Hello!

I am needing to flatten a reinforcement pad for a pressure vessel. I am not well versed in the sheet metal features that Solidworks offers so I have been looking for tutorials on similar shapes for flattening with no luck.  I have tried using the sheet metal features by cutting a small section of the shape out and then inserting a bend to flatten as I do for the shells but am unsuccessful. I get many errors when the program tries to process the bends. I would like to cut the shape into small sections and flatten but I think the curvature is the problem. Has anyone been successful with this type of shape?

Attached are images of the reinforcement pad shape and a sketch of the sections I am trying to create for the flattened version. 

Any advice is appreciated. I am an engineering student just learning the ropes.