Guide for Dimensioning a Piezo Stack Actuator System

The comparison of the application requirements with key performance data of Piezotechnik stack actuators can provide a first feasibility check of an envisaged piezo actuator application.

The two most important key performance indictors of piezo stack actuator are stroke and force. These data are directly related with the size of the stack:

The strong force generation capability is proportional to the base area of the stack.
The displacement capability is proportional to the length of the stack.
Fast response require sufficient power amplifier current.
Precise reaction requires dedicated control system.

The capacity C and the maximum operating voltage U are the key electrical data and is directly related with the size of the stack. In the following table key data are summarized and represent the range of actuator stacks.

Symbol	Meaning	Minimum	Maximum	Special Design
X	displacement	2 µm	100 µm	1 µm - 400 µm
F_b	blocking force	200 N	4 kN	50 kN
A	base area	2 x 3mm²	10 x10 mm²	25 kN
s	active stress	3500N/cm²
S	active strain	0,1%	0,2%
L	length	2 mm	100mm	1 mm, 400 mm
C	capacity	typ. 3 mF/cm³ per active stack volume
U	voltage	-30 to +150 V	0 to 150 V	300 V, 600 V
T	temperature	-25 ^oC	+ 85 ^oC	cryo
rH	humidity	< 60% rH		100%

To start with the design, consider the standard actuator program as a first reference and compare the performance data:

Piezo monolithic stack actuator program. — Standard program of piezo stacks. Special sizes/designs on request.

Actuator Design and Stack Selection

The analysis could be structured in a three-step approach:

Stack selection and sizing
Dimensioning and selection of power supply, peak current, average current or power output, thermal management
Integration and environment e.g. casing, pre-stress, interfaces etc.

Piezo stack selection process. — Stack selection process a) load case identification, Dynamics requirements, Installation and environment.

I) Identify the Load Case - Select the Load-Displacement Type which is Next to it.

II)Follow the Analysis to Deduce Piezo Stack Requirements. Study the Diagram for Load Cases and

III) Click on the red Hyperlink for Further Information

Constant force load on piezo. Piezo theory — Constant Force load case. E.g. mass load, pneumatic or hydraulic pressure.

Constant Load Force

Spring load on piezo actuator. — Spring type load.

spring-mass load on piezo stack. — Dynamic load case. In any dynamic operation mass forces must be considered.

Spring Force Load

Operation of a valve with piezo stack actuator. — Complex load case of a valve operation.

Spring-Mass Load