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[javat33489]

Hello everyone.
Please help.
I'm calculating a rubber cylinder with a cord inside, and the result is a rubber tube.
1. I apply 6 MPa pressure to the inner wall of the rubber, and the calculation holds successfully.
2. When I set the pressure to 15 MPa, I get "failure negative volume" messages immediately after starting. And the calculation goes offline.

I'm also using Massscale 5e-7.

I've tried many solutions: I've refined the mesh, changed the contacts, and changed the section elements. Nothing helps.

Please help me fix this problem. Thank you.

[Nanda]

Hello Javat,

Clearly the culprit seems to be the loading. Could you do a gradual ramp-up of the load? I would try my luck with *CONTROL_ACCURACY and *CONTROL_BULK_VISCOSITY. What ELFORM is in use? What ELFORMs were tested? Please make sure to keep the mass scaling below 5%, as per the general guidelines.

I would also make sure my material parameters are calibrated for a 15 MPA loading.

Regards,

Nanda.

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[javat33489]

Thank you for your reply, sir.

I added the maps *CONTROL_ACCURACY and *CONTROL_BULK_VISCOSITY, but it didn't help.
I tried ELFORM 1, 2, 3, 4, and 10 for rubber and steel parts. Nothing helped.
I looked at the rubber properties; I can apply pressures up to 20 MPa. I used that, but it didn't help.

I also tried going back to 7 MPa, but now even at 7 MPa it immediately gives an error.

I don't know what happened, but it used to work at 7 MPa. I reset the settings, but it still doesn't work.

[Nanda]

How are you applying the load? Could you share the plot of the LCID? 

[javat33489]

My load is 0-20 MPa, from 0 seconds to 0.03, then from 0.03 the pressure remains until 0.04 to reduce the kinetic energy

[javat33489]