5 Installation
PL0xx/PDxxx Piezo Actuator
PZ265E
Version: 1.0.0
27
5.4
Applying a Preload
The tensile stress capacity of piezo actuators is relatively low. It is therefore recommended to
mechanically preload the piezo actuators in the application, either externally in the mechanical
structure or internally in a housing.
Requirements
You have read and understood the general notes on installation (p. 17).
The PL0xx/PDxxx is discharged (p. 40) and short-circuited (p. 41).
Tools and accessories
When installing in a housing: Suitable housing
Suitable guide elements
When creating the preload with a spring:
Suitable preload spring with the following characteristics:
−
The stiffness of the preload spring does not exceed 10 % of the stiffness of the piezo
actuator. This is to minimize the displacement loss. If the stiffness of the preload
spring is equal to that of the actuator, the free displacement drops by half.
The stiffness of the piezo actuator can be calculated as follows:
k
A
Actuator stiffness
F
max
Blocking force*
ΔL
0
Nominal displacement*
* See data table (p. 49).
−
With highly dynamic applications:
The resonant frequency (p. 49) of the preload spring exceeds that of the piezo
actuator.
Applying a preload
Apply the preload near the axis within the core cross section of the piezo actuator.