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View Full Version : How do I calculate the torsional elasicity of a rubber rod


Toric
Feb 26, 2009, 06:20 AM
How can I calculate the elasicity in a rubber rod.

ebaines
Feb 26, 2009, 10:31 AM
See:

http://en.wikipedia.org/wiki/Torsion_(mechanics)

You can determine the material's shear modulus by clamping one end and applying a torque at the other, and seeing how miuch the rod twists. The basic equation is:


G = \frac {TL} {J \phi}


where:
G = Shear modulus, which is basically the torsional modulus you are looking for,
T = torque applied at one end of the rod,
L = length of the rod,
J = the torsion constant for the rod - for a round or tubular rod this is the same as its polar moment of inertia, and
\phi = angle of deflection, in radians.