07-11-2024 - Lecture Hall F

PhD presentation

The Potential of Water Jet Stimulation for Flatfish Trawling

Sterre Bult

Commercial demersal trawl fisheries are a large source of physical disturbance to marine habitats. The tickler chain beam trawl causes large bed disturbances, in addition to high fuel costs owing to high drag forces and a low catch efficiency and selectivity. The objective of this research is therefore to develop a new catching technique without electrical stimuli for sole and plaice that minimizes the bed disturbance and increases the catch efficiency. The project is a collaboration between Wageningen University & Research (WUR) and Delft University of Technology (TUD), with the aim to combine the insights on the avoidance behaviour of flatfish and the impact of various stimuli on the seabed for the design of the new catching technique. At TUD, the bed disturbance as a result of various mechanical and hydrodynamical stimuli will be quantified. The focus will be on the effect of hydraulic stimuli on the seabed, more specifically water jets. I will combine small-scale laboratory experiments and computational fluid dynamics modelling to optimize the bed disturbance, while applying sufficient stimulus to initiate a startle response in flatfish. In this talk, I will discuss preliminary experimental and numerical results, as well as our objectives for the coming years.

07-11-2024 - Lecture Hall F

PhD presentation

Acoustic emission monitoring of corrosion damage in marine structures

Romain Habiyaremye

Corrosion is amongst the main driving damage mechanisms for the degradation of marine assets. For ships, periodic inspections every five years in a dry dock are mandated by classification societies in order to prevent failures. These surveys are costly and leave the ship non-operational for an extended period of time. Corrosion damage can develop in crevices, under aged coatings, and in hard-to-reach places for traditional inspection methods. Complementary to these inspections, recently, the implementation of real-time inspection methods, so-called structural health monitoring systems (SHM) are becoming more prevalent. Acoustic emission (AE) monitoring is a SHM technique that consists in measuring elastic stress waves caused by a rapid release of energy when irreversible changes occur in a material. When these stress waves occur in thin-walled structures, such as ship hulls, these AE signals can travel over relatively large distances, making it possible to monitor large structures with a relatively low number of sensors. This presentation elaborates on the application of AE monitoring for corrosion detection, the challenges facing this technique, and how my research approaches some of these challenges.