INTERACTION BETWEEN STATIC AND DYNAMIC LOADS IN INSTABILITY OF STRUCTURAL SYSTEMS WITH QUADRATIC AND CUBIC NONLINEARITIES

The dynamic instability of a one-degree-of-freedom system is studied under two loading parameters: λ1 associated with a static load and λ2 which represents a dynamic load. The model includes both quadratic and cubic non-linearities, and may display stable as well as unstable behaviour. The equations necessary to evaluate critical loads under different forms of the dynamic load (step, rectangular and impulsive loading) are presented in the first part of the paper. The second part is concerned with the conditions that the different parameters satisfy when the system becomes unstable. © 1993 Academic Press Limited.