Piezoelectricity Material from 3.6 Piezoelectric effect 8.4 Piezoelectric accelerometer Appendix A Extra material on porous polypropylene
Porous polypropylene ------ E ++++ Voltage q , ------ d ++++ p = dq Polarization/dipoles
Effect of tension ------ -F E Increased ++++ voltage Increased ------ polarization ------ ++++ p -F
Polarisasjonstetthet/ overflateladning +σ A + - + - p + - + - d d + - + - + - + - -σ p: dipolmoment/volumenhet σ: flateladning (Q= σA) Totalt dipolmoment: Totalt dipolmoment:
Piezoeectric coefficient Displaced Charge ++++ ------ E Increased voltage in terms of displaced charge Capacitance -F V Polarization Force/Area Increased polarization ------ ++++ p z -F Piezoelectric coefficient
Quartz (SiO2)
PZT
Poling
PVDF
Piezoelektric accelerometer
Piezoelectric tensor
Bending mode
The converse effect (electro->piezo)
Material Parameters