Leveraging Automated Manufacturing for Composite Wind Blades
By Olivier Guillermin, PhD
Director of Product and Market Strategy
Siemens PLM Inc.
Building lighter, more durable and better quality wind blades presents a unique and complex challenge that involves significant risks. New concepts, materials and processes must be found to meet the many requirements for everything from functional and structural design to production.
In this context, automating the manufacture of composites holds the promise of many benefits, including shorter time-to-market, reduced production costs, improved quality and repeatability, and added design tailoring capability.
In fact, the larger wind turbines get, the more important it becomes to adopt automated composites manufacturing processes. Labor intensive manual layup and assembly processes just don’t scale economically. And with the wind industry developing blades that may soon reach 100 m (or 328’ ) in length, a high degree of manufacturing automation is essential to ensure the long term success of this industry.
However, adopting automated manufacturing systems alone doesn’t guarantee that wind turbine manufacturing firms will meet the growing demand for high-quality blades. Indeed, without a way to accurately simulate the producibility of wind blades ahead of time and to fully integrate the design and manufacturing process, automated deposition represents an incomplete solution to a complex challenge.
Value of an early diagnosis
All too often what is being made in the factory is different from what was designed, analyzed and documented in the design office. Issues arise on the shop floor that were not foreseen and inevitably lead to design changes.
Producibility simulation software enables an organization to verify early on in the development process that manufacturing will be able to make the parts as designed. For manufacturing organizations to be successful, designers and stress engineers must have access to producibility simulation data prior to the time their colleagues on the shop floor start manufacturing blades.
Indeed, in order to produce a wind blade to specifications with fewer risks and less waste, one should accurately simulate the manufacturing process and learn of potential problems during the time that early design and optimization are being conducted.
This is especially true for today’s football-field-length blades because they are comprised of thousands of composite plies and core panels. Multiple materials, including glass and carbon-fiber fabrics, various resins and bonding pastes, balsa and foam core may be used in a single blade. The ability to stack and stagger plies in different sequences and orient material fibers along specific directions enables the building of stronger and lighter blades, but it also greatly increases the amount of design and manufacturing data to deal with. Given the complexity of working with so many different materials, it is imperative to accurately simulate how they will fit together once it all hits the manufacturing floor.
Combining accurate simulation of various processes and materials with ease of use by designers and structural engineers, such software solutions ensure that the components of a wind blade—skins, spar caps, web, box beam, and root laminate—will indeed be producible when manufacturing starts.
Such producibility simulation enables the timely discovery of potential problems, including fabric folding, wrinkling or bridging issues. These issues may result from excessive steering, pulling or pushing of the fabric while laying down plies or courses in the blade mold. Ultimately, it can trigger preliminary breakdown of the blade by progressive delamination, debonding and crack propagation, leading to catastrophic failure.
If detected early on by the producibility simulation, these issues can be resolved quickly by changing the ply design in various ways, including ply darting, splicing, redraping, or material and orientation changes. This is all done directly on the computer by using Siemens PLM Software’s Fibersim composites engineering software.
What’s more, materials suppliers and transformers are constantly innovating with new types of fabric weaves or stack-ups which results in new forms of composite materials, some of which are tailored to large composite structures. Among them, Non Crimp Fabric (NCF) and multiaxial fabrics are now extensively used in the wind industry. Such materials present some new and very specific deformation behaviors when draped on the tool. For example, they are more prone to micro-buckling deformations. These deformation modes must be accounted for by the producibility simulation software in order to generate useful information for blades made with these new materials.
The benefits of producibility simulation have been proven in production across multiple industries by companies such as Bombardier Aerospace, BAE systems, Nordex, Sinomatech and others.
With the advent of automated deposition systems for wind blade layup operations, a complete and accurate producibility simulation capability is even more critical. That’s because in traditional manufacturing, the engineers and technicians who are confronted with manual layup issues on the shop floor will often have enough experience and knowledge to devise a workaround on the fly to get them over the hurdle. While this is less than ideal because it is not repeatable and increases the risks of an imperfect blade, at least it keeps the manufacturing process moving.
With automated deposition systems, the machine is unable to figure out “manual” workarounds “on the fly.” Events and alternatives are either pre-programmed or they are not. When the answer to an issue is not available, the machine stops, or may damage the part or the mold. Precious time is wasted halting the automated deposition process for lengthy manual interventions. Such downtimes are major productivity killers and the reason why some companies have delayed adopting automation.
In order to march confidently into the future and control the risks of new technology, such as automated deposition systems for wind blades, it is imperative to root the engineering process in a complete, accurate and reliable producibility simulation of the manufacturing process.
Integrating design and manufacturing
Clearly, making sure that the part is fully producible is paramount before manufacturing starts. But there is a second critical ingredient that is required to produce an efficient and reliable blade manufacturing process: the adoption of an integrated design and manufacturing process.
Manufacturing teams making blades in the factory often encounter problems stemming from the fact that while some data may be available in the design office, either digitally or on paper or in the heads of the designers, some of that data has not made it to the shop floor. Or if it does make it, it is incomplete or not accurate enough for the manufacturing engineers to fully and precisely reproduce the design intent. They are left trying to figure out some of the details and fixing some of the apparent contradictions.
Furthermore, late modifications and design changes performed in the shop— sometimes major ones—are not communicated back to the design and analysis teams due to time pressure and other higher priority tasks.
An integrated design and manufacturing approach will remedy this type of situation. Integrated design and manufacturing is a cornerstone of composites manufacturing. It is critical to reaping the expected benefits of automated deposition applied to wind blades.
For the automated manufacturing process of a blade to be reliable and lead to the expected time and cost savings, a complete, detailed and producible definition of the part must be communicated seamlessly from the 3-D composite model to the digital manufacturing environment and, ultimately, to the machines. The goal is for the machines to produce the part exactly “as designed.”
A seamless link from the 3-D composite model to the automated deposition system conveys consistent, complete and reliable data that reflects engineering intent, detailed ply and core layup definition, manufacturing constraints and exceptions handling.
Such a seamless link is illustrated by the connection between Siemens PLM Software’s NX, Fibersim and Tecnomatix software, which allows the automated transfer of a producible wind blade design to digital manufacturing. By providing complete data about how the fabric should be laid down to avoid manufacturing problems, this link enables the fabrication of wind blade by machine systems that can layup rolls of materials with significant time savings compared to manual processes.
The wind industry is following in the footsteps of aerospace firms by moving to automated deposition of composite materials. While automating wind blade manufacturing can save time and reduce costs, there are significant risks if the machine system is not fed with the appropriate instructions and will result in a producible part definition.
Within the PLM software portfolio, composite design software, such as Fibersim, provides the ability to simulate the fabric deposition completely and accurately to ensure producibility of the design.
In addition, seamless communication of the detailed design to the shop floor using a digital process will ensure that the parts are manufactured as designed and analyzed.
A prominent hotel chain once had an advertising campaign that featured the slogan, “The best surprise is no surprise.” That sentiment pretty well sums up why many managers and engineers who are designing ever larger wind turbine blades are looking to producibility simulation and integrated design: When you’re manufacturing 100-meter wind blades, the last thing you want are surprises.