scholarly journals Влияние ангармонизма на тепловыделение и упрочнение металлов при квазистатическом растяжении

2020 ◽  
Vol 62 (1) ◽  
pp. 125
Author(s):  
Ю.В. Судьенков
Keyword(s):  
Energy Dissipation ◽  
Tensile Stress ◽  
Plastic Flow ◽  
Interaction Potential ◽  
Experimental Studies ◽  
Transverse Strain ◽  
Decisive Effect ◽  
Nonlinear Stage ◽  
Analysis Of Results ◽  
Measured Strain

Abstract In this paper, we present the analysis of results of experimental studies of energy dissipation and variations of the transverse strain coefficients under quasistatic tensile stress of metals. The nature of changes in these processes at different stages of deformation is considered: elastic, nonlinear, transition from elastic to developed plastic flow, and developed plastic flow. It is shown that at all stages there is a correlation of changes in independently measured strain parameters: temperature, transverse strain coefficients, and hardening. The decisive effect of the interaction potential anharmonicity on the nature of the processes of changes in modules and dissipation at the nonlinear stage of deformation is discussed.

The Study of Fire-extinguishing Process of Modelled Fire Seats

2021 ◽  
pp. 57-62
Author(s):  
V.N. Bordakov ◽  
Keyword(s):  
Flow Rate ◽  
Experimental Studies ◽  
Physical Modelling ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Acceptable Error ◽  
Fire Extinguishing ◽  
Fire Zone ◽  
Analysis Of Results ◽  
Fire Extinguishers

Test-fires to determine fire-extinguishers’ efficiency for extinguishing B class fires are conducted by operators equipped with working clothes, which does not comply with the requirements of physical modelling. This is why the ranks of extinguished modelled seats are significantly overestimated. The quantitative results of fire seats’ extinguishing can be comparatively evaluated in accordance with the value of specific flow rate of a fire-extinguishing agent. As it was detected, the specific flow rate of a fire-extinguishing agent does not actually depend on the rank of modelled fire seat when extinguished by an operator wearing thermal-protective clothes. At the same time, it is increasing along with the expansion of the fire zone scale in case the fire is extinguished without special protective clothes. Consequently, to increase the fire-extinguisher’s efficiency data reliability, the certifying tests should be conducted in conditions close to the real application conditions when the first person to firefight is not equipped with such special protective clothes. The experimental studies to determine the specific flow rate of a fire-extinguishing agent used modelled fire seats of various ranks. The analysis of results showed that the fire-extinguishers ensuring generation of drops of prevailing size more than 0,5 mm are required to extinguish the modelled sire seats. The degree of increasing flow rate for the fire-extinguishing agent to eliminate a fire and observation of a safe distance from the flame for an operator are conditioned by the scale of fire zone and affect the specific flow rate of agent required to ensure stable fire-extinguishing. Based on the results of extinguishing the fire seats «34В» or «55В», it is demonstrated that via using a correction factor it is possible, assuming an acceptable error, to evaluate the flow rate of fire-extinguishing agent to extinguish a modelled fire seat of any rank.

scholarly journals Spatial thin-walled reinforced concrete structures taking into account physical nonlinearity in SCAD software. Rod finite element

2019 ◽  
Author(s):  
Sergiy Fialko ◽  
Viktor Karpilowskyi
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Plastic Flow ◽  
Deformation Theory ◽  
Numerical Solutions ◽  
Experimental Studies ◽  
Particle Method ◽  
Reinforced Concrete Beams ◽  
Principal Stresses ◽  
Theory Of Plasticity

This paper considers a spatial frame bar finite element for modeling reinforced concrete beams and columns. Both concrete and reinforcement are described by the equations of the deformation theory of plasticity and the theory of plastic flow. Degradation of concrete during cracking is modeled by the descending branch of the σ – ε diagram (the deformation theory of plasticity), as well as the compression of the yield surface and its displacement in the space of principal stresses (the plastic flow theory). The longitudinal reinforcement is considered discretely. It is assumed that there is no reinforcement slipping in concrete. The paper provides the results of the studies that reveal the causes of computational instability related to the presence of a descending branch of the σ – ε diagram for concrete, and proposes ways to overcome it. The reliability of the obtained results is confirmed by comparing them with the results of experimental studies performed by other researchers, as well as with the results of numerical solutions obtained by the particle method. This paper also provides an example of the nonlinear analysis of the fragment of a multi-storey building from the SCAD Soft collection of problems (www.scadsoft.com).

Analysis of Results of Theoretical and Experimental Studies of the Influence of Radial Gaps in Stepped Slot Seal of Piston Hybrid Energy-Generating Machine

2019 ◽  
Vol 54 (9-10) ◽  
pp. 666-672 ◽  
Author(s):  
V. E. Shcherba ◽  
V. V. Shalai ◽  
A. V. Grigor’ev ◽  
A. Yu. Kondyurin ◽  
E. A. Lysenko ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Hybrid Energy ◽  
Slot Seal ◽  
Analysis Of Results

Shear Behavior Of Anchors On The Basis Of Carbon Fiber At External Reinforcement

2019 ◽  
pp. 59-64
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Carbon Fibers ◽  
Experimental Studies ◽  
Shear Forces ◽  
External Reinforcement ◽  
Concrete Body ◽  
Improve Calculation ◽  
Analysis Of Results ◽  
The Impact

In systems of external reinforcement on the basis of carbon fibers used for strengthening concrete structures, special attention should be paid to the anchoring of carbon reinforcement elements. Taking into account their installation in the external reinforcement system in the reinforced structure, the anchoring elements can work on the shear. At the same time, the nature of such operatioj as a whole is insufficiently studied, which raises many questions both about their calculation and their design. In order to improve calculation and design methods of carbon anchors, special experimental studies of the parameters of anchors and their impact on the bearing capacity of the anchor fastening were carried out. These studies relate to the length of the anchorage in the concrete body, maximum shear forces, ultimate deformations of the anchor etc. According to the results of the experiments conducted, the analysis of results obtained was performed, in particular, various schemes of destruction of anchors were analyzed and the impact of the depth of the anchor, its diameter of the anchor, as well as the type of binder on the degree of theirdestruction were studied.

scholarly journals Influence of the Non-Schmid Effects on the Ductility Limit of Polycrystalline Sheet Metals

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1386 ◽  
Author(s):  
Mohamed Ben Bettaieb ◽  
Farid Abed-Meraim
Keyword(s):  
Single Crystal ◽  
Mechanical Behavior ◽  
Single Crystals ◽  
Plastic Flow ◽  
Yield Criterion ◽  
Experimental Studies ◽  
Crystallographic Structure ◽  
Sheet Metals ◽  
Localized Necking ◽  
The Impact

The yield criterion in rate-independent single crystal plasticity is most often defined by the classical Schmid law. However, various experimental studies have shown that the plastic flow of several single crystals (especially with Body Centered Cubic crystallographic structure) often exhibits some non-Schmid effects. The main objective of the current contribution is to study the impact of these non-Schmid effects on the ductility limit of polycrystalline sheet metals. To this end, the Taylor multiscale scheme is used to determine the mechanical behavior of a volume element that is assumed to be representative of the sheet metal. The mechanical behavior of the single crystals is described by a finite strain rate-independent constitutive theory, where some non-Schmid effects are accounted for in the modeling of the plastic flow. The bifurcation theory is coupled with the Taylor multiscale scheme to predict the onset of localized necking in the polycrystalline aggregate. The impact of the considered non-Schmid effects on both the single crystal behavior and the polycrystal behavior is carefully analyzed. It is shown, in particular, that non-Schmid effects tend to precipitate the occurrence of localized necking in polycrystalline aggregates and they slightly influence the orientation of the localization band.

Comparing Hysteretic Behavior of Flexible Piers with Different Stirrup Ratio and Slenderness Ratio

2011 ◽  
Vol 261-263 ◽  
pp. 576-580
Author(s):  
Xiao Jing Yuan ◽  
Fan Liu
Keyword(s):  
Energy Dissipation ◽  
Bearing Capacity ◽  
Slenderness Ratio ◽  
Experimental Studies ◽  
Bridge Engineering ◽  
Hysteretic Behavior ◽  
Hysteresis Curve ◽  
Skeleton Curve ◽  
Displacement Ductility ◽  
Ductility Factor

Flexible piers have been widely used in bridge engineering due to its superior ductility. The stirrup ratio and slenderness ratio were deemed to have a most important impact on hysteretic behavior of them. Five flexible piers were made under static vertical loads and low cyclic horizontal reversed loads. The process of test was introduced and failure mechanism, hysteretic behavior, skeleton curve, ductility, energy dissipation capacity, and stiffness degeneration of flexible piers were analyzed. Experimental studies show that (1) Failure mode of specimen is bending failure and their ductility factor falls between 4.15 and 6.30; (2) displacement ductility factor improves with increasing of the stirrup ratio. Stirrup could greatly improve the capacity on ductility and energy dissipation, while it has little impact on the bearing capacity; (3) ultimate bearing capacity decline with the increase of slenderness ratio, however, when the slenderness ratio member is larger, the hysteresis curve is fuller and energy-dissipation is better.

Theoretical and Experimental Studies on Stresses in Vacuum Glazing due to Temperature Difference

2013 ◽  
Vol 591 ◽  
pp. 311-315
Author(s):  
Xiao Gen Liu ◽  
Yi Wang Bao
Keyword(s):  
Shear Stress ◽  
Tensile Stress ◽  
Temperature Difference ◽  
Experimental Studies ◽  
Mechanical Stresses ◽  
Calculation Formula ◽  
Distribution Characteristics ◽  
Test Device ◽  
Mechanical Models ◽  
Vacuum Glazing

The existence of a temperature difference across a vacuum glazing causes dimensional differences between the hot and cold glass sheets, with associated mechanical stresses and bending. In order to understand the distribution characteristics of the stresses and deformation in vacuum glazing due to temperature difference, in this work, the mechanical models were established and the calculation formula of the shear stress in the edge seal and bending tensile stress on the surface of the two glass sheets of the vacuum glazing were given. A test device was designed and the maximum tensile stresses and deflection of the vacuum glazing with various temperature difference were tested by experimental, it was shown that they are identical between the experiments and the theories.

Sign in / Sign up

Export Citation Format

Share Document