Evaluation and control of uncertainty in using an active column system

Uncertainty in usage of load-carrying systems mainly results from not fully known loads and strength. This article discusses basic approaches to control uncertainty in usage of load-carrying systems by passive and active means. An active low damped column system critical to buckling is presented in which a slender column can be stabilised actively by piezo stack actuators at one of its ends only. Uncertainty may be controlled in the active column system by temporarily enhancing the bearable axial load theoretically up to three times compared to the passive column system in case of critical loading. However, in the implementation of these approaches, system-specific uncertainty may also occur. In numerical examinations it is shown, that small deviations in measured axial loading may increase the active force significantly to achieve stabilisation. The increase of applied active force might affect lifetime of the piezo stack actuators and thus the stabilising capability o f the active column system.