or in my case a pocketed dog gearbox, heavy warpdrive prop, eaten plastic
gearbox
thrust washer (twice), and lightly loaded cruise prop resonance, resulting
in dramatic exhaust cracking (three times).
Replaced the pocketed dogs and plastic washer, changed to a lighter prop, and no
more cracked exhaust. Magic.
Cheers,
PeteZ
> On Mar 25, 2023, at 10:39 PM, Area-51 <goldsteinindustrial@gmail.com> wrote:
>
>
> Nearly all and everything contemporary produced is completely designed within
a digital computer specified environment; from electronics to mechanical;
covering
design criteria such as Thermal Expansion & Conductivity, Modal Frequency
Vibrational Response, Dynamic Physical Loads & Gravity, Material Elasticity
Stress & Strain, Chemical Interactions... This is a very basic matrix of R&D
analysis.
>
> When a company such as Bombardier develop a power train it is run through the
above matrix before being produced and released for industry use.
>
> The factory supplied 9XX exhaust system will have the above matrix applied
> along
with field testing results which are fed back into the design process upon
a "Continual Improvement" basis, which the end user sees as optional or
mandatory
factory Service Bulletins.
>
> This closed loop system quickly falls apart when third party aftermarket
> components
are brought into the mix; some may cause premature failure, others may
prevent it; it depends upon the applied knowledge of who ever is producing the
component.
>
> The whole exhaust is constantly vibrating at (x)hz at (x)deg and will be
> tested
at the factory based upon the typical operating ranges of the power unit being
in the vicinity of 5100rpm and (x)deg give or take 15% either side. Stress
and strain fatigue points of the exhaust system will naturally be found around
both bending points, and attachment points. Hard mounting the exhaust muffler
to the engine block moves any inertia forces of the exhaust into the engine
block which may or may not be designed to support such loads beyond (x)hrs of
usage at (x)rpm.
>
> A rough running engine or loose fixing somewhere in the mix adds another
> dimension
of vibration into the fatigue failure equation.
>
> This why its important to keep any motor well serviced and tuned and running
smooth.
>
> The short answer to the question is "Cycle Count" but that is just going to be
too cryptic for most to understand.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=510499#510499
>
>
>
>
>
>
>
>
>
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