stress gradient

Dear all.

I'm currently doing some research concerning crack path prediction in brittle thin film.

But I'm struggled to find efficient way to do it.

In reality my case: stress is higly confined within semi infinite narrow rectangular strip patten and out of this rectangular, stress is very low or near 0 compared to stress within the pattern. Crack starts from left side end and propagates within pattern toward right end side of pattern. Crack show wavy propagation behavior with regular period and amplitude. 

 Liu, D., He, Y., Zhang, B., 2013. Towards a further understanding of dislocation pileups in the presence of stress gradients.  Doi: 10.1080/14786435.2013.774096

http://www.tandfonline.com/doi/abs/10.1080/14786435.2013.774096#preview