Reliability analysis for fatigue damage of railway welded bogies using Bayesian update based inspection

Zuo, Fang-Jun,Li, Yan-Feng,Huang, Hong-Zhong Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.2

From the viewpoint of engineering applications, the prediction of the failure of bogies plays an important role in preventing the occurrence of fatigue. Fatigue is a complex phenomenon affected by many uncertainties (such as load, environment, geometrical and material properties, and so on). The key to predict fatigue damage accurately is how to quantify these uncertainties. A Bayesian model is used to account for the uncertainty of various sources when predicting fatigue damage of structural components. In spite of improvements in the design of fatigue-sensitive structures, periodic non-destructive inspections are required for components. With the help of modern nondestructive inspection techniques, the fatigue flaws can be detected for bogie structures, and fatigue reliability can be updated by using Bayesian theorem with inspection data. A practical fatigue analysis of welded bogies is utilized to testify the effectiveness of the proposed methods.

Reliability analysis for fatigue damage of railway welded bogies using Bayesian update based inspection

Fang-Jun Zuo,Yan-Feng Li,Hong-Zhong Huang 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.2

From the viewpoint of engineering applications, the prediction of the failure of bogies plays an important role in preventing the occurrence of fatigue. Fatigue is a complex phenomenon affected by many uncertainties (such as load, environment, geometrical and material properties, and so on). The key to predict fatigue damage accurately is how to quantify these uncertainties. A Bayesian model is used to account for the uncertainty of various sources when predicting fatigue damage of structural components. In spite of improvements in the design of fatigue-sensitive structures, periodic non-destructive inspections are required for components. With the help of modern nondestructive inspection techniques, the fatigue flaws can be detected for bogie structures, and fatigue reliability can be updated by using Bayesian theorem with inspection data. A practical fatigue analysis of welded bogies is utilized to testify the effectiveness of the proposed methods.

Parkinson’s Disease with Fatigue: Clinical Characteristics and Potential Mechanisms Relevant to α-Synuclein Oligomer

Li-Jun Zuo,Shu-Yang Yu,Fang Wang,Yanghui Xia,Ying-Shan Piao,Yang Du,Teng-Hong Lian,Rui-Dan Wang,Qiu-Jin Yu,Ya-Jie Wang,Xiao-Min Wang,Piu Chan,Sheng-Di Chen,Yongjun Wang,Wei Zhang 대한신경과학회 2016 Journal of Clinical Neurology Vol.12 No.2

Background and Purpose The aim of this study was to identify the clinical characteristics and potential mechanisms relevant to pathological proteins in Parkinson’s disease (PD) patients who experience fatigue. Methods PD patients (n=102) were evaluated using a fatigue severity scale and scales for motor and nonmotor symptoms. The levels of three pathological proteins—α-synuclein oligomer, β-amyloid (Aβ)1-42, and tau—were measured in 102 cerebrospinal fluid (CSF) samples from these PD patients. Linear regression analyses were performed between fatigue score and the CSF levels of the above-listed pathological proteins in PD patients. Results The frequency of fatigue in the PD patients was 62.75%. The fatigue group had worse motor symptoms and anxiety, depression, and autonomic dysfunction. The CSF level of α-synuclein oligomer was higher and that of Aβ1-42 was lower in the fatigue group than in the non-fatigue group. In multiple linear regression analyses, fatigue severity was significantly and positively correlated with the α-synuclein oligomer level in the CSF of PD patients, after adjusting for confounders. Conclusions PD patients experience a high frequency of fatigue. PD patients with fatigue have worse motor and part nonmotor symptoms. Fatigue in PD patients is associated with an increased α-synuclein oligomer level in the CSF

Distinct mutations in MLH1 and MSH2 genes in Hereditary Non-polyposis Colorectal Cancer (HNPCC) families from China

( Wen Qian Wei ),( Fang Qi Liu ),( Lei Liu ),( Zuo Feng Li ),( Xiao Yan Zhang ),( Fan Jiang ),( Qu Shi ),( Xiao Yan Zhou ),( Wei Qi Sheng ),( San Jun Cai ),( Xuan Li ),( Ye Xu ),( Peng Nan ) 생화학분자생물학회(구 한국생화학분자생물학회) 2011 BMB Reports Vol.44 No.5

Hereditary non-polyposis Colorectal Cancer (HNPCC) is an autosomal dominant inheritance syndrome. HNPCC is the most common hereditary variant of colorectal cancer (CRC), which accounts for 2-5% CRCs, mainly due to hMLH1 and hMSH2 mutations that impair DNA repair functions. Our study aimed to identify the patterns of hMSH2 and hMLH1 mutations in Chinese HNPCC patients. Ninety-eight unrelated families from China meeting Amsterdam or Bethesda criteria were included in our study. Germline mutations in MLH1 and MSH2 genes, located in the exons and the splice-site junctions, were screened in the 98 probands by direct sequencing. Eleven mutations were found in ten patients (11%), with six in MLH1 (54.5%) and five in MSH2 (45.5%) genes. One patient had mutations in both MLH1 and MSH2 genes. Three novel mutations in MLH1 gene (c.157_160delGAGG, c.2157dupT and c.-64G>T) were found for the first time, and one suspected hotspot in MSH2 (c.1168C>T) was revealed. [BMB reports 2011; 44(5): 317-322]

An improved Corten-Dolan’s model based on damage and stress state effects

Huiying Gao,Hong-Zhong Huang,Zhiqiang Lv,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The value of exponent d in Corten-Dolan’s model is generally considered to be a constant. Nonetheless, the results predicted on thebasis of this statement deviate significantly from the real values. In consideration of the effects of damage and stress state on fatigue lifeprediction, Corten-Dolan’s model is improved by redefining the exponent d used in the traditional model. The improved model performsbetter than the traditional one with respect to the demonstration of a fatigue failure mechanism. Predictions of fatigue life on thebasis of investigations into three metallic specimens indicate that the errors caused by the improved model are significantly smaller thanthose induced by the traditional model. Meanwhile, predictions derived according to the improved model fall into a narrower dispersionzone than those made as per Miner’s rule and the traditional model. This finding suggests that the proposed model improves the life predictionaccuracy of the other two models. The predictions obtained using the improved Corten-Dolan’s model differ slightly from thosederived according to a model proposed in previous literature; a few life predictions obtained on the basis of the former are more accuratethan those derived according to the latter. Therefore, the improved model proposed in this paper is proven to be rational and reliable giventhe proven validity of the existing model. Therefore, the improved model can be feasibly and credibly applied to damage accumulationand fatigue life prediction to some extent.

Lifetime prediction for turbine discs based on a modified Walker strain model

Zhiqiang Lv,Hong-Zhong Huang,Huiying Gao,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

We created three-dimensional models of turbine disc and blades of a type of aero-engine according to their geometries. Extant studies show that low cycle fatigue is the main failure mechanism of turbine disc. By using a non-linear elastic-plasticfinite element method, the static stress and strain state of the critically high stress regions, which can lead to operational failures,are determined. On the basis of stress-strain relation, a modified Walker strain life prediction model is proposed with norequired knowledge on the mean stress correction. Then the predicted life data from the modified Walker strain model arecompared with the testing results. After the verification, the modified Walker strain life prediction model and Miner’s rule wereapplied to predict the lifetime of the turbine disc under various operating conditions.

Determining the Walker exponent and developing a modified Smith-Watson-Topper parameter model

Zhiqiang Lv,Hong-Zhong Huang,Hai-Kun Wang,Huiying Gao,Fang-Jun Zuo 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

Mean stress effects significantly influence the fatigue life of components. In general, tensile mean stresses are known to reduce the fatigue life of components, whereas compressive mean stresses are known to increase it. To date, various methods that account for mean stress effects have been studied. In this research, considering the high accuracy of mean stress correction and the difficulty in obtaining the material parameter of the Walker method, a practical method is proposed to describe the material parameter of this method. The test data of various materials are then used to verify the proposed practical method. Furthermore, by applying the Walker material parameter and the Smith-Watson-Topper (SWT) parameter, a modified strain-life model is developed to consider sensitivity to mean stress of materials. In addition, three sets of experimental fatigue data from super alloy GH4133, aluminum alloy 7075-T651, and carbon steel are used to estimate the accuracy of the proposed model. A comparison is also made between the SWT parameter method and the proposed strainlife model. The proposed strain-life model provides more accurate life prediction results than the SWT parameter method.