Electronics

Torque evaluation – Ansys Maxwell

• Aliosha86
Subscriber

Hi guys,

I am dealing with some torque evaluation. Can someone explain to me how Ansys Maxwell evaluates the torque choosing It as a parameter?

Which formula does Ansys use? Moreover, this torque parameter can be used only when dealing with motors, or for other general cases?

Thank you very much

Subscriber

Hi Aliosha

for calculating torque which is applied to an object (for example a rotor) you can simply select the object, right click --> then choose  assign parameter then choose torque. after analyzing, in the project manager window from results-->solution data you can see the calculated torque. or you can plot torque relative to other variables.

I am not sure how it calculates the torque but I compared the result of calculated torque with  another result which I calculated by electromagnetic torque formula, and they  were identical.

and finally, you can assign parameters (torque) to any object other than motors.

• Aliosha86
Subscriber

Thank you Sader for your answer. I really appreciate. In the parameter you can have also the Force evaluated directly by Ansys. Do you know in which position this force is applied? the center of gravity of the body?

CHeers,

Subscriber

since it is based on finite element, I think it calculates all the forces vector which is applied to the whole body of the object and then sum up those vectors then find  resultant vectors toward x ,y or z

but if you want  to find out how much force is applied to a particular part of an object you would better use ansys work bench , I think it will show the force field and you can find out how much force is applied to a specific part of an object

• Paul Larsen
Ansys Employee

The torque parameter is created with respect to a selected axis, so the torque is calculated with respect to the selected axis.  If you have a net side-ways force on an object, and you move the relative coordinate system further away, causing the torque lever-arm to increase (even moving the coordinate system outside the simulation domain), you can see the torque change because the selected axis is at an increased location w.r.t. the net force on the object.

The force/torque parameters are calculated by default with virtual work method.  We calculate the magnetic energy/coenergy in the simulation, and then evaluate the virtual change in co/energy at the surfaces of the selected objects as if the mesh had moved.  So, the force calculation is like dW/dx (but for all 3 X,Y,Z directions), and the torque calculation is like dW/dtheta, where theta is the angle of rotation w.r.t. the selected axis.

• Aliosha86
Subscriber

Cheers

• Aliosha86
Subscriber

Thank you very much pblarsen for your explanation. Now it make sense. Do you think it would be possible obtaining the same results that comes from setting the parameters in Ansys Maxwell, simply evaluating the torque has the the cross product between the total force and the distance from that axis?

Cheers,
Alessio

• Paul Larsen
Ansys Employee

Hi Alessio,

Not in all cases.  That was more of a "thought example", for example for a case with net force (like a magnet next to a steel plate).  However, many cases have zero net force, but a non-zero torque (like a balanced electric motor).  So, many conditions can affect the difference between evaluated torque and the cross-product of total force crossed with the lever-arm.  These are all consequences of a distributed force density and whether the position w.r.t. the rotational axis is included within the integral or assumed constant to move outside the integral of force density.

• Aliosha86
Subscriber

Thank you Pblarsen,

I appreciate a lot your answer. Now I have a better understanding.

Cheers,