A New Structural-Dynamics Module for Offshore Multimember Substructures within the Wind Turbine Computer-Aided Engineering Tool FAST

摘要

FAST, developed by the National Renewable Energy Laboratory, is a computer-aided engineering tool for aero-hydro-servo-elastic analysis of land-based and offshore wind turbines. This paper discusses the development of a new module (SubDyn), which when integrated to FAST, will enable loads simulations of offshore wind turbines with fixed-bottom, multimember support structures. The main theory and strategies for the implementation of the multimember substructure dynamics module (SubDyn) within the new FAST modularization framework are introduced. SubDyn relies on two main engineering schematizations: (1) a linear frame finite-element beam model (LFEB), and (2) a dynamics system reduction via Craig-Bampton’s method. To test the SubDyn module and preliminarily assess the results against results from a commercial finite-element code, we analyzed a jacket support structure on its own and as part of an offshore system supporting a 5-MW turbine. The preliminary results show good agreement between the two codes.