# Autmobile Propeller Shaft Design Calculation- Part2: Torque in Shaft

The torque in a shaft is responsible for rotating the driveshaft with respect to its axis. The drive shaft transmits torque from the gearbox to the axle and while doing so it develops stress due to the torque (called as torsional stress).

The torsional stress calculation for our cardon shaft design problem goes as below:

• Calculate the polar moment of inertia (J): The polar moment of inertia is calculated as below:

J=(П*d^4)/32 = 613592.3 mm4

Where,

d – Diameter of the driving shaft = 50 mm

• Calculate the max torsional shear stress (Ssmax): The torsional shear stress (shear stress due to the torque in the shaft) can be calculated as below:

Ssmax=(T*d)/(2*J) = 142.6 Mpa

Where,

T – Maximum transferred torque = 3500 Nm

d – Diameter of the driving shaft = 50 mm

J – Poler moment of inertia of the propeller shaft = 613592.3 mm4

From the given input data, we know that the shear yield strength for the driveshaft material is 370 Mpa.

So, we can conclude the prop shaft is safe for the transmitted torque in the shaft (torsional stress).

The next article (part-3) will discuss about the critical speed calculation.

### Shibashis Ghosh

Hi, I am Shibashis, a blogger by passion and engineer by profession. I have written most of the articles for mechGuru.com. For more than a decades i am closely associated with the engineering design/manufacturing simulation technologies.
Disclaimer: I work for Altair. mechGuru.com is my personal blog. Although i have tried to put my neutral opinion while writing about different competitor's technologies, still i would like you to read the articles by keeping my background in mind.

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