Learning Forum

[Fady Elshazly]

Hello,

 

In my Lsdyna model I have two warning messages:

1- Shell thickness is less than 0.5 

2- For element beam, beam distance is too small. 

Would these warnings cause any numerical problems?

 

Also, I want to add contact for (beam to beam) and (beam to shell), what would be the best choice. I have tried several contacts but none produced the desired interaction.

 

Thanks 

[Jim Day]

Please provide the full text of the Warning messages, including the Warning number.

For beam-to-beam, try *CONTACT_AUTOMATIC_GENERAL with SOFT=1 and the beam parts all on SURFA.   Leave the SURFB side blank.

For beam-to-shell, try *CONTACT_BEAM_TO_SURFACE with SOFT=1.

[Fady Elshazly]

Thanks for your reply. 

The warnings are:

1: SECTION_SHELL(ID: 1): thickness is less than 0.5. Refby 2 parts: 1 2..... warning(2)

1: ELEMENT_BEAM(ID: 2449): Beam distance is too small..... warning(47177)

 

For beam-to-beam contact, the contact should be created for each beam part. Say if I have three different beams interact with each other, I will create three contacts, right? 

 

Another question: for discrete beams(form 6), what is the best material to be assigned to act as a nonlinear spring with one axial DOF? 

Thanks 

[Jim Day]

I'm not familiar with those warnings.   Include images that show the warnings exactly as they appear in the LS-DYNA output (d3hsp or mes*).

You can create a part set with all three beam parts and put that part set as SURFA of one *CONTACT_AUTOMATIC_GENERAL.

If are just concerned only about 1 dof, I'd probably use a spring element defined with *ELEMENT_DISCRETE and *SECTION_DISCRETE.  For the material, use *MAT_SPRING_ELASTOPLASTIC or *MAT_SPRING_NONLINEAR_ELASTIC, depending on what sort of nonlinear behavior you want.

 

[Fady Elshazly]

 

Sounds good. Thanks a lot for your reply. Please find the attached screenshots for the warnings. They appear only in model check but not in the d3hsp or mes000 files 

 

[Jim Day]

Those screenshots are from what software?

If LS-DYNA doesn't complain, I wouldn't worry too much about it.