Simplest Test Simulation with Element Rupture

[Wnuczko]

Hi,

I would like to run a calculation with element rupture. This will be Advanced Nonlinear static.

The easiest example I could imagine is a flat bar with reduced section in the middle. Looks like this below:

______ _______
| \/ |-->
|______/\_______|-->

This is a plate model fixed on one side and axially loaded on second side.

Define Material > General tab > Limit Stress > Tension & Compresion > 320
I have created Stress vs Strain Function (0,2 strain results in 320MPa and this is my ultimate stress). This is used in Define Material > Nonlinear > Plastic;
Yield Criterion 0..vonMises;
Init Yield Stress 235;

LGSTRN is checked
NXSTRAT Solver Parameters > Allow Element Rupture is checked.

Right now my simulation runs up to 0,565 time and then stops when max stress is 325MPa.

Questions:
1. Is my example simple enough? Myabe when it breaks it is very unstable and that is the problem?
2. Beside Allow Element Rupture check and Material Definition do I need to do anything more?
3. What I need to do to force element breake and the simulation to continue?
4. Can this be related to the size of load increment in the area of first element breake? Right now I have only 100 load steps equally divided.

Best regards,
Wnuc

 

[rob768]

to my knowledge, you cannot calculate up until the moment of breaking as, like you said so yourself, the model stability becomes an issue. The ratio elongation/stress will be far from realistic.