And the peizoelectric charge constant d31 for the thin plate is calculated by the following equation
d31 = u2/ f1.kq
Where d33 and d31 are the piezoelectric charge constants (c/n) ,U2 is the output voltage on the oscilloscope(v) ,F is stress on an element in the direction x (N. ) , Kg is the charge sensitivity of the piezoelectric sample (pC / mV )
The output voltage from the charge amplifier measurement on the oscilloscope is shown in fig.8 below
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