Complex mode indicator function to find repeated roots or closely coupled modes
Jelena Dimitrijević
Numerical modal analysis by finite element analysis (FEA) and experimental modal analysis (EMA) with multiple references were used to find and estimate modal parameters of closely coupled modes for a selected structure, a rec-tangular aluminium plate. The plate is constructed in such a way to have closely coupled modes. The objective was to find closely coupled modes of the plate using the set of frequency response functions (FRFs) that were obtained as a result of the experimental modal analysis. Modal parameter estimation the complex mode indicator function in ME’scopeVES was applied to the plate to find those modes. Normal mode dynamics by FEA was used to determinate their existence before EMA.
Key words: polyreference method, modal analysis, finite element analysis (FEA), frequency response functions (FRFs), complex mode indicator function (CMIF), closely coupled modes, mode shape, damping.