Advanced solutions for designing wind turbine blades. White Paper

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1 Advanced solutions for designing wind turbine blades White Paper Siemens PLM Software provides a powerful solution that includes functionality dedicated to wind blade design. The software provides productive and flexible functionality for defining composite blade designs while automating many of the repetitive design, simulation and manufacturing tasks particular to working with composites. Answers for industry.

2 White Paper Advanced solutions for designing wind turbine blades 2 Contents Executive summary...3 Revolutionizing the design of wind turbine blades...4 Automated import of a wind blade layup definition...5 Zone-based design...6 Ply course generation based on accurate producibility simulation...7 Generating variable offset surfaces...8 CAD software and system compatibility...9 Conclusion...9

3 White Paper Advanced solutions for designing wind turbine blades 3 Executive summary Designing wind turbine blades is all about balancing aerodynamic performance with structural integrity. The goal is for blades to extract as much energy from the airflow as possible over at least a 20-year lifespan with the lowest possible lifecycle costs. These blades can weigh up to 20 tons and can be required to withstand tens of millions of rotations and fatigue cycles at speeds up to 200 miles per hour at the tip of the blade. They must also withstand bird strikes, harsh sun, heavy rain, snow, ice, hail, gusty winds and lightning strikes. As blades increase in length, reducing weight becomes even more critical because weight increases faster than energy throughput. So the detailed design of the blade must be spot on to avoid internal cracking and delamination, which will lead to failure. Mastering such a precise process typically requires advanced design using tools such as 3D CAD systems and industry-specific composites design software tailored to the needs of engineering wind turbine blades. The layup of the glass plies and core material is manual and labor intensive, resulting in inaccurate and unrepeatable processes. Tooling is very large and expensive, often causing manufacturers to avoid making costly design changes so they can re-use the same tools as much as possible. This, however, limits design optimization and variants. In all, hundreds if not thousands of composite plies of various materials and numerous pieces of core materials must be put in a complex arrangement and run through a sophisticated curing process to produce a wind turbine blade.

4 White Paper Advanced solutions for designing wind turbine blades 4 Revolutionizing the design of wind turbine blades Siemens PLM Software now offers a powerful solution that includes functionality dedicated to wind blade design in the Advanced Composite Engineering Environment module in the Fibersim software portfolio. The software provides productive and flexible functionality for defining composite blade designs while automating many of the repetitive design, simulation and manufacturing tasks particular to working with composites. The new automation tools in the Advanced Composite Engineering Environment (ACEE) reduce potential for error and, by speeding the design process, enable engineers to focus on their expertise: Design innovation, process selection, part performance and quality. The software is flexible enough to easily accommodate the demands of designing the components of wind blades for the complete range of materials and manufacturing processes used to create them. Based on extensive customer input, Siemens PLM Software has developed functionality that exploits the inherent advantages of the newest composite design methodologies, including: Wind blade design import for large blade shells and other blade components Zone-based design for the thick root and spar laminates Ply-based design for highly contoured areas The ACEE features four main categories of tools for preliminary design and automation: Automated import of wind blade layup definitions Accurate ply course generation based on material producibility simulation Generation of variable offset surfaces Smart darting and splicing

5 White Paper Advanced solutions for designing wind turbine blades 5 Automated import of a wind blade layup definition Most wind blade designs have several laminate regions with ply shapes that can be defined using a spreadsheet-like approach. For example, a typical design will include full body skin laminates that cover the entire shell surface, one or more spar cap laminates running along the length of the blade, trailing and leading edge reinforcements and a very thick root laminate that transfers the energy from the blade to the rotor hub. Because each laminate region is independent and ply shapes usually shift or overlap rather than nest, the zone-based design methodology traditionally used in aerospace is not an appropriate approach for wind blades, except as a complementary point solution as described below. Yet, manually creating a ply-based design of a wind blade is extremely time-consuming due to the number of plies (>100) and the complexity of the ply layup. Figure 1: The wind blade design import function in Fibersim enables the import of a spreadsheet-like ply definition to automatically generate the blade layup. The Wind Blade Design Import (WBDI) functionality in the Fibersim portfolio automates the creation of all the plies in the 3D CAD model based on spreadsheet parameters and with minimal geometry input. Based on region-type parameters, the WBDI will automatically create all plies/layers, core and associated geometry to quickly provide the complete 3D blade layup definition.

6 White Paper Advanced solutions for designing wind turbine blades 6 Zone-based design Fibersim supports the design of regular transition regions, such as from a thicker root laminate to thinner shell laminates, by providing you with flexible ways to quickly create zones and material specifications within the 3D CAD model. Once the requirements for the zones have been defined, plies can be automatically generated that account for sequences, materials, orientations, and stagger and drop-off profiles. While Siemens PLM Software does not recommend this design methodology as a general approach to wind blade design, it is a useful complementary point solution for some areas or components of the blade. Figure 2: The zone-based design methodology in Fibersim can be used to automatically generate a series of plies with a regular drop-off profile. It is typically used to control the transition from a thick area, such as the blade root, to a thinner area.

7 White Paper Advanced solutions for designing wind turbine blades 7 Ply course generation based on accurate producibility simulation Wind blades are typically manufactured by laying down full rolls of material side by side along the length of the blade. This effectively involves steering each ply to maintain the overlap with the adjacent ply. And to automate the layup, future automated deposition machines for broadgoods will effectively accomplish the same thing using a guide curve and material width and deformation as the input. Fibersim already provides the ability to generate the appropriate ply courses knowing the type of material and layup technique involved. The Fibersim producibility simulation accurately predicts the material deformations as laid up in the tooling mold. The simulation takes into account deformations and deviations, including wrinkling, folding, bridging and fiber micro-buckling to provide insight into the manufacturing process. At the same time, the laminate layers are divided into ply courses to create a manufacturing definition of the blade. Each course is created based on the type of material used, the desired layup technique and the ability of the material to conform to the mold surface. You can easily optimize the ply course definition to reduce material scrap, accelerate the deposition process and ensure accurate coverage of the blade surface. The ply course definition can then be turned into a dataset for the actual production of the blades, either for hand layup, resin transfer molding or automated deposition. Figure 3: Fibersim provides the ability to quickly generate ply courses from the layer definition of the blade layup. Shown here is a ply course running to the blade tip. The red area indicates that the material is being over-steered, consequently forming undesirable wrinkles during manufacturing. This defect may trigger a weakness in the blade that can eventually result in failure. By accurately simulating the manufacturing process with the ply course generation functionality in Fibersim, you can alleviate the need for rework on the shop floor and ensure better blade quality and performance.

8 White Paper Advanced solutions for designing wind turbine blades 8 Generating variable offset surfaces One of the advantages of designing with composites is that plies of a specific material type and orientation can be placed precisely where they are needed. To minimize overall part weight, only the portion of a part that must withstand the most stress need be designed to be thicker, thus stronger, than other portions. The resulting surface created by the built-up plies varies in thickness. Tasks that require accurate representation of these surfaces, such as creating mockup solids and inner mold lines, have previously been done manually. The unique variable surface offset technology from Siemens PLM Software generates variable offset surfaces for plies in the CAD model. Engineers using this technology can automatically account for manufacturing tolerances and ply thicknesses when generating mockup surfaces for interference checking, mating surfaces that model where two parts join together and tooling surfaces for manufacturing. Figure 4: Shown is a blade inner surface computed by Fibersim from the ply layup and core definition. Accurate computation of inner surfaces is the key to the blade engineering process because internal elements, such as spars and shear webs, depend on the blade shell thickness profile. The ability to provide precise data on the inner surfaces enables glue gap minimization and tool re-use, resulting in reduced blade weight and cost.

9 White Paper Advanced solutions for designing wind turbine blades 9 Conclusion Instead of enforcing a single design methodology for a limited set of manufacturing processes, Fibersim works how engineers think. It supports the complete range of composite materials and manufacturing processes, providing maximum design flexibility, efficiency and ease-of-use. CAD software and system compatibility The ACEE supports the following CAD systems: Siemens NX software, Dassault Systèmes CATIA V5, PTC Creo Parametric (formerly Pro/Engineer). It also supports a variety of Windows operating systems.

10 White Paper Advanced solutions for designing wind turbine blades 10 About Siemens PLM Software Siemens PLM Software, a business unit of the Siemens Industry Automation Division, is a leading global provider of product lifecycle management (PLM) software and services with seven million licensed seats and more than 71,000 customers worldwide. Headquartered in Plano, Texas, Siemens PLM Software works collaboratively with companies to deliver open solutions that help them turn more ideas into successful products. For more information on Siemens PLM Software products and services, visit All rights reserved. Siemens and the Siemens logo are registered trademarks of Siemens AG. Fibersim, Syncrofit and NX are trademarks of Siemens Product Lifecycle Management Software Inc. and/or its subsidiaries in the United States and in other countries. All other trademarks, registered trademarks or service marks belong to their respective holders Siemens Product Lifecycle Management Software Inc. X /12 C Siemens Industry Software Headquarters Granite Park One 5800 Granite Parkway Suite 600 Plano, TX USA Fax Americas Granite Park One 5800 Granite Parkway Suite 600 Plano, TX USA Fax Europe 3 Knoll Road Camberley Surrey GU15 3SY United Kingdom +44 (0) Fax +44 (0) Asia-Pacific 100 How Ming Street Suite , 43F Two Landmark East Kwun Tong Kowloon Hong Kong Fax