PSI - Issue 12

A. Cetrini et al. / Procedia Structural Integrity 12 (2018) 87–101

96 10

Author name / Structural Integrity Procedia 00 (2018) 000 – 000

Fig. 5. Comparison between Tower-Top Fore-Aft displacement vs. Tower-Top Fore-Aft force FRFs

Fig. 6. Comparison between Tower-Top Side-Side displacement vs. Tower-Top Side-Side force FRFs

4.3 Method validation by multibody models Once the equivalent cantilever-beam structure has been constructed, it is possible to build the Nrel FAST multibody model. The structure has been introduced within the FAST code by the method reported in Paragraph 3.2. In this context a linear analysis was carried out which shows how the natural frequencies are still similar to those obtained from the modal analysis for the Fore-Aft direction, Table 3.