Another question for you. Does the torsional response of a flywheel
shaft system vary with the rate of change of the forcing frequency
pulse or just the amplitude and frequency?

Paul Lamar

Jeff Spitzer wrote:

In a perfect analytical solution, the forcing functions are sinusoidal so
there is no "rate of change" factor.  In reality the forcing functions are
not sinusoidal and therefore are not pure forcing functions at the firing
frequency.  The result is that the forcing contains higher frequency
components that often have strengths comparable to the firing frequency.
Another way of saying this is that the actual torque output of an engine is
really like the superposition of a sinusiodal function with a given
amplitude at the firing frequency AND many other sinusoidal functions at
many higher frequencies with a different amplitudes.  In most cases the
effects of the first 3 harmonics of the firing frequencies will be the only
ones of much consequence.  Beware, in the case of an engine with a highly
non-sinusoidal torque vs crank angle the implication is that there are
significant forcing functions lurking within at higher harmonics!

Jeff Spitzer

Which can be said about most internal combustion engines so we need
some sort of dynamic analysis program that can accept a pulse shape
or we could do what Rolls Royce did and spend ten years developing
the PSRU. I think it is better to not take chances and put in an
overkill shaft.

Paul Lamar
 
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