scholarly journals Theoretical and experimental method for determining elastic characteristics of nanomaterials

2019 ◽  
Vol 489 (5) ◽  
pp. 469-472
Author(s):  
V. M. Fomin ◽  
A. A. Filippov
Keyword(s):  
Mechanical Characteristics ◽  
Heterogeneous Material ◽  
Uniaxial Stress ◽  
Analytical Form ◽  
Mechanical Tests ◽  
Stress And Strain ◽  
Binder Phase ◽  
Homogeneous Materials ◽  
Silica Dioxide ◽  
Elastic Characteristics

The method allows determining the mechanical characteristic of nanoobjects was presented. A heterogeneous material consisting of a nanophase and a binder phase was considered, the mass and volume concentrations of components were given. Heterogeneous material is reduced to homogeneous by averaging methods while the mechanical characteristics will be associated with averaged ones. Assuming that the mechanical characteristics of the binder and averaged homogeneous materials are known from mechanical tests, the system of equations allow us to determine the mechanical characteristics of nanoobjects included in this heterogeneous material. It is believed that the mechanical characteristics of bonding and averaged homogeneous materials make it possible to obtain equations of equations that allow one to determine the mechanical characteristics of nano-objects present in this heterogeneous material. Classical mechanical tests were carried out, describing the uniaxial stress and strain states of materials, which made it possible to obtain an analytical form the dependences of the mechanical characteristics of nanophases depending on their size. Specific examples are given for silica dioxide nanoparticles (Aerosil and Tarkosil powders).

Calculations for Uniaxial Stress and Strain Cycling in Plasticity

1984 ◽  
Vol 51 (3) ◽  
pp. 487-493 ◽  
Author(s):  
P. M. Naghdi ◽  
D. J. Nikkel
Keyword(s):  
Type Theory ◽  
Uniaxial Stress ◽  
Mean Value ◽  
Stress And Strain ◽  
Material Response ◽  
Tension And Compression ◽  
Stress Cycling ◽  
The Mean ◽  
Rate Type ◽  
Strain Cycling

Within the framework of an existing purely mechanical, rate-type theory of plasticity, detailed calculations are presented for certain types of material response during stress and strain cycling in a uniaxial homogeneous deformation. These features pertain specifically to material response in stress cycling between fixed values of stress in tension and compression (not necessarily equal in magnitude) resulting in ratcheting of strain, and a type of saturation hardening caused by strain cycling between any two fixed values of strain when the mean value of stress (in tension and compression) tends to zero.

Experimental uniaxial stress and strain derivatives of the Fermi surface of rhenium

1980 ◽  
Vol 58 (8) ◽  
pp. 1191-1199 ◽  
Author(s):  
E. Fawcett ◽  
F. W. Holroyd ◽  
J. M. Perz
Keyword(s):  
Fermi Surface ◽  
Uniaxial Stress ◽  
Stress And Strain ◽  
Strong Anisotropy ◽  
Quantum Oscillations ◽  
Band Structure Calculations ◽  
Landau Quantum ◽  
Derivatives Of ◽  
Structure Calculations ◽  
The Magnetic Field

The derivatives of the areas of extremal orbits on all the small sheets of the Fermi surface of rhenium, with respect to stress and strain along the hexad axis, have been determined from simultaneous measurements of Landau quantum oscillations in magnetostriction and torque, and also in sound velocity and torque. Strong anisotropy is observed in the stress derivatives of orbits in zones five and six as the direction of the magnetic field defining the normal to the orbit is varied; the anisotropy is most pronounced for orbits which come close to the line of degeneracy AL on the hexagonal Brillouin zone face. The derivatives of the small void in zone eight are found to be very large; this is consistent with the results of band structure calculations which show that this feature of the Fermi surface is very sensitive to small changes in the Fermi energy. Cyclotron effective masses for a number of orbits on the void have also been measured.

Thermoplastique Degradation under Heat and Irradiation

2021 ◽  
Vol 904 ◽  
pp. 196-201
Author(s):  
Sonya Redjala ◽  
Said Azem ◽  
Nourredine Ait Hocine
Keyword(s):  
Mechanical Characteristics ◽  
Low Cost ◽  
Impact Resistance ◽  
Ultra Violet ◽  
Analytical Techniques ◽  
Mechanical Tests ◽  
Ultraviolet Rays ◽  
Technical Material ◽  
Effects Of Temperature ◽  
The Impact

The aim of the article is to highlight the effect of the environment on the properties of a polycarbonate (PC). It consists in aging this material under Ultra-violet (UV) combined with temperature for different periods of time, and to reveal the physicochemical and mechanical changes caused by aging. PC is a highly valued technical material for its various important characteristics and low cost. It finds its application in various fields but mainly in those whose requirements are the transparency and the impact resistance. The physicochemical and mechanicals characterizations of the marketed polycarbonate are necessary in order to highlight its intrinsic properties and to develop strategies that can improve its lifespan. In this work, we highlight the physicochemical and mechanical characteristics of virgin and aged polycarbonate. For this, analytical techniques and mechanical tests were used. A comparison of the characteristics revealed the combined effects of temperature and ultraviolet rays.

scholarly journals Evaluation of Microcrystalline Chitosan and Fibrin Membranes as Platelet-Derived Growth Factor-BB Carriers with Amoxicillin

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Kazimiera H. Bodek ◽  
Karolina M. Nowak ◽  
Marcin Kozakiewicz ◽  
Andrzej Bodek ◽  
Marta Michalska
Keyword(s):  
Growth Factor ◽  
Mechanical Characteristics ◽  
Composite Membranes ◽  
Mechanical Tests ◽  
Platelet Derived Growth Factor ◽  
Sem Images ◽  
Elongation At Break ◽  
Microcrystalline Chitosan ◽  
Kinetics Of

The aim of this study was to describe the mechanical and sorption features of homogeneous and composite membranes which consist of microcrystalline chitosan (MCCh) and fibrin (Fb) in various proportions as well as thein vitrokinetics of platelet-derived growth factor-BB (PDGF-BB) released from ten types of membranes in the presence or absence of amoxicillin (Am). The films were characterized by Fourier transform infrared (FTIR) spectroscopy, mechanical tests: breaking strength (Bs) and elongation at break (Eb), as well as SEM images, and swelling study. The influence of the form of samples (dry or wet) on Young’s modulus (E) was also examined. The homogeneous MCCh (M1) and composite M3 and M4 (MCCh : Fb = 2 : 1 and 1 : 1) membranes were characterized by good sorption properties and higher mechanical strength, when compared with Fb (M2) membrane. Connecting MCCh with Fb decreases release of PDGF-BB and increases release of Am. The most efficient release of PDGF-BB was observed in the case of M4 (the optimum MCCh : Fb ratio was 1 : 1) membrane. It was found that the degree of PDGF-BB release from the membrane is influenced by the physicochemical and mechanical characteristics of the films and by its affinity to growth factor PDGF-BB.

Study on Bending and Twisting Mechanical Properties of High Voltage Porcelain Post Insulator

2014 ◽  
Vol 521 ◽  
pp. 334-338
Author(s):  
En Wei Zhang ◽  
Yun Bo Yang ◽  
Wei Song ◽  
Xiao Wei Wei ◽  
Zhi Bin Qiu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Distribution ◽  
Bending Moment ◽  
Element Model ◽  
Mechanical Tests ◽  
Measurement Technology ◽  
Stress And Strain ◽  
Full Account ◽  
Post Insulator ◽  
Stress And Strain Distribution

To study the mechanical properties of porcelain post insulators, the finite element model was established by ANSYS to calculate stress and strain distribution under bending or torsion moments. Mechanical tests based on resistance strain measurement technology were carried out on the actual porcelain post insulators to measure their strain distribution. The results show that sheds will cause strain concentration at the roots of porcelain column whether the post insulator is bearing bending or torsion load. The stress and strain of shed roots gradually increase from top to bottom along the post insulator when bearing bending moment, while they are relatively uniform under torsion moment. It should be taken full account of the stress concentration caused by sheds during the selection or maintenance of porcelain post insulators.

Application of Rheological Model of Material with Microdefects and Nanodefects with Hydrogen in the Case of Cyclic Loading

2015 ◽  
Vol 651-653 ◽  
pp. 592-597 ◽  
Author(s):  
Yuri A. Yakovlev ◽  
Alexander K. Belyaev ◽  
Vladimir A. Polyanskiy
Keyword(s):  
Plastic Deformation ◽  
Stability Analysis ◽  
Rheological Model ◽  
Continuous Medium ◽  
Mechanical Characteristics ◽  
Cylindrical Specimen ◽  
Parametric Instability ◽  
System Stability ◽  
Stress And Strain ◽  
Periodic Loading

The paper deals with the example of application of the two continuum rheological model of materials with microdefects, nanodefects and solute hydrogen for calculation of stress and strain in cylindrical specimen under periodic loading. The model suggested allows one to relate the mechanical characteristics with the hydrogen concentration.The stability analysis of the system metal-hydrogen is carried out. The influence of parameters of the mechanical loading, hydrogen concentration and parameters of sorption and desorption of hydrogen from the surface of the internal defects (traps) of various nature on the system stability is performed.It is shown that influence of hydrogen can be considered as parametric instability of a continuous medium under mechanical deformation.This can be important during forming or plastic deformation of materials and nanomaterials containing hydrogen.

scholarly journals Enhancing the Thermal Stability of Ionogels: Synthesis and Properties of Triple Ionic Liquid/Halloysite/MCC Ionogels

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6198
Author(s):  
Olga V. Alekseeva ◽  
Valeriya D. Shibaeva ◽  
Andrew V. Noskov ◽  
Vladimir K. Ivanov ◽  
Alexander V. Agafonov
Keyword(s):  
Thermal Stability ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Mechanical Characteristics ◽  
Interlayer Space ◽  
Xrd Analysis ◽  
Mechanical Tests ◽  
Water Molecules ◽  
Residual Water ◽  
Thermal Stability Of

In this study, an ionic liquid (IL), 1-butyl-3-methylimidazolium acetate, was used to prepare ionogels with microcrystalline cellulose (MCC) and halloysite (Hal). SEM, XRD, TG, DSC, FTIR spectroscopy, conductometry and mechanical tests were used to study the morphology, structure, thermal behaviour and electrophysical and mechanical characteristics of synthesised ionogels. XRD analysis showed a slight decrease in the interlayer space of halloysite in ionogels containing MCC, which may have been associated with the removal of residual water molecules resulting from hydrophilic IL anions and polymer macromolecules. A change in conductivity and glass-transition temperature of the ionic liquid was revealed due to intercalation into halloysite (a confinement effect) and modification with cellulose. For triple IL/Hal/MCC ionogels, the characteristic thermal degradation temperatures were higher than the corresponding values for IL/Hal composites. This indicates that the synthesised IL/Hal/MCC ionogels are characterised by a greater thermal stability than those of IL/Hal systems.

scholarly journals Effect of storage time and chlorhexidine addition on the mechanical properties of glass ionomer cements

2017 ◽  
Vol 16 ◽  
pp. 1-9
Author(s):  
Juliana de Carvalho Machado ◽  
Cristiane Duque ◽  
Josânia Pitzer de Oliveira ◽  
Angela Scarparo Caldo-Teixeira
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Compressive Strength ◽  
Storage Time ◽  
Mechanical Characteristics ◽  
Mechanical Tests ◽  
Glass Ionomer Cements ◽  
Glass Ionomer ◽  
Strength Tests ◽  
Storage Times

Aims: To evaluate the effect of the chlorhexidine (CHX) incorporation and the storage time on the mechanical properties of glass ionomer cements (GICs). Methods: The following GICs were evaluated: Ketac Molar Easymix (KM), Vidrion R (VR) and Vitromolar (VM), containing or not CHX.  GIC liquid was modified by adding 1.25 % CHX digluconate and then manipulated with the power and placed into the stainless steel cylindrical or bar-shaped molds. GICs specimens were stored into water for 1, 7 and 28 days. After these periods, specimens were submitted to flexural, diametral tensile and compressive strength tests, according to ISO standards. Data from mechanical tests were statistically analyzed using 2-way ANOVA and Tukey tests. Results: Overall, the storage time did not influence any of the mechanical properties of the GICs tested. In contrast, the inclusion of CHX reduced significantly these properties for all GICs tested. KM presented the highest values of compressive strength for all storage times. KM + 1.25% CHX had lower compressive strength results than KM, however, it showed similar results when compared to another GICs without CHX. Conclusions: The presence of chlorhexidine, independent of the storage time, interfered on the mechanical characteristics of GIC.

Interpretation of Experimental Data is Substantial for Constitutive Characterization of Arterial Tissue

2021 ◽  
Author(s):  
Ondrej Lisický ◽  
Anna Hrubanová ◽  
Jiri Bursa
Keyword(s):  
Experimental Data ◽  
Soft Tissues ◽  
Constitutive Models ◽  
Uniaxial Stress ◽  
Mechanical Tests ◽  
Data Sets ◽  
Stress Strain ◽  
Rigorous Approach ◽  
Carotid Wall

Abstract The paper aims at evaluation of mechanical tests of soft tissues and creation of their representative stress-strain responses and respective constitutive models. Interpretation of sets of experimental results depends highly on the approach to the data analysis. Their common representation through mean and standard deviation may be misleading and give non-realistic results. In the paper, raw data of 7 studies consisting of 11 experimental data sets (concerning carotid wall and atheroma tissues) are re-analysed to show the importance of their rigorous analysis. The sets of individual uniaxial stress-strain curves are evaluated using three different protocols: stress-based, stretch-based and constant-based, and the population-representative response is created by their mean or median values. Except for nearly linear responses, there are substantial differences between the resulting curves, being mostly the highest for constant-based evaluation. But also the stretch-based evaluation may change the character of the response significantly. Finally, medians of the stress-based responses are recommended as the most rigorous approach for arterial and other soft tissues with significant strain stiffening.

Reconditioning by Welding of Rims Manufactured from Nonferrous Alloys

2014 ◽  
Vol 1029 ◽  
pp. 61-66 ◽  
Author(s):  
Nicoleta Bularda ◽  
Teodor Heput
Keyword(s):  
Automotive Industry ◽  
Mechanical Characteristics ◽  
Mechanical Tests ◽  
Base Metals ◽  
Adequate Quality ◽  
Nonferrous Alloys ◽  
The Impact ◽  
Unsprung Mass ◽  
Co Emission

At present, in the automotive industry, the trend on the world plane is to fit on the wheels with rims made from nonferrous alloys, based on aluminum, magnesium or titanium. These rims have the advantage that they are lighter than the same rims made from steel, reducing the unsprung mass of the vehicle, and increasing the vehicle performances, that lead to the better handling, the faster braking and the better acceleration. Also, by using the rims made from nonferrous alloys, the increasing of the fuel consumption efficiency and the reducing of the carbon monoxide (CO) emission are obtained. During the traffic, the wheels (rim + tyre) can be subjected to accidental collisions, such as the impact with the pavement, leading to damages of the rims, which must be reconditioned. The paper presents the results of structural examinations and mechanical tests, made on car rims made from nonferrous alloys, degraded and reconditioned by specific welding technologies. The structural and mechanical characteristics determined in the zones reconditioned by welding are at the level of the base metals used to made the investigated rims, that confirm the adequate quality of them, and a low risc to cracking.

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