Methods for removing inertial force from measured wave impact force signals

Winsor, Fraser N. (2000) Methods for removing inertial force from measured wave impact force signals. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (40MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

This report discusses the implementation of three methods for removing or mitigating the so-called inertial force from measured signals resulting from wave impact on components of offshore structure models. The wave impact causes vibration or acceleration in the modeted component. The acceleration is perceived as a force by the measurement transducers. This inertial force component is not scaleable, and must be removed in order to obtain the actual applied force. -- A mitigation method based on the solution of the system equation of motion using normalized coordinates, known as the normal mode method, is investigated. A technique based on the division of the fast Fourier transform of the measured force by the system frequency response, known as the inverse Fourier transform method, is implemented. Finally, the use of digital low pass and band reject filters is examined. -- These techniques are applied to wave impact and decay test measurements from experiments conducted on jacket type fixed offshore structure models. -- The results prove to be less than ideal. The reasons for this are discussed, and recommendations are made for future investigations.

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