We are doing an Impact analysis of a "skull-b
Hello BIOMCH-L members,

We are doing an Impact analysis of a "skull-brain model" using ANSYS/LS-DYNA. But during the analysis, solution process terminates as soon as skull surface touches the 'rigid wall'(target), showing an error message:

"complex sound speed in brick element 51559 cycle 3600".

We have used 'General Node to Surface' contact definition, rigid wall has been modeled with shell 163(thin shell) and skull brain modelled with solid 168 brick element.

wall material taken to be steel/concrete.

After successive failure we have tried with a prototype having simpler spherical geometry, and got error termination along with very same error message.

Can anybody explain the meaning of that error message, or why it appears in ansys/ls-dyna? Can anybody suggest a remedial measure?
We have read ANSYS/LSDYNA users guide. But it appears of little use regarding our problem.

Thanking in advance, anticipating kind response,

yours sincerely,

Shamik Sarkar
Department of Applied Mechanics
Bengal Engineering and Science University
Shibpur
Howrah-3
West Bengal
INDIA.



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