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I have found some load sensors (piezoelectric) that measure relatively small weights (on the order of ~ grams). That's what I need!

However... Around my robot, there will occasionally be bursts of extremely high pressure. These bursts do not need to be measured... they just wash over. The pressure appears, to the sensor, to be a ~ 2,000+ kg

Question: Are these sensors likely to break or fatigue? I realize piezos do not measure via deformation, but still... that's a big load!

Maybe I should just order a few and try...

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This really depends on the sensor. There are sensors which are protected for heigher loads. Usually around 300%-1500% of the rated load for sensors in gram range.

Most manufacturers say, connect the sensor when you are installing it so you can monitor it live so you won't break it.

I'd recommend to check the datasheet of your sensor. This should specify overload. I'd also think of something to prevent your sensor from such high loads.

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    $\begingroup$ Last sentence was the key. the answer was to use a flexure, so that when an overly high pressure burst hits the sensor, the piezo itself does not bear the weight. $\endgroup$ – jdar Mar 27 '14 at 15:35
  • $\begingroup$ Good option, be sure that you check your bandwidth when using such flexure, they might be influencing (a lot if placed incorrectly). $\endgroup$ – 2pietjuh2 Mar 28 '14 at 7:58
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Yes, of course it 'can be crushed' - (imagine I'm standing in front of a ginormous hydraulic press, with an evil grin on my face).

The sensor deforms under pressure. When it deforms far enough it will reach its elastic limit and fail.

The solution is to arrange to transfer the load from the sensor to a stand when the load exceeds the range (and before it exceeds the elastic limit and cracks). For a piezo sensor, this could be as simple as a pin that stops the anvil motion before it destroys the sensor.

If the transient is applied and removed rapidly, but all other changes in force are slow, you could simply put a shock absorber in parallel with the sensor. The shock would take the load during the overpulse.

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