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Journal articles on the topic 'Logarithmic decrement'

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Author: Grafiati

Published: 4 June 2021

Last updated: 4 February 2022

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1

Savinov, A. M., G. M. Nigmetov, S. D. Kovaleva, and T. G. Nigmetov. "DEDETERMINATION OF THE LOGARITHMIC DECREMENT OF NATURAL VIBRATIONS OF BUILDINGS AND STRUCTURESTERMINATION OF THE LOGARITHMIC DECREMENT OF NATURAL VIBRATIONS OF BUILDINGS AND STRUCTURES." STRUCTURAL MECHANICS AND ANALYSIS OF CONSTRUCTIONS, no. 1 (February 25, 2021): 62–65. http://dx.doi.org/10.37538/0039-2383.2021.1.62.65.

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Abstract. For the passport of buildings and structures, it is required to determine the logarithmic damping decrement. The proposed expressions [1, 2] to determine the decrement use the value of the Q-factor, however, an expression is known in which the damping decrement is determined through the logarithm of the ratio of the amplitudes of the damped signal. Comparison of the formulas for calculating the logarithmic decrement of vibrations was carried out using the example of data obtained when testing a beam with reinforcement.

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2

Magalas, Leszek B. "Determination of the Logarithmic Decrement in Mechanical Spectroscopy." Solid State Phenomena 115 (August 2006): 7–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.115.7.

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The comparison between the classical methods and a new algorithm OMI used to compute the logarithmic decrement is reported. The OMI algorithm is tested in the computation of the logarithmic decrement from exponentially damped harmonic oscillations. The OMI algorithm yields high precision in the computation of the logarithmic decrement and the resonant frequency, and the smallest dispersion of experimental points.

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3

Stanislawczyk, A. "Advanced Techniques for Determining High and Extreme High Damping: OMI - A New Algorithm to Compute the Logarithmic Decrement." Key Engineering Materials 319 (September 2006): 231–0. http://dx.doi.org/10.4028/www.scientific.net/kem.319.231.

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A new algorithm OMI (Optimization in Multiple Intervals) for the computation of the logarithmic decrement from exponentially damped harmonic oscillations is described. This method is shown to be effective and computationally compact for high damping materials. A comparison between the OMI algorithm and the four classical methods usually used in the computation of the logarithmic decrement is reported. The OMI algorithm yields high precision in the computation of the logarithmic decrement and the smallest dispersion of experimental points on the plots of mechanical loss spectra. The effect of the acquisition parameters and the experimental conditions on the results of computations of the logarithmic decrement and the relative error is discussed.

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4

Magalas, Leszek B., and T. Malinowski. "Measurement Techniques of the Logarithmic Decrement." Solid State Phenomena 89 (February 2003): 247–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.89.247.

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5

Magalas, Leszek B., and M. Majewski. "Recent Advances in Determination of the Logarithmic Decrement and the Resonant Frequency in Low-Frequency Mechanical Spectroscopy." Solid State Phenomena 137 (March 2008): 15–20. http://dx.doi.org/10.4028/www.scientific.net/ssp.137.15.

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The advantages of the OMI algorithm to compute the logarithmic decrement and the resonant frequency from free decaying oscillations is reported. The OMI algorithm is proved to be the best solution in the computation of the logarithmic decrement and the resonant frequency for high damping levels.

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6

Mayama, Masakazu, and Masatoshi Harada. "Logarithmic Decrement and Dynamic Modulus of Coated Cement Concrete." Key Engineering Materials 302-303 (January 2006): 493–99. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.493.

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This report presents a research on vibration absorption properties of coated cement concrete, by discussing the logarithmic decrement and dynamic modulus obtained from bending vibration test at various temperatures. The effect of temperature and bitumen content on the vibration properties of materials was evaluated. As temperature and/or coating asphalt content increased, coated cement concrete increased logarithmic decrement and resulted in increasing vibration absorption than the conventional cement concrete. The vibration properties of coated cement concrete were similar to those of conventional cement concrete in the low temperature range. The dynamic modulus of coated cement concrete decreased at higher temperatures. The rate of decrease of dynamic modulus at higher temperatures was comparatively small in comparison with the rate of increase of logarithmic decrement.

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7

Little, Jared A., and Brian P. Mann. "Optimizing logarithmic decrement damping estimation through uncertainty propagation." Journal of Sound and Vibration 457 (September 2019): 368–76. http://dx.doi.org/10.1016/j.jsv.2019.05.040.

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8

Magalas, Leszek B., and M. Majewski. "Toward High-Resolution Mechanical Spectroscopy HRMS - Logarithmic Decrement." Solid State Phenomena 184 (January 2012): 467–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.184.467.

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In this work, we present the comparison between different methods used to compute the logarithmic decrement,δ. The parametric OMI method and interpolated DFT (IpDFT) methods are used to compute theδfrom free decaying oscillations embedded in an experimental noise typical for low-frequency mechanical spectrometers. The results are reported forδ= 5×10-4, = 1.12345 Hz and different sampling frequencies, = 1 kHz and 4 kHz. A new YM algorithm yields the smallest dispersion in experimental points of the logarithmic decrement and the smallest relative errors among all investigated IpDFT methods. In general, however, the IpDFT methods suffer from spectral leakage and frequency resolution. Therefore it is demonstrated that the performance of different methods to compute theδcan be listed in the following order: (1) OMI, (2) YM, (3) YMC, and (4) the Yoshida method, Y. For short free decays the order of the best performers is different: (1) OMI and (2) YMC. It is important to emphasize that IpDFT methods (including the Yoshida method, Y) are discouraged for signals that are too short. In conclusion, the best methods to compute the logarithmic decrement are the OMI and the YM. These methods will pave the way toward high-resolution mechanical spectroscopy HRMS.

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9

El-Morsy, Abdel-Wahab, and Ahmed I. Z. Farahat. "Effect of Aging Treatment on the Damping Capacity and Mechanical Properties of Mg-6Al-1Zn Alloy." Scientific World Journal 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/170458.

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The damping capacity and mechanical properties of Mg-6Al-1Zn alloy after heat treatment were investigated. The damping characteristics of un-heat-treated, solution treated, and aged Mg-6Al-1Zn specimens were determined by measuring the damping ratio and the logarithmic decrement of free vibrations of a bending beam clamped at one side. The microstructural evaluations confirmed that theβ-Mg17Al12phase was reprecipitated after aging and increased with an increase in aging time. The peak level of damping ratio and logarithmic decrement was obtained after 34 hr of aging time, over which the damping capacity declined according to increasing amount of strong pining points.

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10

Magalas, L. B., and M. Majewski. "Hilbert-Twin – A Novel Hilbert Transform-Based Method To Compute Envelope Of Free Decaying Oscillations Embedded In Noise, And The Logarithmic Decrement In High-Resolution Mechanical Spectroscopy HRMS." Archives of Metallurgy and Materials 60, no. 2 (June 1, 2015): 1091–98. http://dx.doi.org/10.1515/amm-2015-0265.

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Abstract In this work, we present a novel Hilbert-twin method to compute an envelope and the logarithmic decrement, δ, from exponentially damped time-invariant harmonic strain signals embedded in noise. The results obtained from five computing methods: (1) the parametric OMI (Optimization in Multiple Intervals) method, two interpolated discrete Fourier transform-based (IpDFT) methods: (2) the Yoshida-Magalas (YM) method and (3) the classic Yoshida (Y) method, (4) the novel Hilbert-twin (H-twin) method based on the Hilbert transform, and (5) the conventional Hilbert transform (HT) method are analyzed and compared. The fundamental feature of the Hilbert-twin method is the efficient elimination of intrinsic asymmetrical oscillations of the envelope, aHT (t), obtained from the discrete Hilbert transform of analyzed signals. Excellent performance in estimation of the logarithmic decrement from the Hilbert-twin method is comparable to that of the OMI and YM for the low- and high-damping levels. The Hilbert-twin method proved to be robust and effective in computing the logarithmic decrement and the resonant frequency of exponentially damped free decaying signals embedded in experimental noise. The Hilbert-twin method is also appropriate to detect nonlinearities in mechanical loss measurements of metals and alloys.

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11

Banerjee, Shib Sundar, and Srivasta Ananthan. "STUDY OF THE BILATERAL ASYMMETRY OF PLANTAR MECHANICAL PROPERTIES AS A BIOMARKER FOR THE DIFFERENTIATION OF DIABETIC CONDITION." Biomedical Sciences Instrumentation 57, no. 2 (April 1, 2021): 114–20. http://dx.doi.org/10.34107/yhpn9422.04114.

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Diabetes mellitus is a globally prevalent metabolic disease which results in altered plantar mechanical properties and foot ulcer. In this study, the bilateral asymmetry of mechanical properties for plantar soft tissue is investigated in healthy and diabetic conditions. Myotonometric signals are acquired from sub-metatarsal region of the plantar faces of healthy subjects and patients with varied diabetic age. Mechanical parameters such as dynamic stiffness and logarithmic decrement are extracted from the recorded signal. The asymmetry indices between right and left feet are computed. Statistical analysis shows that the spatial pattern of dynamic stiffness and logarithmic decrement varies significantly between healthy and diabetic subjects. The asymmetry index of dynamic stiffness in the fifth sub-metatarsal head can differentiate between healthy subjects and patients with both high and low diabetic age (p<0.05). The asymmetry index of logarithmic decrement is found to vary significantly between the healthy subjects and patients with higher diabetic age (p<0.05). These results indicate that bilateral asymmetry of myotonometric parameters can be exploited as a possible biomarker to differentiate diabetic patients from healthy subjects and can aid in the early detection of foot ulcer.

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12

Tweten, Dennis J., Zach Ballard, and Brian P. Mann. "Minimizing error in the logarithmic decrement method through uncertainty propagation." Journal of Sound and Vibration 333, no. 13 (June 2014): 2804–11. http://dx.doi.org/10.1016/j.jsv.2014.02.024.

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13

SHEPHERD, A. J., and G. WYATT. "Changes in induced hues at low luminance and following dark adaptation suggest rod-cone interactions may differ for luminance increments and decrements." Visual Neuroscience 25, no. 3 (May 2008): 387–94. http://dx.doi.org/10.1017/s0952523808080358.

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Color contrast describes the influence of one color on the perception of colors in neighboring areas. This study addressed two issues: (1) the accurate representation of the color changes; (ii) the underlying visual mechanisms. Observers matched the hue that was induced in a neutral square when it was set in one of four standard colored surrounds: “red” (+L(−M) relative to neutral), “green” (−L(+M)), “purple” (+S), and “yellow” (−S). The standard and matching displays were viewed haploscopically. The standard neutral square was either a luminance increment, or decrement, both of which appeared the complementary color to the surrounds in which they were inset. In Experiment 1, the surround luminance in each eye's display was either equal, at 18 cd·m−2, or the match surround luminance was reduced to 2.5 cd·m−2. The matches with equal surround luminances could be represented as vector shifts in a logarithmic MacLeod–Boynton (r, b) chromaticity diagram, as described previously (Shepherd, 1997, 1999). The low luminance matches were, however, displaced further from neutral, as if larger chromatic differences were needed. The precise direction of the displacements differed for luminance increments and decrements: the red, green and yellow decrement matches were also displaced vertically downwards in the MacLeod-Boynton diagram. In Experiment 2, dark-adapting before setting repeat color matches displaced the decrement matches vertically, but did not affect the increment matches. Thus, rod intrusion in S-cone pathways may have boosted the S-cone signal for the lowest luminance decrement matches in Experiment 1 and account for the vertical shift in MacLeod-Boynton co-ordinates. The distinct pattern of displacements for low luminance increments and decrements may be explained if the match is set at a cone-opponent, rather than a cone contrast, site and if rod signals have an input only to S-cone decrement, perhaps S-OFF, pathways.

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14

Patrikeev, Alexander V. "Relevant issues of periodic vibration monitoring of buildings and structures." Vestnik MGSU, no. 9 (September 2020): 1221–27. http://dx.doi.org/10.22227/1997-0935.2020.9.1221-1227.

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Introduction. The author proposes a new universal optimization approach to mechanical safety monitoring of buildings and structures in the process of their operation. The new approach involves periodic monitoring of mechanic vibrations. Materials and methods. The methodology of periodic monitoring performable within the framework of general monitoring is based on the analysis of changes in the first natural frequency of a building or a structure and the logarithmic decrement of its damping along three mutually perpendicular axes. The shape and position of resonance peaks of the amplitude spectrum are employed to analyze resonant frequencies and logarithmic decrements of damping. The analysis of those electronically archived parameters is performed, whose values change over time proportionately with vibrations of a monitored facility. The time dependence of the first resonant frequency of a structure is considered as a generalized characteristic of its mechanical safety. Results. The author has shown that findings of the spectral analysis performed in respect of the vibration process are irrespective of a measurement method, provided that the uniformity of external influences is ensured. The frequency dependence of the structure’s first mode of vibrations on time (per year) has two non-linear sections within the entire term of operation. Following the analysis of measurements taken at construction facilities exposed to wind loads, it’s been found that advanced monitoring instruments can identify changes in the value of the first resonant frequency and the damping decrement with a reasonable degree of accuracy. The author believes that this finding has great practical importance. Conclusions. Identification of a trend towards a change in frequency and damping decrement values for the first mode of natural vibrations can help to schedule actions for the improvement of the mechanical safety of an engineering structure, and in some cases it can prevent an upcoming accident.

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15

Majewski, M., and L. B. Magalas. "Critical Assessment Of The Issues In The Application Of Hilbert Transform To Compute The Logarithmic Decrement." Archives of Metallurgy and Materials 60, no. 2 (June 1, 2015): 1105–8. http://dx.doi.org/10.1515/amm-2015-0267.

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Abstract The parametric OMI (Optimization in Multiple Intervals), the Yoshida-Magalas (YM) and a novel Hilbert-twin (H-twin) methods are advocated for computing the logarithmic decrement in the field of internal friction and mechanical spectroscopy of solids. It is shown that dispersion in experimental points results mainly from the selection of the computing methods, the number of oscillations, and noise. It is demonstrated that conventional Hilbert transform method suffers from high dispersion in internal friction values. It is unequivocally demonstrated that the Hilbert-twin method, which yields a ‘true envelope’ for exponentially damped harmonic oscillations is superior to conventional Hilbert transform method. The ‘true envelope’ of free decaying strain signals calculated from the Hilbert-twin method yields excellent estimation of the logarithmic decrement in metals, alloys, and solids.

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16

Nakutis, Ž., and P. Kaškonas. "Bridge vibration logarithmic decrement estimation at the presence of amplitude beat." Measurement 44, no. 2 (February 2011): 487–92. http://dx.doi.org/10.1016/j.measurement.2010.11.012.

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17

Yang, J. C. S., C. H. Marks, J. Jiang, D. Chen, A. Elahi, and W.-H. Tsai. "Determination of Fluid Damping Using Random Excitation." Journal of Energy Resources Technology 107, no. 2 (June 1, 1985): 220–25. http://dx.doi.org/10.1115/1.3231180.

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An experimental investigation has been carried out to verify the validity of the use of the random decrement technique to determine the damping coefficients for a circular cylinder oscillating in water. Data are reported for amplitudes ranging from 0.4 diameters to 0.8 diameters, for water speeds from zero to 0.192 m/s (0.63 ft/sec), and for frequencies ranging from 0.37 Hz to 1.4 Hz. Comparison with other data, which has been reported in the literature or obtained by the authors, shows that the random decrement method yields comparable damping coefficients to those obtained using the logarithmic decrement technique for the range of variables in this experiment.

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18

Majewski, M., A. Piłat, and L. B. Magalas. "Advances in Computational High-Resolution Mechanical Spectroscopy HRMS Part I: Logarithmic Decrement." IOP Conference Series: Materials Science and Engineering 31 (February 20, 2012): 012018. http://dx.doi.org/10.1088/1757-899x/31/1/012018.

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19

Kobelev, N. P., E. L. Kolyvanov, and V. A. Khonik. "An Acoustic Study of Irreversible Structural Relaxation in a Bulk Metallic Glass." Solid State Phenomena 115 (August 2006): 113–20. http://dx.doi.org/10.4028/www.scientific.net/ssp.115.113.

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Irreversible structural relaxation of bulk amorphous Zr52.5Ti5Cu17.9Ni14.6Al10 was studied by means of logarithmic decrement and shear modulus measurements using an inverse torsion pendulum in the frequency range from 5 Hz to 40 Hz. Irreversible contributions to the decrement and shear modulus and their frequency, temperature, and time dependences were investigated. The activation energy spectrum of irreversible structural relaxation has been reconstructed. It has been shown that irreversible structural relaxation can be regenerated by a special heat treatment. The results obtained are discussed within the framework of a phenomenological model, which implies existence of two-well relaxation centers in the glass structure.

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20

Magalas, Leszek B., and A. Piłat. "On-Line Control of Harmonic Oscillations in a Low-Frequency Resonant Mechanical Spectrometer." Solid State Phenomena 115 (August 2006): 299–304. http://dx.doi.org/10.4028/www.scientific.net/ssp.115.299.

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The on-line control unit is used to ensure high-accuracy computations of the logarithmic decrement. It is shown that the excitation process should be on-line low level real-time controlled during mechanical loss measurements to obtain high precision of the computations and to ensure a short-time excitation process.

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21

Irvine, Martin, Joseph Longo, and Frederick Stern. "Forward Speed Calm Water Roll Decay for Surface Combatant 5415: Global and Local Flow Measurements." Journal of Ship Research 57, no. 04 (December 1, 2013): 202–19. http://dx.doi.org/10.5957/jsr.2013.57.4.202.

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Global and local flow measurements for forward speed calm water roll decay are performed in a towing tank for surface combatant model 5415 for both bare hull (BH) and bilge keel (BK) conditions. Roll motion is oscillatory with underdamped exponential decay and linear with respect to initial roll angles less than the average initial roll angle (9°). For larger mean roll angles (> 3°), damped natural frequency is a few percent below the hydrostatic natural roll frequency with larger values for BH than BK condition and increasing Froude number (Fr), whereas for smaller mean roll angles, it sharply increases toward the hydrostatic natural roll frequency. For larger mean roll angles, logarithmic decrement and linear damping linear increase with larger values for BK than BH condition and increasing Fr, whereas for smaller mean roll angles, they sharply increase. For increasing Fr, mean and initial roll angle averaged mean roll angle decreases by 50%; damped natural frequency increases by 6% with larger values for BH than BK condition; and logarithmic decrement/linear damping coefficient increase by a factor of three/four with larger values for BK than the BH condition. Logarithmic decrement and Himeno method linear damping coefficients are qualitatively similar. Nonlinear damping coefficient is two orders of magnitude smaller than linear damping coefficient. Roll reconstruction errors are smallest for Himeno with linear and nonlinear damping. The phase-averaged wave pattern and velocity and axial vorticity fields at x/L = 0.675 initially show larger amplitudes followed by oscillatory exponential decay. Alternating vortex pairs are shed from the bilge keel tip with damped magnitudes for decreasing mean roll angles. The local flow indicates lower frequencies and larger damping than the roll motion.

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22

Magalas, Leszek B., and A. Piłat. "Zero-Point Drift in Low-Frequency Mechanical Spectroscopy." Solid State Phenomena 115 (August 2006): 285–92. http://dx.doi.org/10.4028/www.scientific.net/ssp.115.285.

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The concept of the ‘zero-point drift’, ZPD, is introduced and analyzed on the basis of mechanical loss measurements carried out in a low-frequency mechanical spectrometer – inverted torsion pendulum. It is demonstrated that the ZPD, which modifies damped harmonic oscillations leads to false values of the logarithmic decrement computed from several widely accepted algorithms.

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23

Cooper, J. E. "EXTENDING THE LOGARITHMIC DECREMENT METHOD TO ANALYSE TWO DEGREE OF FREEDOM TRANSIENT RESPONSES." Mechanical Systems and Signal Processing 10, no. 4 (July 1996): 497–500. http://dx.doi.org/10.1006/mssp.1996.0034.

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24

Skel, Vladimir. "Properties of the rubber vibration isolator of the elevator." MATEC Web of Conferences 251 (2018): 03022. http://dx.doi.org/10.1051/matecconf/201825103022.

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The article presents experimental-theoretical studies of rubber shock absorbers of an elevator. Their static and dynamic stiffness in compression and static shear stiffness are determined. Two variants of fastening of rubber prisms were considered: in a cage and without a holder. It is shown that the logarithmic decrement of damping of the rubber cushion lies in the range of values 0.4 ... 0.5.

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25

Iwaki, Fuminori, Ken Mitsubori, Toshiyasu Koike, Yutaka Hirata, and Masakazu Obata. "Influence of Turbocharger Rotational Speed on Logarithmic Decrement and Stimulus Value of Turbine Blade." Journal of The Japan Institute of Marine Engineering 40, no. 5 (2005): 715–19. http://dx.doi.org/10.5988/jime.40.5_715.

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26

Sun, Dan, Xudong Wang, Chengwei Fei, Huan Zhao, Guochen Zhang, and Wenzhong Tang. "Experimental Investigation on Rotordynamic Characteristics and Rotor System Stability of a Novel Negative Dislocated Seal." Shock and Vibration 2019 (June 17, 2019): 1–11. http://dx.doi.org/10.1155/2019/1780390.

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Air-induced force generated in seals is one key factor on the stability of the rotor system. In this paper, a novel negative dislocated seal (NDS) was developed in respect of dislocated bearing theory, to reduce hydrodynamic pressure effect and air-induced force and improve rotor stability as well. A test rig was built to test rotordynamic characteristics and rotor stability of the NDS. The rotordynamic characteristics of seals were investigated based on the unbalanced synchronous excitation method, and seal-rotor system stability was evaluated by the identification method with an electromagnetic bearing exciter. The effects of both rotating speed and inlet/outlet pressure ratio on the rotordynamic characteristics and rotor stability of both NDS and conventional cylindrical labyrinth seal were experimentally investigated. The results show that with the increasing rotating speed, inlet/outlet pressure ratio is promising to reduce the direct stiffness coefficients of seals and the logarithmic decrement rate of seal-rotor system and enhance both cross stiffness and damping coefficient as well. Besides, the developed NDS effectively reduces cross-stiffness coefficients and increases direct damping coefficients and the logarithmic decrement rate of the seal-rotor system, relative to the conventional cylindrical seal. The proposed seal can effectively improve seal stability of turbomachinery.

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27

Xiong, Chun-Bao, Yan-Bo Niu, and Zhi Li. "An investigation of the dynamic characteristics of super high-rise buildings using real-time kinematic–global navigation satellite system technology." Advances in Structural Engineering 21, no. 5 (October 9, 2017): 783–92. http://dx.doi.org/10.1177/1369433217732497.

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This article aims to investigate the dynamic characteristics (e.g. natural frequency and damping ratio) for two super high-rise completed and uncompleted buildings. Real-time kinematic-global navigation satellite system technology is applied to observe the dynamic responses. To improve the positioning accuracy and avoid distortion of the results, a Type 1 Chebyshev high-pass digital filter is used. The natural frequencies and damping ratios of the buildings are determined using the fast Fourier transform analysis and random decrement technique combined with a logarithmic decrement method, respectively. The structural parameters are obtained. The results show that real-time kinematic-global navigation satellite system technology can provide the dynamic responses of super high-rise buildings in an efficient manner and that the dynamic characteristics from field measurements agree well with the results of the numerical simulation.

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28

Murčinková, Zuzana. "Macroscopic dynamic response of mechanical systems involving composites and effect of inner structure on damping properties." Mechanik 92, no. 4 (April 8, 2019): 288–91. http://dx.doi.org/10.17814/mechanik.2019.4.38.

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The paper deals with relation between inner structure of the machine and the composite material used in it and macroscopic dynamic response. It presents the experimental results of testing the relation between inner composite material structure and damping properties presented by logarithmic decrement quantity. Moreover, the paper provides the case study of application the composite material layered structure to the flexographic printing machine and results of that applications presented by printing speed.

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29

Kemp, Connor, and Gary Scavone. "Microstructure Contributions to Vibrational Damping and Identification of Damage Mechanisms in Arundo Donax L: Reed Cane for Woodwind Instruments." MRS Advances 2, no. 35-36 (2017): 1869–88. http://dx.doi.org/10.1557/adv.2017.223.

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ABSTRACTNatural cane reeds (Latin name Arundo Donax L and here termed ADL) have been used on woodwind instruments for centuries with little change. The reed acts as a mechanical valve controlling the energy input into the musical instrument and it is the musician’s first option for altering the instrument’s sound and response characteristics. Despite this, their consistency, variable performance, durability and sensitivity to ambient conditions make it difficult for the musician to find and maintain a reed that responds to their liking. Thus it is desirable to examine the material, microstructural and anatomical properties of the reed and their contributions to vibrational performance with input from mechanical engineers, materials scientists and musicians.The current study is part of an on-going research project, and this paper presents preliminary results. In the present work raw samples of ADL obtained from a manufacturer in pre-cut form are sectioned into longitudinal and transverse specimens for mechanical characterization. Prior to testing, samples are conditioned using an incubation system to 37 degrees Celsius and 90% relative humidity, mimicking in-use conditions of the reed. Initial microstructure analysis of each specimen is completed using optical microscopy to quantify fiber spatial arrangement, size and the existence of micro-cracks along the fiber-matrix interface. X-ray diffraction is also used to quantify the fraction of crystalline cellulose present in each sample. Specimens are then excited over a specific frequency range similar to that of in-use reeds using pressure waves in a non-contact setup. Values of internal friction are obtained as logarithmic decrement values for frequency-dependent decay. One set of specimens is then subjected to cyclic mechanical loading at low frequency (< 1Hz) and stresses up to 15MPa. The other set is maintained at the given environmental conditions using the incubator and aged through temperature and humidity cycling. Comparisons of post-testing microstructure damage and internal friction measurements are then completed to delineate specific degradation mechanisms due to mechanical/fatigue deterioration and moisture cycling. Internal friction is found to be dependent on both frequency, moisture and cyclic loading. Furthermore, the existence of microstructural cracks contributes to increasing decrement values at high frequencies in both fatigued and moisture cycled samples. Statistically significant correlations are discovered between logarithmic decrement and vascular bundle orientation at 700 Hz and logarithmic decrement and parenchyma cell diameter at 1000 Hz. Reductions in internal friction below 400 Hz indicate a decreasing loss modulus (E’’) with increased moisture cycles, although this trend will be tested against a larger sample set in further work.

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30

Ohtomi, K. "Free Vibration of Rectangular Plates Stiffened With Viscoelastic Beams." Journal of Applied Mechanics 52, no. 2 (June 1, 1985): 397–401. http://dx.doi.org/10.1115/1.3169060.

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This investigation treats the free vibration of a simply supported rectangular plate, stiffened with viscoelastic beams. Using a convenient method in which the effects of beams are expressed with Dirac delta functions, the equation of motion can be expressed by only one equation. The frequency equation is obtained by applying the Laplace transformation to the equation of motion. The effects of the volume and the number of beams on the frequency and the logarithmic decrement are clarified.

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31

Dyakonov, А. A., F. Kh Nurkenov, and A. D. Kazansky. "Realization Method of Calculating the Logarithmic Decrement in Turning and Boring CNC Machines Technological Systems." Procedia Engineering 206 (2017): 1227–31. http://dx.doi.org/10.1016/j.proeng.2017.10.623.

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32

Göken, J., J. Swiostek, Dietmar Letzig, and Karl Ulrich Kainer. "Damping Measurements of the Magnesium Wrought Alloys AZ31, AZ61 and AZ80 after Indirect and Hydrostatic Extrusion." Materials Science Forum 482 (April 2005): 387–90. http://dx.doi.org/10.4028/www.scientific.net/msf.482.387.

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Magnesium cast parts as well as indirectly and hydrostatically extruded profiles were used in order to investigate the influence of different microstructures on the damping behaviour of magnesium AZ-alloys. Especially, hydrostatic extrusion leads to a significant grain refinement in the extruded profile compared to indirect extrusion. Strain dependent damping measurements were carried out at room temperature using alloys AZ31, AZ61 and AZ80. Damping was determined as the logarithmic decrement of free bending beam vibrations. The results of these measurements after indirect and hydrostatic extrusion are shown and discussed.

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33

Hinai, Masakatsu, Showhachi Sawaya, and Hakaru Masumoto. "Influence of Heat Treatment and Cold Working on Ageing of Logarithmic Decrement in Al-Zn Alloys." Journal of the Japan Institute of Metals 55, no. 6 (1991): 715–19. http://dx.doi.org/10.2320/jinstmet1952.55.6_715.

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Ahmed, Feroz, and S. B. Kandagal. "Modal Identification of Aircraft Wing Coupled Heave-Pitch Modes Using Wavelet Packet Decomposition and Logarithmic Decrement." Procedia Engineering 144 (2016): 435–43. http://dx.doi.org/10.1016/j.proeng.2016.05.153.

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ISHIHARA, Kunihiko, Harutaka KOIKE, and Hiroshi YANO. "Estimation of Logarithmic Decrement of Rotor Blades under Centrifugal Force(Estimation Method by Using Specific Damping)." Transactions of the Japan Society of Mechanical Engineers Series C 64, no. 624 (1998): 2908–14. http://dx.doi.org/10.1299/kikaic.64.2908.

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LAMARQUE, C. H., S. PERNOT, and A. CUER. "DAMPING IDENTIFICATION IN MULTI-DEGREE-OF-FREEDOM SYSTEMS VIA A WAVELET-LOGARITHMIC DECREMENT—PART 1: THEORY." Journal of Sound and Vibration 235, no. 3 (August 2000): 361–74. http://dx.doi.org/10.1006/jsvi.1999.2928.

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37

Deng, Liqin, Xini Zhang, Songlin Xiao, Baofeng Wang, and Weijie Fu. "Gender Difference in Architectural and Mechanical Properties of Medial Gastrocnemius–Achilles Tendon Unit In Vivo." Life 11, no. 6 (June 17, 2021): 569. http://dx.doi.org/10.3390/life11060569.

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This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius–Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Independent t-tests were utilized to quantify the gender difference in the architectural and mechanical properties of the gMTU. In terms of architectural properties, the medial gastrocnemius (MG)’s pennation angle and thickness were greater in males than in females, whereas no substantial gender difference was observed in the MG’s fascicle length; the males possessed Achilles tendons (ATs) with a longer length and a greater cross-sectional area than females. In terms of mechanical properties, the MG’s vertical stiffness was lower and the MG’s logarithmic decrement was greater in females than in males. Both genders had no remarkable difference in the AT’s vertical stiffness and logarithmic decrement. Gender differences of individuals without training experience and regular exercise habits exist in the architectural and mechanical properties of the gMTU in vivo. The MG’s force-producing capacities, ankle torque, mechanical efficiency and peak power were higher in males than in females. The load-resisting capacities of AT were greater and the MG strain was lesser in males than in females. These findings suggest that males have better physical fitness, speed and performance in power-based sports events than females from the perspective of morphology and biomechanics.

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Дибир, А. Г., А. А. Кирпикин, and Н. И. Пекельный. "ЕКСПЕРИМЕНТАЛЬНЕ ВИЗНАЧЕННЯ ЕНЕРГЕТИЧНИХ УТОМНИХ ХАРАКТЕРИСТИК СПЛАВУ Д16Т (2024) МЕТОДОМ ВІЛЬНИХ КОЛИВАНЬ." Open Information and Computer Integrated Technologies, no. 84 (July 2, 2019): 157–64. http://dx.doi.org/10.32620/oikit.2019.84.08.

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In the process of studying fatigue characteristics of materials, components, assemblies and entire structures, as well as the prediction of durability, it is necessary to know the energy fatigue characteristics of various materials. These parameters include α – a fatigue failure parameter and W-1– irreversibly dissipated energy per loading cycle at stresses equal to the fatigue limit based on N = 107 cycles. The logarithmic damping decrement shows the fraction of irreversibly scattered energy when the oscillations decay from the total elastic energy of the oscillations. It has been proven that for metals fatigue failure is a constant "dangerous" energy. This paper describes the experimental determination of these energy characteristics for one of the most common materials in aviation, D16T (2024). By measuring the logarithmic damping factor in the fatigue test process, the dissipated energy is found over the loading cycle. Tests are conducted at two different loading levels. This allows to obtain a system of two equations to determine the two energy characteristics α and W-1.

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Qin, Yao Chun, and S. Y. He. "Damping Capacities of B/Al Composite Subjected to Thermal-Mechanical Cycling." Materials Science Forum 561-565 (October 2007): 679–82. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.679.

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The damping capacities of B/Al composite subjected to thermal-mechanical cycling (TMC) were studied. The damping capacities, including the mechanical loss Q-1 and the logarithmic decrement δ , increase with increasing the TMC cycles. The damping capacities of B/Al composite increase more greatly under the elevated applied stresses at the same temperature interval and cycles. After the TMC, the damping capacities can increase 10 times than that of as-fabricated B/Al composite. The damping behavior of B/Al composite under the present test condition is primarily associated with the interfacial degradation during the TMC.

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Ding, Yu Feng, Lin Gan, Jun Bo Zhou, and Bu Yun Sheng. "Bearing-Rotor Coupled System Stability Optimization Design Based on Genetic Algorithm." Advanced Materials Research 199-200 (February 2011): 1130–33. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1130.

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The structure parameter of sliding bearing has significant influence on entire shafting. The structural optimization of elliptical sliding bearing based on the genetic algorithm theory is studied in the paper. Shafting logarithmic decrement is taken as the objective function, the bearing width-diameter ratio, relative clearance and main design parameters such as ellipticity is taken as design variables. Mutual coupling effect between sliding bearing and rotor is considered in the optimization model. An elliptical sliding bearing of shafting has been optimized, and the solution result shows that the shafting stability has been increased, it indicates this method is feasible.

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Никаноров, С. П., Б. К. Кардашев, В. Н. Осипов, В. В. Каминский, and Н. В. Шаренкова. "Неупругость и наноструктурная дислокационная деформация сплава алюминия с кремнием с супермодифицированной эвтектической структурой." Журнал технической физики 89, no. 8 (2019): 1219. http://dx.doi.org/10.21883/jtf.2019.08.47894.72-19.

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AbstractYoung’s modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.

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Bęc, Jarosław, and Ewa Błazik-Borowa. "Dynamic properties of façade frame scaffoldings." MATEC Web of Conferences 285 (2019): 00001. http://dx.doi.org/10.1051/matecconf/201928500001.

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The paper presents data on natural frequencies and damping parameters of scaffoldings. The analyzes were made mainly on the basis of acceleration measurements made on scaffoldings on construction sites. These studies were supplemented by numerical analyzes, which allowed to show changing of the natural frequencies of the scaffoldings as the effect of the structure exploitation. Finally, it was found that the scaffoldings are structures with low natural frequencies ranging from 1.0 Hz to 4.0 Hz and a logarithmic decrement of damping at 0.06 in most cases, however differences can be observed with the values as low as 0.03.

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Bilyk, V. A., E. V. Korobko, G. N. Reizina, E. A. Bashtovaya, E. B. Kaberdina, and V. A. Kuzmin. "Vibration Control of Oscillating System Based on Governing Visco-Elastic Characteristics of Absorber by Means of External Electric Signal." Solid State Phenomena 144 (September 2008): 220–25. http://dx.doi.org/10.4028/www.scientific.net/ssp.144.220.

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Electro-rheological fluids (ERF) allow us to create «smart» devices. One of the basic directions of application of such materials is damping in oscillating systems. This work describes simulation model and offers the results of experimental research by rheological properties and damping characteristic of ERF. Control signal is defined by electric field intensity, which is changed within the bounds of 0…0.5 kV/mm. Amplitude of oscillation – up to 5 mm, oscillation frequency is modified within the bounds of 0.5…5 Hz. The logarithmic damping decrement and natural oscillation frequency of oscillating system, shear stress and viscosity of ERF are determined.

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Malakhov, V. V., and S. М. Vykydanets. "Nature of change of logarithmic decrement as a result of cracking in the beams with loop joints." Bulletin of Prydniprovs’ka State Academy of Civil Engineering and Architecture, no. 1 (March 15, 2020): 83–89. http://dx.doi.org/10.30838/j.bpsacea.2312.260220.83.613.

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45

Hinai, Masakatsu, Showhachi Sawaya, and Hakaru Masumoto. "Effect of Heat Treatment and Cold Working on Aging in Logarithmic Decrement of Al–Zn Alloys." Materials Transactions, JIM 33, no. 9 (1992): 856–60. http://dx.doi.org/10.2320/matertrans1989.33.856.

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46

Poddaeva, O. I., A. N. Fedosova, and P. S. Churin. "The influence of the structural vibrations’ logarithmic decrement on its stability in the event of vortex excitation." IOP Conference Series: Materials Science and Engineering 913 (September 12, 2020): 042069. http://dx.doi.org/10.1088/1757-899x/913/4/042069.

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47

Yum, Myung Kul, Seung Hwan Kim, and Yeoung Geun Jung. "Application of ice water to the face during controlled respiration—a measure of basal vagal tone." Cardiology in the Young 4, no. 4 (October 1994): 358–65. http://dx.doi.org/10.1017/s1047951100002341.

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AbstractWe examined the effectiveness of the application of ice water to the face during metronome-controlled respiration (15 breaths per minute) for vagalstimulation. We also examined the importance of basal vagal tone and sympathovagal interaction in determining the individual response to the stimulation. Fifty-three boys, aged 12 and 13, were included in this study. Vagal tone and sympathovagal interaction were assessed by power spectral analysis of the variability of the RR interval (heart rate). Basal heart rate, high frequency power, and low-to-high frequency power ratios were 81 ± 13(58–110 beats/min), 791 ± 1061(56–4161 m.sec2) and 1.08±1.22 (0.04–4.85) during controlled respiration. After application of ice water, 23 children developed frequent nodal escape beats due to severe sinus bradycardia. Minimum heart rate, high frequency power, and low to high power ratios changed to 42± 12 (19–72 beats/min), 1890±1882 (211–7258 m.sec2) and 0.64±0.43 (0.12–1.46). The increased ratio of high frequency power, maximum decrement in heart rate, and its percent after stimulation were 5.44±5.62 (0.63–24.26), 39±14 (10–81 beats/mm) and 47±15 (16–81%), respectively. The increased ratio of high frequency power was correlated with basal logarithmic high frequency power (r=−0.60, p=O.0004). Maximum heart rate decrement was correlated with basal logarithmic high frequency power (r=−0.60, p=O.OO18) and low-to-high frequency power ratio (r=0.27, p=O.O4). We conclude that application of ice water to the faceduring controlled respiration induces powerful vagal stimulation and bradycardia similar to, or even greater than, facial immersion in cold water. There is wide variability of individual response which can be explained by the magnitude of absolute basal vagal tone.

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Yoshihara, Hiroshi, and Masahiro Yoshinobu. "Effect of specimen configuration on the measurement of off-axis logarithmic decrement of solid wood measured by longitudinal and flexural vibration tests." Holzforschung 68, no. 7 (October 1, 2014): 839–41. http://dx.doi.org/10.1515/hf-2013-0241.

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Abstract Douglas fir (Pseudotsuga menziesii) lumber was tested in terms of off-axis modulus of elasticity (MOEoff-axis) and off-axis logarithmic decrement (λoff-axis) by longitudinal and flexural vibration (VTlong and VTflex) methods. Similar to the results obtained in a previous study, these results indicate that the values of MOEoff-axis are dependent on the length-to-width ratio of specimens when the value of off-axis angle (θ) is approximately 15°. Although the λoff-axis values are also dependent on the length-to-width ratio, the dependence is not pronounced over a specific range of θ. To measure the λoff-axis value accurately, as well as the MOEoff-axis value, the specimen should be sufficiently slender.

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Goggin, D. G., J. K. Scharrer, and R. F. Beatty. "Hydrostatic Damper for the Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump (HPOTP)." Journal of Tribology 112, no. 1 (January 1, 1990): 141–46. http://dx.doi.org/10.1115/1.2920219.

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Alternative methods were evaluated for increasing rotor damping on the SSME HPOTP to reduce bearing dynamic loads and extend their useful life. A unique application of a hydrostatic damper was developed by incorporating a hydrostatic element between stationary turbine bearing support components. Damper design is shown to be dependent on accurate rotordynamic response analysis. Optimization to achieve maximum damper performance under high loading conditions and limited supply flow is discussed. Damping levels approaching critical damping were achieved without major modifications. Bearing dynamic loads are reduced up to 70 percent and rotor mode logarithmic decrement was increased from 0.085 to as much as 1.0. Possible opportunities for further improvements in damper performance are also discussed.

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Fu, Hua, Jian Gang Feng, Hua Qiang Han, and Hua Ling. "Experimental Study on Engineering Properties of Cemented Sand and Gravel." Applied Mechanics and Materials 580-583 (July 2014): 1846–51. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.1846.

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The static and dynamic triaxial shear tests and deformation tests on CSG (cemented sand and gravel) are conducted with different amount of added cementing materials. The mechanical indexes and parameters have obvious increments with mixing of cementing material and accumulation of curing days. However the increments will become mild with further adding of cementing material. The deformation curve of CSG test sample is similar to the curve of sand-gravel sample without mixing with any cementing material, and they both follow the trend of semi-logarithmic decrement law. The dynamic permanent deformation of CSG increases with the increments of confining pressure, consolidation stress and dynamic stress. Thus this deformation still can be calculated using the constitutive model of dynamic residual deformation proposed by Zhujiang Shen Academician.

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