I have made a 12" x 12" 2D model. It is fixed along the bottom in the y-axis and fixed at the bottom left corner in the x-axis. A displacement is prescribed along the top of the model.

My problem is that cracks form in the top elements. I am expecting them to form in every element simultaneously because the stress state should be uniform. I decreased the solution step size by 100 times but got the same results.