the reason Victor.?

Victor

The red and error message is because the Dynamic Response 3D analysis type is linear so it can't have contact. But if it's present, CCX quietly changes to nonlinear so it does work but with all the other effects of nonlinear analysis which you told it not to do, hence it's technically an error. Use Nonlinear Dynamic Response 3D instead.

disla

Something has changed positively in the new version.
Nonlinear dynamics runs more stable with contacts, and I've been able to finish analysis that failed in the previous version. Not sure if Victor changed something , my laptop, Solver, good tips or all together...?¿? Anyway grateful