ABSTRACT

This paper presents results from an in-depth investigation of local vibration phenomena and their impact on the fatigue loads of a jacket sub-structure. The analysis is performed in a coupled, aero-hydro-servo-elastic tool ADCoS-Offshore that is based on the finite element method (FEM). Possible regions of resonance are identified from modal analysis studies and a Campbell diagram. Numerous high frequency vibrations in the range of 3.1 Hz – 5.0 Hz involving local eigenmodes coupled with higher order rotor modes are found. Time domain simulations are run for deterministic and stochastic load case categories, where local jacket dynamics is examined. Impact of marine growth on fatigue loads of the lowest braces is presented. Finally, recommendation on relative comparison of local vibration influence on the fatigue loads is given.

Keywords:
substructure, offshore wind turbine, local vibration phenomenon, jacket substructure, brace, support structure, fatigue load, vibration, wind turbine, frequency
Subjects:
Offshore Facilities and Subsea Systems, Facilities and Construction Project Management, Information Management and Systems, Platform design, Offshore projects planning and execution
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2013. International Society of Offshore and Polar Engineers
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