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Numerical simulation is used to study the influence of welding-induced residual stress in welded, tee-stiffened plates focusing on the effect of shakedown. Welding is simulated using 3D thermo-elasto-plastic finite element analysis. The influence of strain hardening and number of load cycles on residual stress shakedown is then investigated. Load versus end-shortening curves are used to characterise the strength and behaviour of stiffened plates under axial compression both before and after shakedown. Results show that the reduction in residual stress due to shakedown occurs entirely during the first load cycle provided that the magnitude of that load is not subsequently exceeded. Both the tensile and compressive welding residual stresses in the plates are reduced by as much as 40% when the applied load causes an average stress equal to 50% of the yield stress. This level of shakedown increased the ultimate strength of tee-stiffened plates by as much as 6% in some cases, but the potential for increase in ultimate strength as a consequence of shakedown was found to depend on the failure mode.

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[1] Existing temperature and salinity ocean climatologies are usually mean fields based on observations collected over many decades. Because of low frequency variability of major features such as the Gulf Stream it is often more appropriate to define the mean for shorter periods, but there are subsequently fewer observations and more problems with aliasing of mesoscale variability. We present a method for removing eddy-related noise from observations using satellite altimeter sea surface height measurements. We demonstrate the technique using Argo observations from the northwest Atlantic and produce mean temperature and salinity fields for an eight year period. The reduction in variance achieved is quantified. Comparison with an existing climatology shows that there is good agreement between the two analyses but that the representation of the Gulf Stream is more realistic in the new climatology.

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