Dear Erik Thank you for your quick response.
I attach the structure that I am dealing with.
When trying the expansion with shell elements, the cylinder starts to expand until the point where it starts to stretch, where it fails to converge. I attach the failing point below. I only fix the sides and apply pressure.

Thus, I considered this as a problem of the bending of the shell elements. What is your opinion on that? Should I go for shell or membrane elements?