I recommend using/continue using:
- Hyperelastic material model
- 2D Axisymmetric geometry. Axis of rotation is Y axis, surface on + X side of Y axis.
- Half symmetry at the center of the length
- Displacement in Y on the end face, with X = 0
- Linear elements, but not too small. PLANE182
- Mesh with element shapes that deform to better shapes, not worse shapes. Start as wide rectangles, end up square.
- uniform reduced integration keyopt, 1, 1
- mixed u-p formulation keyopt, 6, 1
- more substeps and cumulative iterations