Motion-based monitoring of racking stresses in ro-ro ships

Abstract This paper presents a method for monitoring of racking-induced stresses in ro-ro ships. The approach is built on the assumption that the racking stresses are mainly induced by the roll and sway motions and therewith related inertia and gravity forces. The approach involves real-time measurement of the ship motions and scaling of the measured motions with pre-calculated structural responses from finite element analysis. The method is applied to full-scale measurement data from the Wallenius Lines PCTC Mignon. Derived stresses show good agreement with stresses derived from strain gauge measurements, indicating that the method has potential as an alternative to conventional strain-gauge-based monitoring. Motion-based stress monitoring has several potential areas of application such as providing data for decision support, for live assistance and short-term route planning, structural condition reports and for supplying feedback to the design process. Keywords: rackinghull response monitoringfull-scale measurementsfinite element analysisro-ro shipsPCTC Acknowledgements This research has been financially supported by the Swedish Mercantile Marine Foundation (Stiftelsen Sveriges Sjömanshus) and the Swedish Maritime Administration (Sjöfartsverket), which are gratefully acknowledged.