An integrated structural optimization strategy was produced in this study for direct-drive electrical generator structures of offshore wind turbines, implementing a design for an additive manufacturing approach, and using generative design techniques. Direct-drive configurations are widely implemented on offshore wind energy systems due to their high efficiency, reliability, and structural simplicity. However, the greatest challenge associated with these types of machines is the structural optimization of the electrical generator due to the demanding operating conditions. An integrated structural optimization strategy was developed to assess a 100-kW permanent magnet direct-drive generator structure. Generated topologies were evaluated by performing finite element analyses and a metal additive manufacturing process simulation. This novel approach assembles a vast amount of structural information to produce a fit-for-purpose, adaptative, optimization strategy, combining data from static structural analyses, modal analyses, and manufacturing analyses to automatically generate an efficient model through a generative iterative process. The results obtained in this study demonstrate the importance of developing an integrated structural optimization strategy at an early phase of a large-scale project. By considering the typical working condition loads and the machine’s dynamic behavior through the structure’s natural frequencies during the optimization process coupled with a design for an additive manufacturing approach, the operational range of the wind turbine was maximized, the overall costs were reduced, and production times were significantly diminished. Integrating the constraints associated with the additive manufacturing process into the design stage produced high-efficiency results with over 23% in weight reduction when compared with conventional structural optimization techniques.

With the rapid expansion of offshore wind capacity worldwide, minimising operation and maintenance requirements is pivotal. Regarded as a low-maintenance alternative to conventional drivetrain systems, direct-drive generators are increasingly commonplace for wind turbines in hard-to-service areas. To facilitate higher torque requirements consequent to low-speed operation, these machines are bulky, greatly increasing nacelle size and mass over their counterparts. This paper therefore details the structural optimisation of the International Energy Agency 15 MW Reference Wind Turbine rotor through iterative Parameter and Topology Optimisation and the inclusion of additional structural members, with consideration to its mechanical, modal, and thermal performances. With temperature found to have a significant impact on the structural integrity of multi-megawatt direct-drive machines, a Computational Fluid Dynamics analysis was carried out to map the temperature of the structure during operation and inform a consequent Finite Element Method analysis. This process, novel to this paper, found that topologically optimised structures outperform parametrically optimised structures thermally and that integrated heatsinks can be employed to further reduce deformation. Lastly, generative design techniques were used to further optimise the structure, reducing its mass, deformation, and maximum stress and expanding its operating envelope. This study reaches several key conclusions, demonstrating that significant mass reductions are achievable through the removal of cylinder wall geometry areas as well as through the implementation of structural supports and iterative parametric and topology optimisation techniques. Through the flexibility it grants, generative design was found to be a powerful tool, delivering further improvements to an already efficient, yet complex design. Heatsinks were found to lower generator structural temperatures, which may yield lower active cooling requirements whilst providing structural support. Lastly, the link between the increased mass and the increased financial and environmental impact of the rotor was confirmed.

Generative design techniques together with the rapid development of additive manufacturing represent a revolution in the field of structural optimisation processes. In this study, a static structural and modal analysis was integrated to drive a multi-objective generative design optimisation process for a 3 MW direct-drive offshore wind turbine electrical generator rotor structure. This novel optimisation approach implements an automated fittest-for-purpose process including a static structural analysis and a modal analysis as the input for the optimisation strategy algorithm, allowing the exploration of a wide range of non-conventional topologies. If compared with the simple generator rotor disc structure, the results obtained using this innovative method achieved over 7% of weight reduction and a 39% increment in the generator operational range with the consequent growth in the wind turbine energy capture capability. Moreover, this approach generates a vast amount of structural analysis information, crucial at an early stage of the development of large-scale projects for a cost-effective scheme.

New advances in structural optimization techniques and manufacturing methods, such as generative design (GD) and additive manufacturing (AM), are revolutionizing the capabilities to generate high-efficiency and lightweight models in comparison with conventional processes. This study addresses a structural optimization strategy for offshore wind turbine direct-drive generator structures using generative design (GD) and additive manufacturing (AM) techniques. The use of multi-objectives structural optimization processes using GD techniques allows for the exploration of a wide number of unconventional topologies on a tailored, fit-for-purpose strategy, and the implementation of AM methods makes possible the fabrication of complex designs with metallic and composite materials. GD and AM represent a revolution in the field of design optimization, offering flexibility and adaptability while collecting a vast amount of structural analysis data, crucial for a cost-effective approach in the early stages of design projects. The implementation of these techniques demonstrated over 7% weight reduction, a 40% increase in operational range, and a decrease in the cost of manufacturing.

In this paper, the performance of an adapted design of a 0.6 m impulse turbine in a new wave energy conversion device—the Dolphin device—is evaluated. This study is focused on developing an optimised structure in order to maximise the potential of the device and provide a lightweight and robust novel design. For this purpose, initial studies on the system involved 2D CFD simulations combined with parametric optimisation, which validated the use of the turbine system with water as the working fluid. The obtained component geometries were then used for the creation of a 3D CFD model, which was tested in a set-up dynamic simulation environment. Subsequently, the performance of the system was evaluated through the use of referenced experimental analyses. By taking into account the loading conditions present at the blades, as well as the inherent typical loads caused by the rotational speed of the turbine, the system was then optimised using generative design processes. Through the applied methodology, the performance of the turbine was predicted to be 61.79%. Moreover, the generative design optimisation showed a reduction in mass of 60.226% for the blade structure and 69.523% for the rotor structure.