Cracks

Oil tankers and floating oil platforms are robust constructions, or so you might think. In fact, they are riddled with cracks and ruptures. Fortunately, they do not often occur in the skin of the tankers, but in the internal structures that ensure their solidity. For his doctoral research in the Ship Hydromechanics and Structures research group (3mE), Menno van der Horst MSc is testing an instrument that can monitor the formation of cracks in metal and send a signal when they reach a critical state. The project is called Crackguard. ‘The instrument consists of countless sensors that detect disturbances in the metal’s magnetic field,’ explains Van der Horst. ‘Every five years, ships are inspected for metal fatigue. The idea is to place instruments on top of cracks that are identified during these inspections’.

However, the instrument must first undergo extensive testing, which can only be performed on cracks that are growing. Van der Horst is therefore replicating metal fatigue in the laboratory by exposing metal plates to tensile forces for days at a time. ‘In two days, I can replicate the 25-year life expectancy of a piece of metal from an oil tanker’.

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