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Torsional Constant of a Circle

 

Torsional Constant of a Circle formulas

\( J  \;=\;   \dfrac{ \pi \cdot r^4  }{  2  }\) 

\( J  \;=\;  \dfrac{  \pi \cdot d^4  }{ 32  }\)

Symbol English Metric
\( J \) = torsional constant \( in^4 \) \( mm^4 \)
\( d \) = diameter \( in \) \( mm \)
\( \pi \) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\( r \) = radius \( in \) \(mm \)

circle chord 1Torsional constant (also called the polar moment of inertia or polar second moment of area) for a circular cross-section is a measure of its resistance to torsion (twisting).

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