Shallow Roof Example:
This is a classic snap-through benchmark problem used on the course
The characteristics are:
- Pin jointed on two sides
- Free on two sides
- Point load in center
The classic solution uses a quarter symmetry – but it is recommended that a full model is used
However the roof then snaps through to a stable solution with a very different configuration
The load deflection curve for an arc-length solution is shown here:
The initial linear solution is shown, with the dotted line.
The load reaches a maximum at around 590 N and then begins to unload at the start of the snap through.
At zero load and -17 mm deflection, the roof starts to snap back – reversing its displacement.
The load needs to reverse now to stabilize the snap back.
From around -400 N and -15 mm the roof has snapped through ad then recovers into a stable condition.
This new condition includes induced membrane stresses in addition to bending stresses.