Shakedown behaviour of a 90 degree single mitred pipe bends under cyclic in-plane closing moments

This paper presents an experimental investigation into the shakedown and possible ratcheting behaviour of 90 degree single unreinforced mitred pipe bends subjected to cyclic in plane closing moments with a non-zero mean value. Examination is focused on the possibility of ratcheting under a single load in combination with the weakening mechanism from the ovalisation of the mitre. Material response is considered both locally and globally from strain gauges at the location of highest stress and by measuring the displacement of the mitre end. Post yield behaviour comprised of elastic shakedown followed by plastic shakedown until failure. No ratcheting was observed in the experiments.