## Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

## Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

(OP)

Hello~!

I am interested in finding the force and torque exerted onto a PM by another PM within the vicinity.

So I am just wondering if I could use the same force/torque equations (e.g. for the force as shown below-sorry for the messy typeset) between two axially magentised PMs for the diametrically magnetized ones as well:

I see that most cases are calculated for axially magnetized PMs. I am working with two diametrically magnetized NdFeB magnets and got pretty confused as to how I should compute the dynamics (force and torque of one PM (primary) when another is closely present).. as well as how far should the NdFeB PMs be apart so I could ignore the effect of the other PM onto the primary PM. Also, I am not sure if the generally available equations for the axially magnetized PMs can be used in my case.

I am thinking that the magnetization, M through the diametrically and axially magnetized PMs is different in direction, thus the force and torque on either one of the two PMs might be different with different PM dimensions and positions.

Looking forward to hearing from anyone with ideas and advice =) Thank you very much!

I am interested in finding the force and torque exerted onto a PM by another PM within the vicinity.

So I am just wondering if I could use the same force/torque equations (e.g. for the force as shown below-sorry for the messy typeset) between two axially magentised PMs for the diametrically magnetized ones as well:

I see that most cases are calculated for axially magnetized PMs. I am working with two diametrically magnetized NdFeB magnets and got pretty confused as to how I should compute the dynamics (force and torque of one PM (primary) when another is closely present).. as well as how far should the NdFeB PMs be apart so I could ignore the effect of the other PM onto the primary PM. Also, I am not sure if the generally available equations for the axially magnetized PMs can be used in my case.

I am thinking that the magnetization, M through the diametrically and axially magnetized PMs is different in direction, thus the force and torque on either one of the two PMs might be different with different PM dimensions and positions.

Looking forward to hearing from anyone with ideas and advice =) Thank you very much!

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

TTFN

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## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

The "contacting" for diametrical is a point.

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

TTFN

I can do absolutely anything. I'm an expert!

homework forum: //www.engineering.com/AskForum/aff/32.aspx

FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

I realised that I should include an sketch of the setup I am working on for better illustration =)

So these are the two diametrically magnetized cylindrical NdFeB PMs placed beside one another with a distance, d. Both are rotated by independent external sources (I have solenoids to independently drive the PMs). This will affect each PM in terms of the torque and force.

If the expressions for forces and torque in the case of axially magnetized PMs are not compatible in this case, is there any idea how I could find out how it differs in the diametric model? I do not have a software for this, thus I would need to model it mathematically.. (i have spent weeks trying to find a way to do it but I ran out of idea)

I kind of visualised it similar to a bar magnet but it is usually rectangular and not cylindrical. So there's this geometric aspect that I have to think about.

Besides, I could only find force analysis on bar magnets (attract/repel) but not torque as bar magnet is rarely expected to rotate the way I need my cylindrical PMs to rotate axially. Pretty perplexing..

Any ideas and comments are appreciated =) thanks again~

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

TTFN

I can do absolutely anything. I'm an expert!

homework forum: //www.engineering.com/AskForum/aff/32.aspx

FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

prex

http://www.xcalcs.com : Online engineering calculations

http://www.megamag.it : Magnetic brakes and launchers for fun rides

http://www.levitans.com : Air bearing pads

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

IRstuff, in that case, I probably should start exploring some FEA tools. FEA would need some sort of mathematic expressions (e.g. in this case, the magnetic field density computation which contributes to the force and torque) to start with too, yes?

prex, do you mean something like numerical analysis?

One of the complications I see is that these PMs will have to be positioned randomly and the arrangement will be at a distance in terms of x,y and z axes from another. I should be able to take that into account in the vector form of the magnetic field, B_x, B_y, and B_z. But then again, the force and torque onto one when both are rotation independently is a tricky problem =(

Thanks again! =)

## RE: Is the force btw 2 diametrically magnetized magnets & that of 2 axially magnetized ones the same

prex

http://www.xcalcs.com : Online engineering calculations

http://www.megamag.it : Magnetic brakes and launchers for fun rides

http://www.levitans.com : Air bearing pads