Full scale measurements – whipping, springing and warping stresses

Purpose

Wave induced vibrations (whipping & springing) contribute to fatigue and extreme loading. This has been documented by model tests (DNV-CeSOS research). To investigate this in confused sea states with routing, full scale measurements are carried out. The main goal is to document if the effects need to be included in ship design rules. Several factors increase the effects: Larger container ships, climate changes, high tensile steels and future trades due to widening of the Panama Channel.

Benefits

The aim is to establish a guidance note for container vessels to account for wave induced vibrations in design for any trade. This has already been developed for large blunt vessels such as bulk carriers. The results can also be used to improve simplified rule procedures for assessing the torsion response. This is included in the DNV software NAUTICUS.

Features

Container vessels operating in harsh wave environment are instrumented. A monitoring system, with strain sensors, wave radar and various onboard sensors, is used to collect continuous time series and half hour statistics. Combination of strain sensors are used to separate global load components, such as warping, vertical bending, horizontal bending and axial stresses, to determine their relative importance. The measured loading as a function of wave and ship conditions serve as basis for comparison with numerical calculations, model tests, and design procedures.