Piezoelectric accelerometer output problem

[uates]

Hello,

I have two PCB Electronics 356A17 IEPE accelerometers and two NI9230 cDAQ modules. Each accelerometer is connected to one DAQ. The accelerometers range is +-10G. 

My problem occurs when the shock exceeded 10G, the output of the accelerometer goes to very high values and reduces below 0 before going up to 0 again (it's like an oscillation). The shock does not continue it's instantaneous. I attached an output and my DAQ setup. How can I solve this oscillation problem?

Regards,

Ugur

[dsb@NI · Accepted solution]

After overload, sensors take some time to recover (mechanically and electrically). The settling time listed in the specs for the sensor models you listed specify <10 s. Within the settling time after an overload event, there is no amount of processing that would give me confidence in the measured acceleration.

Avoid overloading your sensors. You could damage your sensors and shorten their usable life. If you need to measure higher acceleration levels, invest in additional sensors that can accommodate the maximum expected accelerations. If overloading sensors is unavoidable even with careful mounting procedures, wait until the system has recovered/settled before processing acquired data.

[Henrik_Volkers]

Your sensor and your DAQ both include a highpass filter ... (are not capable to measure a DC acceleration) of different time constants.... so a swing below zero is an expected result.

The blue x channel show a typical signal to a step excitation...  y and z channel look funny, I would assume an input compliance voltage range violation ( or a cable or connector failure (short short-cut ?)).

Beside the fact that it seems that you overload the sensor (no big problem, the peak shock resistivity is ?? 5000g ??), however your data is useless... 

Usually the interesting part is some (tens) of ms during / after the shock....  😉  Maybe your test data  is around  t~19s ??

What are you testing, how do you excite?

[uates]

Thank you for the answers. I discussed the problem with PCB Electronics and we concluded that the problem is same as Doug's explanation.

[qusaimn]

Hello. Is there a reason your accelerometer doesnt show 1g at the start and all 3 axes are 0?

[uates]

Piezo accelerometers do not record static gravity.