FEATURE “Aeronautics”

ew automated manufacturing processes are beingimplemented to help reduce touch labour, improveproduct quality and consistency, and meet demanding

throughput requirements. Technologies such as automatedfibre placement, tape laying and robotic material depositionare being used on an increasing variety of components. While material layup is a significant part of the process, it isnot where the aeronautics and associated challenges end. In-process and post-cure inspection using state-of-the-artautomated NDI equipment is becoming a necessity to ensureengineering requirements are being met. Automated trim anddrill operations using the latest NC-driven routing and waterjet equipment, followed by automated fastener installationand even laser-guided assembly are all key parts of theprocess. While CAD and PLM systems are the primary components ofthe engineering environment, these systems lack thespecialization required to effectively manage the complexairframe data, the key to enabling automated downstreamprocesses.VISTAGY’s AeroSuite™ fills that void. The AeroSuite is acomprehensive software solution that enables aircraftmanufacturers to effectively manage the entire evolvingproduct development process. It is composed of FiberSIM®

composites engineering software, SyncroFIT® for designingand manufacturing airframe assemblies, and the QualityPlanning Environment™ (QPE) to streamline the First ArticleInspection process.

Streamlining automated processes for composite airframe manufacturing

34 jec composites magazine / No58 June - July 2010

FiberSIM is a software suite that addresses the entirecomposite engineering process, from conception, laminatedefinition and ply creation through to simulation,performance optimization, flat pattern generation,documentation and manufacturing. SyncroFIT is a group ofsoftware products for authoring and managing the assemblyinterfaces and the hundreds of thousands of fasteners that aretypical in an airframe. With the QPE, engineers are able togenerate quality plans and inspection data based on designand manufacturing characteristics created by FiberSIM andSyncroFIT and saved in the CAD model.

Considering the manufacturing processThe use of composites introduces a high level of uncertaintyand variability contrary to the well understood structural and

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With the commercial aerospace industry spreading out across the globe, OEMs arefacing growing pressure to be first to market with state-of-the-art aircraft. When youadd the volatility of fuel prices and the need to reduce operating and total lifecyclecosts, you can understand why aircraft manufacturers are rapidly adopting the use ofadvanced composite materials for primary structural components. These componentsinclude fuselage skins and substructure, wing skins, ribs, spars, stringers and shearclips, along with complete empennage assemblies and pressure bulkheads.

STEVEN J. PECK

DIRECTOR OF PRODUCT AND MARKET STRATEGY FOR

AEROSTRUCTURES

VISTAGY, INC.

Illustrated above are simulation results from FiberSIM® based on various materials and manufacturing processes. On the top left, the simulation result formanufacturing producibility of a full-coverage 0-degree layer of woven carbonprepreg is shown. The image on the top right illustrates the producibility challenges that will be encountered when this 0-degree strip of unidirectionalcarbon prepreg is laid up by hand. The image on the bottom shows areas in whichan automated fibre placement machine will be unable to deposit material in thenarrow strip areas of the picture frame ply due to the minimum course capabilityof the machine.

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No58 June - July 2010 / jec composites magazine 35

Simulation

manufacturing behaviour of other materials, such asaluminium. Composite design requires a careful balancebetween the geometric requirements, the material form andthe manufacturing process.

For example, a monolithic skin panel, a T-shaped stringerand a sandwich panel fairing must be treated differently.Likewise, different material forms, such as woven fabric,unidirectional tape or a non-crimp fabric, all representunique design and manufacturing implications.Finally, the manufacturing process, such as hand layup,automated tape laying, automated fibre placement, resintransfer moulding (RTM) or forming, needs to be taken intoconsideration. The specific combination of these variablesinfluences the design approach and, ultimately, the cost andquality of the finished product. Balancing all of theseelements constitutes a significant challenge. A solution thatincorporates simulation capabilities tailored to the specificmaterial and manufacturing process will provide earlyvisibility into the challenges that will occur during the buildprocess.

Improving the engineering environmentIn an effort to increase throughput, cut production costs andimprove quality and repeatability, automated depositionprocesses are quickly becoming the manufacturing methodof choice for composite aerostructure components. Unlikethe NC machining of metals or the injection moulding ofplastics, manufacturers of automated processing equipmentfor composites are installing relatively few systems per yearas opposed to the thousands being installed for theautomated manufacture of other materials. However, someanalysts estimate that within the next decade, more than75% of composite parts will be manufactured with anautomated fibre placement, tape laying or robotic depositionprocess instead of hand layup, which will drive demand fornew systems.

Regardless of the method, it is clear that we are still in thevery early stages of a major transformation in the way thatcomposites are manufactured. Cycle times will decreasesignificantly, part quality will improve, and design-for-manufacturing techniques will evolve to the point wheresurprises will be rare during machine run time.

To keep pace with this evolution, the capabilities ofcomposite design software must likewise evolve. Just as handlayup requires the ability to manage the complex splicingand staggering requirements imposed with fixed-widthconventional materials, producibility simulations that mimichand smoothing techniques and the generation of suitablyshaped flat patterns, automated processes will require theirown set of innovative design-for-manufacturing capabilities.

For example, a machine limitation such as a minimum courselength induces a design constraint which can affect plyboundaries, potentially interfere with mating part footprints,and influence part weight. Identification of such constraintsmust therefore be highlighted and addressed during thedesign process rather than being left for manufacturers toresolve. Ignoring these critical manufacturing requirements indesign will inevitably result in costly design iterations, over-design, and situations where as-built does not conform to as-designed, a significant certification risk.

By working closely with the manufacturers of automateddeposition systems and CAM software for composites, a set ofrequirements has emerged that enhances the engineeringenvironment so that the design of composite components forautomated manufacturing can be fully defined and optimized.

Minimum course length, staggered ply origins, minimum stripwidth and minimum cut angles are some of thesemanufacturing requirements that are part of FiberSIMsoftware. And with the composite manufacturing industryleaning toward machine-independent part definition,additional functions are likely to become part of the designenvironment. However, a separate category of machine-specific, run-time parameters will still remain part of theoffline and machine programming CAM softwareenvironment.

Managing airframe assembly complexities With the increased usage of composites and the ability totailor thicknesses to support loading conditions, thespecification of fasteners is becoming unmanageable. A number of issues, such as material compatibility, holepreparation methods, structural requirements, and cost andlead time implications of specialized fasteners, are raising

The top image shows the ply layup design for a composite fuselage panel generated by VISTAGY’s FiberSIM® software during a CATIA V5 CAD modellingsession. The design data is rapidly and seamlessly transferred to CGTech’s VERICUT Composite Programming & Simulation software (bottom) to generatethe manufacturing data for the automated fibre placement machine and verifythe process.

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concerns. It is generally acknowledged that nearly 15% ofdetail design activity is associated with managing assemblyinterfaces, fasteners and holes. In fact, industry figures showthat more than 50% of these problems are associated withassembly definitions.

When you couple these definition issues with the automateddrilling and fastener methods used to improve quality and cutcycle times, you have significant challenges. You need toprecisely control feed rates and drill speeds through stacks toavoid potential damage to the composite material from drillbreak-through or chip extraction. NC programmers requiredetailed stack thickness and material information to properlythrottle drilling operations. Typically, significant time isrequired to obtain this information on each fastener location. As programs progress through the development process andsubsequently involve sustaining engineering efforts, it will becritical to have a solution that reduces cycle times toimplement changes and eliminate errors. With a clear understanding of these challenges, VISTAGYrealizes the importance of having a solution to manage thecomplexities associated with modern airframes containingnumerous joints and fasteners. This is where SyncroFITcomes in.

With the unique capability to capture assembly jointdefinitions and manage the interactions between bothmodelled and non-modelled components, SyncroFIT isenabling firms to reduce engineering development times,effectively manage the change process, and reduce thenumber of engineering change orders that are typical in anaircraft program. It automates tedious tasks, such ascomputing grip lengths, loading and positioning hardware ortemporarily installing a clearance solid to detect potentialcollisions upon assembly. Managing the airframe as a series of

joint definitions allows the engineer and downstreamconsumers to navigate the assembly in a logical way. Itprovides the capability to fully define the part stack-up andfeed NC programming systems with the information requiredto drive automated drilling and fastening systems.

Keeping up with changeDesign changes in the engineering process are inevitable andcan cause significant disruption. Consider the cascadingimpact of a skin thickness change in a fuselage panel that isimplemented as part of a weight-saving initiative. In anengineering design, such a change may affect laminate stack-up, ply drop-off locations and shapes, the skin inner toolsurface, the substructure mating surfaces, fastenerspecifications and, ultimately, weight and balance. Inmanufacturing engineering, the change may affect the plylayup tables, the bill of materials, the supplier build-topackages and the maintenance and service documentation.

In manufacturing, the change may affect the fibre placementprograms, the composite flat patterns, the automated drillingand fastening program, the laser projection files and theprocess plans. In tooling manufacturing, the skin IML toolingand the substructure tooling may change. Finally, the FirstArticle Inspection plan and other QA documents mightchange as well. The issue is not the implications of a singlechange, but that it takes only a couple of inconsistencies ormissteps in the change process to derail a whole developmentprogram. Getting the change process correct requires acombination of expertise in design, analysis, manufacturingand process planning, all within the context of a compositematerial environment.

Optimizing critical processesManufacturing aeronautics is becoming pervasive in aerospacecomposites. As a result, aerospace firms need to take a morecomprehensive approach to the design and manufacture ofcomposite parts and assemblies. Efficient compositeengineering tools extend beyond CAD, PDM and CAE toencompass an airframe engineering-specific view of theprocess and product details.

Ultimately, the foremost challenge facing designers andmanufacturing engineers is the need to recognize and rapidlyaccommodate the inevitable changes that occur throughoutthe development process without errors and costly delays. Asthe role of composites continues to evolve, softwaredevelopers, including VISTAGY and its partners, arecommitted to delivering solutions that will empoweraerospace firms to continuously optimize the design-to-manufacture process.

More information: www.vistagy.com

The automated detection of an edge distance violation is one of the many designrule checks incorporated into SyncroFIT. Other checks, such as the verification offastener pitch, angularity, countersink depths, and length-to-diameter ratio, dramatically reduce common errors that result in costly engineering changesand rework on the shop floor.

FEATURE “Aeronautics”g…/… Streamlining automated processes for composite airframe manufacturing

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