# SR Series 150V Piezo Ring Stack Actuators

The PiezoDrive SR ring stacks are high performance multilayer actuators with a vacuum compatible polymer coating and a large central aperture. The SR rings stacks are perfectly matched to the range of PiezoDrive amplifiers and driver modules. Applications include: Optics, Microscopy, Nanopositioning, and Precision machining.

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### Specifications

 Order Code Range $\pm$10% Length OD ID Cap. $\pm$20% Blocking Force Stiffness Res. Freq. $AU Buy Now SR080410 14um 10mm 8mm 4.5mm 0.8uF 1300N 130N/um 150kHz$AU88 Buy Now SR080418 28um 18mm 8mm 4.5mm 1.6uF 1300N 65N/um 83kHz $AU130 Buy Now SR120610 14um 10mm 12mm 6mm 2.4uF 3000N 220N/um 150kHz$AU128 Buy Now SR120620 30um 20mm 12mm 6mm 5.0uF 3000 N 100N/um 75kHz \$AU260 Buy Now

### Mounting

Stack actuators should not be exposed to significant tensile loads, unequally distributed loads, off-axis loads, bending moments, or torque.

The maximum recommended tensile load is 10% of the blocking force. In applications that require bi-directional forces or high speed motion, a preload force is recommended with a magnitude greater than the maximum tensile load. This gaurantees that the actuator is always in compression. The maximum recommended preload is 50% of the blocking force.

### Range

The range is specified for an applied voltage of -30V to +150V. If the input voltage is unipolar (0V to +150V) the specified range is reduced by a factor of 0.75. When a stack actuator is driving a stiff spring, the range is reduced by the factor
$$\frac{k_p}{k_p+k_L}$$ where $k_p$ is the actuator stiffness and $k_L$ is the load stiffness.

The travel range can also be reduced by restraining the end plates, e.g. by bonding the actuator to a stiff base. This effect is most significant in actuators with a length less than twice the outside diameter.

### Capacitance

The actuator capacitance is the small-signal capacitance measured at room temperature. Due to hysteresis, the effective capacitance increases with applied voltage. When operating at full range, the effective capacitance is approximately twice the small-signal capacitance. The capacitance also increases with temperature. A temperature increase of approximately 50 degrees C will double the effective capacitance.

### Thermal

Piezoelectric actuators dissipate heat when driven at full range with a high frequency. PiezoDrive actuators can be operated continuously at temperatures up to 85 degrees C. Continuous operation beyond this temperature may damage the actuator.

The dissipated heat is approximately 10% of the applied electrical power. For a sine-wave, the applied electrical power is:
$$P = \frac{V_{p-p}^2 \pi C f}{4}.$$

### Electrical Current Requirements

Calculate Power Bandwidth

The required current is $I = C~ dV/dt$ where $I$ is the current, $C$ is the effective capacitance, and $dV/dt$ is the voltage rate of change. For a sine-wave, the required peak current is equal to:
$$I_p = 2 \pi f V_{p-p}$$ where $V_{p-p}$ is the peak-to-peak voltage. For a triangle wave, the required peak current is equal to:
$$I_p = 2 C f V_{p-p} .$$

### Recommended Drivers

 Amplifier Application PDm200B General purpose, low cost MX200 High Current, Low noise, low cost PDu150 Ultra-low noise PD200 High speed, low noise PX200 High current, low noise

### Connecting Wires

All of the connecting wires are 100mm AWG26 PTFE insulated wires. Other lengths are available on request. Red identifies the positive terminal.

### Vacuum Compatibility

The SA Actuators are supplied with either vacuum compatible polymer encapsulation or a UV cured lacquer coating. Both coatings and the wiring insulation meet the outgassing requirements for NASA SP-R-0022A.

### Options / OEM Customization

• Custom range and dimensions
• Custom wiring arrangement / connectors
• Preload or mechanical amplifier mechanisms

### Piezoelectric Properties

The piezoelectric material is similar to PZT-5H and Navy Type VI.

Property Symbol Value Unit
Piezoelectric constants d33 600 10-12 m/V
d31 -270 10-12 m/V
g33 19.4 10-3 Vm/N
g31 -9.2 10-3 Vm/N
Electro-mechanical coupling coefficients Kp 0.65 NA
Kt 0.37 NA
K31 0.38 NA
Frequency constant Np 1980 Hz-m
Nt 1950 Hz-m
N31 1450 Hz-m
Elastic constant Y33 5.3 1010 N/m2
Y11 7.2 1010 N/m2
Q Factor Qm 80 NA
Dielectric constant e33 ⁄ e0 3500 @1 kHz
Dissipation factor tan δ 2.5 % @ 1 kHz
Currie Temperature Tc 220 C
Density ρ 7.8 g/cm3