Home
|
About Journal
|
Editorial Board
|
Instruction
|
Subscriptions
|
Contacts Us
|
中文
Office Online
Submission Online
Peer Review
Editor Work
Editor-in-chief
Office Work
Journal Online
Accepted
Current Issue
Advanced Search
Archive
Read Articles
Download Articles
Email Alert
Quick Search
Adv Search
2023 Vol. 44, No. 3
Published: 2023-06-28
273
Plastic Deformation, Fracture and Irradiation Effects of Tungsten: A Review
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.053
Tungsten possesses unique physical and chemical properties and mechanical properties, and is widely applied in nuclear energy, aerospace, micro-electromechanical systems and so on as structural materials. The plastic deformation and fracture behavior of tungsten play an important role in affecting its service state. However, tungsten shows different mechanical behaviors from other metal materials, such as non-Schmid effect, tension and compression asymmetry, low fracture toughness and anisotropy, size effect and temperature effect. These behaviors are closely related to the microstructure of tungsten, such as dislocation, grain boundary, grain size and crystallography orientation. Additionally, the generation of dislocations, dislocation rings and other microstructural defects as a result of high-energy particle interactions with tungsten atoms during irradiation conditions has a substantial impact on the plastic deformation and fracture behavior of tungsten. Discovering the physical link between microstructure and mechanical behavior for tungsten, elucidating how irradiation affects mechanical behavior of tungsten have become popular research topics in recent years. This paper reviews the experimental, simulative and theoretical research progresses on the mechanical behavior of tungsten from the atomic scale, the dislocation scale and the single crystal scale to the polycrystalline macroscopic scale. Finally, some key problems for the future study of tungsten are prospected.
2023 Vol. 44 (3): 273-316 [
Abstract
] (
190
)
HTML
(1 KB)
PDF
(0 KB) (
58
)
317
Research Progress on Fracture Mechanics Test of Ferritic/Martensitic Steel in Liquid Lead and Bismuth
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.050
Based on the development and needs of fourth-generation nuclear reactors, lead-based reactors with low melting point have become one of the current research hotspots. As a coolant in lead-based fast reactors, the effect of lead-bismuth eutectic alloy (LBE) on the fracture properties of ferritic/martensitic steels has become a research hotspot. This paper summarizes the research progress of compatibility of ferritic/martensitic steels in liquid lead and bismuth, including liquid metal corrosion (LMC) and liquid metal embrittlement (LME) and analyzes the fracture mechanics in liquid metal environment. The test method is used to describe the effect of liquid lead-bismuth eutectic alloy on the fracture properties of ferritic/martensitic steel. Finally, the microscopic mechanism of the fracture of ferritic/martensitic steel in liquid lead-bismuth is summarized.
2023 Vol. 44 (3): 317-345 [
Abstract
] (
110
)
HTML
(1 KB)
PDF
(0 KB) (
51
)
346
Study on Thermo-elastic Phase Fracture Modelling Based on the Cell-based Smoothed Finite Element Method
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.046
With the rapid development of high-speed aircraft, the influence of high temperature on the structural strength and the failure mode needs to be considered. The phase field fracture method provides a powerful tool to simulate fracture problems. And the Cell-based finite element method (CS-FEM) is an efficient numerical method which is wildly used in mechanical analysis. Hence, in this paper, phase field fracture model is used to simulate the coupling thermo-elastic fracture problem which is implemented with the CS-FEM. The basic theories of thermal conduction and phase field model are briefly reviewed. The governing equations are derived. The variational formula and the linearization of the three-field coupled system are presented. The numerical implementation of thermal-elastic phase field fracture model with CS-FEM is provided. And then, the calculation programs are written to perform two classical numerical tests with staggered strategy in MATLAB software. First, a typical 2D tensile fracture behavior of edge notched square specimen under thermal-mechanical load is calculated. The results show that, for tensile specimens, the temperature difference between the upper and the lower surfaces can advance or delay the crack initiation without considering the influence of temperature on the fracture toughness. The result is in a good agreement with the finite element calculation results, and CS-FEM costs less time and is little more efficient than the FEM one. Second, the multi-cracks propagating and failure behavior of the ceramic plate under thermal shock is simulated by this proposed method. It is found that the number and length of cracks are affected by the temperature difference between inside and outside, and the numerical results can agree well with the experimental ones. This work is an extension of the CS-FEM based on phase-field method and it can provide an effective way to simulate thermal-elastic coupling fracture behavior.
2023 Vol. 44 (3): 346-354 [
Abstract
] (
156
)
HTML
(1 KB)
PDF
(0 KB) (
72
)
355
Numerical Analysis of 3D Fatigue Crack Propagation on Rail Surface
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2023.003
Under the action of cyclic rolling contact load, the problem of cracks on rail surface frequently occur, which seriously threatens the operation safety of high-speed trains. Therefore, it is of great significance to carry out 3D rolling contact fatigue crack propagation analysis on rail surface. Firstly, considering different initial crack angles, a three-dimensional finite element model of rail with initial cracks was established. Cyclic rolling contact load was applied to the rail surface to calculate rolling contact between wheel and rail. Then, the stress intensity factor of the crack front is calculated based on the interaction integral method. Finally, the maximum tangential stress criterion and Paris’s law are used to calculate the crack growth direction and growth rate in the current state, and then the crack shape and size at the next moment are updated. By repeating the above process, the propagation path of the three dimensional crack on the rail surface is predicted. The analysis of the SIF at the crack front during the cyclic rolling loading shows that, with the increase of the initial crack angle, the peak values of KⅠ and KⅡ decrease and increase, respectively, and the equivalent SIF at each position of the crack front decreases gradually. When the node at the crack front is closer to the rail surface, the equivalent SIF is larger. The calculation results of crack propagation show that with increasing the number of cycles, the cracks with different initial angles are deflected and gradually expand towards the rail depth direction. The larger the initial crack angle is, the more cycles are required for the propagation. The evolution curves of crack length with the number of cycles under different initial crack angles were calculated, and it was found that the smaller the initial crack angle is, the higher the crack growth rate is.
2023 Vol. 44 (3): 355-367 [
Abstract
] (
75
)
HTML
(1 KB)
PDF
(0 KB) (
52
)
368
Mechanistic Modelling of the Micro-void Evolution in Martensitic Steels under Multiaxial Loading Conditions
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2023.015
To investigate the effect of plastic crystallographic slip on the evolution of micro-voids in P91 martensitic steels, the present paper proposes a micromechnical finite element model based on the crystal plasticity theory to quantify the effects of stress triaxiality, Lode parameter and crystallographic orientation. The results indicate that under relatively high stress triaxialities, with the increase of the stress triaxiality, the equivalent stress-strain response of the voided martensitic blocks exhibits a rapidly softening characteristic, and the void volume fraction increases rapidly with increasing the equivalent strain. For a given stress triaxiality and the three crystallographic orientations examined, the void coalescence strain of the martensitic block has the minimum value at the [111] orientation and the maximum value at the [110] orientation. At the beginning of the void coalescence, the void shape tends to be ellipsoidal under relatively low stress triaxialities, while the void shape becomes transversely bulge slightly under the relatively high stress triaxialities. Over a certain range of the stress triaxiality and the Lode parameter, there is, in the phase diagram for the failure, a banded transition state between the two failure states of the void coalescence and the void collapse. For the [100] orientation of interest, the band widths are different under different Lode parameters, and the largest width occurs at the Lode parameter L=0.
2023 Vol. 44 (3): 368-380 [
Abstract
] (
206
)
HTML
(1 KB)
PDF
(0 KB) (
62
)
381
Data-driven Fatigue Life Prediction of Additively Manufactured Aluminum Alloys
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.045
The fatigue damage and life prediction of additively manufactured metal material is a hot topic of current research. In this paper, the fatigue life prediction is carried out using a data-driven approach with the typical application of additive manufacturing AlSi10Mg. Considering the limited fatigue test data, a reliable theoretical model and numerical method verified by experiments are used to obtain sufficient fatigue data to make up for the lack of test data. First, a fatigue damage model based on the defect characteristic parameters is proposed, and second, the numerical implementation of the theoretical model is established, and the numerical results are compared with the test results to verify the reliability of the proposed method. Then, the training and prediction of the data-driven model are carried out, and the fatigue life of the additively manufactured AlSi10Mg was predicted by the K nearest neighbor data-driven algorithm. Finally, the variation law of the fatigue life with the internal defects of the additively manufactured and fatigue loads is analyzed in depth, and the influence of the number of the training data and parameters of data-driven model on the prediction accuracy is studied.
2023 Vol. 44 (3): 381-394 [
Abstract
] (
106
)
HTML
(1 KB)
PDF
(0 KB) (
53
)
395
Fatigue Life Estimation of ER8C Wheel Steel Subjected to Atmospheric Pre-corrosion
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2023.013
Abstract：With the increasing of high-speed railway mileage, the wheel webs are subjected to long-term exposure to humid and even marine atmospheres, making corrosion pits be one of the main causes of wheel failure. To more closely match the actual working conditions, in this paper, high-cycle fatigue specimens of ER8C wheel steel are firstly subjected to a 180-day pre-corrosion test under atmospheric conditions. That is different from the artificial accelerated corrosion condition employed in many other studies. Then, the surface morphologies, sizes, and distribution of corrosion pits are characterized by scanning electron microscope (SEM), followed by the high-cycle fatigue tests. The results show that the fatigue limit of pre-corrosion steel is 387 MPa, which is 12% lower than that of the uncorroded steel. This is mainly due to the local stress concentration caused by the corrosion pits on the specimen surface, which accelerates the fatigue crack initiation. And then, laser confocal microscopy is used to measure the pit sizes at the specimen surface and the mean pit size, including depth, width and shape ratio, are obtained. Finally, the equivalent initial flaw size (EIFS), calculated from the mean pit depth and width, is used to predict the remaining life of the wheel steel. This method avoids the difficulties of fatigue crack initiation and short crack growth modeling on the prediction of fatigue life. The calculated remaining life of the wheel steel is more in line with the experimental results and proves the feasibility of the method. In this paper, the main conclusion is that the EIFS can be obtained by counting the mean pit depth and width of the specimen surface pit size . And the method of EIFS allows the calculation of the remaining life of wheel steel after atmospheric pre-corrosion. This verifies the applicability of the EIFS method in fatigue life of materials under atmospheric pre-corrosion.
2023 Vol. 44 (3): 395-405 [
Abstract
] (
79
)
HTML
(1 KB)
PDF
(0 KB) (
54
)
406
New Method for Multiaxial Fatigue Life Evaluation of Notched Specimens
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2023.010
For multiaxial conditions, the local stress-strain history at the notch danger point is used to predict the fatigue life in the local stress-strain method (LSSM), but this method does not take into account the influence of the non-proportional additional hardening and the stress gradient effect on the fatigue damage. Based on the analysis of shear stress and normal stress distribution on the crack initiation plane (critical plane), a mathematical calculation method is proposed to calculate the fatigue damage affected area of multiaxial notched specimen, and a life prediction model is established considering shear/normal stress gradient and non-proportional additional strengthening effect. Firstly, based on the energy method and the critical plane theory, the material plane with the largest strain energy density is defined as the critical plane by using the coordinate transformation principle, and the energy-critical plane method is established to determine the direction of crack initiation. Secondly, taking a specific path on the critical plane as the integral direction, the three-dimensional problem of notched specimen is transformed into a linear problem to simplify the calculation process. Then, the contribution of peak stress and equivalent stress field strength to multiaxial fatigue life is considered comprehensively, and the damage parameter representing the fatigue damage evolution process of multiaxial notched specimen is established. Finally, the feasibility and accuracy of the proposed model are verified by multiaxial fatigue tests of and TC4 alloy, and compared with LSSM model, FS model, SWT model.
2023 Vol. 44 (3): 406-416 [
Abstract
] (
113
)
HTML
(1 KB)
PDF
(0 KB) (
50
)
News
Download
Download
Download
Links
Links
Copyright © Editorial Board of
Supported by:
Beijing Magtech
