As part of the 2018 TEN program for Materials and Structures the demonstrator “Sensor Based Structural Monitoring for input to Inspections Planning" has been developed by DNV GL. The project has demonstrated a generic method where the combination of sensor data with a global 3D model of a structure has allowed for a complete reconstruction of the structural response everywhere in the structure. The benefit of the approach is that only a few sensors capturing the global response, for this case a hull structure, are needed in order to obtain the local response elsewhere in the ship structure.
By using sensor data directly, one is getting rid of the assumptions related to wave loads and structural response which are made in standard desktop analyses. The main drawback of using sensors is that only a limited number of them can be applied, hence for most current implementations, the structural response is only monitored in a few selected areas on a structure. The new method developed in TEN allows to reconstruct the response everywhere in a structure from just a few sensor measurements. The developed method relies on a technology called inverse-FE method which as part of the TEN demonstrator was adapted to the case of a structure floating in waves, making it suitable for structural monitoring of ship and offshore assets in real time.Further, an important element is to perform quality assurance on the sensor data, and also display quality and aggregated results to the user for decision support through a web interface. This includes displaying results directly in the 3D model on the web interface for inspection planning.
Benefit to customers
In the oil and gas industry, as well as maritime, the cost of hull inspections and the safety and operational risks related to hull integrity are two main drivers which push for the development of new ways of monitoring hull structures.
Using the developed technology, the damage risk in the entire structure can be monitored in real time. From that new insight, an optimized inspection and maintenance plan can be developed and updated throughout the life of the structure, leading to safer and more cost-effective operations.
Another key benefit to operators is the possibility of keeping track of the remaining life of the structure, as well as being able to demonstrate it, which is crucial when it comes to selling or redeploying an asset.
Customers engagements and projects
The technology has already been applied on two operational projects, one on a flare tower structure for MODEC in Brazil and a second one on a MOPU jack-up platform for Petronas in Malaysia. As part of the TEN project, the concept was validated using real data for a container vessel and an FPSO. Several FPSO operators have shown interest; one pilot is running with INPEX and a proposal is out with BWO. Sensor providers are also interested to use this technology and DNV GL is discussing cooperation schemes with Light Structures AS which holds a big share of this market. Light Structures AS and several data owners have already signed agreements to place sensor data on Veracity, which can be displayed on several apps in My Services (Nerves of steel, Data Quality as a service and Structure Insight). Sensor data from more than 10 asset designs are already uploaded.