Alcoa's Keensert inserts and studs, shown here, along with Inconel 718 bolts and standard hexagon nuts, went to Mars on the Curiosity Rover. In spacecraft and aircraft, Keenserts provide high resistance to torque-out and pullout loads.
The lightning strike issue isn't about frequency so much as it is about catastrophic results. If you've only got a (for example) 1% chance of something happening, but that something has catastrophic results--people dying, lawsuits--then that's something you've got to protect against, or at least not encourage, in your materials and assembly process selection.
I never thought that lightening strikes on aircraft was so common. I read that it happens 2 times per year on average, per airplane. I have seen electrical discharge responsible for fastener loosening and in some cases, ejecting.
There is a downside to composite pieces, price. Bolting parts together will always be around. I designed a mechanical system that ended up having over 60 bolts.. it was cheaper than with none, that was for sure.
Glad you liked the article. The whole issue of the grounding of composites used in aircraft has been widely misunderstood, so I thought it was a good idea to include some clear discussion on that issue. Could you clarify your question about comparisons between fasteners for composites and fasteners for metal? What sort of comparisons do you have in mind?
Excellent post Ann. I know the longevity of any fastener is dependent upon the application and use. Relative to composite fasteners, do we know how they "stack up" relative to metal fasteners? I have seen no data that tries to correlate life cycles of either type. Great point also about the grounding of composites. I know this must be a huge issue but not talked about too much in the literature.
That's true of course. The question is, given an increase in composite use, whether fasteners will be used in high enough quantities in repair to make up for the lower overall quantities in manufacturing.
Several of the new and noteworthy 3D printers in this slideshow are breaking some boundaries in build volume, new metals printing techniques, or working with high-profile development partners to ensure very high-quality parts and controls.
United Launch Alliance will fly 3D-printed flight hardeware parts on its rockets starting next year with the Atlas V. The company's Vulcan next-gen launch vehicle will have more than 100 production parts made with 3D printing. The main driver? Parts consolidation and 57% lower production costs.
A new report from the National Institute of Standards and Technology (NIST) makes a start on developing control schemes, process measurements, and modeling and simulation methods for powder bed fusion additive manufacturing.
Although bio-based polymers face challenges from petroleum-based polymers, in certain markets they can displace the petro-based incumbents. Here are six new bio-based and renewable plastics for a variety of applications.
BASF has developed tools and initiatives to help engineers use more of its renewable materials in their designs, more effectively, as well as to build parts using them with more predictable performance.
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