Experimental Study of Low-Frequency Effects on the Dynamic Modulus of a Buna-N Rubber

1955 ◽  
Vol 28 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Allen Q. Hutton ◽  
A. W. Nolle
Keyword(s):  
Dynamic Modulus ◽  
Room Temperature ◽  
Temperature Scale ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Frequency Range ◽  
Frequency Increase ◽  
Frequency Effects ◽  
Similar Compound ◽  
Linear Dynamic

Abstract The linear dynamic Young's modulus of a vulcanized Buna-N gum rubber was measured at frequencies of 0.05, 0.10, and 1.00 cps, in the temperature range − 22° C to 30° C, by a method in which a small differential sinusoidal elongation is superimposed on a 5 per cent static elongation. The width of the dispersion range on the temperature scale (the range in which the logarithm of the modulus increases steeply with decreasing temperature) is only about 10° C, contrasted with widths as great as 25° C found in previous measurements on a similar compound at frequencies of several kilocycles. The modulus-temperature plot shifts upward by only about 4° C per decade of frequency increase of the present range, contrasted with about 10° C per decade in the previous measurements at higher frequencies. It is concluded that this elastomer cannot be described properly by means of the “method of reduced variables”, in which the dynamic properties are ascribed to mechanisms having identical temperature dependence, and that the low-temperature behavior is governed by mechanisms distinct from those effective in the audio-frequency range at room temperature.

Nonlinearity in the Dynamic Properties of Vulcanized Rubber Compounds

1954 ◽  
Vol 27 (1) ◽  
pp. 209-222 ◽  
Author(s):  
W. P. Fletcher ◽  
A. N. Gent
Keyword(s):  
Simple Shear ◽  
Dynamic Modulus ◽  
Dynamic Properties ◽  
Mechanical Vibration ◽  
Frequency Range ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Chemical Combination ◽  
Wide Range ◽  
Static Shear

Abstract Measurements are described of the dynamic properties of rubber, loaded with various amounts and types of filler, when subjected to mechanical vibration in simple shear at amplitudes from 0 to 3 per cent shear in the frequency range 20 to 120 c.p.s. The decrease of dynamic modulus with increasing amplitude is shown, for a wide range of filler types and concentrations, to be determined by the amount of stiffening produced by the filler. This relationship is not influenced by variations in the vulcanizing ingredients, reasonable variations in state of vulcanization, addition of softener, or imposition of static shear strain. Rubber compounds stiffened by mixture with, or chemical combination of, other polymers exhibit a smaller order of nonlinearity than that described above and also exhibit much lower hysteresis values within the amplitude range 0 to 3 per cent shear.

Anelastic Phenomena and Cr2N Precipitation in a High Nitrogen Austenitic Steel

2010 ◽  
Vol 89-91 ◽  
pp. 485-490
Author(s):  
Paolo Deodati ◽  
Roberto Montanari ◽  
Ludovica Rovatti ◽  
Nadia Ucciardello ◽  
Andrea Carosi
Keyword(s):  
Austenitic Steel ◽  
Dynamic Modulus ◽  
Room Temperature ◽  
Discontinuous Precipitation ◽  
Phase Changes ◽  
Frequency Range ◽  
High Nitrogen ◽  
Prepared Material ◽  
Frequency Modulation Detection ◽  
Vibrating Reed

Internal friction (IF) and dynamic modulus measurements on a high nitrogen (0.8 wt%) austenitic steel in the temperature range from room temperature to 800 °C have been carried out by using a vibrating reed technique with electrostatic excitation and frequency modulation detection of flexural vibrations in the frequency range of kHz. The IF spectrum of the as-prepared material shows a broad peak superimposed to an exponentially increasing background. The discontinuous precipitation of Cr2N phase changes the characteristics of the peak. The results have been discussed by considering interstitial-substitutional (i-s) interactions.

Propagation of Audiofrequency Sound in High Polymers

1950 ◽  
Vol 23 (1) ◽  
pp. 163-171
Author(s):  
R. S. Witte ◽  
B. A. Mrowca ◽  
E. Guth
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Intermolecular Forces ◽  
Temperature Curve ◽  
Frequency Range ◽  
Dynamic Measurements ◽  
Time Effects ◽  
And Shifts ◽  
Viscoelastic Constants ◽  
Made In

Abstract Velocity and attenuation measurements were made in thin strips of rubber from 0.5 to 5 kc and from −5° to 90° C to obtain the dynamic viscoelastic constants of Butyl and GR-S gum stocks. Above room temperature velocity and attenuation are higher in Butyl gum than in GR-S. In all cases, the velocity increases with decreasing temperature and increasing frequency. The attenuation shows a peak with temperature. For Butyl, the peaks are broad and occur at higher temperatures than for GR-S. For both stocks an increase in frequency gives peaks which are higher, sharper, and shifted to higher temperatures. In some instances, there are indications of peaks in the attenuation versus frequency at frequencies beyond our range of measurement. The behavior of the dynamic modulus in the temperature and frequency range studied is similar to that of the velocity. These results, combined with low temperature static measurements and very low frequency dynamic measurements, indicate a U-shaped modulus-temperature curve whose minimum broadens and shifts to higher temperatures with increasing frequency. This may be explained by a generalization of the kinetic theory of rubber elasticity, taking into account intra- and intermolecular forces, and considering time effects.

Researches on a roller dempfying properties when vibrating a cutting instrument in a bandsaw equipment

2016 ◽  
Vol 6 (3) ◽  
pp. 202-206
Author(s):  
Чепелева ◽  
Marina Chepeleva ◽  
Чепелев ◽  
Stanislav Chepelev ◽  
Чернышков ◽  
...  
Keyword(s):  
Mathematical Description ◽  
Dynamic Properties ◽  
Superposition Principle ◽  
Low Frequency ◽  
Harmonic Vibration ◽  
Experimental Methodology ◽  
Mathematical Apparatus ◽  
Frequency Range ◽  
New Material ◽  
To Receive

The article deals with the usage of new material – the pressed wood together with modifi-cators to detect the dempfying properties to improve a soothing roller in a bandsaw equipment WoodMizerLT 15. The article stresses the idea of the experimental methodology to receive data for the future, further mathematical description of dynamic properties of the bandsaw equipment in low-frequency range of harmonic vibration. The superposition principle is used for the above-mentioned object, so the mathematical apparatus is limited by arrival.

Small Amplitude Dynamic Properties of Ni48Ti46Cu6 SMA Ribbons: Experimental Results and Modelling

2006 ◽  
Vol 128 (3) ◽  
pp. 260-267 ◽  
Author(s):  
C. Remillat ◽  
M. R. Hassan ◽  
F. Scarpa
Keyword(s):  
Fractional Derivative ◽  
Loss Factor ◽  
Small Amplitude ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Viscoelastic Damping ◽  
Compact Representation ◽  
Damping Capacity ◽  
Frequency Range ◽  
Thermally Induced

This work illustrates viscoelastic testing and fractional derivative modelling to describe the thermally induced transformation equivalent viscoelastic damping of NiTiCu SMA ribbons. NiTiCu SMA ribbons have been recently evaluated to manufacture novel honeycombs concepts (conventional and negative Poisson’s ratio) in shape memory alloys for high damping and deployable sandwich antennas constructions. The dynamic mechanical thermal analysis (DMTA) test has been carried out at different frequencies and temperatures, with increasing and decreasing temperature gradients. Thermally induced transformations (austenitic and martensitic) provide damping peaks at low frequency range excitations. On the opposite, the storage moduli are not affected by the harmonic pulsation. As the SMA ribbon increases its stiffness, the damping capacity reduces, and the loss factor drops dramatically at austenite finish temperature. The fractional derivative models provide a compact representation of the asymmetry of the peak locations, as well as the storage modulus change from martensite to austenite phases.

Lexical dynamics for low-frequency complex words

2007 ◽  
Vol 2 (3) ◽  
pp. 419-463 ◽  
Author(s):  
R. H. Baayen ◽  
Lee H. Wurm ◽  
Joanna Aycock
Keyword(s):  
Word Recognition ◽  
Theoretical Analysis ◽  
Lexical Decision ◽  
Target Word ◽  
Low Frequency ◽  
Mixed Effects ◽  
Frequency Range ◽  
Frequency Effects ◽  
Complex Words ◽  
Root Frequency

In this study we examine the word recognition process for low-frequency morphologically complex words. One goal of the study was to replicate and expand upon findings suggesting facilitative effects of morphological relatives of a target word. A second goal was to demonstrate the need for a reinterpretation of root and surface frequency effects, which traditionally have been taken as indicators of parsing-based and memory-driven processing, respectively. In a first study, we used the same stimuli across auditory and visual lexical decision and naming. Mixed-effects statistical modeling revealed that surface frequency was a robust predictor of RTs even in the very low end of the distribution, but root frequency was not. Also, the nature of the similarity between a target and its lexical competitors is crucial. Measures gauging the influence of morphological relatives of the target were facilitative, while measures gauging the influence of words related only in form were inhibitory. A second study analyzing data from the English Lexicon Project, for a large sample of words from across the full frequency range, supports these conclusions. An information-theoretical analysis of root and surface frequency explains why surface frequency must be the most important predictor, with only a marginal role for root frequency.

Effect of Primary Molecular Weight on the Dynamic Properties of Cured Rubber

1959 ◽  
Vol 32 (3) ◽  
pp. 651-661
Author(s):  
E. V. Kuvshinskiĭ ◽  
M. M. Fomicheva
Keyword(s):  
Molecular Weight ◽  
Dynamic Modulus ◽  
Room Temperature ◽  
Dynamic Properties ◽  
Molecular Weights ◽  
Vulcanized Rubber ◽  
Equilibrium Modulus ◽  
Modulus Of Resilience ◽  
Molecular Weight Fractions ◽  
Butadiene Styrene

Abstract 1. Studied were the moduli of resilience and rebound elasticity of the vulcanized rubbers made from fractions of butadiene-styrene rubber “SKS-30-A” at temperatures of 20, 60, and 100° C in the region of molecular weights from 45,000 to 620,000 with various degrees of vulcanization (with variation in the pseudoequilibrium modulus from 5 to 70 kg/cm2). 2. The dynamic modulus of resilience is little dependent on the molecular weight of the original rubber both at room temperature and at higher temperatures. 3. At higher temperatures the elasticity of vulcanized rubber is mainly determined by the degree of vulcanization, the measure of which is the pseudo-equilibrium modulus, and is little dependent on the initial molecular weight. At low temperatures (20° C) elasticity increases with the degree of vulcanization, but it increases at different rates for vulcanized rubbers made from fractions with different molecular weights. At 20° C the increase in the degree of vulcanization increases the elasticity of vulcanized rubbers made from low-molecular fractions (45,000) to a lower degree than of those made from high molecular weight fractions (above 133,000). 4. The value of the maximum elasticity of vulcanized rubbers obtained from rubbers of the same molecular weight is not dependent on the type of accelerator used.

Dielectric and impedance spectroscopy of K+-doped MgAl2O4 nanoparticles

2018 ◽  
Vol 32 (15) ◽  
pp. 1850189
Author(s):  
Javed Ahmad ◽  
S. H. Bukhari ◽  
M. Qadeer Awan ◽  
M. Ehsan Mazhar ◽  
A. R. Makhdoom
Keyword(s):  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Parent Compound ◽  
Low Frequency ◽  
Space Charge Polarization ◽  
Relaxation Phenomena ◽  
Frequency Range

In this study, the dielectric response of Potassium (K[Formula: see text])-doped magnesium aluminates nanoparticles (Mg[Formula: see text]K[Formula: see text]Al2O4, x = 0.0, 0.25, 0.5, 0.75, 1.0) have been investigated as a function of frequency (20 Hz to 2 MHz) at room-temperature. Interestingly, the behavior of dielectric constant indicated the ionic or space charge polarization in the low-frequency range and it remains almost constant at high frequency. However, the value of conductivity increases at higher frequencies which is consistent with the previously reported results for the parent compound MgAl2O4. Moreover, the Cole–Cole plots represent various relaxation phenomena reflecting the existence of grain (boundaries) resistance effects.

LOW‐FREQUENCY IMPEDANCE PARAMETERS OF BASALT, GRANITE, AND QUARTZITE

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 68-75 ◽  
Author(s):  
A. S. Khalafalla ◽  
W. J. Maegley
Keyword(s):  
Room Temperature ◽  
Electrical Impedance ◽  
Analog Circuit ◽  
Low Frequency ◽  
Frequency Variation ◽  
Frequency Range ◽  
Argand Diagram ◽  
Circular Arcs ◽  
Impedance Parameters ◽  
Zero Frequency

An analog circuit digital computer setup was used to evaluate rock electrical impedance and phase angle in the frequency range 0.05 to 2 khz. Room‐temperature measurements were made on several samples of basalt, granite, and quartz. Argand diagram presentation of rock reactance as a function of its resistance at a series of frequencies described a semicircular arc. Rock impedance circular arcs can be used to define the rock resistivity at infinite frequency and the dc resistivity at the limit of zero frequency. Variation of rock resistance with the logarithm of frequency indicated finite rock dielectric dispersions at characteristic frequency ranges. Also, variation of rock reactance with the logarithm of frequency exhibited finite relaxation peaks, which can be used to difine the rock characteristics or turnover frequency as well as a characteristic or relaxation time.

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