(1) Use Three or More Layers of Reduced 8-node Elements in the Thickness Direction
For example, if three layers of reduced elements are used, the computed tip deflection is 4.828 mm; if four layers, 4.581 mm. The computed deflection is reasonable, but they are still larger than the theoretical value (4.281 mm).
(2) Use Two or More Layers of Reduced 20-node Elements or One or More Layer of Fully Integrated 20-node Elements in the Thickness Direction
If only one layer of reduced 20-node elements is used, the problem is not fully defined, which leads to no solution, However, one layer of fully integrated 20-node elements produces 4.284 mm, which is very close to 4.281 mm.
(3) Use Solid-shell Elements
Solid shell elements are excellent in simulating thin shell structures such as pressure or vacuum vessels. Only one layer of elements is needed. Solid shell elements use shell theory to formulate the elements; thus, their results are comparable to those of shell elements. When solid shell elements are used to simulate thin-shell structures, significantly less number of elements could be used than that of solid elements.
