Dear Deenar Apta,

GD^2 is the ancient way to describe the moment of inertia in kgf.m^2.

Nowadays, the moment of inertia is given as I = integral {distance^2 * d(mass)] in kg.m^2

It is the resistance against rotational changes, given by Torque = I * d(omega)/d(t)

Linear equivalent is Force = mass * d(velocity)/d(t)

This value plays a role in drives during acceleration and deceleration and is therefore a valid factor.

This value even influences the settings and characteristics of the protection devices of the electric drive motors and power supply grid.

The mass of the chain and possible load can be assumed on the pitch diameter of the drive sprocket.

The friction can be taken as retarding force, acting as a retarding torque on the sprocket pitch diameter.

Rpm converters s.a. gearboxes and belt drives convert the I with a factor of the gear ratio to the square.

Take a deep breath and start calculating with Newton laws

It takes a well experienced engineer to handle these issues.

Take good care

Teus ■

Originally Posted by Teus Tuinenburg

It takes a well experienced engineer to handle these issues.

In the old days of Imperial units maybe, but these days using metric units it's much easier ■

designer,

Do you really think that an inexperienced engineer can perform such a calculation just because it is in metric units???

Yesterday, I could not even spell the word engineer

and now I am one.

Have a nice day

Teus ■

Well I could, and in Imperial, and without a degree!!! ■

In north America, the inertia reference is in mass (W) x radius of gyration (r)^2 units. Normally, this is expressed in kg-m^2, the same reference units as GD^2. One is 4 x times the other. This becomes a little confusing when the european motor suppliers quote in GD^2 units, but only state the units. You multiply GD^2 x 4 to obtain Wr^2 units?

So, giving a Inertia value in kg-m^2 is not sufficient. Is it radius of gyration or diameter of gyration? ■

Originally Posted by Teus Tuinenburg

designer,

Do you really think that an inexperienced engineer can perform such a calculation just because it is in metric units???

Yesterday, I could not even spell the word engineer

and now I am one.

Have a nice day

Teus

Dear Teus,

It should read.

"And now I are one."■

@ designer

and without experience ?

@ nordell

Originally Posted by nordell

So, giving a Inertia value in kg-m^2 is not sufficient. Is it radius of gyration or diameter of gyration?

There is only one inertia value in kg.m2.

As you said yourself: mass (W) x radius of gyration (r)^2

There is only one RADIUS OF GIRATION.

@ louispanjang

“you is a better engineer than I”

Have a nice day

Teus ■

Who sez engineres kant spel? ■

I thought the inability to spell and use correct grammar was the hallmark of an engineer ■