Documents published in Scipedia

• Real-Time Digital Twin for Structural Health Monitoring of Floating Offshore Wind Turbines

  A. Pastor, J. García-Espinosa, D. Di Capua, B. Servan Camas

  Journal of Marine Science and Engineering (2025). J. Mar. Sci. Eng. 2025, 13, 1953

  
  

  Abstract

  Digital twins (DTs) offer significant promise for condition-based maintenance of floating offshore wind turbines (FOWTs); however, existing solutions typically compromise either on physical rigor or real-time computational performance. This paper presents a real-time DT framework that resolves this trade-off by embedding a hydro-elastic reduced-order model (ROM) that accurately captures structural dynamics and fluid–structure interaction. Integrated in a cloud-ready Internet of Things architecture, the ROM reconstructs full-field displacements, von Mises stresses, and fatigue metrics with near real-time responsiveness. Validation on the 5 MW OC4-DeepCWind semi-submersible platform shows that the ROM reproduces finite-element (FEM) displacements and stresses with relative errors below 1%. A three-hour load case is solved in 0.69 min for displacements and 3.81 min for stresses on a consumer-grade NVIDIA RTX 4070 Ti GPU—over two orders of magnitude faster than the full FEM model—while one million fatigue stress histories (1000 hotspots×1000 operating scenarios) are processed in 37 min. This efficiency enables continuous structural monitoring, rapid *what-if* assessments and timely decision-making for targeted inspections and adaptive control. By effectively combining physics-based reduced-order modeling with high-throughput computation, the proposed framework overcomes key barriers to DT deployment: computational overhead, physical fidelity and scalability. Although demonstrated on a steel platform, the approach is readily extensible to composite structures and multi-turbine arrays, providing a robust foundation for cost-effective and reliable deep-water wind-energy operations.

  Abstract
  Digital twins (DTs) offer significant promise for condition-based maintenance of floating offshore wind turbines (FOWTs); however, existing solutions typically compromise [...]

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• Modal matrix reduction for fully coupled integrated load analysis of floating structures

  B. Servan Camas, I. Berdugo, J. García-Espinosa, A. Pastor

  Marine Structures (2025). Marine Structures 103 (2025) 103845

  
  

  Abstract

  Structural elasticity of floating wind turbines in integrated load analysis (ILA) is typically addressed by modelling the substructure with simplified beam models. The main reason can be found in the computational cost of the structural solver when solving the fully coupled hydroelastic problems. In this work, a reduce order method based on modal matrix reduction is applied to reduce the computational cost of the structural solver. The main idea is to largely reduce the number of degrees of freedom of the structural system by retaining only those modes with significant energy. The seakeeping hydrodynamics is solved using the finite element framework SeaFEM. The structural particulars are introduced into this framework to fully integrate the fluid-structure interaction. The hydroelastic model is also coupled with the wind turbine solver OpenFAST, resulting in a complete aero-hydro-servo-elastic tool for the ILA analysis of floating turbines. A methodology is proposed to identify critical conditions and hotspots based on the structural energy. An application case of the present strategy is presented for a detailed structural design of the well-known OC4-DeepCwind. The consistency of the modal approximation and methodology is verified against the FE structural solution. The capabilities of the proposed ILA framework are demonstrated in a fully coupled and detailed structural analysis, instead of at component level, with a significant reduction of its computational time.

  Abstract
  Structural elasticity of floating wind turbines in integrated load analysis (ILA) is typically addressed by modelling the substructure with simplified beam models. The main [...]

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• Accelerated fully coupled hydro-elastic analysis of ships using a combined full and modal-reduced FEM approach

  J. García-Espinosa, A. Lorente-López, B. Servan Camas, J. Gutiérrez Romero

  Marine Structures (2026). Marine Structures 108 (2026) 104011

  
  

  Abstract

  The numerical simulation of a ship’s hydroelastic structural response is typically carried out using simplified modelling approaches. The main reason can be found in the computational cost of the structural solver when solving the fully coupled hydro-elastic problems. In this work, a two-way coupled fluid-structure interaction model capable of efficiently and accurately computing the hydro-elastic response of a ship using a detailed full-length structural representation is proposed. To reduce the computational cost of the structural solver, a reduced-order method based on modal matrix reduction is applied. The main idea is to largely reduce the number of degrees of freedom of the structural system by retaining only those modes with significant energy. Furthermore, to improve the accuracy of the model, this work proposes a combined methodology in which a residual finite element (FE) solution is computed alongside the reduced model, while still achieving a reduction in the overall computational effort. The seakeeping hydrodynamics is solved using the computational framework SeaFEM. And the structural particulars are introduced into this framework to fully integrate the fluid-structure interaction. An application case of the proposed model strategy is presented for a detailed structural design of a ship. The consistency of the modal approximation and methodology is verified against the full FE structural solution. It shows the capabilities of the proposed framework to perform a fully coupled and detailed structural analysis, instead of at component level, with a significant reduction in computational time.

  Abstract
  The numerical simulation of a ship’s hydroelastic structural response is typically carried out using simplified modelling approaches. The main reason can be found in [...]

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• Accelerated fully coupled hydro-elastic analysis of ships based on modal matrix reduction

  A. López, J. García-Espinosa, J. Gutiérrez Romero, B. Servan Camas, P. Tello

  65.º Congreso Internacional de Ingeniería Naval e Industria Marítima (CIIN 2026), Málaga, España

  
  

  Abstract

  Hydro-elastic effects such as springing, whipping and racking can significantly increase hull stresses and fatigue damage. However, fully coupled time-domain hydro-elastic simulations remain computationally prohibitive for practical ship design due to the high cost of the structural solver. Objective: Develop an efficient two-way coupled hydro-elastic framework capable of capturing resonance effects with full-length detailed structural models, while drastically reducing computational cost.

  Abstract
  Hydro-elastic effects such as springing, whipping and racking can significantly increase hull stresses and fatigue damage. However, fully coupled time-domain hydro-elastic [...]

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• Análisis hidroelástico totalmente acoplado de plataformas eólicas flotantes

  B. Servan Camas, J. García-Espinosa

  65.º Congreso Internacional de Ingeniería Naval e Industria Marítima (CIIN 2026), Málaga, España

  
  

  Abstract

  Structural elasticity of floating wind turbines, in integrated load analysis, are typically addressed by modelling the substructure with simplified beam models. The main reason can be found in the computational cost of the structural solver when solving the fully coupled hydroelastic problems. In this work, a reduce order method based on modal matrix reduction (MMR) is applied to reduce the computational cost. The main idea is to largely reduce the number of degrees of freedom of the structural system by retaining only those modes with significant energy. The seakeeping hydrodynamics is solved using the computational framework SeaFEM, based on the finite element method (FEM). The structural particulars are introduced into this framework to fully integrate the fluid-structure interaction. The hydroelastic model is also coupled with the wind turbine solver OpenFAST, resulting in a complete aero-hydro-servo-elastic tool for the ILA analysis of floating turbines. Moreover a methodology is proposed to identify critical conditions and hotspots based on the structural energy. An application case of the present strategy is presented for a detailed structural design of the OC4-DeepCwind. The consistency of the modal approximation and methodology are

  Abstract
  Structural elasticity of floating wind turbines, in integrated load analysis, are typically addressed by modelling the substructure with simplified beam models. The main reason [...]

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• Análisis hidroelástico totalmente acoplado de plataformas eólicas flotantes

  B. Servan Camas, J. García-Espinosa, I. Berdugo

  En 64.º Congreso Internacional de Ingeniería Naval e Industria Marítima (Gijón, 26–28 de marzo de 2025). Asociación de Ingenieros Navales y Oceánicos de España (AINE).

  
  

  Abstract

  Structural elasticity of floating wind turbines, in integrated load analysis, are typically addressed by modelling the substructure with simplified beam models. The main reason can be found in the computational cost of the structural solver when solving the fully coupled hydroelastic problems. In this work, a reduce order method based on modal matrix reduction (MMR) is applied to reduce the computational cost. The main idea is to largely reduce the number of degrees of freedom of the structural system by retaining only those modes with significant energy. The seakeeping hydrodynamics is solved using the computational framework SeaFEM, based on the finite element method (FEM). The structural particulars are introduced into this framework to fully integrate the fluid-structure interaction. The hydroelastic model is also coupled with the wind turbine solver OpenFAST, resulting in a complete aero-hydro-servo-elastic tool for the ILA analysis of floating turbines. Moreover a methodology is proposed to identify critical conditions and hotspots based on the structural energy. An application case of the present strategy is presented for a detailed structural design of the OC4-DeepCwind. The consistency of the modal approximation and methodology are verified against the FE structural solution. It is shown the capabilities of the proposed ILA framework to perform a fully coupled and detailed structural analysis.

  Abstract
  Structural elasticity of floating wind turbines, in integrated load analysis, are typically addressed by modelling the substructure with simplified beam models. The main reason [...]

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• Anonymized scientific-technical database from the ML-AMAR monitoring campaign

  R. Molina Sánchez, J. García-Espinosa

  ml-amar (2026). 2

  
  

  Abstract

  The project ML-AMAR (Machine Learning Applications in Marine Engineering) aims to develop machine learning tools to optimize the lifecycle management of ships, from design and operation to maintenance and structural monitoring.   The repository includes two public anonymized datasets generated from the ML-AMAR monitoring campaign. Both datasets have been prepared for scientific and technical distribution by removing sensitive information such as exact coordinates, precise timestamps, vessel/sensor identifiers and individual trajectories. The first dataset, ML_AMAR_anonimizacion_version_B_public, contains aggregated information on maritime routes, trip frequencies, departure time slots, trip duration classes, recurrent movement patterns and a non-georeferenced schematic network. It is intended for the analysis of maritime mobility and general route patterns. The second dataset, ML_AMAR_positions_1min_metocean_public_B, is derived from the original one-minute monitoring records. It provides aggregated information on operational state, route phase, distance-to-port classes, metocean conditions and vessel dynamic response. It is intended for scientific and technical analyses of the relationship between navigation, waves, wind and vessel behaviour. In both cases, the data are published only in aggregated and anonymized form. The repository does not include raw files, real GNSS positions, exact timestamps, operational identifiers or confidential correspondence tables between anonymized codes and real locations. Aggregation, discretization and suppression rules have been applied to prevent the reconstruction of individual trips or specific operational patterns. The dataset ML_AMAR_anonimizacion_version_B_public includes aggregated route summaries, trip frequencies, time slot distributions, duration classes, recurrent cycles and a schematic non-georeferenced network. Its main purpose is the analysis of maritime mobility and route patterns. The dataset ML_AMAR_positions_1min_metocean_public_B includes aggregated operational states, route phases, distance-to-port classes, vessel motion statistics and metocean conditions. Its main purpose is the scientific and technical analysis of vessel dynamics and metocean forcing.  

  Abstract
  The project ML-AMAR (Machine Learning Applications in Marine Engineering) aims to develop machine learning tools to optimize the lifecycle management of ships, from design [...]

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• Structural assessment of vessels by dynamic hydroelastic analysis based on modal matrix reduction

  A. López, J. García-Espinosa, J. Gutiérrez Romero, B. Servan Camas, P. Tello

  CIIN 2024

  
  

  Abstract

  During the design of a vessel or marine artefact, one of the main objectives is to ensure a long service life. The structure of these artefacts is essential to achieve this goal, as it is responsible for withstanding the extremely unfavourable stresses of the high seas. The aim of this paper is to present a method of detailed structural assessment by applying a dynamic hydroelastic model [1] that allows structural verification by greatly reducing the calculation time without losing accuracy. The current procedures used for this purpose require a detailed study of each loading condition, which implies many simulation hours and high computational cost. In this model, the high-fidelity structural solution is projected onto the modal basis to get the system modal matrix and extend the response amplitude operators (RAO) to the modal response amplitude operators (MRAO) of the structure. By retaining only those eigenmodes that preserve most of the structural elastic energy, the number of structural degrees of freedom can be significantly reduced. This reduced model has been implemented and coupled in the time domain with the seakeeping software SeaFEM, enabling quick analysis of a large number of load cases of the structure [2]. In this work, the first case study of a ship is presented.

  Abstract
  During the design of a vessel or marine artefact, one of the main objectives is to ensure a long service life. The structure of these artefacts is essential to achieve this [...]

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• Thermoelastic buckling analysis in composite material structures: bridging design gaps in fire resistance

  R. Pacheco-Blazquez, D. Di Capua, J. García-Espinosa

  Materiales Compuestos (Online first).

  
  

  Abstract

  The use of fiber-reinforced polymer (FRP) composites in structural applications is increasingly widespread due to their light weight and load-bearing capacity. However, their behavior under fire exposure presents unique challenges—such as thermal buckling and post-buckling response—that current regulations, including Eurocode and SOLAS, do not specifically address. This work investigates the phenomenon of thermo-inelastic buckling in composites, taking into account their flexibility, thermal degradation, and natural imperfections. A modeling approach is proposed that integrates Felippa’s corotational theory, isotropic damage models with SPROM, and thermo-mechanical coupling. These methodologies are validated across scenarios ranging from one-dimensional to three-dimensional thermal buckling, including experimental validation. The results highlight the limitations of traditional approaches based on slenderness and inelasticity, such as the Tsai-Wu method, and emphasize the need for design frameworks that incorporate structural fire response in composite materials. This work aims to bridge the gap between the growing use of these materials and the design methodologies required for fire-resistant applications.

  Abstract
  The use of fiber-reinforced polymer (FRP) composites in structural applications is increasingly widespread due to their light weight and load-bearing capacity. However, their [...]

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• Thermo-mechanical analysis of laminated composites shells exposed to fire

  R. Pacheco-Blazquez, D. Di Capua, J. García-Espinosa, O. Casals

  Engineering Structures (2020). Engineering Structures, 253 (2020) 113679

  
  

  Abstract

  This paper describes the research performed within the scope of H2020 project FIBRESHIP in the development and validation of a thermo-mechanical model to assess the fire performance of composite structures. A one-dimensional thermal model with pyrolisis is used to obtain the temperature prole across the thickness and later introduced in the thermomechanical model with a quadrilateral shell element approach. The composite constitutive model employed is the socalled Serial/Parallel Rule of Mixtures (SPROM) which has been modied to introduce the effect of the thermal deformation. A set of experimental tests are then used to validate the correctness of the numerical method proposed. The experimental data used to validate the thermal model is the classic Henderson experimental test. The thermomechanical coupling is validated against an original vertical furnace test of a FRP ships bulkhead following on the 2010 FTP Code standards. These validations demonstrate the correctness and accuracy of the proposed decoupled thermomechanical formulation.

  Abstract
  This paper describes the research performed within the scope of H2020 project FIBRESHIP in the development and validation of a thermo-mechanical model to assess the fire [...]

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Articles (Documents not available in Scipedia)

• Estudio dinámico de líneas de fondeo en plataformas flotantes de aerogeneradores marinos

  J. García-Espinosa

  Ingeniería naval, 66-72, 2014

• Avances en el desarrollo de un modelo de elementos finitos para evaluación de un buque de efecto superficie

  J. García-Espinosa, B. Serván, D. Di Capua, P.A. Ubach, E. Oñate

  Ingeniería naval, 922: 68-73

• Estudio del Comportamiento Dinámico Acoplado en Estructuras Offshore

  JEG Romero, BZ Parra, JG Espinosa, JAE Pérez

  Anuario de Jóvenes Investigadores, 39-41, 2014

• Prediction of total resistance coefficients using neural networks

  I Ortigosa, R López, J García

  Journal of Maritime Research 6 (3), 15-26

• Dynamic modelling of mooring for floating offshore structures

  JE Gutiérrez Romero, B Zamora Parra, J García Espinosa, J Esteve

  Computational Methods in Marine Engineering V-Proceedings of the 5th ..., 2013

• Desarrollo de un conjunto de herramientas para el análisis acoplado de aerogeneradores en alta mar

  JE Gutiérrez Romero, B Zamora, J García Espinosa, J Esteve Pérez

  Ingeniería naval, 62-75, 2013

• Stabilized finite element methods for convection-diffusion-reaction, Helmholtz and Stokes problems

  P Nadukandi

  Universitat Politècnica de Catalunya, 2011

• A family of residual‐based stabilized finite element methods for Stokes flows

  E Oñate, P Nadukandi, SR Idelsohn, J García, C Felippa

  International Journal for Numerical Methods in Fluids 65 (1‐3), 106-134, 2011

• Experiencias en el desarrollo y aplicación de herramientas de cálculo y verificación de estructuras marinas para generación de energía

  J García Espinosa, B Serván Camas, D Sá

  49º Congreso de Ingeniería Naval e Industria Marítima, 1-16, 2010

• Análisis estructural del efecto de explosiones a bordo de buques de pasaje

  J García-Espinosa, D Di Capua, D Sá, S Honrubia, F Viejo, E Oñate, R Marí, ...

  Ingeniería naval, 105-114, 2007

• ODD Level Set: A new method for simulation of free surface problems

  JG Espinosa, AV Tomás

  Journal of maritime research 3 (1), 27-40, 2006

• Análisis CFD del movimiento de balance de un portacontenedores

  J García-Espinosa, E Oñate, JB Helmers, MR Chakkor

  Ingeniería Naval, abril, 2004

• Ship hydrodynamics

  E Onate, J García, SR Idelsohn

  Encyclopedia of computational mechanics, 2004

• A methodology for analysis of fluid-structure interaction accounting for free surface waves

  E Oñate, J García, S Idelsohn

  European Conference on Computational Mechanics (ECCM99), 1999

• A stabilized numerical method for analysis of ship hydrodynamics

  J García, E Oñate, H Sierra, C Sacco, S Idelsohn

  Computational fluid dynamics'98, 664-669, 1998

• An alpha-adaptive approach for stabilized finite element solution of advective-diffusive problems with sharp gradients

  E Onate, J García-Espinosa, S Idelsohn

  Computational fluid dynamics'98, 748-753, 1998

• On the stabilization of numerical solution for advective-diffusive transport and fluid flow problems

  E Oñate, J García, S Idelsohn

  Centro Internacional de Métodos Numéricos en Ingeniería, 1996

Books, book chapters and edited books (Documents not available in Scipedia)

• MARINE 2011, IV International Conferencn Marine Engineering: Selected Papers

  L. Eca, E. Oñate, J. García-Espinosa, T. Kvamsdal, P. Bergan

  Springer

• Fluid-Structure interaction applied to blood flow simulations

  E. Soudah, E. Oñate, J. García-Espinosa, J. S. Pérez, A. Mena, E. Heindenreich, J. F. Rodríguez, M. A. Martínez, M. Doblaré

  Advances in Computational Vision and Medical Image Processing, Springer

• Computational Methods in Marine Engineering III (MARINE 2009)

  P. Bergan, B. Pettersen, T. Kvamsdal, E. Oñate, J. García-Espinosa

  CIMNE

• Computational Methods in Marine Engineering II (MARINE 2007)

  P. Bergan, J. García-Espinosa, P. Kvamsdal, T. Kvamsdal, E. Oñate

  CIMNE

• LES turbulence models. Relation with stabilized numerical methods

  A. Valls, J. Garcia-Espinosa, E. Oñate

  Models, Experiments and Computation in Turbulence, CIMNE

• Computational Methods in Marine Engineering (MARINE 2005)

  P. Bergan, J. García-Espinosa, E. Oñate, T. Kvamsdal

  CIMNE

• A general stabilized formulation for incompressible fluid flow using finite calculus and the finite element method

  E. Onate, J. Garcia-Espinosa, G. Bugeda, S.R. Idelsohn

  Fluid dynamics and aeronautics new challenges: a book dedicated to Pierre Perrier. J. Periaux, D. Chamption, O. Pironneau, P.H. Thomas, eds.

Conference papers and presentations (Documents not available in Scipedia)

• A finite element method for fluid-structure interaction with surface waves

  J. Garcia-Espinosa and E. Oñate

  Proceedings of the European Conference on Computational Mechanics (ECCM 2001)

• Finite element analysis of incompressible flows with free surface waves using a finite calculus formulation

  E. Oñate, J. García-Espinosa

  Proceedings of the VI European Congress in Computational Methods in Applied Sciences and Engineering (ECCOMAS 2001)

Technical reports, thesis and other (Documents not available in Scipedia)

• Desarrollo de herramientas de autoaprendizaje multimedia para cálculo de estructuras por ordenador en ingeniería

  J. García-Espinosa, J. Martínez, D. Yebra, M. Cervera Ruiz, E. Oñate, S. Oller, B. Suárez

  Universitat Politècnica de Catalunya. Institut de Ciències de l'Educació, 2013