Abstract
Well designed and implemented Asset Integrity Management strategies are key to ensure safe operations and high availability of assets. In a world where data is king and data-driven decisions are becoming the norm, it will be difficult to imagine such strategies without the extensive use of monitoring technologies.
In the past years, Bureau Veritas has developed a hybrid Structural Health Monitoring technique that combines strain gauge measurements with state-of-the-art hydro-structure simulations. At the core of this approach lies the conversion matrix method: by projecting the structural response on a carefully chosen basis of distortion modes, a relationship can be found between any physical quantities related to hull deformation. In this manner, stresses anywhere on the structure, including un-instrumented structural details, can be expressed as a function of stresses at only a few instrumented locations.
However, accurately reconstructing structural response at locations where local effects are present can be challenging in all types of hybrid monitoring methods. This paper aims to show that these difficulties can be overcome, and the conversion matrix method can be successfully applied to reconstruct the local stress response at side shell stiffeners of an FPSO. Several sensor configurations used as input in the conversion matrix are tested and discussed. Validation is performed by comparing thousands of hours of direct sensor measurements with reconstructed stress time histories. The results show consistent improvement compared to virtual monitoring which is exclusively based on numerical simulations using encountered sea states.
Hybrid Structural Health Monitoring is the key to cost-effective monitoring. By leveraging the power and flexibility of numerical simulations, the capabilities of direct measurements are expanded to reach the entire structure, even at un-instrumented locations subjected to local effects.
