The Creep Buckling of Composite Members

Abstract

The simplified theory put forward in an earlier paper (***)‡ is extended and generalized to cover the case of the thermal creep buckling of prismatic two-member components such as reactor fuel elements, all phases of creep and elastic strains being considered. The tangent modulus approach is used and small deflections are assumed; it is shown that even with these assumptions a solution in closed form can be obtained only in the case of a single rod.

Approximate methods of solution are then discussed, in which primary and secondary creep phases only are considered, but with certain simplifying assumptions. Throughout most of the analysis a modified form of Andrade's creep equation is used, namely ε = αt^1/3+βt+γt³, where α, β, and γ are functions of stress and temperature, ε and t are creep strain and time.

Typical curves are presented, based on data for an aluminium alloy, illustrating the contribution to buckling deflection likely to be expected from primary creep, for the single rod.