Multi-scale high-resolution characterization of dissipation of mechanical energy in solids

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(Institution)
Abstract
701-004
L. B. Magalas Magalas, L.B.(AGH University of Science and Technology); This contribution will discuss multi-scale high-resolution characterization of dissipation of mechanical energy in solids as a means to gain new insight toward solving challenging problems in materials science. We will show how combined different methods (around 30) and algorithms of computing the logarithmic decrement, ?, and resonant frequency, f0, on the same specimen provide a basis for more precise and efficient characterization of exponentially damped harmonic oscillations recorded in a mechanical spectrometer. The time-dependent aspect is considered as a non-avoidable experimental fact, which must be taken into account both in high-resolution mechanical spectroscopy, HRMS, and standard mechanical loss measurements. The analysis offers a more complete self-consistent understanding of the computational procedure to estimate dissipation of mechanical loss energy in solids. The use of a novel optimized interpolated discrete Fourier transform is addressed; the performance of all available methods to compute the logarithmic decrement and resonant frequency is discussed and carefully compared for several experimental conditions. The universal character of the reported powerful solution has proved to be successful in a wide range of resonant frequencies (from 0.1 Hz to kHz) and damping levels (from 0.5 to 10-9). To this end, the disadvantages and detrimental consequences of using classical methods to estimate the logarithmic decrement, ?, and resonant frequency, f0, are also addressed. The method can be readily applied to high (0.5) and ultralow damping (10-8 – 10-9) materials, and materials characterized by a typical damping level, that is, 10-3 – 10-4. In-situ online experimentation is presented and discussed in detail. It is emphasized that the use of the optimized interpolated discrete Fourier transform method to obtain the length (duration of a decaying strain signal) scale mapping information yields new opportunities to increase the accuracy and resolution of mechanical spectrometers, resolve complex internal friction spectra and substantially increase the precision in estimation of elastic moduli.
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