Abstract
Corrosion-induced degradation remains a major challenge in offshore wind energy, impacting reliability, safety, and operational expenditure throughout asset lifecycles. As the sector moves toward larger turbines and deeper installations, substructures are becoming more complex, combining dissimilar materials and exposed geometries that accelerate degradation under marine conditions. To ensure long-term structural integrity, predictive and digitally integrated assessment methods are needed.
This study presents a digital corrosion modelling framework supporting integrity management and maintenance optimisation for offshore wind substructures, with focus on lightweight aluminium components coupled to steel assemblies. Aluminium integration in next-generation floating wind turbines (WT) improves strength-to-weight ratio and corrosion resistance. However, dissimilar assembly is prone to galvanic corrosion, threatening durability. Field observations show severe aluminium corrosion when in electrical contact with stainless steel, prompting updates to NORSOK standards. While NORSOK M-001:2014 permitted such contact, this is no longer acceptable in the 2021 revision. Section 6 of NORSOK M-102 details bolted aluminium-stainless steel joints, but gaps persist regarding frictional effects, mechanical degradation, and corrosion product accumulation.
New predictive tools developed at SINTEF under the Norwegian Centre for Research-based Innovation (SFI BLUES - Floating Structures for the Next Generation of Ocean Industries) assess corrosive environmental effects on material degradation and structural integrity. They build on finite element simulations integrating multi-physics corrosion modelling. The workflow links electrochemical kinetics, degradation mechanisms, and meso-scale structural behaviour to predict how corrosion influences strength and stiffness over time. A case study on aluminium-stainless steel (Al-SS) bolted joints demonstrates the model’s capability. Using experimentally derived parameters from cyclic salt spray testing, simulations predict potential, current density, and mass loss across joint interfaces. Results show galvanic coupling produces up to six times greater aluminium mass loss than aluminium-aluminium (Al-Al) configurations. A significant increase in force for Al-Al assembly compared to Al-SS and uncorroded cases highlights corrosion products’ contribution to frictional response. This was captured by the models, demonstrating realistic corrosion behaviour and the importance of preventive design and material selection to mitigate galvanic effects.
This research contributes to the New Methods and Tools priority area for offshore wind by delivering a scalable, physics-based framework that connects local corrosion processes with system-level digital models. It enables the estimation of the effects of corrosion (material degradation and corrosion products) on the stiffness and stress states providing realistic data to evaluate ultimate stress state and fatigue stress state. By integrating with digital twin environments, it has the potential to enable condition-based maintenance rather than periodic inspection routines, improving both cost efficiency and sustainability of WT farms. It also lays the groundwork for developing standards that account for corrosion-induced mechanical effects in multi-material structures, supporting Europe’s 2050 vision for sustainable, resilient, and cost-effective offshore energy systems.