On the validity of using small-scale fatigue data to design full-scale steel welded structures: testing assumptions on residual stress relief
conference paper
An accurate fatigue life prediction is vital for the effectiveness and safety of a ship structure. The fatigue limit state is typically governing and con servatism is included to provide for a safe design. On the other side, minimizing conservatism is favourable, for reasons of cost, stability and payload (i.e. weight). The fatigue life prediction of full-scale steel welded ship structures is based on fatigue test results of, mostly, small-scale specimens. TNO has performed strain gauge measurements on a specimen, which represents a structural detail that is common in ship structures, that challenge the widely accepted conservative as sumption of lower residual stresses in small scale specimens. This research ex plains the measured strain increase perpendicular to the weld, when cutting small cruciform specimens from a larger plate. To do so, a thermo-mechanical coupled FE analysis is performed, using the Constant Initial Temperature model and a modelling of the restraint relief upon cutting the specimens. This has successfully demonstrated the physical basis for the measurements. These findings provide for a strong argument to assess the conservatism of the fatigue design standards case by-case. The work provides for a computationally efficient framework to predict the effect of stress relief on the effective R-ratio that is applied to small-scale cruciform fillet welded specimens
Topics
TNO Identifier
977778
Source
Proceedings 15th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS), 09-13 OCTOBER 2022 - DUBROVNIK - CROATIA, pp. 1-17.
Source title
15th International Symposium on Practical Design of Ships and Other Floating Structures PRADS 2022
Pages
1-17
Files
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