VALID III

The focus of the Valid II JIP was on the building blocks of a monitoring system to optimise the service life maintenance and sustainment efforts and the associated analysis. Monitoring within the Valid JIPs was largely done with accurate sensors and a fully synchronised measurement system on board. So far this has been the system's requirements.

Over the last few years significant developments have been made in the area of sensors based on micro processor technology. These are low on power consumption and open up the opportunity for a battery operated sensor. The accuracy of these sensors will generally be lower than the ones used so far. On the other hand, installation is much easier and costs are significantly lower. Numerical methods developed over the last decades have opened up the door for virtual monitoring. Also here, the accuracy of the sensors is lower than from a traditional monitoring system. On the other hand, again, costs and effort involved are significantly lower.

OBJECTIVES
Within the Valid III JIP the above developments will be investigated and applied. The objectives of the Valid III JIP are:

• Further improvement of inference methods for obtaining wave data
• Further improvement of long term data collected on USCGC BERHOLF and STRATTON for structural maintenance decisions including:

- Investigation of the possibilities and accuracy of a virtual hull structure monitoring system &
- Development of an production acoustic emission monitoring system.

• Development of low cost and effort fatigue measurement techniques
• Evaluation of reliability based approaches for forecasting long term structural maintenance decisions and valuating uncertainties using design of experiments and value of information

Design of experiments and value of information are key phrases within the Valid III JIP. The figure below shows the different tasks and how they are connected. Information about the wave environment encountered by the ship is essential for analysis of the service life maintenance and sustainment efforts. Wave data can be inferred from different sources.

TASKS
As part of Task 1, wave information inferred from two sources will be investigated. Within Task 2 the analysis of the HSM system data on the USCGC BERTHOLF and STRATTON will be addressed. In addition, the accuracy of a virtual hull structure monitoring system (VHSM) will be investigated. Task 3 will look into on board monitoring options using sensors that do not need extensive cabling. Within the previous Valid projects work on acoustic emission monitoring was done and brought the technique to a level where it can be developed into a production system. This development will partly be done within the Valid III JIP. The data from Task 1 through 4 will be brought together in a reliability analysis task (Task 5) that will among others be used to forecast maintenance needs (Task 6).

PARTICIPANTS
American Bureau of Shipping, BAE Systems, Bureau Veritas, Damen, Danisch Technical University, Defence R&D Canada, DST Group, Ingalls Shipbuilding, Office of Naval Research, Royal Netherlands Navy, TU Delft, United States Coast Guard, University of Michigan and MARIN.