An accelerometer-based approach to hull monitoring beyond the elastic regime

• Main Author: Greenham, Andrew D.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2020
• Subjects: Northwest Passage; Northwest passage; ice covered waters
• Online Access: https://research.library.mun.ca/14815/; https://research.library.mun.ca/14815/1/thesis.pdf

With the efficient shipping route offered by the Northwest Passage, and its rapidly increasing availability to a wider range of ships in the coming years, the prevalence of ice covered waters to ships will be greatly increased. An option for hull-monitoring is explored which allows for damage detection beyond the elastic regime and deep into the plastic regime. This method involves using an accelerometer placed on the inside of the hull, and as an impact causing plastic damage is experienced, accelerometer readings are used to determine the delivered force to the hull. In this thesis a proof of concept for the suggested method is described and shown through a simplified example using finite element analysis. In this proposed method, the accelerometer allows for the structure to be examined from the point of view of the equation of motion. The proposition requires numerical integration from the acceleration data to find the displacement of the damaged area, and calibrations done in finite element analysis for both the stiffness and mass parts of the equation of motion to calculate the delivered force to the hull. The average error at which the proposed model determines force was found to be approximately 7%, which was calculated within the range of plastic flow behavior of the structure during an impact. Further development of this proposed method could have significant benefits such as increased safety for those at sea, better operational awareness of a ship’s capabilities, reduced dry-docking and inspection frequency, and the collection of realistic data from significant ice collisions at sea.