Shock Sensor Question

[Brian Dessent]

Steve.Flanagan at VerizonWireless.com wrote:
> I am not that concerned with what the shocks are doing down track, what I am
> trying to capture is the exact action of the chassis at the time of launch.
> Trying to put 1800HP to the ground, the most critical part of the pass is
> the launch.

Interesting.  I would have never thought that freqs that high would be
transmitted that far through the suspension, but hey, I know next to
nothing about drag racing.  :-)

> should it be attached.  Are they always attached to a coil/spring or can you
> actually bond it to a metal bar and measure the bend, basically when the
> wheelie bars hit the ground, the bars may flex some, this way we could tell
> which bar is hitting harder.  

Yeah, that definitely sounds like it would work.  The best way to
calibrate it would be simply to set the bar up in a vice and hang a
couple of weights off the end and see how much signal you get.  Or, with
the bar all setup on the car, take a spring scale and pull up on the end
and measure signal output vs. how hard you're pulling.  You could try to
derive it analytically, but you'd have to know the material properties,
the cross sectional profile of the beam, etc, and you'd still want some
sort of measured data to back up the calculations.

To deal with the part about the bar rotating, well, you could always try
attaching it to the fixture in which the bar attaches, or some other
place that would otherwise be fixed but expected to bend
ever-so-slightly when the bar flexes.  You might be surprised how much
sensitivity you can get out of some of the sensors with the proper
amplifier circuit.  Go to omega.com and click on "free literature" and
get them to send you their free "Pressure, Strain, and Force Handbook." 
THeir handbooks have a lot of background info and general helpful advice
for how to measure all kinds of stuff, as well as listing all their
products with prices.

Brian

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