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Introducing Radial Magnetic forces....

Introducing Radial Magnetic forces....

Introducing Radial Magnetic forces....

(OP)
Hi to everyone,

I am currently trying to introduce forces to an induction motor but i encountered a little problem.

I was given the radial pressure that a stator suffers with its frequency(f_p). Besides i was told , that this pressure field rotates around the centre axis of the stator at a different frequency value (f_r). This spatial rotatory field looks like its Mode number 2.

I've been trying to introduce this pressure combining both a frequency field and a spatial field but without much success. It looks like it is impossible to create a rotatory spatial field. So in face of that i decided to take the next step.

After trying to get a fomula i discovered that the force answers to the next function: value=F*sin(2*pi*f_p*t)*cos(2*theta-2*pi*f_r*t), where "F*sin(2*pi*f_p*t)" is the pressure term and "cos(2*theta-2*pi*f_r*t)" is the equivalent rotatory spatial field. "Theta" is my angle variable of my coordinate system.

This expression has a time domain, so to turn it into pure frequencies i used matlab, where i made the fast fourier transformation to get the force in the frequency domain. This force is the same for all the nodes in the stator, no matter which "theta" they have. But if the force value is the same, the phase for each node it is not.

I imported to nastran the values of the force,frequency and phase of a node and it works. But it was just one, and i don't know how i could introduce all of them at once as i cannot find a way to define a Non-spatial/frequency-complex field where the phase depends on "Theta". Taking into account that i have 144 nodes, it is unthinkable to introduce them one by one.

Does anyone know an easier way to introduce these forces? If there isnt, how could i introduce the values of the phase for each node at once? Could it be defining a spatial field for the phase variable?

thank you to everyone in advance

Supituki

RE: Introducing Radial Magnetic forces....

(OP)
Hi,

Sorry but i introduced the wrong equation above. f_p and f_r do not exist. There is just a f.

The equation is: F=[F]*cos(mode*p*theta-2*pi*f*t-mode_phase)

theta=angle
p=poles
mode=mode of vibration
f=frequency

How could i introduce this in frequencies and phase for all the nodes in the stator?

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