Torsion bar materials: Affect on rating?

69427

69427

The Artist formerly known as Turbo84
Joined
Mar 30, 2008
Messages
2,972
Location
Clinging to my guns and religion in KCMO.
Tossing around some thoughts on a torsion bar issue (chassis, not suspension). What is the effect of the actual material of the bar (actually, tubing in this case)? I have mild steel and stainless (304) steel tubing on the shelf. Stainless is harder to bend, as evident in an exhaust system, but does that translate into increased torsion value versus mild steel? Seems like it would. I'd like to find some actual material data to compare these two materials.
Thoughts? Info?

thanks,
Mike
 
Torsion formula for Thin walled tubes

strength_of_material_018.gif



where,

=maximum shearing stress, Pa

=Shearing stress at any point a distance x from the centre of a section

r=radius of the section, m

d=diameter of a solid circular shaft, m

=polar moment of inertia of a cross-sectional area, m4

T=resisting torque, N-m

N= rpm of shaft

P=power, kW

=angle of twist, radian

L=length of shaft, m

G=shear modulus, Pa

do=outer diameter of hollow shaft, m

di=inner diameter of hollow shaft, m



and



Top



Torsion formula for Circular Shafts

strength_of_material_023.gif



where,

=Ip, polar moment of inertia for thin-walled tubes

r=mean radius

t=wall thickness


Modulus of Rigidity or G, (shear modulus) is a materials constant. For example: @ room temp

[tr] [td]Material[/td] [td]Shear Modulus[/td] [/tr] [tr] [td]---[/td][td](10^6 psi)[/td] [td](GPa)[/td] [/tr] [tr] [td]Aluminum Alloys[/td] [td]3.9[/td] [td]27[/td] [/tr] [tr] [td]Aluminum, 6061-T6[/td] [td]3.8[/td] [td]24[/td] [/tr] [tr] [td]Aluminum, 2024-T4[/td] [td]4.0[/td] [td]28[/td] [/tr] [tr] [td]Beryllium Copper[/td] [td]6.9[/td] [td]48[/td] [/tr] [tr] [td]Brass[/td] [td]5.8[/td] [td]40[/td] [/tr] [tr] [td]Bronze[/td] [td]6.5[/td] [td]44.8[/td] [/tr] [tr] [td]Carbon Steel[/td] [td]11.2[/td] [td]77[/td] [/tr] [tr] [td]Cast Iron[/td] [td]5.9[/td] [td]41[/td] [/tr] [tr] [td]Concrete[/td] [td]3.0[/td] [td]21[/td] [/tr] [tr] [td]Copper[/td] [td]6.5[/td] [td]45[/td] [/tr] [tr] [td]Glass, 96% silica[/td] [td]2.8[/td] [td]19[/td] [/tr] [tr] [td]Inconel[/td] [td]11.5[/td] [td]79[/td] [/tr] [tr] [td]Iron, Ductile[/td] [td]9.1 - 9.6[/td] [td]63 - 66[/td] [/tr] [tr] [td]Iron, Malleable[/td] [td]9.3[/td] [td]64[/td] [/tr] [tr] [td]Kevlar[/td] [td]2.8[/td] [td]19[/td] [/tr] [tr] [td]Lead[/td] [td]1.9[/td] [td]13.1[/td] [/tr] [tr] [td]Magnesium[/td] [td]2.4[/td] [td]16.5[/td] [/tr] [tr] [td]Molybdenum[/td] [td]17.1[/td] [td]118[/td] [/tr] [tr] [td]Monel metal[/td] [td]9.6[/td] [td]66[/td] [/tr] [tr] [td]Nickel Silver[/td] [td]6.9[/td] [td]48[/td] [/tr] [tr] [td]Nickel Steel[/td] [td]11.0[/td] [td]76[/td] [/tr] [tr] [td]Nylon[/td] [td]0.59[/td] [td]4.1[/td] [/tr] [tr] [td]Phosphor Bronze[/td] [td]5.9[/td] [td]41[/td] [/tr] [tr] [td]Plywood[/td] [td]0.09[/td] [td]0.62[/td] [/tr] [tr] [td]Polycarbonate[/td] [td]0.33[/td] [td]2.3[/td] [/tr] [tr] [td]Structural Steel[/td] [td]11.5[/td] [td]79.3[/td] [/tr] [tr] [td]Stainless Steel[/td] [td]11.2[/td] [td]77.2[/td] [/tr] [tr] [td]Steel, Cast[/td] [td]11.3[/td] [td]78[/td] [/tr] [tr] [td]Steel, Cold-rolled[/td] [td]10.9[/td] [td]75[/td] [/tr] [tr] [td]Titanium, Grade 2[/td] [td]5.9[/td] [td]41[/td] [/tr] [tr] [td]Titanium, Grade 5[/td] [td]5.9[/td] [td]41[/td] [/tr] [tr] [td]Titanium, 10% Vanadium[/td] [td]6.1[/td] [td]42[/td] [/tr] [tr] [td]Wood, Douglas Fir[/td] [td]1.9[/td] [td]13[/td] [/tr] [tr] [td]Z-nickel[/td] [td]11[/td] [td]76[/td] [/tr]
 
Thanks for the chart info, TT. Looks like there's no appreciable difference in stainless versus the common steels. Might as well save my money and use up the cheap stuff.

Thanks again.
 
You must log in or register to reply here.
Top