How to select

There might be a number of actuators that can fulfill the displacement vs. force requirements, i.e. whose characteristics include the load curve. A first starting point for selecting candidates can be the comparison of the different actuator designs based on actuator blocking force vs. free displacement or stroke - also to be found in the section Different actuator designs.

Finally, the actuator must be used in the best conditions. Typically, an actuator can tolerate a certain range of external force. For example, we do not recommend to use linear stack (NAC20xx-Hxx or NAC21xx-Hxx) in tension. This means that, if the load has to be both pushed and pulled, a preload must be added in parallel to the actuator, to make sure that the actuator is only submitted to compressive stress. Such a preload should be designed to have a stiffness much lower than the actuator (factor 10). This ensures that the preload does not ”divert” too much of the strain energy from the piezoelectric actuator.