Device for the measurement of non-periodic and non-linear structural vibrations

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The research focus of the Structural Mechanics Group of the Institute of Aircraft Propulsion Systems is on nonlinear structural vibrations. Central topics are the development of methods for nonlinear experimental modal analysis, the dynamics of turbomachinery blades subjected to frictional contacts impact, and vibration mitigation using impact absorbers. The large-scale equipment applied for closes an important gap in the existing possibilities for the measurement of structural vibrations in order to address current research questions in these areas. An essential feature is that the structural vibrations are measured without contact and simultaneously at several measurement points. The non-contact acquisition avoids the distortion of the dynamics by sensors attached to the structure, especially for thin-walled structures and and structures subjected to fluid flow. The simultaneous acquisition allows the study of the often non-periodic or transient nonlinear energy transfer within mechanical systems. The instrument provides highly accurate, three-dimensional information as required, starting from small amplitudes where sufficiently linear behavior is present, up to large amplitudes where nonlinear phenomena occur. The instrument covers a wide frequency band in order to be able to investigate higher vibration modes as well as to observe the energy transfer between low and high frequencies typical of nonlinear and impact processes. The accessories enable precise alignment of the measurement points and ensure good repeatability of the experiments by means of an automatic modal hammer.