|   Why do Romic ti springs have fewer 'turns' than the steel? | Deano_Taylor
May 22, 2003 2:08 AM | | All the Romic ti springs I've seen have fewer 'turns' than their counterpart steel springs. I guess this helps this makes them lighter still, but why else? Does the 'springier' nature of ti mean that less turns are required? |
| Ti has lower Torsional Modulus | Sunny
May 22, 2003 8:49 AM | | then steel. For the same cross section of wire/rod, it takes less force to twist the Ti version. To make up for this, fewer turns are used to maintain the same rate. Some info can be found here |
| Many reasons | Dougal
May 23, 2003 6:33 PM | | There are several reasons. Firstly as sunny pointed out titanium is more elastic than steel, so a spring with the same turns and size will need bigger wire to keep the spring rate the same. Secondly fewer turns means less wire and thinner wire which makes for a lighter spring, but higher stress and strain on the material.
I guess the approach is pick the intended life of your spring, then from fatigue diagrams work out the maximum stress the material can handle for that many cycles. From there you make the spring with as few turns as possible and as thinner wire as possible to save as much weight.
If you want to measure up your spring (wire diameter, number of turns, max compression and inside diameter) I can tell you the stress the material is under and predict the rate. Interestingly enough the FOX spring on my bike runs up to 1000MPa stress at full compression. Fox seems to have some damn good steel to make these from, it should have died by now.
Dougal.co.nz |
| |
