赵永翔
从事机械强度可靠性和安全性及机械系统维修性与寿命周期工程的教学与研究。
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 姓名：赵永翔
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学术头衔：
博士生导师， 优秀教师/优秀教育工作者
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学科领域：
机械设计原理与方法
 研究兴趣：从事机械强度可靠性和安全性及机械系统维修性与寿命周期工程的教学与研究。
赵永翔，男，1963年出生，教授，博士生导师。四川省有突出贡献专家，四川省学术和技术带头人，全国百篇优秀博士学位论文作者，教育部优秀青年教师资助计划资助对象，四川省（杰出）青年科技基金、茅以升铁道科技奖和詹天佑铁道科技成就奖获得者。中国机械工程学会高级会员，《International Journal of Fatigue》和《机械强度》杂志编委，第5届设计与制造前沿国际学术会议(ICFDM’02)和第18届国际反应堆结构力学大会(SMiRT18)分会主席。
从事机械强度可靠性和安全性及机械系统维修性与寿命周期工程的教学与研究。提出了疲劳“有效短裂纹准则”及“逆序局部观测法”；揭示了群体短裂纹交互作用与演化的物理机制和疲劳行为存在随机性的本质原因，解决了国际上长期没有查明这一原因的难题。试验新发现了材料的“随机循环应力―应变响应”和“完全平均应力松弛”现象；揭示了随机循环应力―应变关系、随机循环应变/应力―寿命关系和随机疲劳裂纹扩展行为是有机相关的三大随机疲劳行为；建立了表征随机循环应力―应变和循环应变/应力―寿命现象的新模型及测定模型参数的广义极大似然法；对现有以循环应力比与循环应变比等同的疲劳分析方法提出了挑战；初步建立了以材料局部随机循环应力―应变模型为核心的应变疲劳可靠性设计分析方法新体系。提出了综合考虑数学自洽性、数理一致性和工程可应用性，确定有限疲劳可靠性数据良好统计分布模型的原则与方法。阐明了产品在使用过程中的不可逆劣化特征，提出了考虑性能劣化、与分布类型无关、可保持元件或系统在临界可靠度以上水平工作的“等劣化模型”与“广义等劣化模型”。
先后主持国家、省、部级科研项目12项。发表相关学术论文80余篇, 已被SCI、EI收录50余篇次，SCI引用80篇次；排名第1、2获得了省级科技进步二等奖2项，排名第1获得国家专利(ZL 02276616.2) 1项。研究生有2人次获国家、省部级个人优胜奖，3人次获省级科技进步二等奖，其中1名博士生获得了首届“中国青少年科技创新奖”。

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【期刊论文】Interaction and evolution of short fatigue cracks
赵永翔， Y. X . ZHAO， Q. GAO and J. N. WANG
Blackwell Science Ltd. Fatigue Fract Engng Mater Struct 22, 459467，0001，（）：
1年11月30日
Distinguishing the different contributions to fatigue damage of short cracks having different sizes and locations on the specimen surface, three new concepts, referred to as effective short fatigue cracks (ESFCs), dominant effective short fatigue cracks (DESFC), and density of ESFCs, respectively, are introduced to facilitate an understanding of the mechanism of interaction and evolution of short cracks. These concepts are interrelated and in conjunction produce an 'effective short fatigue crack criterion'. Replica observations of 19 smooth axial specimens of 1Cr19Ni9Ti stainless steel weld metal during lowcycle fatigue tests reveal that the short cracks contribute to the fatigue damage of specimens due to the formation of a critical density of ESFCs. The density reflects the local microstructural growth conditions ahead of the DESFC tips. The DESFC behaviour is a result of interactive short cracks, and this behaviour is deemed suitable to describe the collective behaviour of short cracks. In the microstructural shortcrack stage, the DESFC are located in the weakest zone. Due to an irregular microstructural barrier effect, the crack density is higher in this zone and increases with fatigue cycling to reach a maximum value at the transition point into the physical shortcrack stage. Then, due to the effects of accelerating coalescence and the DESFC size shielding the formation of new cracks, the density decreases rapidly and tends gradually to a saturation value. This is why the shortcrack growth rate is high initially and tends gradually to that of longcrack behaviour. The difference and change in local microstructural growth conditions ahead of DESFC tips are the intrinsic cause of the statistical behaviour of short cracks and the scatter of fatigue lives.
short fatigue cracks， crack interaction， damage evolution， 1Cr19Ni9Ti stainless steel， weld metal.，

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赵永翔， Y. X . ZHAO， Q. GAO and J. N. WANG
Blackwell Science Ltd. Fatigue Fract Engng Mater Strut 22, 469480，0001，（）：
1年11月30日
An experimental stndy into microstructural effects on short fatigue crack behaviour of 19 stainless steel weld metal smooth specimens during lowcycle fatigue is performed by a socalled ‘effective short fatigue crack criterion’. This material has a mixed microstructure in which it is difficult to distinguish the grains and measure the grain diameter. The columnar grain structure is made up of matrixrich δ ferrite bands, and the distance between the neighbouring rich δ ferrite bands is an appropriate measure ment for characterizing this structure. Particularly, the effective short fatigue cracks (ESFCs) always initiate from the bands of δ ferrite in the matrix in the weakest zone on one of the specimen surface zones which is orientated in accordance with the inner or outer surface of welded pipe from which the specimens were machined. These cracks exhibit characteristics of the microstructural short crack (MSC) and the physically small crack (PSC) stages. The average length of the ESFCs at the transition between MSC and PSC behaviour is ≈40μm, while the corresponding fatigue life fraction is ≈0.3 at this transition. Different from previous test observations, the growth rate of the dominant effective short fatigue crack in the MSC stage still shows a decrease with fatigue cycling under the present lowcycle fatigue loading levels. A statistical evolution analysis of the growth rates reveals that the short fatigue crack growth is a damage process that gradually evolves from a nonordered (chaotic) to a perfectly independent stochastic process, and then to an ordered (historydependent) stochastic state. Correspondingly, the microstructural effects gradually evolve from a weak effect to a strong one in the MSC stage, which maximizes at the transition point. In the PSC stage, the effects gradually evolve from a strong to weak state. This improves our understanding that the short crack behaviour in the PSC stage is mainly related to the loading levels rather than microstructural effects.
stainless steel， weld metal， lowcycle fatigue， microstructure， short fatigue cracks.，

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赵永翔， Y.X. Zhao a， *， J.N. Wang a， Q. Gao b
Nuclear Engineering and Design 205(2001)241249，0001，（）：
1年11月30日
Modeling of random cyclic strainlife (CSL) relations of engineering material should be a basis of strainbased fatigue reliability analysis. A statistical model for the relations of a nuclear engineering material, 1Cr18Ni9Ti stainless steel pipeweld metal under temperature of 240℃, is presented. In the model, a verified distribution, i.e. lognormal distribution, is used as an appropriate assumed distribution of the material fatigue life data. Based on the CoffinManson law, the relations are modeled by mean valueand standard deviationcyclic curves of the logarithm of fatigue life. Then, fatigue analysis at an arbitrarily given probability can be made conveniently according to the normal distribution function. An approach for estimating the curves and their confidence bounds is developed by a linear regression technique. Different from the existent reliability analysis methods that considered the material constants in the law as independently random variables, present work treats them as dependently random variables from the fit of test data. Availability of the model has been indicated by an analysis of the material test data.

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赵永翔， Y.X. Zhao*
Materials Science and Engineering A344(2003)229239，0001，（）：
1年11月30日
The size evolution of surface short cracks in 1Cr18Ni9Ti pipeweld metal is investigated in this paper. A local viewpoint is used to explain the observed evolution of cracking phenomena. The socalled'effectively short fatigue crack criterion' is used to characterize distributed populations of cracks. Special attention is paid to the initiation zone of dominant effectively short fatigue cracks (DESFCs) and then the zones ahead of the DESFC tips. The results reveal that the evolutionary size exhibits significant characteristics of microstructurally short crack (MSC) and physically short crack (PSC) stages. Fatigue damage is contributed largely to the initiation, and irregular growth, of effectively short fatigue cracks (ESFCs) in the MSC stage. In the PSC stage, the damage is due mainly to the DESFC growth, and partially to the growth of ESFCs and the coalescence of ESFCs themselves and with the DESFC. The damage processes involve gradual transitions from a nonordered/chaotic status in the fatigue initiation regime, to an independently random status at the boundary between the MSC and PSC stages. Finally, a subsequent transition occurs to a historydependent random status.
Short fatigue cracks， Crack size， Damage evolution， Effectively short fatigue crack criterion， 1Cr18Ni9Ti pipe， Weld metal

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【期刊论文】Random cyclic stressstrain responses of a stainless steel pipeweld metal IIa modeling
赵永翔， Y.X. Zhao a， *， Q. Gao b， J.N. Wang a
Nuclear Engineering and Design 199(2000)315326，0001，（）：
1年11月30日
This paper pays special attention to an issue that there is a significant scatter of the stressstrain responses of a nuclear engineering material, 1Cr18Ni9Ti stainless steel pipeweld metal. Efforts are made to reveal the random fatigue damage character by fracture surface observations and to model the random responses by introducing probabilitybased stressstrain curves of RambergOsgood relation and its modified form. Results reveal that the fatigue damage is subjected to, 3D interacting and involved microcracks. The three stages, namely microstructural short cracks (MSC), physical short cracks (PSC) and long cracks (LC) subdivided by Miller and de los Rios, can give a good characterization of the damage process. Both microand macrobehaviour of the material have the character of three stages. The 3D effects are strong in the MSC stage, tend to a gradual decrease in the PSC stage, and then show saturation after going to the LC stage. Intrinsic causes of the random behaviour are the difference and evolution of the microstructural conditions ahead of the dominant crack tips. The'effectively short fatigue crack criterion' introduced by Zhao et al. in observing the material surface short crack behaviour could facilitate an understanding of the mechanism of interaction and evolution. Based on the previous obtained appropriate assumed distribution, normal model, for the cyclic stress amplitude, the probabilitybased curves are approximated by the mean value and standard deviation cyclic stressstrain curves. Then, fatigue analysis at arbitrarily given reliability can be conveniently made according to the normal distribution function. To estimate these curves, a maximum likelihood method is developed. The analysis reveals that the curves could give a good modeling of the random responses of material.

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赵永翔， Y.X. Zhao a， *， J.N. Wang a， Q. Gao b
Nuclear Engineering and Design 199(2000)303314，0001，（）：
1年11月30日
This paper pays a special attention to the issue that there is a significant scatter of the stressstrain responses of a nuclear engineering material, 1Cr18Ni9Ti stainless steel pipeweld metal. Statistical investigation is made to the cyclic stress amplitudes of this material. Three considerations are given. They consist of the total fit, the consistency with fatigue physics and the safety in practice of the seven commonly used statistical distributions, namely Weibull (twoand threeparameter), normal, lognormal, extreme minimum value, extreme maximum value and exponential. Results reveal that the data follow meanwhile the seven distributions but the local effects of the distributions yield a significant difference. Any of the normal, lognormal, extreme minimum value and extreme maximum value distributions might be an appropriate assumed distribution for characterizing the data. The normal and extreme minimum models are excellent. Other distributions do not fit the data as they violate two or three of the mentioned considerations.

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赵永翔， Y.X. Zhao*
Reliability Engineering and System Safety 79(2003)301308，0001，（）：
1年11月30日
Conventional preventive maintenance (PM) policies generally hold same time interval for PM actions and are often applied with known failure modes. The same time interval will give unavoidably decreasing reliabilities at the PM actions for degradation system with imperfect PM effect and the known failure modes may be inaccurate in practice. Therefore, field managers would prefer policy with an acceptable reliability level to keep system often at a good state. A PM policy with the critical reliability level is presented to address the preference of field managers. Through assuming that system after a PM action starts a new failure process, a parameter socalled degradation ratio is introduced to represent the imperfect effect. The policy holds a law that there is same number of failures in the time intervals of various PM cycles, and same degradation ratio for the system reliability or benefit parameters such as the optimal time intervals and the hazard rates between the neighboring PM cycles. This law is valid to any of the failure modes that could be appropriately referred as a'general isodegrading model', and the degradation ratio as a'general isodegrading ratio'. In addition, life cycle availability and cost functions are derived for system with the policy. An analysis of the field data of a loading and unloading machine indicates that the reliability, availability and cost in life cycle might be well modeled by the present theory and approach.
Preventive maintenance， Degradation， Critical reliability， Life cycle， Availability， Cost

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赵永翔， Y.X. Zhaoa， *， Q. Gaob， J.N. Wanga
Reliability Engineering and System Safety 67(2000)17，0001，（）：
1年11月30日
The case of limited data implies that some unknown uncertainties may be involved in fatigue reliability analysis. For the sake of statistical convenience, for consistency with the relevant physical arguments and, most importantly, to ensure the safety in design evaluation, an approach is developed to determine an appropriate distribution, from four possible assumed distributions—threeparameter Weibull, twoparameter Weibull, lognormal and extreme maximumvalue distributions. The approach makes allowance for consistency with the fatigue physics and checking tail fit effects. An application to nine groups of fatigue life data of 16Mn steel (Chinese steel) welded plate specimens shows that the lognormal distribution and the extreme maximumvalue distribution may be the appropriate distributions of the fatigue life under limited data.
Fatigue， Extreme maximumvalue distribution， Reliability analysis

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【期刊论文】A Probabilistic Assessment of the Design SN Curves for 1Cr18Ni9Ti PipeWelded Joint
赵永翔， Y. X. Zhao
Journal of Pressure Vessel Technology MAY 2003, Vol. 125:195200，0001，（）：
1年11月30日
probabilistic assessment is made of the design SN curves for 1Cr18Ni9Ti pipewelded joint. The material exhibits a character of random cyclic stressstrain and fatigue life responses. Then, both the S and N in the virtual stress amplitudefatigue crack initiation life (SN) data are random variables. A general maximum likelihood method, which considers the randomness of the test SN data, is developed to model the probabilistic SN relations of material. The design SN curves with reduction factors of 20 on cycles, 2 on stress and 2.5 on stress applied to the bestfit SN curve of test data as used in the ASME code and general practice, are assessed in a probabilistic sense. The results reveal that in the lower S regime the 20 and 2.5 reduction factor curves may be appropriate, while the reduction factor of 2 is slightly nonconservative. But in the higher S regime these curves are all much more conservative. The intrinsic cause is that the standard deviation of logN exhibits an increase with the S decreasing, while the constant reduction factors do not consider this increase. It is shown that from the general statistical scatter of SN data the design SN curves should be appropriately determined by a probabilistic approach.

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【期刊论文】A methodology for strainbased fatigue reliability analysis
赵永翔， Y.X. Zhao*
Reliability Engineering and System Safety 70(2000)205213，0001，（）：
1年11月30日
A significant scatter of the cyclic stress
Low cycle fatigue， Reliability， Random cyclic stressstrain responses， Reactor， Pipe， Weld metal

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