Nonlinear Modes of Jointed Structures by Malte Krack, March 2023
Nonlinear Modes of Jointed Structures
Professor, University of Stuttgart
Normal modes characterize the vibration signature and simplify the quantitative analysis of the vibration response. Most work on nonlinear modes has focused on conservative, smooth systems. This stands in polar opposite to the dissipative, inherently non-smooth frictional contact interactions within joints. In the past decade, the Extended Periodic Motion Concept has proven itself as a useful definition for nonlinear modes in that case. This tutorial covers this concept, computational and experimental methods, single-nonlinear-mode theory, and nonlinear-mode-based reduced-order modeling. Opportunities and limitations for the application to friction damping of turbine blades are demonstrated. Recent progress is also shown in fluid-structure interaction, substructuring, and the effects of non-unique residual traction.
Malte Krack obtained his doctoral degree in Mechanical Engineering at the University of Hannover, Germany, in 2014. In 2015 he joined Alexander Vakakis' group at the University of Illinois at Urbana-Champaign as a postdoctoral research fellow. In 2016, he was appointed as a tenure-tracked professor at the University of Stuttgart in the Aerospace Engineering Department, where he became a full professor in 2021. His primary research area is the nonlinear vibrations of structures subjected to contact nonlinearities. Activities span the range from the fundamental development of computational and experimental methods to application-oriented projects on friction damping and impact absorbers with the German turbomachinery industry.