Expert: Paul Soderman - 2/11/2007

Question
question is related to Automobile design but due to lack of auto design expert I m posing this question to you.
* While designing the test rig for a clutch or in other words to test the endurance limit of a Clutch Assembly we need to replace the whole vehicle with a disc or plate ,so that the whole of vehicle can be assumed to be a disc and and connected to the shaft connecting to clutch.
can you tell me relationship between the Gross Vehicle Weight (GVW) and Inertia of the disc which will replace the Vehicle?

Answer
Abhisek
This is a little out of my field, but I assume that the moment of inertia of the test plate should be the same as the moment of inertia of the vehicle being simulated.  That way, applying the clutch will try to twist the plate in the same way it would twist the vehicle. Course the vehicle is on the ground, which supplies a lot or resistance to rotation.  Any way, you can go to http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html to get the basic equations required to estimate the moment of inertia of the vehicle and plate.  The Gross Vehicle Weight enters the equation through the mass term in the equations.  Good luck.
Paul