You do realize that the increase in strength is purely in the localized
bending stress where yield strength matters right? You'll still need to brace
it for stiffness.
In any case, here's what we did to determine what size tubing we need to use:
- determine what OD and thickness are commonly available
- calculate bending strength and bending stiffness (Sy*I/c and EI) for
1"x.083" mild steel.
- calculate bending strength and stiffness for the size of tubing determined
to be common.
- pick the lightest one (least area) that exceeds the strength and stiffness
of 1"x.083" mild steel.
Note: make sure you get an accurate documentation for the steel you're getting
(Such as steel type and heat treat and if possible the tested yield and
ultimate strength for that batch).
To lighten the frame some more, also think about using the same OD steel but
much thinner wall for non critical areas (or smaller OD). Make sure that you
keep safety as the top priority.
While you can mig weld chromoly with mild steel filler (preferable so the
welded joint isn't brittle), it definitely requires more skill. Also, we ran
through many drill bits, hole saws and band saw blades for the few chromoly
parts that we used.
Andre S
/// unsubscribe/change address requests to majordomo@autox.team.net or try
/// http://www.team.net/mailman/listinfo
/// Archives at http://www.team.net/archive/mini-baja
|