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PROBABILISTIC MODELS FOR LONG FATIGUE CRACK GROWTH RATES OF LZ50 AXLE STEEL 被引量:5
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作者 ZHAO Yong-xiang(赵永翔) +9 位作者 HE Chao-ming(何朝明) YANG Bing(杨冰) HUANG Yu-zhong(黄郁仲) GAO Qing(高庆) WU Ping-bo(邬平波) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2005年第8期1093-1099,共7页
Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity... Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-△K relations, the confidence-based da/dN-△K relations, and the probabilistic- and confidence-based da/dN-△K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible. 展开更多
关键词 LZ50 steel long fatigue crack growth rate average stress THRESHOLD probabilistic model
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New model of propagation rates of long crack due to structure fatigue 被引量:2
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作者 刘建涛 杜平安 +1 位作者 黄明镜 周晴 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第5期575-584,共10页
By comparison of the characteristics of existing models for long fatigue crack propagation rates, a new model, called the generalized passivation-lancet model for long fatigue crack propagation rates (GPLFCPR), and ... By comparison of the characteristics of existing models for long fatigue crack propagation rates, a new model, called the generalized passivation-lancet model for long fatigue crack propagation rates (GPLFCPR), and a general formula for characterizing the process of crack growth rates are proposed based on the passivation-lancet theory. The GPLFCPR model overcomes disadvantages of the existing models and can describe the rules of the entire fatigue crack growth process from the cracking threshold to the critical fracturing point effectively with explicit physical meaning. It also reflects the influence of material characteristics, such as strength parameters, fracture parameters and heat treatment. Experimental results obtained by testing LZ50 steel, AlZnMgCu0.5, 0.5Cr0.5Mo0.25V steel, etc., show good consistency with the new model. The GPLFCPR model is valuable in theoretical research and practical applications. 展开更多
关键词 long fatigue crack THRESHOLD cyclic stress ratio fracture roughness propagation model
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NEW METHOD FOR MEASURING RANDOM THRESHOLDS OF LONG FATIGUE CRACK PROPAGATION
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作者 赵永翔 杨冰 +2 位作者 梁红琴 邬平波 曾京 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2005年第6期761-766,共6页
A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds... A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available. 展开更多
关键词 long fatigue crack random threshold local probabilistic Paris relation LZ50 steel
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Nonequilibrium Statistical Modeling of Fatigue Crack Growth Behaviour
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作者 胡海云 邢修三 《Journal of Beijing Institute of Technology》 EI CAS 2001年第3期240-245,共6页
In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macros... In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macroscopic properties is modified to take into consideration the microstructural features of a material, thereby allowing a rationalisation of the experimental data of short fatigue crack growth and long fatigue crack growth. The nonequilibrium statistical theory thus developed relates the growth of cracks with a dislocation mechanism to simulate short fatigue crack growth with the long fatigue crack growth behaviour and predicts the fatigue crack growth rates throughout the fatigue lifetime. The results is finally compared with that of other fatigue theories. 展开更多
关键词 short fatigue crack long fatigue crack fluctuation growth rate nonequilibrium statistical theory
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