Stopping a disk with a disk
Stopping a disk with a disk
(OP)
Not sure whether this is the right forum but here goes.
I have two disks of the same material and same radius. One is rotating and accelerating the other is stationary.
The stationary one is spring loaded which when released is pushed into the spinning disk to stop it spinning.
Is there some way to analytically derive the linear force needed to be applied to the stationary disk to stop the spinning disk ?
Thanks
I have two disks of the same material and same radius. One is rotating and accelerating the other is stationary.
The stationary one is spring loaded which when released is pushed into the spinning disk to stop it spinning.
Is there some way to analytically derive the linear force needed to be applied to the stationary disk to stop the spinning disk ?
Thanks





RE: Stopping a disk with a disk
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
Otherwise, it is a simple matter of applying law of friction to infinite radii, find the friction force for each element, multiply by r and integrate over r0 to r1, where r0 is inner radius and r1 is outer radius.
But I really do not see any practical or engineering need for such an excersise. So, I ask: What are you going to use it for?
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
It is one of three different prototype choices for a safety mechanism on a rehabilitation robot. The others being a cenrifugal clutch and a disk caliper set up. Unfortunatly space and wieght are issues so although the disk on disk set up is not conventional it is looking like the most light weight. Well its looking like the most light wieght that all depends on the kind of linear force actuation that is needed
I have managed to experimentally collect acceleration data, but am getting a headache trying to equate the linear force to the generated torque.
I know that the torque is equal to the angular acceleration mulitplied by the angular moment of inertia and that the stopping force is related to the linear spring force time the kinetic coeffiecant of friction. But for some reason I cant get my head around linking the two together!
Thanks for your time,
Nic
RE: Stopping a disk with a disk
Use SI units to get answer in newtonmeters.
Example: R0=0.05 m R1=0.15 m P=10 N k=0.4
T=.4x100x6.28x(0.003375-0.000125)/3=0.27 Nm.
You seem to need much more spring force than my 100 N to get any usable torque.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
I get the unit Nm^3 for torque. That cannot be right. Should be Nm.
Hmm...
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
P is total force from spring. You must divide by total area before using it in the formula.
So, your torque should be 0.27/0.0628=4.3 Nm. Which sounds better.
Better check this before using it in a design.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
So, if you input P=(spring force)/(disk area) in the formula in my first post, you will get torque in Nm.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
So P is the pressure, yes that makes sense.
Thanks again was very good of you to help me.
Nic
RE: Stopping a disk with a disk
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Stopping a disk with a disk
RE: Stopping a disk with a disk
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...