Paul wrote:

I have three motor mounts that take 400 pounds of thrust in the radial
direction. The radial spring rate is  400 pounds per inch for
the two front mounts and 200 pounds per inch for the rear mount.
What radial load  does each mount see? Ignore static weight and torque loads.

Paul Lamar

No takers so far. Is this too hard for you hotshots? :-)


Paul Lamar

Paul,

       assume displacement  = 0.1", all mounts will move the same
amount (assume engine and non-rubber parts of mount are rigid).

So,   the stiff mounts will see 40 lbs each and the soft mount will see 20 lbs
each.  This will happen with 100 lbs thrust load.  This will stay in porportion
as long as you stay in the linear range of the rubber, which is actually fairly
small.  For these little mounts you may get into the strain hardening area
in just 0.1 or 0.2 inches travel, where the stiffness is increasing.  If we
ignore the strain stiffening effect, 0.4" for 400 lbs.  But I'll bet less due
to nonlinear rubber behavior.

Bill

Long EZ builder & pilot
BSME, MSME

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