how to generate cracks (surface/internal) in cad model

I didn't got your answer by the way will u plz discus this along with rendering.

Yes i have to do stress analysis will u help me by guiding how i will generate surface and internal crakes.

Internal cracks are a far more interesting topic than surface ones which are nothing more than cosmetic affectations. Of course internal cracks only matter if you are doing stress analysis... The steps would necessarily remain TBD by the need.