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TABLE 20.7 Properties of Some Stacked (Multilayer) Actuators
Length × Width × Thickness (mm)
Standard or Ext. Diam. × Intern. Diam. × V max Stroke F max
Part No. Material Shape Thickness (mm) (V) (µm) (kN)
A01 Pz26 Rectangle 2.5 × 2.0 × 2.0 200 1.8 0.5
A06 Pz26 Square 10 × 10 × 2.0 200 2.0 10
A16 Pz27 Square 10 × 10 × 2.0 200 3.2 5.0
A21 Pz26 Ring 6.0 × 2.0 × 2.0 200 1.7 2.5
A27 Pz26 Ring 25 × 15 × 2.0 200 2.2 31
A37 Pz27 Ring 25 × 15 × 2.0 200 3.4 16

Due to stacked design, strong pushing force is developed:

∆lA
F = ------------- (20.38)
Ls 33 Y

where L is the length of the stack, A is the area of elements, and s 33 , Y are compliance and Young’s modulus,
respectively.
For reference, Ferroperm Piezoceramics’ multilayer actuator supply catalog [6] extract is presented in
Table 20.7.
If long travel is required, piezoelement expansion can be amplified by using bimorph or levers. Bimorph
is a composite cantilever of two layers (Fig. 20.82(b)). One of them is of structural material and the other
of piezomaterial. Piezomaterials can be used for both layers. In this case, first layer will expand, the second
one contract. However, this results in low stiffness.

Application Areas
Due to inherent properties in piezomaterials, actuators with a lot of engineering advantages can be
developed. Some examples are compact and lightweight, large force, broad operating frequency range,
high stability, solid state, displacement proportional to applied voltage, 50% energy conversion
efficiency.
They are used in micromanipulation, noise and vibration suppression systems, valves, laser and optics,
ultrasonic motors, positioning devices, relays, pumps, in automotive industry, industrial automation
systems, telecommunications, computers, etc. Some of the applications are shown in Fig. 20.83.
(a) Suppression of oscillations. Piezoactive materials-based dampers convert mechanical oscillations
into electrical energy. Generated energy is then shunted to dissipate the energy as heat, i.e.,
oscillation energy is eliminated. The principle scheme is given in [2].
(b) Microrobot. Robot platform legs are piezoactuators. By applying voltage to the electrodes, piezo-
legs are lengthened, shortened, or bent in any direction in a fine movement.
(c) Micropump. Diaphragm is actuated by piezoactuator, input and output check valves are subse-
quently opened for liquid or gas pumping. Advantages are fast switching and high compression
rate.
(d) Microgripper. Piezoactuator works on contraction for gripping motion based on the compliant
mechanism. Gripper is of very small size and almost any required geometrical shape.
(e) Micromanipulator. Due to the unlimited resolution, piezoactuators are used in numerous posi-
tioning applications.
(f) Microdosage device. Piezoactuators allow high precision dosage of a wide variety of liquids in a
range of nanoliters for various applications.

©2002 CRC Press LLC