SubDyn is a structural-dynamics module for simulating multi-member substructures. It is based on a linear FEM and a dynamics system reduction and can be coupled to FAST to enable aero-hydro-servo-elastic simulations of offshore fixed-bottom wind turbines.

by Rick Damiani, Ph.D., P.E. and Huimin Song, Ph.D.
National Wind Technology Center

SubDyn is a time-domain structural-dynamics module for multi-member fixed-bottom substructures that has been coupled into the FAST aero-hydro-servo-elastic computer-aided engineering (CAE) tool. Substructure types supported by SubDyn include monopiles, tripods, jackets, and other lattice-type substructures common for offshore wind installations in shallow and transitional water depths. SubDyn can also be used to model lattice support structures for land-based wind turbines.

SubDyn follows the requirements of the FAST modularization framework, couples to FAST version 8, and provides new capabilities (relative to prior versions) for modeling the substructure dynamic loading on multi-member substructures. SubDyn can also be driven as a standalone code to compute the mode shapes, natural frequencies, and time-domain responses of substructures, uncoupled from FAST and in the absence of external loading other than gravity and interface motion.

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 (C-B) method, together with a Static-Improvement method, greatly reducing the number of modes needed to obtain an accurate solution.

You may download the following files from our server:


  • SubDyn Change Log

    This is a list of changes made to the code in each release.

  • SubDyn Manual (draft version)

    This is the theory guide and usage overview for SubDyn. Please refer to it when trying to understand how the program works. This file is contained in the archives, but is included here for quick access.

SubDyn Archives (1.03.00, 11-Apr-2016)

  • SubDyn Archive for Windows® (EXE 10.5 MB)

    This is a self-extracting archive of SubDyn for Windows®. It contains the SubDyn source code, sample input files, documentation, change log, and sample driver programs.

  • SubDyn Archive (tar.gz 6.3 MB)

    This is a compressed archive of SubDyn for non-Windows® users. It contains the SubDyn source code, sample input files, documentation, and change log.

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NWTC Information Portal (SubDyn). Last modified 12-April-2016 ; Accessed 24-January-2020