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.
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.
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.
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?
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.
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.
Last week, the bill for reforming chemical regulation, the TSCA Modernization Act of 2015, passed the House. If it or a similar bill becomes law, the effects on cost and availability of adhesives and plastics incorporating these substances are not yet clear.
The latest crop of coating and sealant materials and devices has impressive credentials. Many are designed for tough environments with broad operating temperature ranges, and they often cure faster, require fewer process steps, and produce less waste.
A new program has been proposed for testing and certify 3D printing filaments for emissions safety. To engineers who've used 3D printers at home this is a no-brainer. It's from a consumer on Kickstarter, and targets use in homes and schools.
For the last 50 years, the Metal Powder Industries Federation (MPIF) has sponsored an awards competition for creative solutions to designing and fabricating near-net-shape parts using powder metal (PM) technologies. Here are the seven Grand Prize winners of the 2015 contest.
Graphene 3D Lab has added graphene to 3DP PLA filament to strengthen the material and add conductivity to prints made with it. The material can be used to 3D print conductive traces embedded in 3D-printed parts for electronics, as well as capacitive touch sensors.
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