Average Stress over a thin shell

[ansysbeginner789]

I am trying to model an inflatable fabric tube with half-hemispheres as end caps. So far I have been using Ansys Workbench 13 to model. I have created shell geometry (using a revolved sketch) to model the fabric (1mm thickness) but when I run the solver I get a varying range of values for equivalent stress where they should be exactly the same. So it seems that to find an accurate stress figure for my model I would need to sum the stresses over an area that is removed from the end caps (because the stresses near the end caps are not representative of the stress seen in the cylinder portion of the tube) and calculate an average stress. How can I do this? A step by step explanation would be most helpful!