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 acomputer-aided engineering tool for aero-hydro-servo-elastic analysisof land-based and offshore wind turbines. This paper discusses thedevelopment of a new module (SubDyn), which when integrated toFAST, will enable loads simulations of offshore wind turbines withfixed-bottom, multimember support structures. The main theory andstrategies for the implementation of the multimember substructuredynamics module (SubDyn) within the new FAST modularizationframework are introduced. SubDyn relies on two main engineeringschematizations: (1) a linear frame finite-element beam model (LFEB),and (2) a dynamics system reduction via Craig-Bampton’s method. Totest the SubDyn module and preliminarily assess the results againstresults from a commercial finite-element code, we analyzed a jacketsupport structure on its own and as part of an offshore systemsupporting a 5-MW turbine. The preliminary results show goodagreement between the two codes.