Dear Arvind,

I did not get the problem completely.....what i get is you want to simulate a tensile test till rupture or well beyond yielding  somewhere up to necking zone and you want to simulate the initiation of micro-cracks and their growth etc...If you want to do so....as per my understanding it is a damage mechanics problem..... you need a properly calibrated damage model for that .....you may read some thing on Gurson-Tvergaard-Needleman (GTN) damage law.....that may work...

Check the work of Gurson at the followoing link.

https://www.researchgate.net/researcher/60287082_AL_Gurson

Hope I understood the problem correct.

Regards