Dave or Tom,
Last time I saw that formula it was a simple conversion from frequency to
EI product assuming a uniform rod of the unclamped length that the
frequency was taken at. Is that still the case? If not, could one of you
send me the current version?
Thanks,
Alan Brooks
At 12:26 PM 6/4/2009 -0400, you wrote:
At 11:49 AM 6/4/2009, Tom Wishon wrote:
When Tom Mace left the industry to go back to the academic world at Cal
Poly SLO, I had him do a complete full out EI of multiples of all my
shaft designs and flexes so I would be able to compare the EI curves to
see their relationship to our Bend Profile software's progressive beam
length frequency graphs. While the shape and orientation of the EI
curves were different, in relation to each other by each different shaft,
they were the same as what we output in our bend profile measurement
work. I've always agreed that our BP measurements were NOT actual
stiffness measurement, but with this correlation check to EI, I am
satisfied they are valid for shaft to shaft comparison of relative
stiffness differences in shafts.
Thanks for that, Tom.
From what I can tell from the Bend Profile software, I think I understand
the formula used to go from your profile measurements to EI profiles. It
is a very simplified formula, much simpler than Brillouette's work, but
it may well be close enough for practical purposes.
One of the things on my to-do list is a comparison of the simplified
formula and the Brillouette formula, using some profiles I have measured
for the a variety of shafts. I have in my basement "lab" a frequency
profiler, an NF-4 deflection profiler, and an EI machine. At least part of
my motivation for this is to reclaim the space now used by the EI machine.
If I have a reliable and accurate way to get an EI profile from other
measurements (like frequency or NF-4), then I don't need the EI machine
any more.
Somehow, that project never seems to pop to the top priority. When you're
retired, on a nice day the top priority tends to be playing golf.
:-)
Cheers!
DaveT
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