explain why hollow shafts are preferred to solid shafts for transmitting torque?
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Answered by
5
Let me list down a few of the advantages first.
In comparison to a solid shaft, a hollow shaft is of less weight, for a given length and diameter. This is pretty obvious and wont be requiring any further explanation. Moreover it’s a good idea to go ahead with hollow shafts, if we our emphasis is on weight reduction and cost-cutting.

Hollow shafts are much better to take torsional loads compared to solid shafts. As shown in the figure, shear stress in a “shaft subjected to torsion” varies linearly from zero at the center to the maximum at the boundary. Inside a solid shaft, most of the material experiences / carries a shear stress whose value is much below the maximum shear stress [Interior portion of the shaft]. But at the same they are adding to the weight, without contributing much to the capability of the shaft to carry torsional load.
Shear stress at a point in a hollow shaft (τ)(τ) is given by , τ=TrIpτ=TrIp
where τ=τ=Shear stress in a hollow shaft
TT = Torque in shaft (N-m)
rr = radial distance from the center to the point of interest (m)
Ip=Ip=Polar area moment of inertia (m4m4)
Average shear stress[ (Min. Shear stress + Max. Shear Stress))/ 2 ] in a hollow shaft will be higher compared to a solid shaft and it’s value is more closer to the maximum shear stress.
In comparison to a solid shaft, a hollow shaft is of less weight, for a given length and diameter. This is pretty obvious and wont be requiring any further explanation. Moreover it’s a good idea to go ahead with hollow shafts, if we our emphasis is on weight reduction and cost-cutting.

Hollow shafts are much better to take torsional loads compared to solid shafts. As shown in the figure, shear stress in a “shaft subjected to torsion” varies linearly from zero at the center to the maximum at the boundary. Inside a solid shaft, most of the material experiences / carries a shear stress whose value is much below the maximum shear stress [Interior portion of the shaft]. But at the same they are adding to the weight, without contributing much to the capability of the shaft to carry torsional load.
Shear stress at a point in a hollow shaft (τ)(τ) is given by , τ=TrIpτ=TrIp
where τ=τ=Shear stress in a hollow shaft
TT = Torque in shaft (N-m)
rr = radial distance from the center to the point of interest (m)
Ip=Ip=Polar area moment of inertia (m4m4)
Average shear stress[ (Min. Shear stress + Max. Shear Stress))/ 2 ] in a hollow shaft will be higher compared to a solid shaft and it’s value is more closer to the maximum shear stress.
Answered by
4
⇒The hollow shafts are preferred to solids shafts because the strength of hollow shaft is more than the solid shafts.
⇒And also the natural frequency of the hollow shafts is more as compare to solid shafts.
⇒More importantly the hollow shafts have more moment of inertia which helps it to transmit more torque.
⇒Hollow shafts require less energy to operate.
⇒The strength to weight ratio for hollow shafts is pretty good as compare to solid shafts.
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