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Prediction of Cold Dwell-Fatigue crack growth of Titanium Alloys

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Acta Metallurgica Sinica(English Letters) 2015年第5期28卷 619-627页

作者： Ke Wang Fang Wang Wei-Cheng Cui A.-Li Tian School of Naval Architecture and Ocean Engineering Shanghai Jiao Tong University Hadal Science and Technology Research Center (Shanghai Engineering Research Center of Hadal Science and Technology) Shanghai Ocean University School of Naval Architecture and Ocean Engineering Jiangsu University of Science and Technology

The dwell effect of the material can reduce the fatigue lives of titanium alloys at room temperature. A unified fatigue life prediction method developed by the authors＇ group is modified in this paper to predict dwell-fatigue crack growth taking into account the effects of dwell time and maximum stress. The modified model can be successfully used to predict the crack growth rate and calculate the fatigue life of different titanium alloys under pure fatigue and dwell-fatigue conditions. It is validated by comparing prediction results with the experimental data of several titanium alloys with different microstructures, dwell time, hydrogen contents, stress ratios and stress levels.

关键词： Titanium alloy Dwell-fatigue Fatigue crack growth

Stress Corrosion crack growth Behavior of Titanium Alloy/Bioactive Glasses Sandwiches in Simulated Human Physiological Environment

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Journal of Materials Science & Technology 2002年第5期18卷 387-391页

作者： DaCHEN J.M.McNaney E.Saiz A.P.Tomsia R.O.Ritchie Department of Materials Science，Shanghai Jiao Tong University，Shanghai 200030，China Department of Materials Science and Engineering，University of California，Berkeley，CA 94720，USA Materials Sciences Division，Lawrence Berkeley National Laboratory，Berkeley，CA 94720，USA Materials Sciences Division，Lawrence Berkeley National Laboratory，Berkeley，CA 94720，USA

Based on a series of newly developed bioactive glasses having suitable thermo-mechanical properties to allow application as fixation agents between bone and titanium alloy biomedical implants, the stress corrosion crack growth (SCCG) behavior of their interfaces with Ti6AI4V was investigated in simulated body fluid (SBF) with the objective of discerning the salient mechanisms of crack advance and to assess the reliability of the bonds. Results indicated that crack growth rates in Ti6AI4V/glass/Ti6AI4V sandwich specimens were nearly the same as or slightly lower than those in the bulk glasses at comparable stress intensities; indeed, cracks would prefer to propagate off the interface, suggesting that the Ti6AI4V/glass interface has relatively good crack-growth resistance. Mechanistically, interfacial crack growth appears to be controlled by the classic stress corrosion mechanisms for silicate glasses, with no discernible effect of bioactivity on the SCCG behavior being observed.

关键词： Stress corrosion Titanium alloy Bioactive glass crack growth

A NEW APPROACH TO PREDICTING INTERFACIAL crack growth

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Applied Mathematics and Mechanics(English Edition) 1997年第1期18卷 37-44页

作者：胡互让吴承平 Department of Mechanical Aerospace and Manufacturing Engineering Syracuse University 13244 Syracuse NY U.S.A. Chongqing Jiaotong Institute 630074 Chongqing P.R. China

A new approach, called β=0 approach is presented for use in the prediction ofinlerfocial crack growth. This approach is a kind of transformation. It transforms anoscillatory stress field to a nonoscillatory case by adjusting the elastic constants of thematerials involved. The interface toughness locus is also changed according to the newmaterial properties. It is shown that this approach will predict the exact same criticalload as interfacial fracture mechanics does. Finally several examples are presented toshow how to enforce β=0 while keeping the energy release rate unchanged.

关键词： interfacial crack crack growth β=0 approach critical load

NUMERICAL SIMULATION OF crack growth IN BRITTLE MATRIX OF PARTICLE REINFORCED COMPOSITES USING THE XFEM TECHNIQUE

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Acta Mechanica Solida Sinica 2012年第1期25卷 9-21页

作者： Zhiyong Wang Li Ma Linzhi Wu Hongjun Yu Center for Composite Materials Harbin Institute of TechnologyHarbin 150001China

crack growth in particle reinforced composites is significantly influenced by the character of the reinforcement *** accurately deal with such problems,the extended finite element method （XFEM） was employed and *** simulations are accomplished by using a new domain expression of an interaction integral for evaluating stress intensity factors （SIFs）,and by adopting the maximum hoop stress criterion for crack-growth direction *** deflection/attraction mechanisms and their associated energy release rate variations are *** is shown that the applied numerical method allows a considerable flexibility and can be used in more general *** crack-tip shielding and amplifying behaviors are clearly observed.

关键词： crack growth energy release rate crack-tip shielding and amplifying extended finite element method

Characteristics of crack growth in High Performance Concrete Subjected to Fire

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Journal of Materials Science & Technology 2005年第1期21卷 118-122页

作者： GaifeiPENG SammyYinNinCHAN JianhuaYAN YefengLIU QuanxinYI FacultyofCivilEngineering&Architecture BeijingJiaoTongUniversityBeijing100044China Wong&ChengConsultingEngineersLtd. HongKongChina BeijingUniversityofTechnology Beijing100022China

An experimental investigation was conducted to identify the characteristics of crack growth in high performance concrete (HPC) subjected to fire, including two parts of work, i.e. crack growth resistance determinations and cracking observations, using concrete of three strength grades 40 MPa, 70 MPa, and 110 MPa. The crack growth resistance curves (R-curves ) of HPC subjected to high temperatures were determined using notched three-point bend beam specimens of 100 mm×100 mm×300mm. The R-curve (crack growth resistance curve) flattening shows that the crack growth resistance has been significantly reduced by elevated temperature. Concrete with a higher strength grade has a steeper R-curve, with a higher fracture toughness but a shorter critical crack growth. The shorter critical crack growth means that concrete of a higher strength grade has a more brittle behavior. The concrete cracking observations reveal that the consequences of rapid heating are quite different from those of slow heating. For slow heating at a rate of 0.5℃/min, HPC suffered no obvious cracking below 600℃ even if it had a high moisture content. Explosive spalling is an extreme case of the internal cracking driven mainly by vapor pressure. All these results confirmed the vapor pressure mechanism for spading behavior which should be more significant for denser concrete. The crack growth ranges obtained from the R-curve determination results are in good agreement with those measured in the concrete cracking observations.

关键词： High performance concrete Fire resistance Explosive spoiling crack growth Vapor pressure

Thermal shock resistance and crack growth behavior of Aurivillius phase Bi4Ti3O12-based ferroelectric ceramics

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Progress in Natural Science:Materials International 2021年第2期31卷 248-254页

作者： Qian Xu Shaoxiong Xie Yu Chen Qingyuan Wang MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and Environment Sichuan University School of Mechanical Engineering Chengdu University College of Materials Science and Engineering Sichuan University

A type of W/Cr co-doped Bi4Ti3O12(ab. BTWC) ceramics were synthesized utilizing the traditional solid-state reaction process, and its thermal shock resistance(TSR) as well as the crack growth behavior was systematically investigated by water quenching technology. It can be found by the succeeded fractographic analysis that many edge thermal cracks began to appear in the samples subjected to thermal shock with ΔT=400°C. According to an integrated TSR model, the critical thermal-shock temperature difference ΔTCwas calculated to be 356°C. Moreover, it can be noticed that the indenter induced crack growth behaviors under thermal shock loads presented three stages, i.e. no growth, large growth, and moderate growth, along with ΔT increasing from 0°C to 700°C. Finally, the asymmetry of P-E hysteresis loops was observed and understood by the orientated polarization of defect dipoles after the sample was thermally shocked, while the water-quenching process above the Curie temperature of the ceramics could lead to a random orientation of the defect dipoles. This research can not only evaluate the service conditions of Bi4Ti3O12high-temperature piezoceramics, but also understand the failure mechanism of bismuth layer structured ferroelectric ceramics in the case of thermal shock.

关键词： Bi4Ti3O12ceramics TSR crack growth Temperature difference

Fatigue crack growth Behavior of Eutectoid Steel Rail

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Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 507-512页

作者： CEN Yaodong CHEN Lin JI Chunjiao WANG Huijun BAO Xirong School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010China

The fatigue crack behavior of U75V rail under different quenching rates was studied using SEM and *** results show that the pearlite interlayer spacing and fatigue crack growth rate decrease,and the deflection path of cracks and the number of branching cracks of U75V rail increases with an increase of cooling *** tearing edge of unstable region transites from pearlite lamellae to *** fatigue crack growth path is closely related to the orientation of lamellae in pearlite *** are three modes direction of fatigue crack growth path and pearlite lamellar,which are parallel,vertical and 45°angle,and most of the branch cracks occur at an angle of 45°between the lamellar direction and the crack *** specifically,the deflection paths of cracks and branching crack have a relaxation effect on the stress intensity at the crack tip,which restrains the fatigue crack growth rate.

关键词： fatigue fracture crack growth rail microstructure

EFFECT OF SULPHURIZING-OXIDIZING ENVIRONMENT ON CREEP crack growth OF Ni-BASE SUPERALLOY GH30

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Acta Metallurgica Sinica(English Letters) 1992年第1期5卷 43-47页

作者： ZHANG Yuanhu ZHANG Yun HU Shanghai Jiaotong Univ Shanghai China

An investigation was made on the creep crack growth behaviour under static load at 1023 K for Ni-base superalloy GH30 exposed to air and air+10% SO_*** results showed that in the region of low stress intensity factor,the creep crack growth rate is higher in air+10% SO_2 than in air only,while in the high region,it is *** fractograph of specimens has been analyzed,and the mechanism of creep crack growth together with the influences of sul- phur and oxygen has been discussed as well.

关键词： Ni-base superalloy creep crack growth environment

Nonlinear finite element analysis of crack growth at the interface of rubber-like bimaterials

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Science China(Physics,Mechanics & Astronomy) 2011年第10期54卷 1866-1874页

作者： YANG XiaoXiang FU MingWang WANG XiuRong LIU XiaoYing School of Mechanical Engineering and Automation Fuzhou University Fuzhou 350108 China Department of Mechanical Engineering The Hong Kong Polytechnic University Hung Horn Kowloon Hong Kong China

This paper presents the characteristics of the crack growth at the interface of rubber-rubber and rubber-steel bimaterials undertensile deformation using the non-linear finite element method. By using the commercial finite element software ABAQUS,the J integral calculations are carried out for the initial interface crack in the interfaces in-between two Neo-Hookean materials,two Mooney-Rivlin materials, Neo-Hookean and Mooney-Rivlin rubbers, Neo-Hookean and Polynomial, Mooney-Rivlin andPolynomial, and the Mooney-Rivlin and steel bi-materials. The computational results of the maximum J integral directionaround the crack tip illustrate the possible direction of crack growth initiation. Furthermore, it is found that the crack bends tothe softer rubber material at a certain angle with the initial crack direction if the crack depth is relatively small. For the crackwith a larger depth, the crack propagates to grow along the interface in-between the bimaterials.

关键词： rubber-like materials bimaterials interface crack J integral crack growth non-linear finite element method