Effect of variation of component dimensions and weld profiles on the free vibration response of stiffened plates

This investigation focused on the variations observed in the natural frequencies of fabricated stiffened plates, due to the inherent variations obtained in dimensions of components and in the spacing between the girders of stiffened plates; also the variations in the size of weld profiles connecting the various components were taken into account. The present analytical study was based on the earlier experimental work done by Agung Budipriyanto (2005) in his PhD thesis. Both experimental and numerical investigations were carried out for determining the free vibration responses of the stiffened plates considered above. 99.73% confidence level of the normally distributed, measured data sets, lying between µ−3σ and µ+3σ were used to generate finite element analysis (FEA) models. The FEA models were categorized as models without and with weld profiles. From all the analyses, it was observed that the variation in dimensions of components of stiffened plates and in weld profiles produced a maximum variation in natural frequencies between −5.04% to +4.59%. If differences much larger than these differences (between the virgin and the present state) are observed during the dynamic monitoring of the ship, immediately more detailed diagnostic, prognostic and remedial measures should be instituted so that the operational sequences do not lead to further incapacitating damages in the ship.