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Text version of the page 
U Table 2 illustrates the differentpiezoelectric actuator displace-
ment modes for PZT ceramics.By convention, index 3 isalways aligned in the poling
direction of the material. Thesmall-signal values of the rele-
vant piezoelectric deformation
coefficients d 3 , the material expands in thelongitudinal direction while at
the same time shrinking in the
transverse direction, as can be
seen from the material defor-
mation figures in Table 2.
Whether the actuator is of a
longitudinal or transverse typedepends only on the displace-ment which is used. The shear
mode is different, because in
the electric field and the poling
direction are perpendicular to
each other. The PICA 33 , d 31 and d 15 forthe different actuator materials
can be found in Table 1.The longitudinal mode is usedfor most linear actuators in this
catalog. In this mode, the elec-
tric field, the poling direction as
well as the mechanical strain or
displacement, have the same
orientation. Keep in mind that
the longitudinal deformation isalways accompanied by atransverse deformation. When
driven with a positive voltage TM -Shearactuators use the shear dis-
placement in the poling direc-tion.To get the displacements of theindividual layers in a multilayer
actuator to add while using the
appropriate electrical contact
configuration, the poling orien-
tations of adjacent layers have
to alternate (see Table 2). Table 2: Piezoelectric actuator modes in PZT ceramics ModeMaterial deformationMultilayer actuator configurationRemarks LongitudinalThe longitudinalmode is the most
important. It is used for PICMA ∆ L EP ® -,PICA ∆ L U TM -Stack-, PICA EP TM -Thru-, PICA U L TM EP -Power- and the Z-axis of PICA +- 3 312 E P L EP TM -Shear actua-tors. i EP EP relevant deformation coefficient: d 33 TransverseThis mode is usedfor standard bending
actuators (bimorphs
or trimorphs) as well as for pure con-tractors and tubes. ∆ L ∆ L EP U U EP +- 3 L 312 E P EP i EP relevant deformation coefficient: d 31 ShearThis mode is usedfor the X- and Y-axesof the PICA ∆ L TM ∆ -Shearactuators. L EP U EP where: U +- E 1 P L EP Ei vector component of the electric field 132 EP i EP P polarization direction EP U applied voltage relevant deformation coefficient: d i current 15 L induced displacement © PI 1998–2006. Subject to change without notice. This data sheet is superseded by any newrelease. The newest release is available for download at www.pi.ws. 06/10/30.0 42
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