Shaft diameter is chosen to carry torque with limited shear stress and twist.
Power P=Tω links torque and speed, so T=P/ω. Shaft diameter is chosen so shear stress stays below allowable and twist stays below a limit. Higher speed means lower torque for the same power.
A 15 kW motor at 1500 rpm gives T≈95.5 N·m.
Shaft diameter is set by torque and allowable shear stress, and it must also control twist and critical speed.
Shaft diameter is chosen to carry torque with limited shear stress and twist.
Shaft diameter is set by torque and allowable shear stress, and it must also control twist and critical speed.
Convert power and speed to torque, then use the torsion formula with the allowable shear stress to find the minimum diameter.
No. They also carry bending from gears and belts and may need fatigue checks, so the combined stress governs.
Typical applications include sizing a pump shaft for a given motor power and speed, choosing a diameter for a conveyor drive that carries a fixed torque and checking that a shaft stays within twist limits at its operating speed.
Study "Shear and torsion" first (topic 52 of 106 in Engineering Mechanics). It covers the groundwork this topic builds on.
Gearbox trades speed for torque. Keyways concentrate stress. Combine with bending for real shafts.
A 15 kW motor at 1500 rpm gives T≈95.5 N·m.
The next topic is "Shear force and bending moment diagrams", which builds directly on this one.
It is classed as Intermediate in Engineering Mechanics (topic 53 of 106). It is an intermediate topic. Work through the beginner topics in Engineering Mechanics first.
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