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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Advanced rotor technologies' taking place on Tuesday, 11 March 2014 at 11:15-12:45. The meet-the-authors will take place in the poster area.

Jean-Daniel LECUYER Dassault Systèmes, France
Co-authors:
Jean-Daniel LECUYER (1) F P
(1) Dassault Systèmes, Vélizy-Villacoublay Cedex, France

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Jean-Daniel LECUYER obtained his MSc in Mechanical Engineering from the Institut National des Sciences Appliquées at Lyon in 2002. After a first experience in an aeronautic company as a stress engineer, he joined SIMULIA France (formerly ABAQUS, part of the Dassault Systèmes company) as a technical expert for support, training and pre-sales activities. Two years ago, he joined the Energy, Process & Utilities Industry team of Dassault Systèmes to highlight the experiences that our Energy customers can live by using our applications. A specific focus has been on the composite blade design, simulation and manufacturing.

Abstract

Topology and parametric CAE-based structural optimization of wind turbine composite blades

Introduction

The goal of optimization of any structure is to have a design with the best possible reliability and performance. Optimization of a composite blade is generally a manual process based on the experience of a few experts, and by using simplified models. However, such simplified models are not able to track the real behavior of the structure (local bucking, load stiffness effects…). This paper will show how blade manufacturers can benefit by adopting automated topology, shape and parametric optimization solutions with a computer-aided approach in a context of design optimization of composite wind turbine blades.

Approach

Three types of optimization techniques are available:
• Parametric optimization where some parameters such as thickness, dimensions… could be modified,
• Shape optimization where the general layout of the part to optimize is fixed and only minor changes are allowed by repositioning surface points
• Topology optimization where the shape of the part can be completely modified by removing material while looking at the best stiffness.

The context for this study is to optimize a blade for a static test by providing the best bending stiffness, but by ensuring suitable eigenfrequencies and by reducing, or even avoiding any local or buckling effect.

Main body of abstract

Topologic optimization is mainly efficient during the concept phase of the design by identifying areas of improvement in the preliminary design. In this method, the designer can use an automated and iterative process that will help him/her have a well-designed blade that minimizes weight, while maximizing stiffness and durability. Shear web or cores are the best examples of areas where topologic optimization can be very valuable. For such optimization, an initial domain that includes the optimized shape, the relevant objectives (mass reduction, maximum deflexion, etc.) and the constraints (manufacturing constraints, stress level or Tsai-Hill constraint, etc.) must be defined. The optimized shape results will give trends by taking into account the anisotropic effects of the material. A detailed composite design (layup) can then be defined using these results as inputs.

Parametric optimization is fully relevant for the composite optimization, right from the conceptual design phase. Using a design of experiments based on a finite element analysis, and other engineering parameters, the most influential composite parameters (essentially the thicknesses of each material-orientation couple) can be identified. This can then be optimized to find the best values of those parameters according to the specific objectives and constraints. Parametric optimization can also be used later in the composite design process, at the detailed design phase, to optimize the composite layup at specific areas. Sub-modeling techniques can help to reduce the computing time by focusing on zones of the global composite model.

Conclusion

The design of a composite wind turbine blade is complex because any modification in one area may have a significant impact in other areas. Topology optimization can help the designers in the early concept phase. Parametric optimization provides a larger range of capabilities ; and can be used from the concept phase through the detailed phase of the design. By using a realistic 3D models with sell finite elements and a nonlinear solver, it is possible to take into account nonlinear effects such as buckling or load stiffness that are mandatory for a realistic optimization.


Learning objectives
Thanks to this paper, the attendees understand and are able to identify where topology and parametric optimizations based on real simulation (3D with non-linear solvers) have values dedicated to the wind industry to optimize composite blades by defining the best material and orientation layups.