Re: Fine wire tensile strengths?

Jul 31, 2010 4 Replies


I've been asked to 'light-up' aircraft models, such as,


>
>
formatting link

>
>It is suspended from a rope.
>I need to use very fine 120V wire (like magnetic wire),
>the model uses 8# test monofilament right now and weighs
>1/2 # , but a strong wind requires that 8# test.
>Is there a table that gives wire gauge & tensile strength?
>The current will likely be a max of 1/2 amp.
>Ken

You can pick the material and look up the yield strength.



In Imperial units, maybe steel wire (like music wire) you could use



300,000 PSI, say.

So for something that would break at 20lbs you would need



7E-5 in^2, which is about 0.01" diameter, if I did the sums correctly.

You should calculate and test the strength and self-heating effect before using it, of course.


Best regards, Spehro Pefhany


"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

OK. diameter for wire gauges found here:

formatting link

Yeild strength for several alloys can be found here:

formatting link

Using 60,000 psi for yeild strength we want 30,000 or 40,000 psi for test strength. Thus to get 8 lb test we need 8/30,000 ~= 266 E-6 square inches. Solved for diameter D=sqrt(A/(2*pi)) for A=sqrt(266/6.28) about 6.5 mils. Thus from the table, 2 #39 enameled magnet wire lightly twisted ought to provide the mechanical strength needed and a complete circuit and handle 18 mA without trouble.

Just pi. But since it's diameter, not radius, it's 2*sqrt(A/pi).

Tim

Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms

AFAIUI, usually "x pound test" mono line has an actual typical breaking point 20-100+% higher than x, so more safety margin might be required.

Gosh, i am at 50% of _yeild_ strength already. Do you really think i need more margin?

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required