I am try to do a simulation with multiscale models. I would like to simulate a crack growth on a patch of elastic material (for example, cell membrane) through the stretching process. The middle part of the patch is modeled by molecular dynamics, while the outer part is modeled by FEM. When I stretch the patch, firstly a pore formation will be observed in the middle part modeled by molecular dynamics, then the pore grows into a crack and extend into outer part which is modeled by FEM. The most difficult part is how to let the crack go through the coupling boundary of MD and FEM, spread from the MD part to FEM part. Does any one have suggestion or related experience? I would really appreciate your kindly help.