MecMovies 4.0 : M6.21: Maximum Torque for Composite Shaft

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Diagram shows an aluminum shaft A B with a support at A, marked 1 of length 4,000 millimeters and a brass shaft B C with a support at C, marked 2 of length 3,000 millimeters with a flange in between at B. The shafts are centered on the x axis. A torque T is applied at B. An internal torque T subscript 1 is applied on the post towards A and an internal torque T subscript 2 is applied on the post towards C.

Draw a $FBD$ around flange $B$ .

Assume positive internal torques $T_{1}$ and $T_{2}$ in shafts $(1)$ and $(2)$ .

The equilibrium equation obtained from this $FBD$ is:

$\sum_{} M_{X} = - T_{1} + T_{2} + T = 0 ∴ T = T_{1} - T_{2}$