The measurement of the bulk modulus of polymers and its loss factor in the 1 to 10 kHz frequency range

1980 ◽  
Vol 67 (S1) ◽  
pp. S23-S23
Author(s):  
Geoffrey L. Wilson
Keyword(s):  
Bulk Modulus ◽  
Loss Factor ◽  
Frequency Range

scholarly journals Are Single Polymer Network Hydrogels with Chemical and Physical Cross-Links a Promising Dynamic Vibration Absorber Material? A Simulation Model Inquiry

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5127
Author(s):  
Leif Kari
Keyword(s):  
Simulation Model ◽  
Loss Factor ◽  
Polymer Network ◽  
Vibration Absorber ◽  
Vibration System ◽  
Frequency Range ◽  
Dynamic Vibration Absorber ◽  
High Loss ◽  
Dynamic Vibration ◽  
Cross Links

Tough, doubly cross-linked, single polymer network hydrogels with both chemical and physical cross-links display a high loss factor of the shear modulus over a broad frequency range. Physically, the high loss factor is resulting from the intensive adhesion–deadhesion activities of the physical cross-links. A high loss factor is frequently required by the optimization processes for optimal performance of a primary vibration system while adopting a dynamic vibration absorber, in particular while selecting a larger dynamic vibration absorber mass in order to avoid an excess displacement amplitude of the dynamic vibration absorber springs. The novel idea in this paper is to apply this tough polymer hydrogel as a dynamic vibration absorber spring material. To this end, a simulation model is developed while including a suitable constitutive viscoelastic material model for doubly cross-linked, single polymer network polyvinyl alcohol hydrogels with both chemical and physical cross-links. It is shown that the studied dynamic vibration absorber significantly reduces the vibrations of the primary vibration system while displaying a smooth frequency dependence over a broad frequency range, thus showing a distinguished potential for the tough hydrogels to serve as a trial material in the dynamic vibration absorbers in addition to their normal usage in tissue engineering.

A New Methodology for the Accurate and Consistent Identification of Modal Parameters Using Multi-FRF Analysis

1995 ◽  
Author(s):  
R. M. Lin ◽  
S.-F. Ling
Keyword(s):  
Eigenvalue Problem ◽  
Loss Factor ◽  
Frequency Response Function ◽  
Natural Frequencies ◽  
Identification Problem ◽  
Modal Parameters ◽  
Frequency Range ◽  
Case Examples ◽  
Measured Frequency Response ◽  
Damping Loss Factor

Abstract A new method for the estimation of modal parameters is presented in this paper. Unlike the majority of the existing methods which involve complicated curve fitting and interpolative procedures, the proposed method calculates the modal parameters by solving eigenvalue problem of an equivalent eigensystem derived from measured frequency response function (FRF) data. It is developed based on the practical assumption that only one incomplete column of the FRF matrix of the test structure has been measured in a frequency range of interest. All the measured FRFs are used simultaneously to construct the equivalent eigensystem matrices from which natural frequencies, damping loss factor and modeshape vectors of interest can be directly solved. Since the identification problem is reduced to an eigenvalue problem of an equivalent system, natural frequencies and damping loss factors identified are consistent. Further procedures for normalizing the identified eigenvectors so that they become mass-normalized are developed. Numerical case examples are given to demonstrate the practicality of the proposed method and results obtained are indeed very promising. It is believed that with the availability of such identification method, modal analysts’ dream of intelligent and full automatic modal analysis will become a reality.

Apparatus for the Direct Determination of the Dynamic Bulk Modulus

1957 ◽  
Vol 30 (2) ◽  
pp. 449-459
Author(s):  
J. E. McKinney ◽  
S. Edelman ◽  
R. S. Marvin
Keyword(s):  
Natural Rubber ◽  
Bulk Modulus ◽  
Direct Measurement ◽  
Static Pressure ◽  
Direct Determination ◽  
Preliminary Evaluation ◽  
Air Bubbles ◽  
Frequency Range ◽  
Piezoelectric Crystals

Abstract An apparatus has been developed for the direct measurement of the real and imaginary parts of the dynamic bulk modulus of solid and liquid materials over the frequency range of 50 to 10,000 cps. Piezoelectric crystals serving as driver and detector, together with the sample and a confining liquid, are contained in a cavity small compared with the wavelength of sound at these frequencies. Static pressure is superposed to eliminate the effect of small air bubbles. The complex compliances of the sample, confining liquid, and the cavity, are additive in this region, where the compliance is pure dilatation. The dynamic compliances of several natural rubber-sulfur mixtures were obtained in a preliminary evaluation of the behavior of the apparatus.

scholarly journals Dielectric Relaxation in Temperate Glaciers

1967 ◽  
Vol 6 (48) ◽  
pp. 897-909 ◽  
Author(s):  
P. W. F. Gribbon
Keyword(s):  
Dielectric Relaxation ◽  
Loss Factor ◽  
Relaxation Times ◽  
Frequency Range ◽  
Spreading Factor ◽  
Cold Surface ◽  
Relative Temperature ◽  
Low Frequencies ◽  
Glacial Ice ◽  
Impurity Ion

The dielectric relaxation ofnévéand glacial ice has been studied on two temperate glaciers in Greenland and France. Measurement of the capacitance and loss tangent in the audio-frequency range of thin parallel wires placed on the surface of a glacier gaveϵ′, the relative permittivity, andϵ″, the loss factor of thenévé. The relaxation time can be expressed in terms of the frequencyfmat the maximumϵ″ value of the Cole-Coleϵ″−ϵ′ diagram, and its variation with depth was derived from the Cole-Cole diagrams obtained for different wire separations.For wet 0°C. surface snow in Greenland,fm≈ 4 kHz. and decreased with the increase in density and form factor at greater depths, while for the low-density, cold surfacenévéin Francefm≈ 2 kHz. and increased with the increase in temperature at greater depths. All Cole-Cole diagrams showed both impurity-ion losses at low frequencies below 6 kHz., and a spreading factor of the distribution in relaxation times caused by the changes in the physical properties of the glacier with depth. Although the method could not measure temperatures absolutely, relative temperature differences and the position of the 0°C. isotherm were detected when a temperature gradient existed in a glacier.

Determination of Dynamic Bulk Modulus of Elastomers Using Pressure Measurement

1993 ◽  
Vol 66 (5) ◽  
pp. 749-753 ◽  
Author(s):  
B. P. Holownia ◽  
E. H. James
Keyword(s):  
Bulk Modulus ◽  
Pressure Measurement ◽  
Frequency Range ◽  
Novel Method ◽  
Pressure Changes

Abstract A novel method of determining dynamic bulk modulus of elastomers, by measurement of pressure changes of the fluid in which the specimen is immersed, was successful in principle. The frequency range covered was between 100 Hz and 1200 Hz which was limited by the power of the oscillator used.

Dielectric Properties of Eucalyptus urophylla Under an Ultra-Wide Frequency Range

2020 ◽  
Vol 12 (8) ◽  
pp. 1236-1241
Author(s):  
He Xia ◽  
Wang Yong ◽  
Li Yunyan ◽  
Wei Yanqiang ◽  
Quan Peng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Loss Factor ◽  
Wide Frequency Range ◽  
Dielectric Loss Factor ◽  
Regression Equations ◽  
Eucalyptus Urophylla ◽  
Frequency Range ◽  
Tangential Directions

Dielectric properties of Eucalyptus urophylla wood were measured by using a network analyzer over an ultrawide frequency range between 0.2 GHz and 20 GHz. The effects of moisture content (MC), temperature and frequency on the dielectric permittivity and the dielectric loss factor of Eucalyptus urophylla were investigated along different grain directions. The results showed that the dielectric permittivity along with the dielectric loss factor increased significantly with the elevation in MC. At the frequency of 2380 MHz with the MC increasing from 0% to 100%, the dielectric permittivity along different grain directions (including longitudinal, radial and tangential directions) increased by 180%, 110% and 112%, respectively, while the loss factor along these three directions increased by 1642%, 3703% and 5058%, respectively. In addition, the increase in dielectric properties of Eucalyptus urophylla wood was determined with the temperature elevating. When the temperature elevated from 20 °C to 140 °C, the dielectric permittivity at 2380 MHz along the longitudinal, radial and tangential directions, increased by 19%, 14% and 15%, respectively, while the loss factor increased by 133% at most. As the radio frequency increased, the dielectric permittivity of wood decreased. Regression equations satisfactorily described the dielectric properties of wood along different grain directions with different moisture contents.

Experimental Measurement of Dynamic Bulk Modulus Using Holography

1985 ◽  
Vol 58 (2) ◽  
pp. 258-268 ◽  
Author(s):  
B. P. Holownia
Keyword(s):  
Bulk Modulus ◽  
Room Temperature ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Limiting Factor ◽  
Frequency Range ◽  
Holographic Method ◽  
Indirect Methods ◽  
Servo Valve ◽  
Hydraulic Servo

Abstract The results show that the dynamic bulk modulus for NBR at room temperature is about 50% higher than the static bulk modulus in the frequency range of 1–200 Hz. The limiting factor was the servo-valve used which does not give enough dynamic pressure fluctuations above 200 Hz to obtain accurate results of the dynamic bulk modulus. The holographic method discussed here offers a number of advantages over other methods used in measuring dynamic bulk modulus. (i) The samples are of realistic size and any soft spots in the sample which would distort the results can be immediately identified. (ii) Dynamic bulk modulus can be measured accurately in the frequency range of 1 Hz–1000 Hz or higher, provided the hydraulic servo-valve used can respond in the frequency range. Work is already in hand which extends this frequency range to 1200 Hz. (iii) The change of volume of the sample is a direct measurement unlike other indirect methods, therefore, there is more confidence in the results.

scholarly journals Dielectric Properties of Ternary ( ) ( )x ( ) x ZnO MgO PO 30 2 5 70− (x = 5, 8, 13) Glasses

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
S. F. Khor ◽  
Z. A. Talib ◽  
W. M. Daud ◽  
H. A. A. Sidek ◽  
W. M. M. Yunus ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Empirical Data ◽  
Loss Factor ◽  
Low Frequency ◽  
Frequency Range ◽  
Melt Quenching ◽  
Dipolar Relaxation ◽  
Temperature Range

(ZnO)30(MgO)x(P2O5)70-x glasses of the composition x = 5, 8 and 13 mol % have been prepared by melt quenching technique. The dielectric permittivity (89) and loss factor (8:) were measured in the frequency range from 0.01 Hz to 1 MHz and in the temperature range 303 to 573 K . From the results there are evidence of dipolar relaxation occurring between 103 – 106 Hz while at low frequency the spectrum is dominated by dc conduction which manifested by the 1/@ slope of loss factor plot. Value of the relaxing frequency (@p) plotted against 1/T shows one electrical transportation mechanism. The empirical data was sufficiently fitted by using Harviliak-Negami equation.

scholarly journals Dielectric and Conductivity Properties of Some Wood Composites

2016 ◽  
Vol 8 ◽  
pp. 51-60
Author(s):  
K.Ch. Varada Rajulu ◽  
B.N. Mohanty
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Low Temperature ◽  
Temperature Region ◽  
Loss Factor ◽  
Wood Composites ◽  
Frequency Range ◽  
Increasing Temperature ◽  
Coaxial Probe

This study presents the dielectric and conductivity properties as function of temperature and frequency of wood based composites. These properties were measured by an open-ended coaxial probe at frequency range between 100 kHz to 100MHz, temperature from 30OC to 200OC which is fully computer interfaced. It has been observed that dielectric constant (ε') and dielectric loss factor (ε") increase with increasing temperature and decrease with increasing frequency. At low temperature region, the conductivity depends significantly on the frequency. However, with the increase in temperature dielectric relaxation takes place and the dependency of the conductivity on frequency get reduced. The patterns of variation were established for the studied specimens and discrepancies were discussed. The study of dielectric properties will help in improving the drying, heating and gluing processes of wood and wood based products.

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