acceleration to displacement

[cpalka]

Hi Henrik

I have a servo-hidraulic machine and a can put it doing a sinusoidal movement, for example 0.5mm amplitude and 5Hz.

I try to get the sinusoidal with the geophone, but nothing appears a sin wave.

Could be the high voltage in geophone? Can you change the circuit to reduce more the input voltage in geophone?

Are the machine parameters good for testing or should I change it?

Best regards

Carlos Palha

[Henrik_Volkers]

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@cpalka wrote:

Hi Henrik

I have a servo-hidraulic machine and a can put it doing a sinusoidal movement, for example 0.5mm amplitude and 5Hz.

I try to get the sinusoidal with the geophone, but nothing appears a sin wave.

Could be the high voltage in geophone? Can you change the circuit to reduce more the input voltage in geophone?

Are the machine parameters good for testing or should I change it?

Best regards

Carlos Palha

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A sine at 5 Hz with 0.5 mm displacement amplitude results in ~16 mm/s velocity (and ~0.49 m/s²) with 28 V/m/s sensitivity the expected voltage output amplitude is ~0.45 V.. well within the range.

The IEPE sensor should be (@~1 mV/m/s² sensitivity)  ~0,5 mV amplitude.

Increasing the frequency to 16 Hz @ 500 µm amplitude results in v=~50 mm/s and a=~5m/s².

Another point: Do you have the bare geophone, or is there already a damping resistor included?

Do you have a scope you can hook on?

[cpalka]

Hi Henrik

Thanks for the good explanation

With 5Hz and 0.5mm (0.25mm amplitude) and an accelerometer I get similar results for displacement.

About geophone, I can get good results  (I think it is input voltage)

I use a bare geophone

What you mean scope to hook on?

[cpalka]

Hi Henrik

Seems geophone works fine for freq upper than 10Hz.

With your circuit the signal changes a lot for better.

With machine at 10Hz and sin .4mm (0.2mm Amp) and adjusted sensitivity for 19mV/mm/s it gives an Amp= 0.199 to 0.201mm

With 8Hz and 0.6mm  the geophone measures about 0.22mm

With 15Hz  0.3mm  the geophone measures about 0.16mm

With 15Hz  0.2mm  the geophone measures about 0.11mm