stretching simulation

Hi All,,

I am trying to simulate stretching behaviour of my composite material depend on the fibre orientation using mesh relaxation in kangaroo. As you can see in images below, the shape of the material will change when I pull/ stretch in certain distance and then, two free edges will meet when I stretch in larger distance.

The problem is that I always have the planar mesh when I tried to stretch my model. Does anyone have suggestion how to simulate this??

Thank you,