Hello Everyone,

I am a student and I am doing FEM simulation on different fracture mechanics specimens. Now I am doing a simulation of Specimen(reactangular) with embedded elliptical crack under Tension load(also shear load). I'm facing some problems with this simulation warning appears:

1)"Loading condition might make main crack under compression at nset_. "The crack propagation direction can not be predicted. A value of zero provide for it".

2)The J integral values are negative.

I have used normal to crack surface as crack propagation direction. I am not getting the above mentioned warnings with other specimens like Tension specimen with penny shaped crack(circular). Unfortunately I do not know how to specify q vectors in every node correctly. Also I am not getting a converged solution(Stress intensity factor)for this specimen .

I would be grateful if anyone can suggest the solution/or techinque to solve this issue or tutorials or journals for the Elliptical crack FEM Simulation

Thanks and Regards