Snap-Through Buckling

Snap-Through Buckling

Snap-through buckling is a mode of instability and a type of buckling where an elastic system under a specific load will pass from one equilibrium state to another, different equilibrium state.

An example of snap-through buckling is a jumping popper toy, which resembles a rubber spherical cap turned inside-out. The inside-out shape remains stable while held at the edges but leaving it on a surface causes it to experience a rapid change in deformation, called the ‘snap’. The significant deformations will stop when it reaches its second equilibrium state. During this, the toy will leap upwards.

Although the knowledge of a second state of equilibrium is useful to engineers, the amount of displacement which is common in snap-through buckling will often represent the failure of the system.

Snap-through buckling is simulated using a particular type of non-linear analysis. The load, however, has to be applied in a way that is different to a normal buckling or structural analysis. There, the load increment is kept constant across many different load steps until the analysis converges or buckling occurs. However, to analyse snap-through buckling, the load is modified by a factor at each time increment, so that the solution follows a specified path until convergence is achieved. This is called the Arc-Length Method, which records the additional load and displacement pairs of the equilibrium path.

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