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19 pages, 5384 KiB

Open AccessArticle

RBF-Based Integrated Optimization Method of Structural and Turning Parameters for Low-Floor Axle Bridge

by Xiaoke Li, Wenbo Xing, Qianlong Jiang, Zhenzhong Chen, Wenbo Zhao, Yapeng Xu, Yang Cao, Wuyi Ming and Jun Ma

Metals 2024, 14(3), 273; https://doi.org/10.3390/met14030273 - 25 Feb 2024

Viewed by 853

Abstract

The axle bridge plays a crucial role in the bogie of low-floor light rail vehicles, impacting operational efficiency and fuel economy. To minimize the total cost of the structure and turning of axle bridges, an optimization model of structural and turning parameters was [...] Read more.

The axle bridge plays a crucial role in the bogie of low-floor light rail vehicles, impacting operational efficiency and fuel economy. To minimize the total cost of the structure and turning of axle bridges, an optimization model of structural and turning parameters was built, with the fatigue life, maximum stress, maximum deformation, and maximum main cutting force as constraints. Through orthogonal experiments and multivariate variance analysis, the key design variables which have a significant impact on optimization objectives and constraints (performance responses) were identified. Then the optimal Latin hypercube design and finite element simulation was used to build a Radial Basis Function (RBF) model to approximate the implicit relationship between design variables and performance responses. Finally, a multi-island genetic algorithm was applied to solve the integrated optimization model, resulting in an 8.457% and 1.1% reduction in total cost compared with the original parameters and parameters of sequential optimization, proving the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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12 pages, 1594 KiB

Open AccessArticle

Evaluating the Residual Life of Long-Term Equipment Made of Structural and Heat-Resistant Steel by Using the Structural–Mechanical Criterion

by Nikolay Ababkov, Alexandr Smirnov and Vladimir Danilov

Metals 2023, 13(6), 1075; https://doi.org/10.3390/met13061075 - 5 Jun 2023

Viewed by 921

Abstract

The use of acoustic and magnetic methods of non-destructive testing to detect zones of stable localization of deformation in order to assess and predict the performance of long-term equipment is of scientific and practical interest at present. A structural–mechanical criterion was developed that [...] Read more.

The use of acoustic and magnetic methods of non-destructive testing to detect zones of stable localization of deformation in order to assess and predict the performance of long-term equipment is of scientific and practical interest at present. A structural–mechanical criterion was developed that reflects the relationships between the structural and substructural states, internal stress fields and stable localization of deformations with the characteristics of non-destructive tests in the metal of long-term equipment made of structural 0.2 C steel and heat-resistant 0.12C-1Cr-1Mo-1V steel. The values of the structural–mechanical criteria K_s.-m for structural 0.2 C steel and for heat-resistant 0.12C-1Cr-1Mo-1V steel, corresponding to the moment of stable localization of deformation, are established. At the same time, it is recommended to replace the checked equipment nodes due to the exhaustion of the resource. The proposed and justified approach to assessing and predicting the performance and residual life of long-term power equipment, based on the identified relationships between the structural and substructural states, internal stress fields and stable localization of deformations with the characteristics of non-destructive tests and the calculation of the structural–mechanical criterion, was applied at a number of power plants in the Kemerovo region—Kuzbass. A methodology was developed for evaluating the residual life, based on the identification and use of relationships between structural and substructural states, internal stress fields and stable localization of deformations with the characteristics of non-destructive tests and the calculation of a structural–mechanical criterion. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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11 pages, 1918 KiB

Open AccessArticle

Effect of Temperature on the Kinetics of Localized Plasticity Autowaves in Lüders Deformation

by Vladimir I. Danilov, Dina V. Orlova, Vadim V. Gorbatenko and Lidiya V. Danilova

Metals 2023, 13(4), 773; https://doi.org/10.3390/met13040773 - 15 Apr 2023

Cited by 1 | Viewed by 895

Abstract

The paper analyzes the elastoplastic transition in Fe–0.025 wt. % C at a temperature of 296–503 K and strain rate of 6.67·10⁻⁶–3.33·10⁻³ s⁻¹. The analysis shows that the lower yield stress increases by a power law with increasing [...] Read more.

The paper analyzes the elastoplastic transition in Fe–0.025 wt. % C at a temperature of 296–503 K and strain rate of 6.67·10⁻⁶–3.33·10⁻³ s⁻¹. The analysis shows that the lower yield stress increases by a power law with increasing the strain rate, and that its rate sensitivity decreases linearly with increasing the test temperature. At temperatures lower than 393 K, the rate sensitivity of the lower yield stress is normal, and at 393–503 K, it is zero. In the range 393–503 K, the kinetics of the Lüders bands is changed from steady to discrete, and the higher the strain rate, the higher the temperature of this transition. Using the available data on the dynamics of dislocations and diffusion of interstitial impurities in the test alloy, it is demonstrated that the kinetics of Lüders bands are controlled by the effect of dynamic strain aging. If the arrest time of mobile dislocations t_w at barriers which are overcome via thermal activation is comparable with the precipitation time of interstitial atoms t_a at these dislocations, the motion of a Lüders band is discrete, and the band represents an excitation wave of localized plasticity; its refractory period is determined by the time of dynamic strain aging. If t_a >> t_w, the band moves monotonically and represents a switching autowave. The results of the analysis suggest that the effect of serrated yielding at the lower temperature boundary of blue brittleness can be suppressed by increasing the strain rate. When the arrest time of dislocations t_w decreases, the comparability of t_w and t_a is broken, and no excitation autowave is formed. The data reported in the paper can be used to develop warm rolling technologies for materials with a sharp elastoplastic transition. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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20 pages, 1566 KiB

Open AccessArticle

The Macroscopic Phenomena in Plasticity

by Lev Zuev and Svetlana Barannikova

Metals 2023, 13(2), 278; https://doi.org/10.3390/met13020278 - 30 Jan 2023

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Abstract

In this paper, the fundamental principles of plastic flow localization are briefly outlined. During the development of plastic flow, there is a changeover in the localization patterns conforming to the corresponding stage of work hardening based on the autowave nature of plastic flow [...] Read more.

In this paper, the fundamental principles of plastic flow localization are briefly outlined. During the development of plastic flow, there is a changeover in the localization patterns conforming to the corresponding stage of work hardening based on the autowave nature of plastic flow localization. In particular, the evolution of plastic flow from yield point to fracture involves the following four stages of autowave generation: switching autowave → phase autowave → stationary dissipative structure → collapse of autowave. The most intriguing localization pattern is attributed to a phase autowave, which forms at the stage of linear work hardening. The characteristics of the phase autowave (propagation velocity, dispersion, and grain size dependence of the wavelength) have been determined experimentally. Moreover, an elastic-plastic strain invariant is introduced to describe the elastic and plastic properties of the deforming medium, as well as to establish the above characteristics of autowaves. A hypothetic quasi-particle, corresponding to the autowave of localized plasticity, is considered and its potential properties are estimated to interpret the localization process characteristics. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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11 pages, 2060 KiB

Open AccessArticle

Autowave Criteria of Fracture and Plastic Strain Localization of Zirconium Alloys

by Lev B. Zuev, Svetlana A. Barannikova and Dina V. Orlova

Metals 2022, 12(1), 95; https://doi.org/10.3390/met12010095 - 4 Jan 2022

Cited by 3 | Viewed by 997

Abstract

Plastic deformation and fracture of Zr–1% Nb alloys exposed to quasi-static tensile testing have been studied via a joint analysis of stress-strain curves, ultrasound velocity and double-exposure speckle photographs. The possibilities of ductility evaluation through the ε_xx strain distribution in thin-walled parts [...] Read more.

Plastic deformation and fracture of Zr–1% Nb alloys exposed to quasi-static tensile testing have been studied via a joint analysis of stress-strain curves, ultrasound velocity and double-exposure speckle photographs. The possibilities of ductility evaluation through the ε_xx strain distribution in thin-walled parts of zirconium alloys are shown in this paper. The stress-strain state of zirconium alloys in a cold rolling site is investigated considering the development of localized deformation bands and changes in ultrasound velocity. It is established that the transition from the upsetting to the reduction region is accompanied by the significant exhaustion of the plasticity margin of the material; therefore, the latter is more prone to fracture in this zone exactly. It is shown that traditional methods estimating the plasticity margin from the mechanical properties cannot reveal this region, requiring a comprehensive study of macroscopically localized plastic strain in combination with acoustic measurements. In particular, the multi-pass cold rolling of Zr alloys includes various localized deformation processes that can result in the formation of localized plasticity autowaves. Recommendations for strain distribution division over the deformation zone length in the alloy in the pilger roll grooves are provided as well. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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19 pages, 6058 KiB

Open AccessArticle

Structural-Phase State, Mechanical Properties, Acoustic and Magnetic Characteristics in the Sustainable Deformation Localization Zones of Power Equipment Made of Structural and Heat Resistant Steels

by Nikolay Ababkov, Alexandr Smirnov, Vladimir Danilov, Lev Zuev, Natalya Popova and Elena Nikonenko

Metals 2021, 11(10), 1638; https://doi.org/10.3390/met11101638 - 14 Oct 2021

Cited by 3 | Viewed by 1259

Abstract

The paper presents the results of the analysis of the microstructure, mechanical properties, acoustic and magnetic characteristics of the metal of pipelines that are part of heat and power equipment, after long-term operation, made of structural and heat-resistant steels in the zones of [...] Read more.

The paper presents the results of the analysis of the microstructure, mechanical properties, acoustic and magnetic characteristics of the metal of pipelines that are part of heat and power equipment, after long-term operation, made of structural and heat-resistant steels in the zones of localization of plastic deformation. Samples of 0.2 C steel and 0.12C-1Cr-1Mo-1V steel were studied in the initial state, as well as after operation for 219 and 360 thousand hours, respectively. As a result of the studies carried out for each sample, the phase composition was determined (qualitatively and quantitatively), and the following parameters of the fine structure were calculated: volume fractions of structural components of steel (pearlite and ferrite), scalar ρ and excess ρ± dislocation density, curvature-torsion of the crystal lattice χ, amplitude of internal stresses (shear stress and long-range stresses). All quantitative parameters of the structure are determined both in each structural component of steel, and in general for each sample. The structure of the metal of all specimens after deformation before the formation of zones of stable localization of deformations consists of a ferrite-pearlite mixture, and for specimens after operation before fracture only of unfragmented and fragmented ferrite. Ferrite, which occupies the bulk of the material, is present both unfragmented and fragmented. For all samples, the ratios ρ ≥ ρ_±, χ = χ_pl, σ_L ≥ σ_d were calculated, which indicate whether there is a danger of the initiation of microcracks in metal samples. For specimens without operation and after operation without damage in zones of stable localization of deformations, these conditions are met, and for specimens after operation until destruction, they are not met. It was found that the structural-phase state in the zones of localization of deformations has a direct effect on the characteristics of non-destructive tests. Thus, for all investigated samples, the values of such parameters as the delay time of the surface acoustic wave, the attenuation coefficient, the amplitude of the received signal, and the intensity of magnetic noise in the zones of deformation localization were established. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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14 pages, 2919 KiB

Open AccessArticle

Kinetics of Plastic Deformation Localization Bands in Polycrystalline Nickel

by Svetlana A. Barannikova and Mikhail V. Nadezhkin

Metals 2021, 11(9), 1440; https://doi.org/10.3390/met11091440 - 11 Sep 2021

Cited by 1 | Viewed by 1682

Abstract

Jerky flow has recently aroused interest as an example of complex spatiotemporal dynamics resulting from the collective behavior of defects in Al- and Mg-based alloys under loading. This paper presents the results of the study of the macroscopic strain localization kinetics in Nickel [...] Read more.

Jerky flow has recently aroused interest as an example of complex spatiotemporal dynamics resulting from the collective behavior of defects in Al- and Mg-based alloys under loading. This paper presents the results of the study of the macroscopic strain localization kinetics in Nickel 200 (99.5 wt % purity). Uniaxial tension of flat samples is monitored at room temperature in the load–unload mode at a constant strain rate and total deformation increment up to 5%. The stress–strain curves reveal jerky flow from the yield point to the formation of the neck. The digital speckle correlation method evidences the movement of localized plastic deformation bands under the conditions of the Portevin–Le Chatelier effect (PLC). It is shown that stress drops during jerky flow in Ni are accompanied by the formation of morphologically simple single PLC bands. It is established that, with an increase in total deformation, the number of PLC bands and their velocity of motion along the sample decrease, while their time period increases. Moreover, an increase in total deformation leads to an increase in the parameters of the force response (i.e., time period and stress drop magnitude). It is found that the criterion of damage for PLC bands as a function of the total strain has a sigmoidal shape. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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11 pages, 1691 KiB

Open AccessArticle

Plasticity Autowave Characteristics of Metals and the Periodic Table of Elements

by Lev B. Zuev

Metals 2021, 11(8), 1270; https://doi.org/10.3390/met11081270 - 11 Aug 2021

Cited by 2 | Viewed by 1433

Abstract

In this paper, the general laws of localized plastic flow development are described for the linear work hardening stages of nineteen metals. The correlations are established and discussed between their element position in the periodic table of elements and the parameters of the [...] Read more.

In this paper, the general laws of localized plastic flow development are described for the linear work hardening stages of nineteen metals. The correlations are established and discussed between their element position in the periodic table of elements and the parameters of the autowave process of localized plastic flow in these elements. Patterns of plastic flow are considered for nineteen metals from the 3rd, 4th, 5th, and 6th periods of the periodic table of elements. A conditional characteristic of plasticity is introduced and its relationship with the position of the metals in the periodic table of elements is established. Correlations between the plastic properties and other metal characteristics were analyzed. Some quantitative models are proposed for explaining the observed dependency origin by the drag of moving dislocation by electron gas in metal crystals. Observed correlations indicate the existence of a close bond between localized plastic flow in deforming medium with the lattice characteristics of the elements and their electron structures. Full article

(This article belongs to the Special Issue Kinetics of Plastic Deformation in Metallic Materials)

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