Measurement Techniques of the Logarithmic Decrement

A comparison of eight algorithms used in computations of the logarithmic decrement and three algorithms used for measurements of the resonant frequency of free decaying oscillations is reported. Basic definitions and measuring principles of the logarithmic decrement and error analysis for tested algorithms are briefly described. It is demonstrated that it is possible to tailor high quality mechanical loss spectra for a number of various experimental situations by appropriate selection of the numerical algorithms and optimization of several parameters used in signal acquisition of exponentially damped harmonic oscillations. The described strategy can be applied in mechanical spectroscopy, internal friction measurements, and mechanical damping measurements in general.