Chapter 10 Torsion Tests
Chapter 10 Torsion Tests
Chapter 10 Torsion Tests
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<strong>Torsion</strong>al stresses for large<br />
plastic strains<br />
• Beyond the torsional yield strength, the torque-twist angle<br />
relationship is no longer linear and in the plastic range the shear<br />
stress in the bar at the outer fiber can be calculated from<br />
1 dM<br />
= 3<br />
' T<br />
2πa<br />
⎝ dθ<br />
⎛ ' T ⎞<br />
τ ⎜θ<br />
+ 3M<br />
⎟ Eq.8 Or τ ( BC + 3CD)<br />
a<br />
Where θθθθ’ = θ θ θ θ /L<br />
• At maximum point, dθ<br />
.<br />
The ultimate torsional shear<br />
strength or modulus of<br />
rupture in the bar at the outer<br />
fibre is<br />
3M<br />
τ = Eq.9<br />
u<br />
2πa<br />
⎠<br />
dM T<br />
max<br />
3<br />
0 ' =<br />
=<br />
2πa<br />
Method of calculating shear stress<br />
from torque-twist diagram.<br />
Suranaree University of Technology May-Aug 2007<br />
a<br />
Tapany Udomphol<br />
1 3
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