Characterization of the Mechanical and Vibration Behavior of Flax Composites with an Interleaved Natural Viscoelastic Layer

2018 ◽  
pp. 186-194
Author(s):  
Daoud Hajer ◽  
El Mahi Abderrahim ◽  
Rebiere Jean-Luc ◽  
Taktak Mohamed ◽  
Haddar Mohamed
Keyword(s):  
Viscoelastic Layer ◽  
Vibration Behavior

Influence of the Poisson's ratio on the efficiency of viscoelastic damping treatments

2021 ◽  
Vol 263 (3) ◽  
pp. 3790-3794
Author(s):  
Lucie Rouleau ◽  
Isadora Ruas Henriques ◽  
Jean-François Deü
Keyword(s):  
Poisson’S Ratio ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Indirect Measurement ◽  
Poisson's Ratio ◽  
Viscoelastic Layer ◽  
Temperature Dependent ◽  
Complex Shear ◽  
Damping Treatments

An efficient way of mitigating noise and vibration is to embed viscoelastic patches into the host structure. Viscoelastic properties are of significant importance in determining the performance of the passive damping treatment. The behaviour of homogeneous isotropic materials is described by two elastic constants (generally the Young modulus and the Poisson ratio, or the shear and bulk moduli), which are frequency- and temperature-dependent in the case of viscoelastic materials. In practice, the Poisson's ratio is often considered as independent of temperature and frequency. One goal of this work is to numerically evaluate the validity of this assumption and its limitations (frequency range, thickness of the viscoelastic layer). To this end, a thermo-mechanical characterization of a viscoelastic material is carried out by dynamic measurements of the complex shear and bulk moduli, allowing the indirect measurement of the frequency- and temperature-dependent Poisson's ratio. Moreover, the measurements of the Poisson's ratio (direct or indirect) can lead to considerable uncertainties. For instance, large discrepancies have been observed when characterizing the Poisson's ratio of polymer foams. Another goal of this work is to investigate the influence of those uncertainties on the dynamic response of a damped structure.

Vibration behavior of long shape vegetables

2007 ◽  
Vol 3 (1) ◽  
pp. 21-46 ◽  
Author(s):  
Viktoria Zsom-Muha ◽  
József Felfödi
Keyword(s):  
Resonant Frequency ◽  
Fruits And Vegetables ◽  
Experimental Tests ◽  
Close Correlation ◽  
Effective Length ◽  
Stiffness Coefficient ◽  
Acoustic Response ◽  
Vibration Behavior ◽  
Response Method

The acoustic response method is one of the most important dynamic methods used for assessment of the mechanical texture of different fruits and vegetables. The method is based on the mechanical excitation of the sample and the assessment of its resonant frequency. Different approaches are known for the interpretation of the vibration behavior of the samples having definite shapes. According to the most widely used interpretation, the stiffness of the sample ( s ) is dependent on the resonant frequency ( f ) and the mass ( m ) of the sample. The aim was to extend the acoustic response method to typically non-spherical samples (carrot, cucumber, etc.) to find a correct interpretation of the behavior of the sample and to introduce a stiffness coefficient suitable for characterization of the mechanical properties of a long shaped sample. According to Finite Element Modeling and experimental tests on carrot samples a close correlation was found between the resonant frequency and the effective length of the sample in a given shape range. A principally new stiffness coefficient was proposed for long shaped samples. It was found to be suitable for the characterization of the hardness of the vegetables in a wide size range.

Characterization of the vibrational behaviour of flax fibre reinforced composites with an interleaved natural viscoelastic layer

2017 ◽  
Vol 128 ◽  
pp. 23-31 ◽  
Author(s):  
Hajer Daoud ◽  
Abderrahim El Mahi ◽  
Jean-Luc Rebière ◽  
Mohamed Taktak ◽  
Mohamed Haddar
Keyword(s):  
Flax Fibre ◽  
Viscoelastic Layer ◽  
Reinforced Composites ◽  
Fibre Reinforced Composites

Characterization of the torsional vibration behavior of circular and rectangular cross-sectional arc springs: Theory and experiments

2021 ◽  
Vol 63 (2) ◽  
pp. 113-118
Author(s):  
Samet Fidanciogullari ◽  
Ahmet Yildiz
Keyword(s):  
Torsional Vibration ◽  
Experimental Tests ◽  
Experimental Results ◽  
Experimental Characterization ◽  
Cross Sectional ◽  
Vibration Behavior ◽  
The Masses ◽  
Theory And Experiments ◽  
Good Agreement

Abstract This paper is about the theoretical and experimental characterizations of the torsional vibration behavior of circular and rectangular cross-sectional arc springs. Firstly, the dynamic behaviors of arc springs with different cross-sectional wire profiles designed for a dual mass flywheel are modeled by mathematical formulations. After that, experimental tests are performed to verify these models and it is observed that the stiffness characterizations are in good agreement with experimental results. Lastly, the masses of two different arc springs are compared by regarding the same vibration stiffness criteria and it is demonstrated that the rectangular wire provides an arc spring with a 9.44 vol.-% lighter structure. Thus, the outcomes of this paper can be good references for the manufacturer about the numerical and experimental characterization of dual mass flywheel springs, especially for rectangular wire arc springs.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

Characterization of Coherent, Ordered Precipitates in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 144-145
Author(s):  
B. H. Kear ◽  
J. M. Oblak
Keyword(s):  
Stable Phase ◽  
Nickel Base Superalloy ◽  
Alloy 718 ◽  
Commercial Alloy ◽  
Precipitate Morphology ◽  
Continuous Precipitation ◽  
Nickel Base ◽  
Base Superalloy ◽  
Strengthening Precipitate

A nickel-base superalloy is essentially a Ni/Cr solid solution hardened by additions of Al (Ti, Nb, etc.) to precipitate a coherent, ordered phase. In most commercial alloy systems, e.g. B-1900, IN-100 and Mar-M200, the stable precipitate is Ni3 (Al,Ti) γ′, with an LI2structure. In A lloy 901 the normal precipitate is metastable Nis Ti3 γ′ ; the stable phase is a hexagonal Do2 4 structure. In Alloy 718 the strengthening precipitate is metastable γ″, which has a body-centered tetragonal D022 structure.Precipitate MorphologyIn most systems the ordered γ′ phase forms by a continuous precipitation re-action, which gives rise to a uniform intragranular dispersion of precipitate particles. For zero γ/γ′ misfit, the γ′ precipitates assume a spheroidal.

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