Editor's Note: Boeing has recently called for the inspection of 787 Dreamliners after it has found signs of delamination on the fuselage of the first passenger jetliner built of carbon-fiber composites. Here, Robert Yancey at Altair Engineering raises delamination issues and the challenges surrounding subcontractors’ use of various techniques to make composite parts. He explains how simulation can prevent such composite production issues and, eventually, delamination.
The recent delamination issue with the Boeing 787 reported in the news (787 Delamination
) highlights the challenges in moving to different manufacturing methods with new materials. There are tremendous advantages to the use of composite materials but there is less experience manufacturing with these materials and these types of problems are bound to occur. As stated by Boeing, there is no safety issue here but it is slowing down the production line.
There is always variability in any manufacturing process. Designers are increasingly able to take into account this variability when designing airplanes. Simulation methods play an increasingly important role here since they allow engineers to look at the variability of the manufacturing process and its effect on performance of the part. Robust design is the terminology used to describe this type of engineering. The goal is to create designs that are not very sensitive to variations in the manufacturing process or material properties. If a design is good on paper – but with a slight variation in material properties or manufacturing process it becomes unstable – it can create significant problems down the road. Different variations can stack on top of one another to further create situations where the component will not perform to specification. Simulation is key to the robust design process since it allows designers to quickly cycle through many different manufacturing and material property variables and analyze their effect.
Often, designers are able to come up with designs that are relatively insensitive to variations within the prescribed specifications of the part. Material suppliers still have to deliver materials conforming to specifications and manufacturers still need to follow proper manufacturing procedures, but if followed, the risk of failure is greatly reduced. About the author:
Robert Yancey is Senior Director of Global Aerospace and Marine for Altair Engineering and is responsible for business development for global aerospace and marine markets. He received a bachelor’s degree from Massachusetts Institute of Technology, a master’s degree from Virginia Polytechnic Institute and State University and earned his Ph.D. in materials engineering from the University of Dayton. He currently resides in the Seattle area.
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