As you can see by the formula, the influence of the diameter is to the
fouth power, a small change in diameter means a big change in
torsional stiffness.
Marty Sasaki
On Tue, Sep 1, 2009 at 4:45 PM, slo_mi<slomi_at_eunet.yu> wrote:
>
>
> For two dimensional diferent wires of same quality (same modulus)
> angle of wire twist Phi under torque T is:
>
> Phi2=Phi1*(T2/T1)*(L2/L1)*(D1/D2)^4
>
> where are:
> Phi is angle of rotation,
> T is torque
> L is lenght
> D is diameter
> index 1 is for first wire, index 2 for second wire.
> If you know data for one wire you can calculate data for the second.
> Try this with data of Akihiro Danjo, where L2/L1=1, and Phi1=Phi2. In this
> case is:
>
> T1/T2=(D1/D2)^4
>
> And so on ....
>
> --- In Indoor_Construction_at_yahoogroups.com, Tapio Linkosalo
> <tapio.linkosalo_at_...> wrote:
>>
>> Akihiro Danjo wrote:
>> >
>> >
>> > > I built my first attempt last weekend, and about 20cm of 0.3mm wire
>> > > gives about 30 g*cm for 360 degrees rotation, but that may be a little
>> > > too loose? Going up to 0.35mm wire would double the stiffness...
>> >
>> > Tapio san,
>> > Is your data correct?
>> > I have a data and it says, 10cm (not 20cm) wire,
>> > 0.30mm = 43 gcm
>> > 0.33mm = 61 gcm
>> > 0.36mm = 79 gcm
>> > per turn.
>> > If this is correct, I think you should use 20cm of 0.36 (or 0.40) mm
>> > wire.
>>
>> Grhm, not quite. The torque wire is rather 12 to 14cm long, not 20. It
>> still seems to deflect full turn on 30g*cm rather than 40, but I'll have
>> to check that. Maybe my wire is 0.28 rather than 0.30, and thus looser...
>>
>>
>>
>> -Tapio-
>>
>
>
--
Marty Sasaki
Arlington, MA, USA
http://www.martys-simple-things.com/
marty.sasaki_at_gmail.com
Received on Tue Sep 01 2009 - 14:26:30 CEST