Discussion Forum

Hello all,

I'm trying to model the inflation of a silicone rubber enclosure in response to a parametric sweep of internal pressures. My current model is a vertically oriented quarter sphere, as shown in the attached GIF. The internal boundary has a pressure condition for the sweep, the side boundaries have a symmetry condition, and the outside boundary is free. Additionally, I'm using a 3D structural mechanics stationary study with an Ogden approximation to model the part as a hyperelastic material.

The ultimate goal is to orient the geometry horizontally rather than vertically, and to use a half ellipsoid rather than a quarter sphere. Holding all other parameters equal, I've attempted to run the same study on a quarter sphere, hempisphere, quarter ellipsoid, and half ellipsoid, with the geometries oriented both vertically and horizontally. For reasons I have not been able to understand, only the vertical quarter sphere yields a converged solution (refer to the .mph file attached) that makes sense. All the other configurations either don't converge, or they yield a solution that doesn't make sense.

I don't see why changing the geometry in what seems like a subtle and insignificant manner leads to such drastic changes in the convergence of my model. If someone can lend their expertise and point me in the right direction, it would be much appreciated.