One of the core services of MARIN is to carry out measurement campaigns on board ships and to analyse the collected data. Currently, MARIN is carrying out a project, of which the main aim is to optimize the service life maintenance and sustainment efforts based on data from a hull structure monitoring system.
The focus of the Valid 2 JIP is on the building blocks of a monitoring system to optimize the service life maintenance and sustainment efforts and the associated analysis. The final task in the project will provide an example of how the data collected within the Valid projects can be used to improve the design and planning of maintenance needs. For this reliability based approaches will be used. Participating in the project are American Bureau of Shipping, BAE Systems, Bureau Veritas, Damen, Defence R&D Canada, DGA hydrodynamics, DST Group, Lloyd’s Register, Ingalls Shipbuilding, MARIN, Office of Naval Research, TU Delft and United States Coast Guard.
Of course an important objective of the project was the development and installation of a prototype minimum hull structure monitoring system. The system should be able to quantify fatigue life and extreme load of USCG WMSL class hull structure. Early 2015 the system was developed. In September 2015 it was successfully installed on USCG WMSL STRATTON. The location of the sensors was optimized using state-of-the-art-numerical tools in combination with methods developed within its predecessor project, the Valid JIP. On an older class of ships, the USCG WHEC SHERMAN, an acoustic emission monitoring system was installed in the summer of 2015.
To assist in the analysis of the collected on board data, laboratory tests will be carried out to evaluate fatigue measurement and analysis approaches for early crack detection. As part of these tests among others the effect of regular versus irregular loading will be investigated.
As a wave radar is an important cost driver in a monitoring system, a new SAWB method was developed. The method uses the extensive database that was build up during the Valid JIP. Based on the measured roll and pitch motions, the most probable significant wave height is selected from the database. The first comparison of measured and calculated wave height have shown the method to be promising.