Statically
Determinate Torsion Members
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In a Nut Shell: A torsion member for which
its support reactions and internal torques can be evaluated by the
equations of equilibrium is said to be statically determinate. If the torsion member is overconstrained (more supports than necessary), then it
is statically indeterminate and more information is
needed to determine the support reactions and internal torques. This same concept also applies to
axial and bending members. Consider the two examples
shown below. In the top figure the
stepped shaft is supported at end A only. Then the torque at support A can be
determined from equilibrium by summing moments along the shaft. On the other hand in the bottom figure the
stepped shaft is restrained at both ends of the
shaft. So there are two unknown
torques – one at each end. i.e. The
torque at A and the torque at
C. But there is only one equation of
equilibrium – sum of moments along the shaft. So there is insufficient information
provided by equilibrium to determine these torques and more
information is required to analyze this application. Click here to jump to
statically indeterminate torsion applications. Click here for examples of
statically determinate torsion applications. |
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