# Control Algorithm For Sine Excitation On Nonlinear Systems

Document type: Conference Papers No A Control Algorithm For Sine Excitation On Nonlinear Systems.pdf Andreas Josefsson, Martin Magnevall, Kjell Ahlin Control Algorithm For Sine Excitation On Nonlinear Systems IMAC XXIV 2006 Society for Experimental Mechanics St. Louis, USA Blekinge Institute of Technology School of Engineering - Dept. of Mechanical Engineering (Sektionen för teknik – avd. för maskinteknik)School of Engineering S- 371 79 Karlskrona, School of Engineering S- 371 79 Karlskrona+46 455 38 50 00http://www.bth.se/ing/ andreas.josefsson@bth.se, martin.magnevall@bth.se, kjell.ahlin@bth.se English When using electrodynamic vibration exciters to excite structures, the actual force applied to the structure undertest is the reaction force between the exciter and the structure. The magnitude and phase of the reaction force isdependent upon the characteristics of the structure and exciter. Therefore the quality of the reaction force i.e. theforce applied on the structure depends on the relationship between the exciter and structure under test.Looking at the signal from the force transducer when exciting a structure with a sine wave, the signal will appearharmonically distorted within the regions of the resonance frequencies. This phenomenon is easily observed whenperforming tests on lightly damped structures. The harmonic distortion is a result of nonlinearities produced by theshaker when undergoing large amplitude vibrations, at resonances.When dealing with non-linear structures, it is of great importance to be able to keep a constant force level as wellas a non-distorted sine wave in order to get reliable results within the regions of the resonance frequencies. Thispaper presents theoretical methods that can be used to create a non-distorted sinusoidal excitation signal withconstant force level. Mechanical Engineering\Structural Dynamics control algorithm, sine excitation, shaker, nonlinear, harmonic distortion