Dear friends / distinguished imechanicians,

I am trying to use micromechanics in  foams to numerically compute the elastic constants using one unit cell. I see some literature available when simple unit cell shapes are assumed (like cubical or hexagonal). However there is nothing specific about modelling for tetrakaidecahedral foams. Assuming the right boundary conditions would be critical for computing the constants. I am not able to come up with a reapeating pattern for determining the places to apply the boundary conditions.

Have any of you done something similar to this and if yes, would you want to throw some light on the same.

 Thanking you

Prasanna 

I am modelling a system subjected to a thermal shock, where in there are both vertical cracks (mode I ) and also infacial cracks (cracks that primarily fail by delaminaton-mode II)

 For vertical cracks, Iam able to get reasonable answers for mode I crack propagation in ABAQUS using a critical crack opening displacement criterion. However when it comes to interfacial crack, I dont know how to propagate it becz all the criterion in the debond subroutines in abaqus assume a mode I kind of crack opening.

Is my assumption wrong ? Can anyone help me out in this?

Thanks