Will trade a whole CD full of cad files for an FEA on this 30 mm wide
steel ring.
The 40 mm dia. steel rollers exert a force of 2000 pounds or 900 Kg
radially outward. I also would like the contact stresses as well if
possible.
The Rockwell hardness is C64.
--------------------------------------------
I am homing in on a cheap 120,000 RPM turbo compound gear box. Mostly off
the shelf parts.
Paul Lamar ...No rotor no motor.
----------------------------------------------
Paul,
I loaded 4340 from my standard library. This is 4340 normalized and not
hardened all the way to it's max hardness.
The red areas are questionable only in that I assumed a "nip" between the
plant gears and the ring gear as 1mm. If I used an infinitely sharp nip
you'd slice right through the material no mater how strong it is and that's
not realistic.
I don't have a lot of time on this (15min) so there is no tuning.
I did discover that if you do a study without an external constraint of some
kind the part zips off into space because the software iterates through the
nodes and even the least amount of force difference 10^-13 in this case
causes the ring gear to drive out of sight. Interesting to watch!
So, I put a constraint opposite one of the contact points to keep the ring
gear from flying off.
-Ben
Thanks Ben! Wonderful!!!! We are on the verge of a major breakthrough in
fuel consumption of the turbo compound rotary amounting to 15% to 20%
better. One false start with the Rotrex gear box I am afraid.
------------------------------------------
If I am doing the conversion right N/m^2 5.979 + 008 is 86,000 psi.
Does that sound about right?
Paul Lamar ...No rotor no motor.
Hi Paul,
That's correct. Since, you're heat treating it up to 100ksi you can slide
the stress scale down proportionally. The 86Ksi comes out of the library.
I didn't bother to edit it.
86ksi is not bad for something like gears. There is a tradeoff between
toughness and strength, they are not synonymous. You alloy up but there are
all kind of issues with trying to go with stronger material at the expense
of machinability. That's why PSRU tend to grow in size with increasing
horsepower.
Let me run another study with 100ksi material.
-Ben
Don't bother. I have another one that is more important Ben.
I'll get a dwg on it to you shortly. It is very simple.
BTW what would be the spring rate on that ring. In other words pounds per
inch of deflection.
Paul Lamar ...No rotor no motor.
----------------------------------------------------------
Take the 2,000lb load and divide it by the max displacement.
In this case it was .3829mm. That's equal to .3829mm/25.4mm/in which is
0.001507480314960629921259842519685 (lol) and that equals
1326717.1585270305562810133194045 or 1.3 million pounds per inch. In other
words, this ring is no spring!
Are you getting 2,000lbs from the centrifugal force on a planet gear zipping
around inside that orbit? Is the orbit gear moving, too?
-Ben
--------------------------------------------------------------------
No. What we intend to do is heat the outer ring to about 500 F or so and
drop it down over cold soaked rollers. This will apply a constant pressure
in the line contact area.
Another part of the design is these three 5 mm thick telescopic rings the
outer one of which is 40 mm in dia and 30 mm long. Again loaded with 2000
pounds or 900 Kg. Consider the block a 2000 pound block or 900 Kg made from
4340 with a 100,000 psi yield. Same for the rings.
My question is does this configuration act like a leaf spring and result in
lower stresses in the individual rings than would be the case if it was one
solid ring 15 mm thick 40 mm OD? And what are they? Spring rate?
I'll show the complete design shortly.
Hopefully we will be able to do a FEA on the complete assemble.
Paul Lamar ...No rotor no motor.
-----------------------------------------------
Hi Paul,
That configuration would be studied as a laminate with transverse shear as
zero. I'm afraid this configuration is more prone to distortion than a
solid ring of the same size and weight. You can mitigate the effects of
this by bonding the rings or mechanically connecting them together via
splines or fasteners.
The good news is that this design doesn't have an unconstrained point(s) as
would leaf springs. Therefore, the loads would track around the circle and
meet at the other side. However, it does this 3 independent times and there
is no benefit from shear constraints between members.
The short answer is that this is not a leaf spring and it's not a solid
cylinder. It's somewhere in between.
-Ben
----------------------------------------------------------
I am to infer then it is not possible to determine the stress
in the individual rings taking them all together?
How about if we divided the load assuming each one took one third
and doing them individual. In that case we might want to tailor
the thickness so the outer ring had the thinnest wall and the inner
ring the thickest wall? In the final design they will be pressed
together. Perhaps this is a level of sophistication we don't
need to delve into at this point?
Here are some 3D's of the final friction reduction drive.
It has its own small dry sump oil system to keep the temp rise
down. The dry sump system is of traditional spur gear design.
Cooling fins on the ring might be used to reduce the temp rise.
The considerable centrifugal loads from the rollers and
bearings are taken by the rotating all steel planet carrier.
The bearings are heavy duty off the shelf Torrington rollers with
basic load ratings of 7000 pounds and max speeds of 25,000 RPM.
Input shaft dia is 3/8th OD and output shaft 5/8th OD roughly.
Power transmission goal is 50 HP with 120,000 RPM in
and about 12,000 RPM out. Overall efficiency should be above
95%.
The OD of the unit is about four inches.
The unit is designed to extract excess HP from a turbo charger
and return it to the e-shaft of the rotary thereby significantly
increasing the power without increasing the fuel consumption.
Your basic 1950's turbo compound technology.
Power is taken from the planet carrier with the ring stationary
and part of the housing. Rotating direction of the output shaft
is therefore the same as the input shaft making it compatible with
the stock Mazda Turbo II engine.
Paul Lamar ...No rotor no motor.
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