@peteroznewman nnDear peter, I mentioned that paper just to describe the similar subject, that paper simulated double membrane airfoil ( at top and bottom), but my problem as shown as in the first comment is a single membrane airfoil that only has a membrane at top and looks like this:nsimply put, there is membrane (supposed a very thin beam) that its end constrained like attached photo, it must have a pre-stress in X- axis, because of the purposes that i mentioned at previous comments. how to apply thisn