Uniform pressure inflates an initially flat sheet into a curved shape. This example explores a geometrically nonlinear response using a linear-elastic material.
Pressure and large deformation
The local input defines an elastic modulus of 200, Poisson’s ratio 0.3, and shell thickness 0.5 in consistent model units. Pressure rises to 0.01 in the first step and stays constant in the second, where tighter convergence controls are restored. The saved run reaches total time 2.
There are 11 exported states. Playback interpolates their displacement and stress fields; it does not solve the states between them. Time denotes static load-step progress, not physical inflation speed.
Reconstructing the pillow
The solved region is one quarter of the upper sheet. The outer rim has symmetry constraints normal to the initial sheet, while x = 0 and y = 0 define the in-plane symmetry boundaries. Full pillow reflects the result across all three planes, following the original example’s postprocessing. Turn it off to inspect the solved region.
The exported mesh contains quadratic hexahedra representing the expanded shell. The viewer retains midside nodes on its triangulated exterior. Reflections share the animation data, keeping loading light. True scale ×1 shows the saved displacement; amplification is only a display setting.
Reading the response
The chart compares prescribed pressure with the maximum vertical nodal displacement. Its marker follows playback. Pressure comes from the input ramp; displacement comes from the saved results. No reaction-force history is saved in static.dat, so this is a pressure–uplift curve.
The source example discusses sensitivity to shell formulation, hourglassing, and nonlinear convergence. A linear-elastic material does not imply a straight pressure–displacement curve under large deformation. This page displays your existing solution rather than comparing alternative element formulations.