I'm trying to simulate a soft pnuematic actuator (artificial muscle) with two components, Skeleton cover by Skin, and operate with vacuum pressure inside to create contraction and generate force.

I tried to simulate it in Ansys Static Structural by apply negative pressure at skin, fix one end of skin, define frictionless contact of skin to skeleton (also skin to skin) and turn on large deflection. Material is LDPE for skin and Brass C26000 for skeleton.

Since skin is a thin membrane (0.2 mm), I use shell element at the skin. And after some digging, I found that I have to use membrane element by adding add some command to the skin to calculate only membrane stiffness (No bending).

I'm not sure how to set the simulation setting to obtain the correct result without any warning and error. I also attach PDF file for some picture that I mention.

Please, give me some advice.