Re: Calculation Of Inertia Resistance
Dear Prakash,
What do you actually want to calculate?
Any formula, which you use, must have the same dimension left from the equal sign and right from the equal sign.
The moment of Inertia I has the dimension of kg.m^2
The dimension of omega is radians/sec, in which the radians are considered dimensionless as just being the ratio of the radius of a circle to the circumference of the same circle (m/m = dimensionless)
alpha is an angle in radian and therefore dimensionless.
I = mass x (distance to rotational axis)^2
Or the integral of this equation: I = Integral (R^2 * dm)
I x alpha is therefore kg.m^2 (moment of inertia times a dimensionless number). Whether this is right depends on the rest of the equation.
Further:
Drive torque = Tangential Force x Radius (Nm)
Acceleration torque = I x d(omega)/d(time) (Nm)
Power = drive torque x omega (Nm/sec = Watt)
Kinetic energy of rotating system = x I x omega^2 (Nm = Joule)
Radial acceleration = I x omega^2 / Radius
A torque is a force x a perpendicular distance
Energy is a force x a distance in the same direction as the force
Power is energy per unit of time.
The above theory is for a mass at a distance R from the centre of rotation.
In case of a rotating body around an axis (f.i. a rotor), the distance R must be replaced by the radius of inertia:
i = SQRT ( I/mass)
Wikipedia can be very helpful (and complicated)
Success
Teus ■
Teus
Inertia Resistance
Thanks Mr.Teus
I want to calculate inertial torque required to overcome the system.
My system has regular geometry like barrel and both ends supported by bearings.
To fix up the motor power i need to calculate inertial resistance and frictional resistance in the system.
frictional resistance at the bearing points has calculated,while calcualting inertial resistance i got struckup how to calculate.
from ur explanation I * alpha to use accelerate the system...and to add both torques?
am i right....
once again thanks for ur comments ■
Re: Calculation Of Inertia Resistance
Dear Analysis,
“I * alpha” means nothing to me.
Equilibrium of torques is given by:
Drive torque = Load torque + acceleration torque
Drive torque = function1(omega)
Load torque = function2(omega)
Acceleration torque = I * d(omega)/dt
omega = 2 * pi * rpm / 60
Thus:
function1(omega) = function2(omega) + I * d(omega)/dt
Solving this equation in the time domain until d(omega) becomes zero, gives you the acceleration time of your system.
When d(omega) = 0, then drive torque = load torque.
You can make your own spreadsheet to do this calculation. I did that once.
Quite a bit work though.
Thanks to Newton.
Have a nice day
Teus ■
Teus
Calculation of Inertia Resistance
Dear all,
I have bit vague about calculation of inertia resistance in my geometry.i have rotational system of regular geometry,i have calculated the "I"value .
which equation i have to use I * alpha or I *w^2(omega^2),or they both in same....
In some calculations later equation is used....
Prakash ■