Collapse Predictions of a Weld Repaired Cylinder

The decision of whether or not to weld repair corrosion damage is significant as the process of reclaiming the original thickness through welding is not benign.  As a consequence of the thermal contraction of the molten weld metal, welding results in distortions which are held in equilibrium with a structurally dependent internal stress state.  Currently, the effect of these internal stresses and distortion on the collapse of an externally pressurized cylinder is interest as it may impose unfavourable operational restriction, which could be lifted with an improved knowledge.  Through detailed numerical simulations, the influence that the welding history has on the onset of plastic collapse is of interest.  Prior to these simulations, the validation of a series of bead-on-plates were undertaken to gain confidence in capability of the welding models.  These simulations included predictions of the transient temperature, stress-strain and displacements, and are necessary pre-cursors to introduce an equilibrated distortion and internal stress state within the cylinders.  Once initialized with various fabrication histories, the collapse simulations predict that there is only a 5% improvement associated with the weld overlay repair of the cylinder compared with an un-repaired corrosion patch.