scholarly journals MODELING PLASTIC DEFORMATION OF POLYCHRYSTALLINE STRUCTURAL ALLOYS UNDER BLOCK-TYPE NONSYMMETRICAL REGIMES OF SOFT LOW-CYCLE LOADING

2019 ◽  
Vol 81 (1) ◽  
pp. 63-76
Author(s):  
I. A. Volkov ◽  
L. A. Igumnov ◽  
I. S. Tarasov ◽  
D. N. Shishulin ◽  
S. N. Pichkov ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Experimental Studies ◽  
Hysteresis Loops ◽  
Isotropic Hardening ◽  
Block Type ◽  
Deformation Model ◽  
Plasticity Model ◽  
Defining Relations ◽  
Thermal Plasticity ◽  
Cycle Loading

Processes of plastic deformation of polycrystalline structural alloys under block-type nonstationary regimes of soft low-cycle loading are considered. Modified Korotkikh's thermal-plasticity model pertaining to the class of yield theories with translation-isotropic hardening is used as defining relations of plasticity. The modification of Korotkikh's model consists in using a different formulation of evolutionary equations for the displacement of the yield surface center (the micro-stress tensor), used for block-type nonstationary regimes of low-cycle loading for describing effects of setting under a hard loading regime (controlled strains) and ratcheting under a soft loading regime (controlled stresses) of the plastic hysteresis loop. Determining the material parameters and scalar functions of the plastic deformation model, assessing its adequacy and scope of application was done based on the experimental studies of the deformation process of laboratory specimens made of stainless steels of the austenite (SS316L, SS304) and ferrite (20MnMoNi5-5) classes in the conditions of uniaxial and multiaxial, proportional and non-proportional regimes of soft block-type cyclic loading. Comparison of the numerical results with the experimental data indicates that the developed plasticity model qualitatively and quantitatively, accurately enough for engineering purposes, describes the main effects of plastic deformation (displacements of the plastic hysteresis loops and decreasing strain amplitudes) under block-type nonstationary nonsymmetrical regimes of soft low-cycle loading.

scholarly journals Evaluation of fatigue life of polycrystalline structural alloys

2018 ◽  
Vol 226 ◽  
pp. 03021
Author(s):  
Ivan A. Volkov ◽  
Leonid A. Igumnov ◽  
Aleksandr A. Ipatov
Keyword(s):  
Plastic Deformation ◽  
Damage Accumulation ◽  
Failure Process ◽  
Block Type ◽  
Elastoplastic Behavior ◽  
Evolutionary Equations ◽  
Defining Relations ◽  
Cycle Loading ◽  
Main Effects ◽  
Kinetics Of

A mathematical model describing the processes of elastoplastic deformation and damage accumulation under low-cycle loading has been developed, based on the viewpoint of mechanics of damaged media (MDM). The MDM model consists of three interrelated parts: defining relations describing elastoplastic behavior of the materials, taking into account its dependence on the failure process; evolutionary equations describing the kinetics of damage accumulation; strength criteria of the damaged material. In order to assess the reliability and scope of applicability of the defining relations of mechanics of damaged media, the processes of plastic deformation and damage accumulation in variety of structural steels in low-cycle tests have been numerically analyzed, and numerical results obtained have been compared with the data of full-scale experiments. It is shown that the presented model of mechanics of damaged media adequately describes, both qualitatively and quantitatively, with accuracy, necessary for practical calculations, the main effects of the processes of plastic deformation and damage accumulation in structural alloys under block-type non-stationary non-symmetrical low-cycle loading.

Modeling Plastic Deformation of Structural Alloys under Block-Type Nonsymmetrical Regimes of Low-Cycle Loading

2019 ◽  
Vol 40 (11) ◽  
pp. 2018-2026
Author(s):  
I. A. Volkov ◽  
L. A. Igumnov ◽  
I. S. Tarasov ◽  
D. N. Shishulin
Keyword(s):  
Plastic Deformation ◽  
Block Type ◽  
Cycle Loading

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

Magnetic Properties of Nanocrystalline (Nd,R)-(Fe,Co)-B (R = Pr, Ho) Alloys after Melt Spinning, Severe Plastic Deformation and Heat Treatment

2020 ◽  
Vol 312 ◽  
pp. 235-243
Author(s):  
Lev Aleksandrovich Ivanov ◽  
Tatiana P. Kaminskaya ◽  
Irina Semenovna Tereshina ◽  
Vladislav Davydov ◽  
Vladimir V. Popov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Melt Spinning ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Nanocrystalline State ◽  
Force Microscopy ◽  
Atomic Force ◽  
Deformation And Heat Treatment

Magnetic force microscopy (MFM) and magnetometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to study the magnetic and structural properties of the (Nd,Pr)-Fe–B and (Nd,Ho)-(Fe,Co)-B alloys. The alloys are synthesized using an arc or induction furnaces. The nanocrystalline state of the (Nd,Ho)-(Fe,Co)-B alloys is reached by two techniques, namely, melt spinning (MS) and severe plastic deformation (SPD). Hydrogenation and multistage treatment of (Nd,Ho)-(Fe,Co)-B alloys, which includes severe plastic deformation of melt-quenched ribbons and subsequent heat treatment, is also used. The surface morphology and domain structure of samples are studied. These pictures are used to interpret the observed magnetic hysteresis loops of the samples. It was found that multistage treatment allows one to obtain samples with higher values of coercivity due to the formation of a special microstructure with oval grain (the aspect ratio equal to ∼ 3).

scholarly journals Physics-based plasticity model incorporating microstructure changes for severe plastic deformation

2019 ◽  
Vol 347 (8) ◽  
pp. 601-614 ◽  
Author(s):  
Ziyad Zenasni ◽  
Mohamed Haterbouch ◽  
Zoubir Atmani ◽  
Samir Atlati ◽  
Mohammed Zenasni ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Plasticity Model ◽  
Microstructure Changes

Study of Surface Layer Hardening after Treatment Complex Tool

2020 ◽  
Vol 303 ◽  
pp. 89-96
Author(s):  
K.S. Mitrofanova
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Strain State ◽  
Experimental Studies ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Technological Inheritance ◽  
Multiple Loading ◽  
Surface Layer Hardening ◽  
Solidified Body

The results of experimental studies of the thin surface layer of samples made of steel 45 after treatment with surface plastic deformation (SPD) multiradius roller (MR-roller) are presented. On the basis of the apparatus of the mechanics of technological inheritance, taking into account the effect of the solidified body, a model of the process according to the scheme of multiple loading-unloading of metal, taking into account the phenomenology of the SPD process and the properties of the material, is created. Distributions of parameters of the stress-strain state in the deformation centre are obtained, the parameters of roughness and microhardness of the surface layer are investigated.

Crystallographic Textures Variation in Asymmetrically Rolled Steel

2010 ◽  
Vol 638-642 ◽  
pp. 2811-2816 ◽  
Author(s):  
Sebastian Wroński ◽  
Krzysztof Wierzbanowski ◽  
Brigitte Bacroix ◽  
Mirosław Wróbel ◽  
M. Wroński
Keyword(s):  
Finite Element Method ◽  
Plastic Deformation ◽  
Low Carbon Steel ◽  
Deformation Model ◽  
Texture Formation ◽  
Rolled Steel ◽  
Low Carbon ◽  
The Finite Element Method ◽  
Asymmetric Rolling ◽  
Macro Scale

The crystallographic texture formation in low carbon steel during asymmetric rolling was studied experimentally and analysed numerically. Modelling of plastic deformation was done in two scales: in the macro-scale using the finite element method ( FEM) and in crystallographic scale using the polycrystalline deformation model (LW model). The stress distribution in the rolling gap was calculated using FEM and next these stresses were applied in LW model of polycrystalline plastic deformation. In general, the predicted textures agree very well with experimental ones.

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