line spring elements

Hello, All

***Problem ***

Failure pressure for Steam generator tube having 2 axial cracks. I am following one paper in that paper they found failure pressure by finding J and K values for line spring elements for different pressure. The pressure at which it approach material JIC(92N/mm) and KIC(65Mpa*sqrt(m)) value is considered as failure pressure or coalescence pressus

**Modelling** 

Hello, All
I am trying to model steam generator tube of length 110 , radius 11mm, thickness 1.27mm. It has 2 axial cracks of length 6.35mm. length between 2 cracks is 0.254mm. 

As line spring elements cannot be created using Graphical user interface I first need input file. So I modelled the tube with shell elements S8R without any crack (once this model will run I will get input file and can modify it). As per paper which I am following the fracture coalescence pressure is 60Mpa means at this pressure J integral exceed the critical JIc. 

**Material Property**