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.
This slideshow includes several versions of multi-materials machines, two different composites processes including one at microscale, and two vastly different metals processes. Potential game-changers down the line include three microscale processes.
UL is partnering with metals additive manufacturing (AM) supplier EOS to provide AM training to EOS's customers. It's designed to promote correct usage of AM technologies by OEMs and others in manufacturing.
To commemorate Earth Day, we take a look at the state of ocean plastic. If things don't change, by 2050 the oceans will contain more plastic than fish by weight. Here are the problems, as well as some solutions.
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