Browsing by Keyword "Structural dynamics"
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Item A Simplified Modeling Approach of Floating Offshore Wind Turbines for Dynamic Simulations(2022-03-18) López-Queija, Javier; Robles, Eider; Llorente, Jose Ignacio; Touzon, Imanol; López-Mendia, Joseba; Tecnalia Research & Innovation; RENOVABLES OFFSHORECurrently, floating offshore wind is experiencing rapid development towards a commercial scale. However, the research to design new control strategies requires numerical models of low computational cost accounting for the most relevant dynamics. In this paper, a reduced linear time-domain model is presented and validated. The model represents the main floating offshore wind turbine dynamics with four planar degrees of freedom: surge, heave, pitch, first tower foreaft deflection, and rotor speed to account for rotor dynamics. The model relies on multibody and modal theories to develop the equation of motion. Aerodynamic loads are calculated using the wind turbine power performance curves obtained in a preprocessing step. Hydrodynamic loads are precomputed using a panel code solver and the mooring forces are obtained using a look-up table for different system displacements. Without any adjustment, the model accurately predicts the system motions for coupled stochastic wind–wave conditions when it is compared against OpenFAST, with errors below 10% for all the considered load cases. The largest errors occur due to the transient effects during the simulation runtime. The model aims to be used in the early design stages as a dynamic simulation tool in time and frequency domains to validate preliminary designs. Moreover, it could also be used as a control design model due to its simplicity and low modeling order.Item Vibration-Based SHM Strategy for a Real Time Alert System with Damage Location and Quantification(Springer Science and Business Media Deutschland GmbH, 2021-01-11) Fernández-Navamuel, Ana; Zamora-Sánchez, Diego; Varona-Poncela, Tomás; Jiménez-Fernández, Carlos; Díez-Hernández, Jesús; García-Sánchez, David; Pardo, David; Rizzo, Piervincenzo; Milazzo, Alberto; E&I SEGURAS Y RESILIENTES; Tecnalia Research & InnovationWe present a simple and fully automatable vibration-based Structural Health Monitoring (SHM) alert system. The proposed method consists in applying an Automated Frequency Domain Decomposition (AFDD) algorithm to obtain the eigenfrequencies and mode shapes in real time from acceleration measurements, allowing to provide a diagnosis based on a Support Vector Machine algorithm trained with a database of the modal properties in undamaged and damaged scenarios accounting for temperature variability. The result is an alert system for controlling the correct performance of the structure in real time with a simple but efficient approach. Once the alert is triggered, the undamaged mode shapes (which could be previously stored in a database of modal parameters classified by temperature) and the current (damaged) mode shapes, can provide guidance for further application of Finite Element Model Updating (FEMU) techniques. The method is trained and validated with simulations from a FE model that is calibrated employing a genetic algorithm with real data from a short-term vibration measurement campaign on a truss railway bridge in Alicante (Spain).