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Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process
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Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Physics".

Deadline for manuscript submissions: closed (10 November 2023) | Viewed by 30283

Special Issue Editors

Dr. Xianjun Pei

E-Mail Website
Guest Editor
School of Mechanical Engineering, Southeast University, Nanjing 211189, China
Interests: fatigue and fracture; welding and joining; structural integrity; residual stress; computational method; mechanics of welded structures
Special Issues, Collections and Topics in MDPI journals
Dr. Pasqualino Corigliano

E-Mail Website
Guest Editor
Università degli Studi di Messina, Messina, Italy
Interests: fatigue; marine structures; welded joints; digital image correlation; infrared thermography; finite element analysis; explosion welding; composites; shipbuilding
Special Issues, Collections and Topics in MDPI journals
Dr. Haibo Yang

E-Mail Website1 Website2
Guest Editor
1. College of Water Conservancy and Civil Engineering, Shandong Agricultural University, Taian, China
2. School of Ocean Engineering, Harbin Institute of Technology at Weihai, Weihai 264200, China
Interests: fatigue performance analysis of welded structures; multiaxial stress state; fatigue lifetime prediction; fatigue crack initiation and propagation; traction structural stress method
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Material fatigue is regarded as one of the most important factors for determining the service life and safety of engineering components under cyclic loads. Thus, accurate evaluations and lifetime prediction of fatigue behavior remain a major concern during and after the design of such constructions. These concerns are particularly prominent in welded joints, where significant changes in material behavior, residual stresses and a complex weld geometry are present. Furthermore, the need to join dissimilar materials to produce improvements, such as protection from corrosion, self-weight reduction and a better mechanical response, require in-depth investigations and the development of new welding techniques. However, despite these difficulties, welded joints are considered indispensable for most engineering constructions. In addition, as with most other manufacturing processes, welding technologies are constantly advancing to match industry needs and expectations. In conjunction with developments in engineering, modern fatigue concepts also continue to evolve and improve. Due to these factors, studies on fatigue regarding welded joints and the modeling of welding processes are becoming essential. Therefore, this Special Issue is dedicated to presenting the state-of-the-art advances in fatigue studies and lifetime predictions regarding welded joints. High-quality contributions, which present original concepts and new methodologies, with a clear indication of the progress made from existing literature, are encouraged. Research on the mathematical modeling of welding processes and the fatigue/fracture behavior of welded structures is also welcomed.

Dr. Xianjun Pei
Dr. Pasqualino Corigliano
Dr. Haibo Yang
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • fatigue
  • welded structures
  • welded joints
  • residual stress
  • welding process
  • modelling
  • finite element analysis
  • dissimilar welding

Published Papers (20 papers)

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Research

11 pages, 3146 KiB  
Article
A Numerical Procedure for Shakedown Analysis of Thick Cylindrical Vessels with Crossholes under Dual Cyclic Loadings
by Yangxi Chen, Xin Jin, Yan Guo, Jian Zhao and Sujuan Guo
Materials 2023, 16(9), 3364; https://doi.org/10.3390/ma16093364 - 25 Apr 2023
Viewed by 940
Abstract
A modified numerical procedure for the shakedown analysis of structures under dual cyclic loadings, based on the Abdalla method, is proposed in this paper. Based on the proposed numerical procedure, the shakedown analysis of the thick cylindrical vessels with crossholes (TCVCs) under cyclic [...] Read more.
A modified numerical procedure for the shakedown analysis of structures under dual cyclic loadings, based on the Abdalla method, is proposed in this paper. Based on the proposed numerical procedure, the shakedown analysis of the thick cylindrical vessels with crossholes (TCVCs) under cyclic internal pressure and cyclic thermal loading was carried out. The effects of material parameters (elastic modulus and thermal expansion coefficient) and crosshole radius on the elastic shakedown limit of TCVCs are discussed and, finally, normalized and formularized. Furthermore, the obtained shakedown limit boundary formulation is compared with FEA results and is verified to evaluate the shakedown behavior of TCVCs under cyclic internal pressure and cyclic thermal loading. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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20 pages, 4225 KiB  
Article
Study on Mix Proportion Optimization and Microstructure of Coal-Based Solid Waste (CSW) Backfill Material Based on Multi-Objective Decision-Making Model
by Xinyuan Zhao, Ke Yang, Xiang He, Zhen Wei, Xiang Yu and Jiqiang Zhang
Materials 2022, 15(23), 8464; https://doi.org/10.3390/ma15238464 - 28 Nov 2022
Cited by 6 | Viewed by 973
Abstract
The preparation of underground-backfill material from CSW can be used for large-scale disposal of solid waste. The proportion of backfill material plays an important role in transportation and backfilling effect, and the mix-proportion optimization of backfill material is essentially a multi-factor and multi-objective [...] Read more.
The preparation of underground-backfill material from CSW can be used for large-scale disposal of solid waste. The proportion of backfill material plays an important role in transportation and backfilling effect, and the mix-proportion optimization of backfill material is essentially a multi-factor and multi-objective optimization problem. In this paper, to obtain the mix proportion of backfill materials with optimal comprehensive-evaluation indexes, and suitable for the engineering application, the fluidity and strength of backfill material, mainly composed of coal gangue(CG), fly ash (FA), flue gas desulfurization gypsum (FGD gypsum), and gasification coarse slag (GCS), were tested by single-factor transformation method, and the effects of various solid wastes on the slump-flow, bleeding rate and early strength of backfill material were analyzed. The optimal mix proportion of CSW with the slump-flow, bleeding rate, and 3-day and 7-day strengths as the evaluation indicators is FA: GCS: FGD gypsum: CG = 25%:25%:25%:25%, according to the multi-objective decision model. Furthermore, the comprehensive evaluation index that meets the requirements of mine backfilling is obtained by changing the ordinary portland cement (OPC) content, that is, the optimal OPC content is 10% of the total solid waste, and the mass concentration is 78%. Finally, the pore structure, micromorphology, and composition of the backfill material with the optimal mix proportion were studied by Mercury Intrusion Porosimetry (MIP), X-ray Diffraction (XRD), and Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS). The research results provide a good reference for the field application of CSW for underground backfilling. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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18 pages, 12081 KiB  
Article
Research on Load Reverse Engineering and Vibration Fatigue Analysis Technology of Rapid Box Wagon
by Ji Fang, Xiangwei Li, Dailin Zhang, Xueli Zhang and Wendong Shao
Materials 2022, 15(23), 8322; https://doi.org/10.3390/ma15238322 - 23 Nov 2022
Cited by 1 | Viewed by 995
Abstract
The overall stiffness and modal frequency of the car body of a rapid box car are reduced by the design of the full-side open movable side door structure. The vibration fatigue performance of the welded structure in this car body needs to be [...] Read more.
The overall stiffness and modal frequency of the car body of a rapid box car are reduced by the design of the full-side open movable side door structure. The vibration fatigue performance of the welded structure in this car body needs to be verified. The rigid-flexible coupling model of the rapid box wagon was established first, and the model was verified by modal test data. By the application of the virtual iteration method on this model, the displacement excitation loads of this vehicle were acquired. The effectiveness of the load reverse obtaining technology was verified through the comparison between calculated data and the experimental data. Based on the rigid-flexible coupling model and the load obtained by reverse engineering, the fatigue life of the welded structure in the car body was evaluated through the modal structural stress method. The calculated results show that the car body structure obtains obvious modal vibration, which leads to short fatigue life in several weld lines. According to the application requirements of this wagon, the local improvement scheme was proposed, and the effect of the improvement program was evaluated. In this paper, a new fatigue evaluation technology based on the load reverse method of test data was proposed, which provides a theoretical basis for the structural design and program improvement of railway vehicles. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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16 pages, 9595 KiB  
Article
Micromechanical Observation and Numerical Simulation for Local Deformation Evolution of Duplex Stainless Steel
by Jian Zhao, Yanru Shi, Sujuan Guo and Mingliang Zhu
Materials 2022, 15(22), 8076; https://doi.org/10.3390/ma15228076 - 15 Nov 2022
Cited by 2 | Viewed by 1063
Abstract
The characteristics of local strain distribution and evolution of duplex stainless steel during the tensile process were studied using the digital image correlation (DIC) technique. In addition, the finite element inversion of nanoindentation experiments of austenitic and ferrite phases in duplex stainless steel [...] Read more.
The characteristics of local strain distribution and evolution of duplex stainless steel during the tensile process were studied using the digital image correlation (DIC) technique. In addition, the finite element inversion of nanoindentation experiments of austenitic and ferrite phases in duplex stainless steel was carried out to obtain the stress–strain response of the two phases. Further, based on the representative volume element (RVE) and the material parameters obtained from the finite element inversion method, the local stress and strain behavior of duplex stainless steel at microscale was simulated numerically. The results fit well with the experiments, showing that the austenite phase is softer than ferrite phase, with the larger strain zone concentrated in the austenite phase and the larger stress zone concentrated in the ferrite phase. The grain boundaries are prone to obvious stress and strain concentrations. The local stress and strain distributions are influenced by the shape and interaction of the grains, while the distribution features become more obvious as the load increases. The research results effectively reveal the two-phase interaction and local failure mechanism of duplex stainless steel, and may provide a reference for material preparation and safety design of related structures. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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24 pages, 18234 KiB  
Article
Experimental Study on Hot Spot Stresses of Curved Composite Twin-Girder Bridges
by Rui Zhao, Yongjian Liu, Lei Jiang, Bowen Feng, Yisheng Fu and Chenyu Zhang
Materials 2022, 15(22), 7920; https://doi.org/10.3390/ma15227920 - 9 Nov 2022
Cited by 1 | Viewed by 1223
Abstract
Curved composite twin-girder bridges are suitable for mountainous areas, due to their advantages of light self-weight, excellent mechanical performance, and fewer construction requirements. It has been found that many composite twin-girder bridges collapsed due to fatigue failure. However, the literature review showed no [...] Read more.
Curved composite twin-girder bridges are suitable for mountainous areas, due to their advantages of light self-weight, excellent mechanical performance, and fewer construction requirements. It has been found that many composite twin-girder bridges collapsed due to fatigue failure. However, the literature review showed no relevant studies on the fatigue performance of curved composite twin-girder bridges. Because of this, the specimen of 1:2 scale curved composite twin-girder bridge in accordance with the design scheme of Xizhen Bridge in China was designed and tested. Three possible fatigue details were selected: cruciform connections, transverse attachments, and transverse splices named Class I, Class II, and Class III. For the test data of nominal stress (NS), equations were proposed to convert the strain value into the internal force of the fatigue detail position. The stress caused by torsion accounts for 2.8% of the total stress, which is almost negligible. The fatigue evaluation process based on the hot spot stress (HSS) S-N curve method is presented. The HSS method is more conservative than the NS S-N curve method in predicting the fatigue life of complex structures with high-stress concentrations. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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27 pages, 8498 KiB  
Article
A State-Based Peridynamic Flexural Fatigue Model for Contact and Bending Conditions
by Junzhao Han, Hao Yu, Jun Pan, Rong Chen and Wenhua Chen
Materials 2022, 15(21), 7762; https://doi.org/10.3390/ma15217762 - 3 Nov 2022
Cited by 1 | Viewed by 1697
Abstract
To address flexural fractures and predict fatigue life, an ordinary state-based peridynamic (PD) fatigue model is proposed for the initiation and propagation of flexural fractures. The key to this model is to replace the traditional partial differential fracture model with a spatially integral [...] Read more.
To address flexural fractures and predict fatigue life, an ordinary state-based peridynamic (PD) fatigue model is proposed for the initiation and propagation of flexural fractures. The key to this model is to replace the traditional partial differential fracture model with a spatially integral peridynamic model. Based on the contact and slip theory, the nonlocal peridynamic contact algorithm is confirmed and the load transfer is through the contact area. With the 3D peridynamic J-integration and the energy-based bond failure criterion, the peridynamic fatigue model for flexural cracks’ initiation and propagation is constructed. The peridynamic solid consists of a pair of gear contact surfaces and the formation and growth of flexural fatigue cracks evolved naturally over many loading cycles. The repeated load is transferred from the drive gear to the follower gear using the nonlocal peridynamic contact algorithm. The improved adaptive dynamic relaxation approach is used to determine the static solution for each load cycle. The fatigue bending crack angle errors are within 2.92% and the cycle number errors are within 10%. According to the experimental results, the proposed peridynamic fatigue model accurately predicts the location of the crack without the need for additional criteria and the fatigue life predicted by the simulation agrees quite well with the experimental results. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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11 pages, 2964 KiB  
Article
Morphological Changes of Calcium Carbonate and Mechanical Properties of Samples during Microbially Induced Carbonate Precipitation (MICP)
by Zhaorui Gu, Qing Chen, Lishuang Wang, Shuang Niu, Junjie Zheng, Min Yang and Yunjun Yan
Materials 2022, 15(21), 7754; https://doi.org/10.3390/ma15217754 - 3 Nov 2022
Cited by 7 | Viewed by 1762
Abstract
Recently, microbially induced carbonate precipitation (MICP) has shown potent potential in the field of civil engineering. The calcium carbonate crystals produced by bacteria during the MICP process play a central role in sticking the soil. However, the morphological changes of calcium carbonate crystals [...] Read more.
Recently, microbially induced carbonate precipitation (MICP) has shown potent potential in the field of civil engineering. The calcium carbonate crystals produced by bacteria during the MICP process play a central role in sticking the soil. However, the morphological changes of calcium carbonate crystals in this process and the mechanical performance of soil in the corresponding stages have not been clearly explored. In this paper, the alterations in the morphology of calcium carbonate crystals were continuously observed via scanning electron microscopy during the MICP process in one week, and the mechanical changes of the samples were monitored every day, so as to reveal the relationship between the morphology of calcium carbonate crystals and the mechanical performance of the samples. The results show that the calcium carbonate crystals undergo a gradual change from ellipsoid to rhombic at the 72nd hour. The mechanical properties of both were greatly improved, among which the compressive strength was increased by 2.78 times compared with the previous time point, and the flexure strength was increased by 2.57 times; this time point was also the time when calcite appears. In addition, we found direct evidence on the first day that bacteria act as the nucleation site of calcium carbonate formation. The above findings have certain guiding significance for the in-depth understanding of the internal microscopic changes of MICP and the influence of calcium carbonate morphology on sample mechanics. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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15 pages, 7980 KiB  
Article
Evaluation of Thermal Fatigue Life and Crack Morphology in Brake Discs of Low-Alloy Steel for High-Speed Trains
by Jinnan Wang, Yunbo Chen, Lingli Zuo, Haiyan Zhao and Ninshu Ma
Materials 2022, 15(19), 6837; https://doi.org/10.3390/ma15196837 - 1 Oct 2022
Cited by 4 | Viewed by 2447
Abstract
Effective braking in high-speed trains is one of the major bottlenecks in expediting the technology and possibilities to improve speed. Although substantial progress has been made to increase operating speed, perhaps, thermal fatigue cracking in brake discs is a primary constraint so far. [...] Read more.
Effective braking in high-speed trains is one of the major bottlenecks in expediting the technology and possibilities to improve speed. Although substantial progress has been made to increase operating speed, perhaps, thermal fatigue cracking in brake discs is a primary constraint so far. Thermal fatigue cracking is the major cause of brake disc failure in high-speed trains, especially trains with a speed of 350 km/h or above. In this study, new material composition is proposed for brake discs of high-speed trains. A comprehensive investigation is presented based on fatigue crack initiation and propagation, along with wear and micro-hardness characterization. Thermal fatigue tests at various thermal cycles between 20 ℃ and 700 ℃ were performed and the experimental results are compared with fatigue properties of a commercial brake disc material. An experimental trial revealed that thermal cracks normally initiate and propagate along the oxidized grain boundaries; nevertheless, crack propagation is restricted by the fine precipitates and lath structure of martensitic. Moreover, crack length at the initiation and propagation stage is predicted through crack growth rate and favorable grain size in the crack vicinity. Thermal fatigue life can be improved by dictating the microstructure and precipitate morphology of cast steel by tailoring the alloying composition. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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17 pages, 8061 KiB  
Article
Controlling Welding Residual Stress and Distortion of High-Strength Aluminum Alloy Thin Plates by a Trailing Hybrid High-Speed Gas Fluid Field
by Guangtao Zhou, Biao Liu, Wei Song, Huachen Li, Jingzhen Kuang and Mingwang Qiu
Materials 2022, 15(18), 6451; https://doi.org/10.3390/ma15186451 - 16 Sep 2022
Cited by 2 | Viewed by 1524
Abstract
This paper presents an investigation of the welding residual stress and distortion of LY12 high-strength aluminum alloy (6061) by improving the local welding thermal and mechanical fields. A trailing hybrid high-speed gas fluid method was proposed and applied to decrease the welding residual [...] Read more.
This paper presents an investigation of the welding residual stress and distortion of LY12 high-strength aluminum alloy (6061) by improving the local welding thermal and mechanical fields. A trailing hybrid high-speed gas fluid method was proposed and applied to decrease the welding residual stress and distortion of 6061 aluminum alloy efficiently. Firstly, the temperature and stress fields were calculated using the finite element simulation method, considering a trailing hybrid high-speed gas fluid field. The distance between the aerodynamic load and the heat source action was a key factor determined by the simulation method. In addition, the reasonable effective range of gas pressure was obtained. Subsequently, welding and distortion tests were conducted on the self-developed device under conventional welding and high-speed gas fluid field conditions. The results showed that an aerodynamic load under 30 MPa of gas pressure was available near the area at a distance of 20–28 mm from the heat source for thin plate welding distortion. The peak longitudinal residual tensile stresses in the weld’s mid-length section decreased by 77.73%, the peak residual compressive stresses decreased by 69.23% compared with conventional welding, and the deflection distortion disappeared almost entirely. The maximum deflection of the distortion was only 1.79 mm, which was 83.76% lower than the 11.02 mm of the conventional welding distortion. This validates that the method can simultaneously and greatly eliminate the welding residual stress and distortion. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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19 pages, 10399 KiB  
Article
Residual Stress Redistribution Analysis in the Repair Welding of AA6082-T6 Aluminum Alloy Joints: Experiment and Simulation
by Zhihao Chen, Yanjuan Duan, Ping Wang and Hongliang Qian
Materials 2022, 15(18), 6399; https://doi.org/10.3390/ma15186399 - 15 Sep 2022
Cited by 5 | Viewed by 1635
Abstract
Residual stress has a three-dimensional scale effect (length, depth, and width) in the process of repair welding, which has a detrimental impact on the service of the aluminum alloy welded structures in high-speed trains. This paper aims to systematically analyze the effects of [...] Read more.
Residual stress has a three-dimensional scale effect (length, depth, and width) in the process of repair welding, which has a detrimental impact on the service of the aluminum alloy welded structures in high-speed trains. This paper aims to systematically analyze the effects of the repair welding dimension on the residual stress redistribution and obtain the optimal repair welding principles. A combination of blind-hole drilling method and stress linearization in BS7910 was adopted to investigate residual stress redistribution under various repair welding dimensions. The results indicate that repair welding dimension was in accordance with the principle of “SNL (shallow, narrow and long)” and the optimal repair length, depth, and width of butt joints in this study were 15t, 0.25t, and t, respectively (t is the plate thickness of butt joints). Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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16 pages, 6032 KiB  
Article
Magneto-Thermo-Elastic Theoretical Solution for Functionally Graded Thick-Walled Tube under Magnetic, Thermal and Mechanical Loads Based on Voigt Method
by Tiane Li, Jiabao Li, Xuekang Liu and Yaozhi Luo
Materials 2022, 15(18), 6345; https://doi.org/10.3390/ma15186345 - 13 Sep 2022
Cited by 1 | Viewed by 955
Abstract
In this study, the mechanical responses of a functionally graded thick-walled tube simultaneously under magnetic, thermal and mechanical loads are studied. Based on the assumption that the volume fraction of each phase material is distributed as a power function, the Voigt method is [...] Read more.
In this study, the mechanical responses of a functionally graded thick-walled tube simultaneously under magnetic, thermal and mechanical loads are studied. Based on the assumption that the volume fraction of each phase material is distributed as a power function, the Voigt method is used to obtain the stress–strain relationship of the functionally graded materials (FGMs). The influences of the relevant material parameters including volume fraction, thermal expansion coefficient, and Poisson’s ratio on the magneto-thermo-elastic theoretical solution are deeply studied and discussed. Furthermore, when some of the parameters are set as special values, the research results can be degenerated to two coupled loads which are consistent with the existing researches. The results of this paper provide theoretical support for the practical design and application of the FGM tube under the combined action of magnetic, thermal and mechanical loads. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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11 pages, 3297 KiB  
Article
The Effect of Nucleating Agents on Enzyme-Induced Carbonate Precipitation and Corresponding Microscopic Mechanisms
by Yuanjiang Yang, Mingdong Li, Xueqing Tao, Shiai Zhang, Jia He, Liping Zhu and Kejun Wen
Materials 2022, 15(17), 5814; https://doi.org/10.3390/ma15175814 - 23 Aug 2022
Cited by 7 | Viewed by 1832
Abstract
Plant urease has the advantages of high activity and small size in enzyme-induced calcium carbonate precipitation (EICP). However, there area lack of nucleation sites for calcium carbonate in EICP. Sucrose and sorbitol, which are readily available and inexpensive, have the potential to provide [...] Read more.
Plant urease has the advantages of high activity and small size in enzyme-induced calcium carbonate precipitation (EICP). However, there area lack of nucleation sites for calcium carbonate in EICP. Sucrose and sorbitol, which are readily available and inexpensive, have the potential to provide nucleation sites for EICP as nucleating agents. To explore the effects of the two nucleating agents on EICP, the productivity of calcium carbonate, unconfined compressive strength (UCS) and microscopic mechanisms were tested. It is found that the productivity of EICP can be increased as much as 5.1% by the addition of sorbitol with an optimal content of 5%, and the productivity of EICP can be increased as much as 12.3% by the addition of sucrose with an optimal of 4%. The UCS of EICP-treated sand increases by 2.2 times after being improved by sorbitol with a content of 5.2%, the CaCO3 content of EICP-treated sand with sorbitol added increased by 1.5% compared to conventional EICP-treated sand. These results show that the two nucleating agents are effective for improving EICP. The SEM images verify that sorbitol/sucrose can compensate for the lack of nucleating sites in EICP and explicate the effect of nucleating agents on EICP. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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17 pages, 8384 KiB  
Article
Key Technologies of Physical and Virtual Test Rig for Railway Freight Car body
by Shangchao Zhao, Xiangwei Li, Dongpo Wang and Wenquan Li
Materials 2022, 15(15), 5439; https://doi.org/10.3390/ma15155439 - 8 Aug 2022
Cited by 2 | Viewed by 1440
Abstract
On the one hand, considering that the traditional fatigue method of railway freight cars is based on damage as a parameter, the influence of stress waveform cannot be considered. On the other hand, physical experiments have the characteristics of lag, long period, and [...] Read more.
On the one hand, considering that the traditional fatigue method of railway freight cars is based on damage as a parameter, the influence of stress waveform cannot be considered. On the other hand, physical experiments have the characteristics of lag, long period, and high cost. The full-scale physical test and virtual test of car body are carried out. First of all, the data processing method of small deletion and the inverse problem load acquisition method based on data to data are proposed. Secondly, the dynamic stress calculation method with the bench as the boundary is proposed. Finally, taking the obtained load as the input of the physical and virtual bench, a new fatigue test method for simulating the running attitude of the car body line is completed. The acceleration RMS error of the C70E gondola body is less than 6%, the stress RMS is less than 13%, and the equivalent mileage is 3.125 million highway test results show that the car meets the life requirements of the car body. The inverse problem analysis results of virtual and physical tests are basically consistent, and the study of this method provides a basis for improving the fatigue reliability of freight car bodies. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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14 pages, 3857 KiB  
Article
Experimental Study on the Optimization of Coal-Based Solid Waste Filling Slurry Ratio Based on the Response Surface Method
by Zhen Wei, Ke Yang, Xiang He, Jiqiang Zhang and Guangcheng Hu
Materials 2022, 15(15), 5318; https://doi.org/10.3390/ma15155318 - 2 Aug 2022
Cited by 11 | Viewed by 1325
Abstract
The large production and low comprehensive utilization rate of solid waste from coal power base affects the efficient and coordinated development of regional resources and the ecological environment. In order to promote utilization of solid waste from coal power base, coal gangue, fly [...] Read more.
The large production and low comprehensive utilization rate of solid waste from coal power base affects the efficient and coordinated development of regional resources and the ecological environment. In order to promote utilization of solid waste from coal power base, coal gangue, fly ash, and gasification slag are mixed as raw materials to prepare filling materials, and a study on the evolution law of the mechanical properties of coal-based solid waste filling body is systematically carried out. After clarifying the physical and chemical properties of the filling materials, the Box–Behnken experimental design method was used to study the effects of slurry mass fraction, coal gangue, fly ash, and gasification slag on the strength of the filling body based on the response surface-satisfaction function coupling theory. Furthermore, a multivariate nonlinear regression model was constructed for the strength of the filling body at different maintenance ages. Based on the analysis of variance (ANOVA) and the response surface function, the impact mechanism of influencing factors and their interaction on the strength of filler were revealed. The results show that the strength of the filler is affected by single factors and interactions between factors. The interaction of slurry mass fraction and gangue dosing has a significant effect on the strength of the filler in the early stage; the interaction of fly ash and gangue dosing has a significant effect on the strength of the filler in the middle stage; the interaction of slurry mass fraction and gasification slag dosing has a significant effect on the strength of the filler in the final stage. The mixed filling materials significantly affect the strength of the filler as the maintenance time is extended. The mixed filling materials are extensively interlaced with the hydration products, calcium alumina, and calcium silicate hydrate (C-S-H) gel, forming a stable three-dimensional spatial support system as the maintenance time increases. The best ratio to meet the requirements of mine filling slurry pipeline transportation and filling body strength was selected using the regression model and the proposed economic function of filling material. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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14 pages, 6166 KiB  
Article
A New Stored Energy Model Based on Plastic Work of Back Stress during Cyclic Loading in Polycrystalline Metal
by Haifeng Xu, Xiaopeng Li, Wei Li, Peng Jiang, Yuanbo Zhao and Yinghonglin Liu
Materials 2022, 15(15), 5267; https://doi.org/10.3390/ma15155267 - 30 Jul 2022
Cited by 2 | Viewed by 1202
Abstract
Two mesomechanics models were analyzed in an attempt to reveal the relationship between stored energy and back stress. It has been indicated that the portion of elastic stored energy due to residual microstresses (ESR) is closely related to intergranular back [...] Read more.
Two mesomechanics models were analyzed in an attempt to reveal the relationship between stored energy and back stress. It has been indicated that the portion of elastic stored energy due to residual microstresses (ESR) is closely related to intergranular back stress (Xinter), and the stored energy of dislocations inside grains (ESD) can be estimated with the plastic work of intragranular back stress (Xintra). Then, the evolution of back stress during cyclic loading was studied, and the plastic work of back stress (WpB) was calculated with the low cycle fatigue experimental data of Ti-6Al-4V. The result shows that WpB is partially released at every reverse loading, sufficient to reproduce the evolution of stored energy correctly under cyclic loading. The study also reveals that partially released energy is related to the decrease of Xinter at the initial state of reversal loading resulting from the reduction of the plastic strain incompatibility between grains. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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23 pages, 16692 KiB  
Article
Effect of Residual Stress Induced by Different Cooling Methods in Heat Treatment on the Fatigue Crack Propagation Behaviour of GH4169 Disc
by Menglong Fan, Chuanyong Chen, Haijun Xuan, Hailong Qin, Mingmin Qu, Songyi Shi, Zhongnan Bi and Weirong Hong
Materials 2022, 15(15), 5228; https://doi.org/10.3390/ma15155228 - 28 Jul 2022
Cited by 5 | Viewed by 1443
Abstract
In this study, the effects of residual stress induced by three different cooling methods during heat treatment on the crack propagation behaviour of the GH4169 disc were investigated. Different levels of stress fields were induced to the specially designed discs by using air [...] Read more.
In this study, the effects of residual stress induced by three different cooling methods during heat treatment on the crack propagation behaviour of the GH4169 disc were investigated. Different levels of stress fields were induced to the specially designed discs by using air cooling (AC), air jetting cooling (AJC) and water quenching (WQ) methods and were quantitated by numerical simulation. These discs were then subjected to prefabricated cracking, and crack propagation tests were conducted on a spin tester with two load spectrums. Crack growth behaviour was depicted via the surface replica technique and fracture morphology. Regarding the linear superposition of residual stress and centrifugal force, the crack propagation behaviour of different discs was simulated using the FRANC3D software. AJC and WQ introduced compressive residual stress (−259 MPa and −109 MPa, respectively) into the disc compared with the AC method (about −1.5 MPa). The AJC method increases the crack propagation life of the disc by introducing residual compressive stress into the area near the surface of the central hole to inhibit the opening of the crack surface. When the fatigue load was low, this inhibition effect was more significant. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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12 pages, 8775 KiB  
Article
Life Prediction Method of Dissimilar Lightweight Materials Welded Joints with Precrack under Coupled Impact-Fatigue Loading
by Zhengshun Ni, Tao Xiong, Jie Lei, Liuping Wang, Tong Gao, Jianwu Yu and Chengji Mi
Materials 2022, 15(14), 5077; https://doi.org/10.3390/ma15145077 - 21 Jul 2022
Cited by 1 | Viewed by 1433
Abstract
This paper aims to explore the fatigue life estimation approach of welded joints with precrack under coupled impact and fatigue loading, and the base metal is dissimilar 5083H111 and 5754 aluminum alloy. Impact tests are first carried out on the dissimilar lightweight materials [...] Read more.
This paper aims to explore the fatigue life estimation approach of welded joints with precrack under coupled impact and fatigue loading, and the base metal is dissimilar 5083H111 and 5754 aluminum alloy. Impact tests are first carried out on the dissimilar lightweight materials welded joint with precrack located in the middle of the specimen, and a stress and strain field is obtained to determine the fatigue damage model parameters by using finite element dynamic analysis to simulate the impact process. Based, on the S-N curve of welded joints, the predicted life expectancy is found to be inconsistent with the experimental results. According to the continuum damage mechanics, the lifetime assessment model is presented to calculate both impact and fatigue damage. The estimated results agree well with the experimental ones. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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18 pages, 12315 KiB  
Article
Study on the Initiation of Interface Crack in Rock Joints
by Xin Chen, Wei Gao, Shuangshuang Ge and Cong Zhou
Materials 2022, 15(14), 4881; https://doi.org/10.3390/ma15144881 - 13 Jul 2022
Cited by 1 | Viewed by 1225
Abstract
The interfacial fracture of rock joints is an important although easily ignored issue in jointed rock engineering. To conduct this study, an interface crack model of rock joints was proposed. By analyzing the ratio of stress intensity factor to fracture toughness, the fracture [...] Read more.
The interfacial fracture of rock joints is an important although easily ignored issue in jointed rock engineering. To conduct this study, an interface crack model of rock joints was proposed. By analyzing the ratio of stress intensity factor to fracture toughness, the fracture mode of the interface crack was studied. Based on the Mohr-Coulomb criterion, an interface fracture criterion considering T-stress was established. To verify the proposed fracture criterion, laboratory and numerical tests were conducted. Finally, the effect of relative critical size α, internal friction angle φ and cohesion c on the initiation of an interface crack was comprehensively discussed. It is concluded that the proposed fracture criterion can predit the initiation of the interface cracks properly. With an increase in cohesion c, mode II fracture toughness KIIC also clearly increases. When the absolute value of KI is small, the effect of α is much larger than that of φ. In addition, with an increase in the absolute value of the mode I stress intensity factor, the φ of the joint plays a more important role in the initiation of the interface crack. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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15 pages, 5389 KiB  
Article
Fatigue Life Prediction of CFRP-Strengthened RC Beams with Flexural Crack under Hygrothermal Environments
by Xinyan Guo, Hangyue Cui, Yilin Wang and Zhanbiao Chen
Materials 2022, 15(13), 4681; https://doi.org/10.3390/ma15134681 - 4 Jul 2022
Cited by 3 | Viewed by 1324
Abstract
The durability of reinforced concrete (RC) beams strengthened with carbon fiber-reinforced polymer (CFRP) is a worldwide concern in structural engineering. As an important part of the strengthened beam, the performance of the CFRP–concrete interface under hygrothermal environments is a delicate problem. In this [...] Read more.
The durability of reinforced concrete (RC) beams strengthened with carbon fiber-reinforced polymer (CFRP) is a worldwide concern in structural engineering. As an important part of the strengthened beam, the performance of the CFRP–concrete interface under hygrothermal environments is a delicate problem. In this paper, the fatigue behavior of CFRP-strengthened RC beams is analyzed by a theoretical model. In the model, CFRP–concrete interface degradation under hygrothermal environments is involved. Since interface debonding and rebar fracture induced by intermediate cracking are two typical failure modes, the damage models of rebar and the CFRP–concrete interface are established. Based on the theoretical model, the failure mode of CFRP-strengthened RC beams can be predicted, and fatigue life can be determined. The results showed that IC debonding is more likely to occur under hygrothermal environments. The accurate prediction of failure modes is essential for fatigue life prediction. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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12 pages, 3570 KiB  
Article
An Energy-Based Method for Lifetime Assessment on High-Strength-Steel Welded Joints under Different Pre-Strain Levels
by Chengji Mi, Zhonglin Huang, Haibo Wang, Dong Zhang, Tao Xiong, Haigen Jian, Jiachang Tang and Jianwu Yu
Materials 2022, 15(13), 4558; https://doi.org/10.3390/ma15134558 - 28 Jun 2022
Cited by 4 | Viewed by 1192
Abstract
Pre-loading on engineering materials or structures may produce pre-strain, especially plastic strain, which would change the fatigue failure mechanism during their service time. In this paper, an energy-based method for fatigue life prediction on high-strength-steel welded joints under different pre-strain levels was presented. [...] Read more.
Pre-loading on engineering materials or structures may produce pre-strain, especially plastic strain, which would change the fatigue failure mechanism during their service time. In this paper, an energy-based method for fatigue life prediction on high-strength-steel welded joints under different pre-strain levels was presented. Tensile pre-strain at three pre-strain levels of 0.2%, 0.35% and 0.5% was performed on the specimens of the material Q345, and the cyclic stress and strain responses with pre-loading were compared with those without pre-loading at the same strain level. The experimental work showed that the plastic strain energy density of pre-strained welded joints was enlarged, while the elastic strain energy density of pre-strained welded joints was reduced. Then, based on the strain energy density method, a fatigue life estimation model of the high-strength-steel welded joints in consideration of pre-straining was proposed. The predicted results agreed well with the test data. Finally, the validity of the developed model was verified by the experimental data from TWIP steel Fe-18 Mn and complex-phase steel CP800. Full article
(This article belongs to the Special Issue Fatigue Behavior, Lifetime Prediction and Modeling of Welding Process)
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