Processing of Modal Test Results Taking into Consideration the Damping Nonlinear Dependence on the Oscillation Frequency

Abstract

The paper proposes a technique for processing the modal testing results; it is based on the damping representation in the resonant peaks vicinity as a function of the oscillation frequency. This approach is used to improve quality in the modal parameters identification of systems with the nonlinearity manifestation. The technique makes it possible to account for alterations in damping in the resonant peaks vicinity (mainly arising due to the damping dependence on the oscillation amplitude), as well as for the peaks' significant asymmetry (usually associated with manifestation of the hysteresis with the decreasing or increasing oscillation frequencies). Processing based on the experimentally obtained amplitude-frequency and phase-frequency characteristics allows constructing a damping function that characterizes alteration in damping in the structure depending on the oscillation frequency. The damping function is approximated in the resonant peaks vicinity by the second-degree polynomial to determine relationship between the polynomial coefficients. Then, the least squares method is used to select the iterative damping coefficient for each oscillation tone taking into account the tones' mutual influence. The technique is implemented in the MATLAB environment. Verification was carried out by comparing the processing results with the results obtained using the PolyMAX, Time MDOF and Half Power methods

Please cite this article in English as:

Dmitriev S.N., Khamidullin R.K. Processing of modal test results taking into consideration the damping nonlinear dependence on the oscillation frequency. Herald of the Bauman Moscow State Technical University, Series Mechanical Engineering, 2024, no. 2 (149), pp. 63--81 (in Russ.). EDN: NGEVCP

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