author=poynt99 link=topic=4603.msg111215#msg111215 date=1711906073
I hope that with Brad's next response or two we can close this matter and continue focusing on the replication.
Otherwise, maybe this debate on force and torque theory could be moved to a separate topic, as I am not sure of the specific relevance of this debate?
Between my last post, and this one-yes, lets hope that those that do not understand, finally do.
First lets clear this up.
Bistander said-
No, the scales display a force value. .Yes, the scales show a force value, as clearly indicated in my graphs, and i have never said they dont.-see below.
What i did say was-the scales show the value of the applied torque, by way of the value of force being imparted on the scales.
In my last post chatGPT clearly showed i was correct.
Bistander said-
The torque value isn't known until the moment arm is consideredIf you wish to know the value of torque of the motor driving the drum, then yes, you need the moment arm considered.
If you wish to know the torque value the rotating drum is applying to the belt, then the moment arm value is 0, as there is no distance between the belt and rotating drum.
So the scales actually show the value of the torque being applied to the belt, by the rotating drum, by way of applying a force to the scales, by the belt.
Now, how is a stall torque of a motor calculated ?
I will ask chatGPT this very question, although i am sure the mechanically minded already know-well most anyway.
Q-if a set of scales is attached to the outer perimeter of a rotor, that is attached to a dc motor, can this measure the stall torque value of the motor.
A-
Yes, attaching scales to the outer perimeter of a rotor connected to a DC motor can potentially measure the stall torque value of the motor indirectly. When the motor stalls, it means that the torque being applied by the motor is equal to the opposing torque (usually frictional or resisting torque). At this point, the rotor stops rotating, and the scales attached to it will measure the force exerted on them due to this opposing torque.
However, it's essential to consider some factors:
Sensitivity and Calibration: The scales need to be sensitive enough to measure the small force exerted during stalling accurately. Also, the scales need to be properly calibrated to provide accurate measurements.
Mechanical Design: The attachment of scales to the rotor should be robust and stable to ensure accurate measurement without any unwanted movement or deformation.
Safety: It's crucial to ensure that the setup is safe and that there is no risk of the rotor or any other component causing harm during stall testing.
Interpretation: The force measured by the scales will need to be converted into torque units using the appropriate conversion factor based on the distance from the center of the rotor to the point of force application
.[/glow]
This is how stall torque is calculated when the shaft of the motor is what is delivering the torque, so the radious between the center of the shaft delivering the torque, to the point where the scales are attached, must be known to calculate the torque value.
But with a pulse motor, such as the ones we were testing, has a fixed shaft at the center of axis, and does not provide any torque to the rotor.
With a pulse motor, the torque imparted onto the rotor, is applied to the outer edge of the rotor, via the Lorents force-as Bistander stated.
The scales are also attached to the outer edge of the rotor, and so they are attached to the same radius value as the applied torque is attached to.
The R value is there for 0, and so, like in a prony brake test, the scales show the value of the applied torque, by way of a force being applied to the scales.
Once again, see screen shot below showing this clearly explained by chatGPT.
This is how torque is calculated on the outer rim of a pulse motor that has a fixed shaft, where the scales are attached to the same radius point at which the torque is applied to the rotor.
The torque value is not calculated at the center of axis, as the shaft at the center of axis is fixed, and does not provide torque to the rotor.
If you did include R from the center of axis to the point at which the scales are attached, you have just calculated the torque value of a fixed shaft that does not and cannot provide torque.
So, i would like you all to think about this, and just ask yourself-how do you calculate the torque being imparted by the Lorentz force on the outer edge of the rotor of a pulse motor, where that pulse motor has a fixed shaft that does not provide or have a torque imparted on it ?
I have provided the graphs and direct answer to direct questions for chatGPT
It has been clearly explained by both myself and chatGPT.
So yes Poynt, i hope this solves this disagreement.
Brad
Never let your schooling get in the way of your education.
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