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Cracking evolution behaviors of lightweight materials based on

Y. Luo, S. C. Wu, Y. N. Hu, Y. N. Fu

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 461-481 doi: 10.1007/s11465-018-0481-2

摘要：

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomography can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional (3D) X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects (porosity, void, inclusion, precipitate, etc.) or artificial defects (notch, scratch, pit, etc.) strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.

关键词： fatigue crack initiation and growth     fatigue damage mechanism     damage tolerance     defect characterization     laser welded aluminum alloys    

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A study on fatigue damage of asphalt mixture under different compaction using 3D-microstructural characteristics

Jing HU, Pengfei LIU, Bernhard STEINAUER

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 329-337 doi: 10.1007/s11709-017-0407-9

摘要： The aim of this paper is investigating the microstructural characteristics of asphalt mixture under different compaction powers. In order to achieve this aim, a test track was built to provide asphalt mixture specimens and X-ray computed tomography (XCT) device was used to scan the internal structure. The aggregate particles and air-voids were extracted using Digital Image Processing (DIP), so the relationship between compaction and air-voids was determined at first, and then, the effect of aggregate particles on the morphology of air-voids can be evaluated, finally, fatigue properties of asphalt mixture with different air-void ratio were measured by indirect tensile fatigue test as well. The research results release the distribution of microstructures in asphalt pavement. 3D fractal dimension is an effective indicator to quantize the complexity of aggregate particles and air-voids; suffering the same compaction power, aggregates cause different constitutions of air-voids in asphalt mixture; investigation in this paper can present the essential relationship between microstructures and fatigue properties.

关键词： asphalt mixture     microstructure     morphology     digital image processing     fatigue damage    

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Review of the damage mechanism in wind turbine gearbox bearings under rolling contact fatigue

Yun-Shuai SU, Shu-Rong YU, Shu-Xin LI, Yan-Ni HE

《机械工程前沿（英文）》 2019年 第14卷 第4期   页码 434-441 doi: 10.1007/s11465-018-0474-1

摘要： Wind turbine gearbox bearings fail with the service life is much shorter than the designed life. Gearbox bearings are subjected to rolling contact fatigue (RCF) and they are observed to fail due to axial cracking, surface flaking, and the formation of white etching areas (WEAs). The current study reviewed these three typical failure modes. The underlying dominant mechanisms were discussed with emphasis on the formation mechanism of WEAs. Although numerous studies have been carried out, the formation of WEAs remains unclear. The prevailing mechanism of the rubbing of crack faces that generates WEAs was questioned by the authors. WEAs were compared with adiabatic shear bands (ASBs) generated in the high strain rate deformation in terms of microstructural compositions, grain refinement, and formation mechanism. Results indicate that a number of similarities exist between them. However, substantial evidence is required to verify whether or not WEAs and ASBs are the same matters.

关键词： rolling contact fatigue (RCF)     white etching area (WEA)     white etching crack (WEC)     adiabatic shear band (ASB)    

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Estimation of fatigue damage of airplane landing gear

LIU Ke-ge, YAN Chu-liang, ZHANG Shu-ming

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 424-428 doi: 10.1007/s11465-006-0051-x

摘要： Taking the main landing gears of fighter and transport airplanes as examples, the fatigue life was estimated by means of the Miner s rule and from the spectrum of the real measurements. The computed results show that the landing damage to the fighter and transport airplanes is 75% and 60% of the total damage, and the damage caused by the landing stroke is 40% of the landing-gear damage. The fatigue damage properties can provide important information for reliable designing and the structural optimization.
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确定性疲劳累积损伤理论进展

杨晓华,姚卫星,段成美

《中国工程科学》 2003年 第5卷 第4期   页码 81-87

摘要：

著名的Miner-Palmgren线性累积损伤理论的提出已有70余年，但由于疲劳问题的复杂性，迄今为止还没有一个模型的工程应用价值能与该理论媲美。疲劳累积损伤理论仍在发展与完善中。文章根据疲劳损伤与疲劳累积损伤理论的特点，将确定性疲劳累积损伤理论分成两大类，即线性累积损伤理论和非线性累积损伤理论，并将主要的非线性累积损伤理论分成五类：a. 基于损伤曲线法的非线性累积损伤理论；b. 基于材料物理性能退化概念的非线性累积损伤理论；c. 基于连续损伤力学概念的非线性累积损伤理论；d. 考虑载荷间相互作用效应的非线性累积损伤理论；e. 基于能量法的非线性累积损伤理论。文章分析了每一类模型中有代表性模型的物理背景，回答了模型在疲劳累积损伤理论中存在的主要问题，简要评述了模型的优缺点，讨论了确定性疲劳累积损伤理论的几个关键问题。

关键词： 疲劳     线性与非线性     累积损伤     损伤力学     能量    

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Contact fatigue life prediction of a bevel gear under spectrum loading

Pan JIA, Huaiju LIU, Caichao ZHU, Wei WU, Guocheng LU

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 123-132 doi: 10.1007/s11465-019-0556-8

摘要： Rolling contact fatigue (RCF) issues, such as pitting, might occur on bevel gears because load fluctuation induces considerable subsurface stress amplitudes. Such issues can dramatically affect the service life of associated machines. An accurate geometry model of a hypoid gear utilized in the main reducer of a heavy-duty vehicle is developed in this study with the commercial gear design software MASTA. Multiaxial stress–strain states are simulated with the finite element method, and the RCF life is predicted using the Brown–Miller–Morrow fatigue criterion. The patterns of fatigue life on the tooth surface are simulated under various loading levels, and the RCF curve is numerically generated. Moreover, a typical torque–time history on the driven axle is described, followed by the construction of program load spectrum with the rain flow method and the Goodman mean stress equation. The effects of various fatigue damage accumulation rules on fatigue life are compared and discussed in detail. Predicted results reveal that the Miner linear rule provides the most optimistic result among the three selected rules, and the Manson bilinear rule produces the most conservative result.

关键词： bevel gear     rolling contact fatigue (RCF)     multiaxial fatigue criterion     load spectrum     damage accumulation rule    

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Subsurface damage pattern and formation mechanism of monocrystalline -GaO in grinding process

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0677-3

摘要： Monocrystalline beta-phase gallium oxide (β-Ga2O3) is a promising ultrawide bandgap semiconductor material. However, the deformation mechanism in ultraprecision machining has not yet been revealed. The aim of this study is to investigate the damage pattern and formation mechanism of monocrystalline β-Ga2O3 in different grinding processes. Transmission electron microscopy was used to observe the subsurface damage in rough, fine, and ultrafine grinding processes. Nanocrystals and stacking faults existed in all three processes, dislocations and twins were observed in the rough and fine grinding processes, cracks were also observed in the rough grinding process, and amorphous phase were only present in the ultrafine grinding process. The subsurface damage thickness of the samples decreased with the reduction in the grit radius and the grit depth of cut. Subsurface damage models for grinding process were established on the basis of the grinding principle, revealing the mechanism of the mechanical effect of grits on the damage pattern. The formation of nanocrystals and amorphous phase was related to the grinding conditions and material characteristics. It is important to investigate the ultraprecision grinding process of monocrystalline β-Ga2O3. The results in this work are supposed to provide guidance for the damage control of monocrystalline β-Ga2O3 grinding process.

关键词： monocrystalline beta-phase gallium oxide     grinding process     subsurface damage     nanocrystals     amorphous phase    

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船体结构疲劳寿命的评估

李靖宇,田常录

《中国工程科学》 2006年 第8卷 第2期   页码 51-54

摘要：

船舶事故分析表明，疲劳破坏是其结构破坏的主要形式。由于船体中节点的多样性以及节点荷载的复杂性，使得船体结构的疲劳校核计算也相当复杂，所以工程中提出了一些简化方法。介绍了船体结构疲劳强度校核的基本原理，疲劳载荷和疲劳累积损伤计算方法；编写了船体结构疲劳强度校核程序，并用其评估了大型油轮（VLCC）在典型节点处的疲劳寿命。

关键词： 船体结构     疲劳寿命     累积损伤    

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交叉模态对结构随机振动疲劳损伤的贡献

朱学旺,刘青林

《中国工程科学》 2008年 第10卷 第10期   页码 36-41

摘要：

以小阻尼简支梁为例，讨论了交叉模态对随机振动疲劳损伤累积的贡献；结构的响应分析采用模态叠加方法，随机振动疲劳损伤累积分析采用Miner线性疲劳损伤准则。数值模拟结果表明,即使是小阻尼稀疏模态结构，交叉模态对结构振动疲劳损伤累积的贡献也是不容忽视的。

关键词： 交叉模态     结构随机振动     疲劳损伤累积     随机振动响应     模态叠加     小阻尼稀疏模态系统    

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Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

Jia XU,Zhen-yu ZHOU,Zhong-yu PIAO

《机械工程前沿（英文）》 2016年 第11卷 第3期   页码 227-232 doi: 10.1007/s11465-016-0395-9

摘要：

The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-on-disc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

关键词： accumulated damage     spray coating     rolling contact fatigue     acoustic emission    

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Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 781-792 doi: 10.1007/s11709-021-0733-9

摘要： During the construction of lightweight cellular concrete (LCC), material damage frequently occurs, causing the degradation and deterioration of the mechanical performance, durability, and subgrade quality of LCC. The construction-induced damage can be more significant than those from the service environment of LCC, such as freeze–thaw (F–T) action in cold regions. However, the effect of construction-induced damage on LCC during F–T cycles is often ignored and the deterioration mechanisms are not yet clarified. In this study, we investigated the factors causing damage during construction using a sample preparation method established to simulate the damage in the laboratory setting. We conducted F–T cycle tests and microstructural characterization to study the effect of microstructural damage on the overall strength of LCC with different water contents under F–T actions. We established the relationship between the pore-area ratio and F–T cycle times, pore-area ratio, and strength, as well as the F–T cycle times and strength under different damage forms. The damage evolution is provided with the rationality of the damage equation, verified by comparing the measured and predicted damage variables. This study would serve as a guide for the construction and performance of LCC in cold regions.

关键词： lightweight cellular concrete     construction-induced damage     freeze-thaw action     microstructure     degradation mechanism    

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锌液冷却管损坏机理的研究

袁望姣,何将三

《中国工程科学》 2005年 第7卷 第9期   页码 56-60

摘要：

炼锌工业中广泛使用由无缝钢管冷弯而成的冷却管来实现锌液的冷却。冷却管的使用寿命非常短，消耗量相当大。锌液的表面张力小，渗透性强，腐蚀性强，能与冷却管中的铁元素生成铁-锌合金，能溶解冷却管中碳、硅等元素，锌液对冷却管的强腐蚀性，是影响锌液冷却管使用寿命的决定性因素；锌液冷却管的损坏是高温腐蚀和应力腐蚀共同作用的结果，热应力和残余应力促使其损坏由高温腐蚀向应力腐蚀发展；冷却管损坏位置由热应力和残余应力共同决定，其中热应力起主导作用。

关键词： 锌液     冷却管     损坏机理     高温腐蚀     应力腐蚀    

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Damage mechanism and evaluation model of compressor impeller remanufacturing blanks: A review

Haiyang LU, Yanle LI, Fangyi LI, Xingyi ZHANG, Chuanwei ZHANG, Jiyu DU, Zhen LI, Xueju RAN, Jianfeng LI, Weiqiang WANG

《机械工程前沿（英文）》 2019年 第14卷 第4期   页码 402-411 doi: 10.1007/s11465-019-0548-8

摘要： The theoretical and technological achievements in the damage mechanism and evaluation model obtained through the national basic research program “Key Fundamental Scientific Problems on Mechanical Equipment Remanufacturing” are reviewed in this work. Large centrifugal compressor impeller blanks were used as the study object. The materials of the blanks were FV520B and KMN. The mechanism and evaluation model of ultra-high cycle fatigue, erosion wear, and corrosion damage were studied via theoretical calculation, finite element simulation, and experimentation. For ultra-high cycle fatigue damage, the characteristics of ultra-high cycle fatigue of the impeller material were clarified, and prediction models of ultra-high cycle fatigue strength were established. A residual life evaluation technique based on the “ - - ” (where was the nonlinear parameter, was the Vickers hardness, and was the fatigue life) double criterion method was proposed. For erosion wear, the flow field of gas-solid two-phase flow inside the impeller was simulated, and the erosion wear law was clarified. Two models for erosion rate and erosion depth calculation were established. For corrosion damage, the electrochemical and stress corrosion behaviors of the impeller material and welded joints in H S/CO environment were investigated. (critical stress intensity factor) and d /d (crack growth rate, where is the total crack length and is time) varied with H S concentration and temperature, and their variation laws were revealed. Through this research, the key scientific problems of the damage behavior and mechanism of remanufacturing objects in the multi-strength field and cross-scale were solved. The findings provide theoretical and evaluation model support for the analysis and evaluation of large centrifugal compressor impellers before remanufacturing.

关键词： remanufacturing     centrifugal compressor impeller     remanufacturing blank     damage mechanism     evaluation model    

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Atomistic understanding of interfacial processing mechanism of silicon in water environment: A ReaxFF

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 570-579 doi: 10.1007/s11465-021-0642-6

摘要： The interfacial wear between silicon and amorphous silica in water environment is critical in numerous applications. However, the understanding regarding the micro dynamic process is still unclear due to the limitations of apparatus. Herein, reactive force field simulations are utilized to study the interfacial process between silicon and amorphous silica in water environment, exploring the removal and damage mechanism caused by pressure, velocity, and humidity. Moreover, the reasons for high removal rate under high pressure and high velocity are elucidated from an atomic perspective. Simulation results show that the substrate is highly passivated under high humidity, and the passivation layer could alleviate the contact between the abrasive and the substrate, thus reducing the damage and wear. In addition to more Si-O-Si bridge bonds formed between the abrasive and the substrate, new removal pathways such as multibridge bonds and chain removal appear under high pressure, which cause higher removal rate and severer damage. At a higher velocity, the abrasive can induce extended tribochemical reactions and form more interfacial Si-O-Si bridge bonds, hence increasing removal rate. These results reveal the internal cause of the discrepancy in damage and removal rate under different conditions from an atomic level.

关键词： silicon     ReaxFF     molecular dynamics     friction     damage    

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Mechanism of hepatocellular damage in rat caused by low serum selenium

LU Yi, QU Bo, LIU Chang, YU Liang, Liu Xuemin, WANG Haohua, JIANG An, ZHANG Xiaogang

《医学前沿（英文）》 2008年 第2卷 第3期   页码 255-258 doi: 10.1007/s11684-008-0048-4

摘要： The aim of this paper is to investigate the mechanism of hepatocellular damage in rats caused by low serum selenium. Thirty six rats were randomly divided into 2 groups: group A (fed with low-selenium diet from the Keshan Disease area with the content of selenium being 0.017 mg/kg); group B [fed with selenium-supplemented diet and 0.3 mg/L selenium (NaSeO) was added to the drinking water]. Both were respectively fed for 12 weeks. At the end of the 12 week, the levels of serum selenium, glutathione peroxidase (GPX) and malondialdehyde (MDA) in hepatic tissue were measured; the hepatocellular ultrastructure and apoptosis were observed as well. The levels of serum selenium and GPX in group A were markedly lower than those in group B. MDA level in group A was significantly higher than that in group B. Under the electron microscope (EM), the mitochondria were remarkably changed in group A. The rate of liver cell apoptosis appeared much higher in group A as well. It indicated that the damage caused by selenium deficiency was through the process of oxidation. Selenium deficiency led to apoptosis of hepatocytes where oxidative damage to mitochondria might be the cause.

关键词： process     glutathione peroxidase     hepatocellular damage     group     Keshan Disease    

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标题 作者 时间 类型 操作

Cracking evolution behaviors of lightweight materials based on

Y. Luo, S. C. Wu, Y. N. Hu, Y. N. Fu

期刊论文

A study on fatigue damage of asphalt mixture under different compaction using 3D-microstructural characteristics

Jing HU, Pengfei LIU, Bernhard STEINAUER

期刊论文

Review of the damage mechanism in wind turbine gearbox bearings under rolling contact fatigue

Yun-Shuai SU, Shu-Rong YU, Shu-Xin LI, Yan-Ni HE

期刊论文

Estimation of fatigue damage of airplane landing gear

LIU Ke-ge, YAN Chu-liang, ZHANG Shu-ming

期刊论文

确定性疲劳累积损伤理论进展

杨晓华,姚卫星,段成美

期刊论文

Contact fatigue life prediction of a bevel gear under spectrum loading

Pan JIA, Huaiju LIU, Caichao ZHU, Wei WU, Guocheng LU

期刊论文

Subsurface damage pattern and formation mechanism of monocrystalline -GaO in grinding process

期刊论文

船体结构疲劳寿命的评估

李靖宇,田常录

期刊论文

交叉模态对结构随机振动疲劳损伤的贡献

朱学旺,刘青林

期刊论文

Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

Jia XU,Zhen-yu ZHOU,Zhong-yu PIAO

期刊论文

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

期刊论文

锌液冷却管损坏机理的研究

袁望姣,何将三

期刊论文

Damage mechanism and evaluation model of compressor impeller remanufacturing blanks: A review

Haiyang LU, Yanle LI, Fangyi LI, Xingyi ZHANG, Chuanwei ZHANG, Jiyu DU, Zhen LI, Xueju RAN, Jianfeng LI, Weiqiang WANG

期刊论文

Atomistic understanding of interfacial processing mechanism of silicon in water environment: A ReaxFF

期刊论文

Mechanism of hepatocellular damage in rat caused by low serum selenium

LU Yi, QU Bo, LIU Chang, YU Liang, Liu Xuemin, WANG Haohua, JIANG An, ZHANG Xiaogang

期刊论文