The approach of the Collaborative Research Centre CRC 805 – Control of Uncertainty in Load-Carrying Systems in Mechanical Engineering – of the Technische Universität Darmstadt describes and assesses uncertainty, and develops new technologies and methods to control uncertainty. In this work, the CRC 805 approach is used to describe and assess the scatter in the properties of a piezoelectric stack actuator and the mechanical structure to be actuated, e. g. the blocking force and the structure stiffness, as an uncertainty in the numerical evaluation of the stack actuator’s mechanical forces and strokes with its working diagram. An active system with a beam that is lateraly loaded by an active force from a single piezoelectric stack actuator was taken as a case of study.

The description of the assumed scatter in the actuator’s and beam’s properties within the working diagram and the numerical assessment of their influences on the actuator’s mechanical forces and strokes by means of worst-case analyses and Monte Carlo-simulations showed an uncertainty region around each nominal operating point and the distribution of potential operating points within. Any uncertainty region showed respectively a linear and nonlinear increase together with a growing mechanical preload and electric voltage on the stack actuator.

The operating points of identical stack actuators connected with beams were measured in a test rig of the active system for quasistatic and dynamic electric voltages in order to validate the results of the worst-case analyses and Monte Carlo-simulations. Additional factors like nonlinearities in the piezoelectric material of the stack actuators, the influence of mechanical preload on the actuator stiffness and the finite stiffness of the test rig induce that the measured forces and strokes are up to 33% and 35% smaller than their assumed values from the working diagram. A model update of the working diagram with multidimensional regressions is performed to avoid an overestimation of the actuator’s forces and strokes. The numerical and experimental results presented in this dissertation show the potential of the CRC 805 approach in the description and assessment of the variations in the mechanical forces and strokes of a stack actuator caused by scatter in the actuator’s properties and those of the mechanical structure to be actuated.