Bullet impact simulation problem

Altair Forum User

Dear all, 

 

I'm facing with the simulation of the impact of a bullet on a steel plate. The bullet travels at 710 m/s and the plate is 6.3 mm thick. The bullet and the plate are simulated with solid element (BRICK). P14_SOLID is used for the solid and the johnson-cook material model (M2) is used for the steel plate and the bullet. The interface is a type7 vith bullet nodes as slave and plate as master. 

 

Radioss return to me the error 'ZERO OR NEGATIVE VOLUME FOR 3D-ELEMENT'. 

 

in PSOLID definition i've used both the Isolid option 1 and 24 and the Ismstr option 2 for large deformations but the error still remain. Does anyone could tell me something?

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Altair Forum User

Hi Alessio,

The NEGATIVE VOLUME error happens when solid elements are very deformed and their characteristic length goes to 0. For large strain formulation the time step of an element goes to 0 when the element is compressed. In RADIOSS Starter input file (Runname_0000.rad), use Ismstr =2 in the solid property and  in RADIOSS Engine file (Runname_0001.rad) use the option/DT/BRICK/CST which will set the time step value tmin at which the solid elements will switch to small strain.This means that the solid elements using Ismstr =2 will use large strain formulation while their time step remains greater than tmin, and will then switch to small strain formulation.

Please try with the attached model file.

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