Formulation of optimal design under creep-damage conditions

Abstract

When elastic structures are designed for either minimum weight or maximum load under a strength constraint, structures of uniform strength, also called fully stressed designs, are optimal in most cases. In general, however, the condition of uniform strength is neither a necessary nor a sufficient condition of optimality The exceptions, when structures of uniform strength are nonoptimal, are mainly connected either with the static indeterminacy of a structure or with geometric changes being taken into account. On the other hand, the condition of uniform strength of structures may not be a sufficient optimality condition if it does not result in a unique solution. Hence, following Gallagher (1973), the fully stressed design method (FSDM) is, in general, a first step towards the exact optimal design when more rigorous optimization approaches are used.