共查询到20条相似文献,搜索用时 0 毫秒
1.
1. IntroductionThe initiation and propagation behavior of short cracks occupy a sigllificant fractionof the fatigue life of unflawed ..ie.ialll--3]. FOr this reason all understanding of the basiccharacteristics of short cracks in a smooth specimen is very importallt. There have beensome studies concerned with the multiplication of cracks dllring fatiglle ill carbon steels[3--4]and a stainless steeds]. In particular Goto reported that there is a colltilluous formationof microcracks during the … 相似文献
2.
3.
4.
5.
SHORT FATIGUE CRACK BEHAVIOUR IN ISO-STRESS SPECIMENS 总被引:1,自引:0,他引:1
HOGN Youshi LU Yonghua ZHENG Zhemin Institute of Mechanics Academia Sinica Beijing China Institute of Mechanics Academia Sinica Beijing China 《金属学报(英文版)》1990,3(4):276-281
Fatigue tests were made on a vibration machine using specially designed specimens to investi-gate the initiation and propagation features of short fatigue cracks in a weld metal.The spec-imens were triangular in shape so that when loaded as a cantilever beam the surface tensilestress is constant.Test results show that short fatigue cracks mainly originate from slip bandswithin ferrite grains.The development of short fatigue cracks is marked by a gradual increasein crack density with fatigue cycles.Coalescence of short cracks leads to crack propagationand the crack path is predominantly transgranular. 相似文献
6.
X.S. Wang) S.Q. Zhn) N. Kawagoishi) H. Nisitani) ) Department of Engineering Mechanics Tsinghua University Beijing China ) Faculty of Engineering Kagoshima University Kagoshima - Japan 《金属学报(英文版)》2001,14(4):271-279
1. Introduction Estimation of the fatigue life of a component under cyclic loading is of great interest in the modern engineering design against plastic deformation or conventional fracture. The fatigue process of materials may be approximately divided into two stages, i.e. the fatigue crack initiation and its propagation. The latter is more significant in service, because most of the fatigue life of many engineering components is spent on the crack growth, especially the small crack growth. … 相似文献
7.
CHEN Zheng Northwestern Polytechnical University Xi′an China Lab.No. Northwestern Polytechnical University Xi′an 《金属学报(英文版)》1991,4(2):135-138
Threshold of fatigue for short through cracks for Al-Li alloy 8090 was evaluated to be lowerthan that of long cracks,and to decrease with the shortening of the crack length.The correla-tion among the threshold,crack wake,and crack tip shielding of the short fatigue cracks wasdiscussed.The super demarcation length and lowest theoretical threshold of short through fa-tigue cracks were presented. 相似文献
8.
本文研究了8090Al-Li合金穿透疲劳短裂纹的门槛值,测定了不同长度短裂纹的门槛值和裂纹闭合效应,探讨了该合金疲劳短裂纹门槛值、裂纹尾迹和裂尖屏蔽之间的关系,给出了该合金穿透疲劳短裂纹的上界值和理论最低门槛值。 相似文献
9.
BEHAVIOUROFINITIATIONANDGROWTHOFSHORTFATIGUECRACKSWUZhixue;XUHao(InstituteofMechanicalEngineering,NortheasternUniversity,Shen... 相似文献
10.
GAO Hua CHEN Youxuan LI Ming Shanghai University of Engineering Science Shanghai ChinaCHEN Dehai Shanghai Dalong Machinery Shanghai China Associate Professor Dept.of Materials Shanghai University of Engineering Science Shanghai China 《金属学报(英文版)》1991,4(1):59-64
The effect of proportional and non-proportional overloading on mode l fatigue crack growthhave been studied,and the influences of crack tip plastic zone,crack tip blunting as well ascrack closure were discussed.Proportional(model I)overloading may cause more seriouscrack growth retardation than non-proportional(mixed mode)overloading.Therefore,forestimating the fatigue life of engineering structures to simplify a real overload which may of-ten be non-proportional as a proportional one is not always safe. 相似文献
11.
PEI Hongxun Institute of Corrosion Protection of Metals Academia Sinica Shenyang China Institute of Corrosion Protection of Metals Academia Sinica Shenyang China 《金属学报(英文版)》1989,2(4):284-292
Based on the experimental study of complex biaxial mode Ⅰ fatigue crack growth and thediscussion on Von Mises'theory,a new approach is proposed for correlating crack propaga-tion rate under both in-phase and out-of-phase biaxial stress cycling.The results emphasizethe contribution of plasticity to fatigue crack growth. 相似文献
12.
在双轴加载条件下对Ⅰ型疲劳裂纹扩展进行了研究。载荷范围从0.08σ_s到0.71σ_3,包括比例加载和非比例加载。基于对Von Mises理论的讨论,提出一个新的力学参数。双轴加载条件下的弹塑性参数P成功地描述了双轴比例加载和非比例加载下的疲劳裂纹扩展。 相似文献
13.
STUDYONFATIGUEDAMAGEBELOWTHEFATIGUELIMITANDTHECOAXINGEFFECTSWUZhixue;LUWengeandXUHao1)(FushunPetroleuminstitute,Fushun113001,... 相似文献
14.
HE Jiawen HU Naisai ZHANG Dingquan Xi''''an Jiaotong University Xi''''an China Professor Research Institute for Strength of Metals Xi''''an Jiaotong University Xi''''an China 《金属学报(英文版)》1993,6(2):96-100
Residual stress concentration at a notch depends on both notch geometry and yield strength ofthe material.It varies through the depth,and its magnitude may be higher than the theoreticalone.Compressive residual.stress concentration at the notch of shot-peened specimen of softmaterial is easily to he relaxed,with the surface damage during shot-peening results in a mi-nor contribution to the fatigue limit.Compressive residual stress increases the crack closureeffect at the notch and may lead to a non-propagating crack. 相似文献
15.
研究了A537钢在3.5%NaCl水溶液中,阳极溶解条件下以不同方式叠加在主载荷ΔP上的小幅载荷对疲劳裂纹扩展da/dN~ΔK曲线的影响,并与空气中的结果进行比较,讨论了阳极溶解影响小幅载荷行为的机理.结果表明:空气中幅度小于30%ΔP的小载荷叠加在主载荷底部时对裂纹扩展没有影响,而阳极溶解能使这些主载荷底部的小幅载荷对裂纹扩展过程产生重要作用,在阳极溶解条件下,即使是幅度为零的保持载荷(B0)对裂纹扩展也具有明显的加速作用;虽然阳极溶解对主载荷顶部的幅度为30%ΔP(T30)和70%ΔP(T70)的小载 相似文献
16.
17.
采用微电极体系和试样背后打孔技术,对300M超高强度钢在3.5%NaCl水溶液中腐蚀疲劳裂纹尖端微区溶液电化学行为进行研究,在极化和无极化条件下分别测试裂化溶液的电位△E和pH值的变化,结果发现,无极化条件下,裂尖pH下降,电位上升,裂尖前沿电位和pH值随裂化分布不均匀,在极化条件下,裂尖电化学特征随极化电位变化而表现不同,基于裂尖电化学行为规律,对腐蚀疲劳裂放展规律进行解释。 相似文献
18.
H.C.Yang Y.Tu M.M.Yu J.Zhao 《金属学报(英文版)》2004,17(4):597-600
Low cycle fatigue tests and crack growth propagations tests on P91 pipe base metal and its weld joints were conducted at three different temperatures: room temperature, 550℃ and 575℃. The strain-life was analyzed, and the changes in fatigue life behavior and fatigue growth rates with increasing temperature were discussed. The different properties of the base metal and its weld joint have been analyzed. 相似文献
19.
对[112]双滑移取向铝单晶体进行了对称拉压疲劳试验,详细观察和对比研究了正表面和侧表面(包含两个主滑移系Burgers矢量)上的疲劳损伤与裂纹萌生过程.在正表面上两个主滑移系滑移台阶是相互平行的,呈典型的持续滑移带(PSB)损伤形貌;而在S面上则始终未见PSB,但有晶体学关系不明确的呈波纹形不均匀分布的形变花样产生,并发展导致微裂纹的萌生,其尺寸可与正表面上的PSB裂纹相匹比。由此进一步证实了循环形变累积所致的内部组织损伤是疲劳裂纹萌生的基本因素.和单滑移取向单晶体相比,在复滑移条件下的显著交滑移过程明显地促进了试样的疲劳损伤和裂纹萌生. 相似文献
20.
环境对AISI321不锈钢疲劳裂纹扩展过载效应的影响 总被引:5,自引:0,他引:5
研究了3.5%NaCl溶液对恒应力强度因子范围△K控制下AISI321不锈钢疲劳裂纹扩展过载行为的影响.与在空气中的结果比较表明,两种条件下存在相似的过载延缓效应,但是环境极大地削弱了过载对疲劳裂纹扩展的延缓效应,削弱程度随过载比不同而变化,以“损失循环数”表征约为40%-70%,以“过载影响区尺寸”表征则为30%-40%.分析表明,用“损失循环数”表征过载对裂纹扩展的延缓效应不够充分,无法区分环境对裂纹闭合的削弱和增强作用,“过载影响区尺寸”可以区分环境对过载塑性形变增强裂纹闭合的综合影响.对断口的SEM分析发现,过载造成的塑性形变在溶液中比在空气中受到更多的磨损,表明环境对过载延缓效应的削弱除了对裂尖的影响外,还包括对过载导致的塑性诱发裂纹闭合的影响. 相似文献