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Evaluation of Methods for Identification of Structural Damping Using Continuous Wavelet Transformation, Application to Numerical And Real Data

Damping in mechanical systems is phenomena of energy dissipation. It comes in many forms and it is still not entirely studied. Structures and machines can be damped by mechanism that which have different external and internal natures. This includes: molecular microstructure effects, friction between parts, fluid interactions, etc. Generally, structural damping can be classified either as hysteretic or viscous. Hysteretic damping arises from internal friction on level of microcrystalline structure in the material. Viscous damping is proportional to velocity and affects system response in the range of system resonance. In practice many types of damping acts simultaneously and concept of equivalent viscous damping is used instead. In this work we are testing methods that detect damping ratios using time-frequency signal decomposition. This is achieved using a continuous wavelet transformation of free response signal. The evaluation of the damping identification methods is performed on numerically simulated and real laboratory models. The numerical simulation of the damping detection is performed on 2DOF model with a proportional viscous damping assumed. The practical damping identification is verified on measuring longitudinal vibrations of the free bar.

continious wavelet transfor; damping identification; longitudinal vibrations

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