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Variable effective spring rate torsional vibration "attenuator" - or "absorber"?

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Autodidact

Well-Known Member
Joined
Oct 21, 2009
Messages
4,511
Location
Oklahoma
(Note: Everything in this first post with the exception of the variable effective rising rate idea and picture #6 is to be disregarded. The force diagrams and calculations in pics #2, #3, #4, & #5 are nonsense.)

This is the first sketch I made:
Somewhat crude. Then I made a diagram and calculated the "effective" spring rate for two different increments and this seemed to affirm that the effective spring rate DID increase but some thing looked funny so I built a model from plywood and some music wire, diagramed the model and calculated the change in effective spring rate for two increments and then replicated the calculation on the model using an inexpensive Chinese made 550 lb rated game scale and the test generally correlated with the paper math. The second dwg below is the resolution of the forces in the system, the third dwg is the first diagram I made (not of the model), the fourth dwg is the initial calculation showing an increase in the "effective spring rate" and the fifth dwg is the results of the experiment with the model:
As I learn more about this thing I think it should look more like picture #6 with the links colinear with a radius and the spring arms under a slight preload so that the system can smoothly transition from positive to negative torque values.
The linkage works just like the variable rate linkage on the swingarm of a motocross bike.
The idea for this is to have a very soft INITIAL rate like at idle so the engine won't beat the gear box to death and a much stiffer rate at higher power settings and do both things with very strong stiff springs.

Bret
 

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