Nonlinear Interactive Buckling: Sensitivity and Optimality∗

ABSTRACT The nonlinear buckling behavior of discrete systems in which two eigen-modes interact is studied. A variable parameter affecting the design is introduced to allow a change in the closeness of the two eigenvalues. The sensitivity of the critical equilibrium states to combined changes in the design and imperfection parameters is considered through the concept of “sensitivity surfaces.” The analysis is used to discuss the sensitivity of structural systems optimized on the basis of the Simultaneous Mode Design Principle.