Rivet Size & No of Rivets vs current (Amperes) Requirement 1

[MCA1983]

Hello,

while designing a unloaded bracket, client has provided a current requirement as 30 Amperes. based on the current, I need to select rivet size and no of rivets. for example, 30 Amperes current, I can go with 3 rivets with 4.8 mm diameter fastener or 4 rivets with 4 mm diameter. attachment has aluminum rivet sizing details.
my question is what's the relation between rivets size/no of rivets versus current (amperes)? why we need to select 3 rivets with 4.8 diameter or 4 rivets with 4 mm diameter to achieve the current requirement? I'm not able to correlate the about data. could anyone help me to understand the reasoning for this selection. thanks in advance

 

[IRstuff]

?? Your table explains this (N+1 or N+2 margin included)

Divide the current by the admissible current per rivet to find the nominal number and you'll see that the number of rivets required is either 1 or 2 more than the nominal.

You can use the camera button to place images inline as below

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[WKTaylor]

MCA..., IRs... This does not seem like any tables I have seen for aircraft... except for, maybe, short-to-ground... or lightning strike diversion.

I 'see the table', but am wondering where it 'came from' and what is it's detailed purpose, IE: short-to-ground or continuous... and what voltage [VDC, VAC] and what sheet metal type and thickness are nominal.

Also, most grounding rivets are typically 1100 [A] for min resistance [relative to 'buck-hardened Al alloy' rivets with poor conductor finishes.]... and long-term corrosion resistance... accompanied by a bonding jumper to adjacent primary structure. WHEN they eventually 'blow-out' structural integrity in not compromised.



Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[Sparweb]

MCA1983,
Rivets aren't installed in ways that support electrical conductivity. The fact that they *Usually DO* doesn't mean that this is controlled by their installation method. Many rivets are installed "wet" or dipped in paint before driving, for example. That is meant to isolate and/or seal the joint and clearly wouldn't conduct much electricity as a result. Internal to the aircraft where rivets are not likely to be installed wet, they may still be installed with anti-corrosion coatings and on painted parts. None of these structural considerations are conducive (pun intended) to electrical current.

What's usually done instead is the measurement of resistance to ground (airframe). There are specific guidelines and they are *approved data* in that case. Failing the ground resistance test can be remedied by installation of bonding straps, which is also very common. It's an obvious compromise but it's done this way because it is much easier to fix a bad ground that it is to fix a compromised airframe structure.

 

[MintJulep]

Intentionally designing a current path through a "bracket" riveted (or bolted) to some other thing is a bad idea. For many reasons. Not only on an aircraft.

Please stop and find a knowledgeable electrical engineer to help.

 

[EdStainless]

If these are for grounding, wouldn't you need to install with abrasive grease for good contact?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[rb1957]

if these are for grounding, use a grounding stud. why not ??

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.