Inelastic deformations in a solid circular cylinder subjected to cyclic torsion and heating

Abstract

An analysis is given of the behaviour of solid circular elasto-plastic bars subjected to torsion and a transient temperature distribution. Use is made of a ‘method of successive elastic solutions’ for which a numerical procedure is developed. A particular study is made of the transient and residual stress distributions, the variation with time of twist per unit length and the growth and disappearance of plastic zones for the situation where the transient temperature distribution is brought about by an instantaneous rise in surface temperature. The influence upon behaviour of strain-hardening in the material and of the temperature dependence of yield stress are noted in particular. The effects of cyclic variations of torque and surface temperature are examined with a view to determining a sequence that is most detrimental to the bar in terms of its incremental collapse. An account is given of experiments with mild steel bars subjected to torsion and thermal cycles of rapid surface heating and slow cooling. A reasonable agreement between theory and experiment is noted during a first thermal cycle. Repeated thermal cycles exhibit the phenomenon of incremental collapse.