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Very high cycle fatigue resistance improvement of Mg-Gd-Zn-Zr alloy by introducing curved long-period stacking ordered lamellae

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Journal of Magnesium and Alloys 2025年第3期13卷 1218-1231页

作者： Min Zhan Xinglin Yang Shoucheng Shi Yao Chen Lang Li Bing Xue Yongbo Li Wanshuang Yi Qingyuan Wang Chao He Key Laboratory of Deep Earth Science and Engineering Ministry of EducationCollege of Architecture and EnvironmentSichuan UniversityChengdu 610065China Failure Mechanics&Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Science and Technology Research Center China Yangtze Power Corp(CYPC)Yichang Hubei 443002China Hubei Technology Innovation Center for Smart Hydropower Wuhan Hubei 430000China School of Architecture and Civil Engineering Chengdu UniversityChengdu 610106China

Magnesium alloys with long-period stacking ordered(LPSO)structures are known for their impressive static mechanical strength,but the consistent occurrence of slip-cracking along the LPSO lamellae,which do not effectively impede the movement of basal dislocations,has prompted concerns about their very high cycle fatigue(VHCF)*** this study,an extruded Mg-Gd-Zn-Zr alloy was developed,showcasing exceptional VHCF resistance due to its bimodal structure comprisingﬁne grains and coarse grains consisting of curved LPSO *** investigation on the crack initiation mechanism revealed that slip-induced cracking predominantly occurs inﬁne-grained regions rather than in the interior of coarse *** extrusion process aligns the basal planes of most coarse grains parallel to the axial direction,and the presence of curved LPSO lamellae acts as barriers to the movement of basal dislocations,thereby effectively increasing the threshold for slip-cracking along the basal ***,fatigue damage manifests in the form of slip bands and micro-cracks within the interior ofﬁne grains,ultimately resulting in fatigue crack initiation,propagation andﬁnal fracture.

关键词： Very high cycle fatigue Mg-Gd-Zn-Zr alloy Crack initiation Curved LPSO lamellae Micro-cracks

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Energy field intensity approach for probabilistic notch fatigue assessment under size effect

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Chinese Journal of Aeronautics 2025年第2期38卷 111-127页

作者： Ding LIAO Shunpeng ZHU Jiewei GAO Xuekang LI José CORREIA Rui CALÇADA Qingyuan WANG School of Mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Department of Civil Engineering Faculty of EngineeringUniversity of PortoPorto 4200-465Portugal School of Mechanical Engineering Xihua UniversityChengdu 610039China Kunming Shipborne Equipment Research and Test Center Kunming 650051China Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Advanced Research Institute Chengdu UniversityChengdu 610106China

The development of modern engineering components and equipment features large size,intricate shape and long service life,which places greater demands on valid methods for fatigue performance *** a smooth transformation between small-scale laboratory specimens’fatigue properties and full-scale engineering components’fatigue strength has been a long-term *** this work,two dominant factors impeding the smooth transformation—notch and size effect were experimentally studied,in which fatigue tests on Al 7075-T6511(a very high-strength aviation alloy)notched specimens of different scales were carried *** analyses identified the evidence of the size effect on notch fatigue damage ***,the Energy Field Intensity(EFI)initially developed for multiaxial notch fatigue analysis was improved by utilizing the volume ratio of the Effective Damage Zones(EDZs)for size effect *** particular,it was extended to a probabilistic model considering the inherent variability of the fatigue *** experimental data of Al 7075-T6511 notched specimens and the model-predicted results were compared,indicating the high potential of the proposed approach in fatigue evaluation under combined notch and size effects.

关键词： Notch fatigue Size effect Energy field intensity Life prediction Probabilistic modelling

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Finite element and long short-Term memory analysis for impact of nanoparticle shape on hybrid nanofluid flow in a lid-driven cavity

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Journal of Computational Design and engineering 2025年第4期12卷 14-25页

作者： Rashid, Umair Mawire, Ashmore Wang, Qingyuan Chamkha, Ali J Yang, Kun Institute for Advanced Study Chengdu University Chengdu610106 China North-West University Mmabatho2745 South Africa Failure Mechanics and Eng. Disaster Prevention and Mitigation Key Laboratory of Sichuan Province Sichuan University Chengdu610065 China Faculty of Engineering Kuwait College of Science and Technology Doha District35004 Kuwait

The significance of nanoparticle shapes is evident in various domains of detecting trace metals in biomolecular assays and nanotechnology applications. The present study focused on copper and aluminum-water hybrid nanofluid flow inside a lid-driven cavity. The heated elliptic-shaped obstacle is emended inside the lid-driven square cavity. The hybrid nanofluid contained water and two categories of nanoparticles with sphere, column, and lamina shapes. The solution of the projected model governing equations is evaluated by the Galerkin Method. Long short-Term memory is used to ensure the accuracy of the solution and comparison of results. The characteristics of hybrid nanofluid are presented as streamlines, isothermal contour plots, kinetic energy, and heat transfer. The graphical description shows that lamina-shaped nano-sized particles dominate the distribution of temperature and heat transfer. The long short-Term memory approach demonstrated high accuracy in our comparative analysis. © 2025 The Author(s).

关键词： Metal nanoparticles

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Energy field intensity approach for probabilistic notch fatigue assessment under size effect

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Chinese Journal of Aeronautics 2025年第02期 115-131页

作者： Ding LIAO Shunpeng ZHU Jiewei GAO Xuekang LI José CORREIA Rui CALC ADA Qingyuan WANG School of Mechanical and Electrical Engineering University of Electronic Science and Technology of China Department of Civil Engineering Faculty of EngineeringUniversity of Porto School of Mechanical Engineering Xihua University Kunming Shipborne Equipment Research and Test Center Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province College of Architecture and EnvironmentSichuan University Advanced Research Institute Chengdu University

The development of modern engineering components and equipment features large size,intricate shape and long service life, which places greater demands on valid methods for fatigue performance analysis. Achieving a smooth transformation between small-scale laboratory specimens' fatigue properties and full-scale engineering components' fatigue strength has been a long-term challenge. In this work, two dominant factors impeding the smooth transformation — notch and size effect were experimentally studied, in which fatigue tests on Al 7075-T6511(a very highstrength aviation alloy) notched specimens of different scales were carried out. Fractography analyses identified the evidence of the size effect on notch fatigue damage evolution. Accordingly, the Energy Field Intensity(EFI) initially developed for multiaxial notch fatigue analysis was improved by utilizing the volume ratio of the Effective Damage Zones(EDZs) for size effect correction. In particular, it was extended to a probabilistic model considering the inherent variability of the fatigue phenomenon. The experimental data of Al 7075-T6511 notched specimens and the model predicted results were compared, indicating the high potential of the proposed approach in fatigue evaluation under combined notch and size effects.

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Rock Dynamic Crack Propagation Behaviour and Determination Method with Improved Single Cleavage Semi-circle Specimen Under Impact Loads

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Acta Mechanica Solida Sinica 2020年第6期33卷 793-811页

作者： Fei Wang Meng Wang Zheming Zhu Jianhui Deng Mohaddeseh Mousavi Nezhad Hao Qiu Peng Ying Failure Mechanics&Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering(Sichuan University) Ministry of EducationChengdu 610065China School of Engineering The University of WarwickCoventry CV47ALUK

This paper studied the rock dynamic fracture propagation under impact loads elaborately with a determination method proposed to calculate crack propagation dynamic stress intensity factor(DSIF).By utilizing the split-Hopkinson pressure bar,the impact experiments with an improved single cleavage semi-circle(ISCSC)specimen were conducted to illuminate the dynamic crack propagation ***,the fracture characteristics and crack propagation velocity were obtained by the crack propagation *** experiments with a numerical approach,the crack propagation dynamic stress intensity factors were calculated by an experimental—numerical method with fractal ***,a finite difference model was developed based on the tensile fracture softening damage *** the analysis of numerical and experimental results,the crack propagation behaviour and mechanism of crack arrest were discussed *** results demonstrate that the novel ISCSC specimen shows a definite advantage in determining crack propagation and arrest ***,the crack arrest DSIF is larger than the average propagation DSIF with a sharp ***,the numerical simulation results which agree well with the actual crack propagation illustrate that the crack arrest should be dominated by the compressive stress perpendicular to the crack path,and there were several arrest pauses existing in the transitory crack arrest process.

关键词： Impact loads Crack propagation Crack arrest Numerical simulation Fractal method Dynamic stress intensity factor

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Active learning accelerated Monte-Carlo simulation based on the modified K-nearest neighbors algorithm and its application to reliability estimations

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Defence Technology（防务技术） 2023年第10期28卷 306-313页

作者： Zhifeng Xu Jiyin Cao Gang Zhang Xuyong Chen Yushun Wu School of Civil Engineering and Architecture Wuhan Institute of TechnologyWuhan430200PR China School of Mechanical and Electrical Engineering Wuhan Institute of TechnologyWuhan430200PR China Failure Mechanics&Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu610065PR China

This paper proposes an active learning accelerated Monte-Carlo simulation method based on the modified K-nearest neighbors *** core idea of the proposed method is to judge whether or not the output of a random input point can be postulated through a classifier implemented through the modified K-nearest neighbors *** to other active learning methods resorting to experimental designs,the proposed method is characterized by employing Monte-Carlo simulation for sampling inputs and saving a large portion of the actual evaluations of outputs through an accurate classification,which is applicable for most structural reliability estimation ***,the validity,efficiency,and accuracy of the proposed method are demonstrated *** addition,the optimal value of K that maximizes the computational efficiency is ***,the proposed method is applied to the reliability estimation of the carbon fiber reinforced silicon carbide composite specimens subjected to random displacements,which further validates its practicability.

关键词： Active learning Monte-carlo simulation K-nearest neighbors Reliability estimation Classification

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Fatigue behaviour of welded joints assembled by longitudinal corrugated plates

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Journal of Central South University 2015年第7期22卷 2752-2760页

作者：王志宇王清远刘永杰孙美 Department of Civil Engineering & Mechanics Institute of Architecture and EnvironmentSichuan University Sichuan Provincial Key Laboratory of Failure Mechanics and Engineering Disaster Prevention & Mitigation (Sichuan University) Department of Accounting and Corporate Finance Business School Sichuan University

Fatigue is usually the cause for the cracks identified at bridge elements in service. With an increase in the introduction of corrugated steel web girders in recent highway bridge construction, the understanding of the fatigue behaviour of welded details in such structures becomes an important issue for the design. The typical welded details were represented as welded joints assembled by longitudinal corrugated plates. All the experiments were performed under fatigue loading using a servo-control testing machine. The test results from the failure mode observation with the aid of infrared thermo-graph technology show that the failure manner of these welded joints is comparable to that of the corrugated steel web beams reported previously. It is indicated from the stiffness degradation analysis that the welded joints with larger corrugation angle have higher stiffness and greater stiffness degradation in the notable stiffness degradation range. It is shown from the test S-N relations based on the free regression and forced regression analyses that there is a good linear dependence between lg(N) and lg(ΔS). It is also demonstrated that the proposed fracture mechanics analytical model is able to give a prediction slightly lower but on the safe side for the mean stresses at 2 million cycles of the test welded joints.

关键词： corrugated web fatigue behaviour S-N relation stiffness degradation fracture mechanics

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Evaluation of fatigue strength improvement by CFRP laminates and shot peening onto the tension flanges joining corrugated steel webs

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Materials 2015年第8期8卷 5348-5362页

作者： Wang, Zhi-Yu Wang, Qing-Yuan Liu, Yong-Jie Department of Civil Engineering and Mechanics Sichuan University Chengdu610065 China Sichuan Provincial Key Lab. of Failure Mechanics and Engineering Disaster Prevention and Mitigation Sichuan University Chengdu610065 China

Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates. © 2015 by the authors.

关键词： Welds

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Effect of ultrasonic peening treatment on the fatigue behaviors of a magnesium alloy up to very high cycle regime

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Journal of Magnesium and Alloys 2022年第3期10卷 659-673页

作者： Yao Chen Fulin Liu Chao He Lang Li Chong Wang Yongjie Liu Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province Sichuan UniversityChengdu 610065China MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China

Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation ***,crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation *** initiate as Mode Ⅱ crack within the original grain,but deflect to Mode I crack outside of the original cracked grain.A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack *** of the original cracked grain,Mode I crack propagation below the threshold ΔK_(σ-th) is responsible for the formation of fine granular area(FGA,a nano-grain layer).Based on the Numerous Cyclic Pressing(NCP) model,it is proposed that crack type should be another necessary condition for the formation of FGA.

关键词： Ultrasonic peening treatment Very-high-cycle fatigue Crack initiation mechanism Fine granular area Nanograins.

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Fatigue behaviour of CFRP strengthened open-hole steel plates

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Thin-Walled Structures 2017年 115卷 176-187页

作者： Wang, Zhi-Yu Wang, Qing-Yuan Li, Lihui Zhang, Ning Department of Civil Engineering Institute of Architecture and Environment Sichuan University Chengdu China Sichuan Provincial Key Laboratory of Failure Mechanics and Engineering Disaster Prevention & Mitigation Sichuan University Chengdu China School of Architecture and Civil Engineering Chengdu University Chengdu China

Open-hole details have gained widely application in bolted connections subjected to fatigue loading. Although the use of carbon fibre reinforced polymer (CFRP) can be efficient in strengthening critically stressed tension area, its benefit in improving the fatigue life of open-hole details has not been extensively evaluated. This paper presents the results of an experimental and finite element analytical study on the fatigue behaviour of CFRP strengthened open-hole steel plates. The merits resulted from CFRP strengthening are investigated and compared with some others from referred open-hole fabrication methods and these with artificial initial cracks or notches as reported in the literature. Typical failure modes, local strain evolution and stiffness degradation behaviour of the test open-hole details are reported. The fatigue life results are evaluated and compared against the design curves of the AASHTO. The results show that the use of single and triple layered CFRP strengthening results in fatigue life enhancement of nearly 20% and 60% respectively in contrast to bare steel open-hole plates. Incorporating the stress ratios allowing for fibrous rupture and steel-adhesive interface failure, the fatigue life of CFRP strengthened specimens can be properly evaluated. Finally, the geometric and configuration parameters of CFRP on the stress concentration of the open-hole details are studied based on finite element modelling. It is demonstrated that the studied stress concentration can be reduced with the increase of the modulus of carbon fibre and the number of CFRP layers. The contribution of the effective width of CFRP to the decrease of stress concentration is also discussed. © 2017 Elsevier Ltd

关键词： Carbon fibers

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