Critical Fracture energy release rate for cohesive zone model

Hi,

 

I am trying to estimate the critical fracture energy release rate for a cohesive zone model of metal laminates bonded together.

On using the lap - shear test( mode 2 debonding of the laminates) I am able to find the total energy released on delamination.

For a zone of length L and width w my experiment provides the total energy released as area under load - displacement plot = U.

I am also able to obtain the fracture energy release rate per unit width as u =  U/(w*L). My question is can this be used as input critical energy release rate for traction separation behavior in abaqus i.e Gc (area under the traction separation curve for a single element). 

As there could be many cohesive elements in unit length along the fracture front, I assume that the cumulative fracture energy released by all the elements in unit length  = u. Hence Gc/element_length = u, however I find that many use Gc as u.

I would be very grateful for any suggestions as to which approach is correct.

 

thanks,

Shouvik