Guide for Dimensioning a Piezo Stack Actuator System

Stack actuator key performance data

 

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 mm

100 mm

1 mm - 400 mm

Fb

blocking force

200N

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

2mm

100mm

1mm, 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 performance data:

 

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

 

 

Actuator Design and Stack Selection

 

The analysis should follow a three-step procedure:

  1. Stack selection and sizing
  2.  Dimensioning and selection of power supply, peak current, average current or power output, thermal management
  3. 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.

 

Identify the load case and select the load-displacement type which is next to it. Follow the analysis to deduce piezo stack requirements. Select and click on the diagram for further details.

Constant force load on piezo. Piezo theory
Constant Force load case. E.g. mass load, pneumatic or hydraulic pressure.
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.
Operation of a valve with piezo stack actuator.
Complex load case of a valve operation.