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Force and torque from stress tensor



 

Hello,

 

As you know I'm simulating an induction motor. Now I'm calculating torque and force from stress tensor of two poles motor. I have calculated as Meeker says in his manual and I have seen example of horsecore in femm web. To calculate Fmax, I'm simulating in magnetostatic and I take 180º of the one pole airgap. I get the following values:

§         contour length : 1.499e-1 m

§         core length: 0.140 mf

§         force from stress tensor one pole: 2914e+3 x ? 7.398e+2 y N/m

§         |f| = 2914 N/m *0.140 = 407.96 N

§         Bn^2 one pole : 6.030e-002 Tesla^2

§         Areo one pole :0.020986 m

§         Fmax = B^2a/2uo =  503.5 N

§         torque from stress tensor one pole : 8.258e-002 N*m/m

§         torque one pole : 8.258e-2*0.140 = 0.01156 Nm

§         diameter rotor: 96e-3m

§         torque max one pole = fmax*diameter/2 =503.5 * 96e-3/2 = 24.168 Nm

§         torque max two pole = fmax*diameter = 48.336 Nm

§         torque from stress tensor two pole = 2.636e-001 N*m/m

§         torque  two pole :  0.036904 Nm

The forces calculate from femm and from me are similars but torques aren´t them. I don?t understand torque from stress tensor, is this torque the torque max can I have obtain? Can I calculate the max electromagnetic torque at magnetostatic? Or I have to calculate with nominal frequency = 50Hz and starting current?

What relations is between force and torque? I have high force but the torque is too low.

Thank you in advance

 

Alberto Pérez


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