Elastic instability

Summary

Elastic instability is the loss of stability of an equilibrium of an elastic structure when the load passes a critical value. Below that value a small disturbance only makes the structure wobble about its equilibrium; above it the structure moves away to a different shape. For conservative loads the test is energetic: an equilibrium is stable when it is a strict local minimum of the total potential energy. Buckling of columns, plates and shells is the main example, and the subject is a part of bifurcation theory.