An A380 wing panel is being assembled on this automated line using Electroimpact E4380 automatic drilling and insertion systems for permanent fastener installation. The machines clamp the skin and stringer together, drill holes, insert and form aluminum rivets. They also drill and coldwork holes and then insert titanium pins or lockbolts.
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.
How can automakers, aerospace contractors, and other OEMs get new metal alloys that are stronger, harder, and can survive ever higher temperatures? One way is to redesign their crystalline structures at the nanoscale and microscale.
Although a lot of the excitement about 3D printing and additive manufacturing surrounds its ability to make end-products and functional prototypes, some often ignored applications are the big improvements that can come by using it for tooling, jigs, and fixtures.
A fun and informative tour you can attend at the upcoming Design & Manufacturing Minneapolis, MD&M Minneapolis, and other events there, is the Materials Innovation Tour on Wednesday afternoon. I'll be leading it.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies.
You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived.
So if you can't attend live, attend at your convenience.