Print Email Facebook Twitter Ice-induced Vibrations of Vertically Sided Model Structures Title Ice-induced Vibrations of Vertically Sided Model Structures: Comparison of structures with circular and rectangular cross-section subjected to the frequency lock-in regime Author Owen, Cody (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Offshore and Dredging Engineering) Contributor Metrikine, A. (graduation committee) Hendrikse, H. (mentor) van den Berg, M.A. (graduation committee) Muskulus, Michael (mentor) Popko, Wojciech (graduation committee) Ziemer, Gesa (mentor) Hinse, Philipp (graduation committee) Degree granting institution Delft University of Technology Programme European Wind Energy Masters (EWEM) Project Ice-induced Vibrations of Offshore Structures Date 2017-09-29 Abstract Offshore wind energy has very recently begun expanding into subarctic regions with seasonally ice-infested waters like the Baltic Sea. For offshore wind turbines with conventional support structures such as monopiles and jackets that are typically flexible and vertically sided, the phenomenon known as ice-induced vibrations can develop. In response to the growing interest in offshore wind in the Baltic Sea and in further validating a state-of-the-art numerical model for ice-structure interaction, the Ice-induced Vibrations of Offshore Structures(IVOS) project has been coordinated with the Hamburg Ship Model Basin (HSVA) and many academic and industry partners—including TU Delft and NTNU—in order to enhance understanding of the topic via a comprehensive laboratory testing campaign.In this thesis, specific data are selected fromthe extensive IVOS Phase 2 tests such that a comparative analysis is performed between two different model-scale structures, one with circular cross-section and another with rectangular cross-section, that were subjected to ice-induced vibrations in the frequency lock-in regime. Preceding the comparative analysis, the data from the IVOS Phase 2 tests are organized into a database and post-processing tools are developed to facilitate further research by supplying analysis-ready data sets. Included in the post-processing tools is an attempt to determine ice-induced global loads from uncalibrated tactile sensor data, which offers insight into the relationship between the relative pressure distributions along the ice-structure interface and the ice-induced global forces on the model structure.The comparative analysis garnered qualitative information about the frequency lock-in regime and buckling failure of ice. It is observed that frequency lock-in vibrations usually persisted regardless of buckling events. For the frequency lock-in regime, the ice-induced global loads on the circular cross-section structure are generally lower than those for the rectangular cross-section structure. It is unclear whether the difference in global loads between the structures is caused by the difference in cross-sectional shape, other structural properties, ice properties, or combinations thereof. The analysis of the energy of the system is intriguing but does not offer lucid conclusions. However, the quasi-figure-eight pattern from the x-direction and derived y-direction structural displacements is an enlightening discovery that may explain inconsistencies in the energy of the system. Based on the general configuration of the test apparatus from the IVOS Phase 2 tests and the results from the comparative analysis, it can be concluded that ice-induced vibrations of the model-scale structures in the frequency lock-in regime should be regarded as a two-dimensional problem. Subject Ice-induced vibrationsmodel-scalevertically sidedcross-section To reference this document use: http://resolver.tudelft.nl/uuid:18b05231-6b53-4d1b-8531-caf3c31848ea Embargo date 2017-10-23 Part of collection Student theses Document type master thesis Rights © 2017 Cody Owen Files PDF MScThesis_Cody_C_Owen.pdf 13.11 MB Close viewer /islandora/object/uuid:18b05231-6b53-4d1b-8531-caf3c31848ea/datastream/OBJ/view