Experimental and Numerical Investigation of Stress Concentration Factor of Cable Steel Wire with Corrosion Pits

Rou Li,Changqing Miao,Meiling Zhuang 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.5

Fatigue crack initiates from corrosion pits in various metallic structures, leads to the decline of the fatigue life. In the present study, the effects of the width, depth, angle and spacing of primary and secondary pits on failure mechanism and stress concentration factor are investigated by the experimental and numerical analysis. The results show that depth-width ratio of corrosion pits is the critical factor that affects the dangerous area and stress concentration factor. The development of secondary pits will lead to the multiplier effect of stress concentration factor. The maximum stress is basically located at the mouth or middle part of secondary pits. In addition, the pit angle does not change the distribution of dangerous area, but with the pits angle increasing, the stress concentration factor increases as a whole. The contours that classical butterfly-like distribution rotates and the rotation angle is basically the same with that of the corrosion pits. Furthermore, with the pits spacing increasing, the stress concentration factor increases gradually and converges to the fixed value, which is equal to the stress concentration factor under the single pit. Finally, the relationship between the pits parameters and stress concentration factor is systematically predicted.

Combined Assessment of Serum Alpha-Synuclein and Rab35 is a Better Biomarker for Parkinson’s Disease

Hung-Li Wang,Chin-Song Lu,Tu-Hsueh Yeh,Yu-Ming Shen,Yi-Hsin Weng,Ying-Zu Huang,Rou-Shayn Chen,Yu-Chuan Liu,Yi-Chuan Cheng,Hsiu-Chen Chang,Ying-Ling Chen,Yu-Jie Chen,Yan-Wei Lin,Chia Chen Hsu,Huang-Li 대한신경과학회 2019 Journal of Clinical Neurology Vol.15 No.4

Background and Purpose It is essential to develop a reliable predictive serum biomarker for Parkinson’s disease (PD). Te accumulation of alpha-synuclein (αSyn) and up-regulated expression of Rab35 participate in the etiology of PD. Te purpose of this investigation was to determine whether the combined assessment of serum αSyn and Rab35 is a useful predictive biomarker for PD. Methods Serum levels of αSyn or Rab35 were determined in serum samples from 59 sporadic PD patients, 19 progressive supranuclear palsy (PSP) patients, 20 multiple system atrophy (MSA) patients, and 60 normal controls (NC). Receiver operating characteristics (ROC) curves were calculated to determine the diagnostic accuracy of αSyn or/and Rab35 in discriminating PD patients from NC or atypical parkinsonian patients. Results The levels of αSyn and Rab35 were increased in PD patients. The serum level of Rab35 was positively correlated with that of αSyn in PD patients. Compared to analyzing αSyn or Rab35 alone, the combined analysis of αSyn and Rab35 produced a larger area under the ROC curve and performed better in discriminating PD patients from NC, MSA patients, or PSP patients. When age was dichotomized at 55, 60, 65, or 70 years, the combined assessment of αSyn and Rab35 for classifying PD was better in the group below the cutof age than in the group above the cutof age. Conclusions Combined assessment of serum αSyn and Rab35 is a better biomarker for discriminating PD patients from NC or atypical parkinsonian patients, and is a useful predictive biomarker for younger sporadic PD patients.

Experimental and modeling study of viscoelastic behaviors of magneto-rheological shear thickening fluids

Gang Rou Peng,Weihua Li,Tongfei Tian,Jie Ding,Masami Nakano 한국유변학회 2014 Korea-Australia rheology journal Vol.26 No.2

Nowadays, both Magneto-rheological Fluid (MRF) and Shear Thickening Fluid (STF) have separatelyattracted considerable interest due to the fast reversible response to either external magnetic field or abruptshearing loading. In this paper, we fabricated a combined phase of Magneto-rheological Shear ThickeningFluid (MRSTF), where the 25 wt% STF is applied as medium phase with the addition of varied fractionsof iron particle. The investigation of the dynamic behavior of this novel material under oscillatory shear waslaunched in a parallel-plate rheometer. The relevance of the dynamic behavior to strain amplitude,frequency and external magnetic field were investigated and discussed. A four-parameter viscoelastic modelwas applied to reconstruct the mechanical behavior of the MRSTF under different working conditions, andthe parameters were identified within the Matlab optimization algorithm. The comparison between theexperimental data and the model prediction results indicated that the four-parameter model could predictviscoelastic material with desired accuracy. The MRSTF exhibits features of both components, while pronemore to MRF with the inception of external field excitations.

Experimental and modeling study of viscoelastic behaviors of magneto-rheological shear thickening fluids

Peng, Gang Rou,Li, Weihua,Tian, Tong Fei,Ding, Jie,Nakano, Masami 한국유변학회 2014 Korea-Australia rheology journal Vol.26 No.2

Nowadays, both Magneto-rheological Fluid (MRF) and Shear Thickening Fluid (STF) have separately attracted considerable interest due to the fast reversible response to either external magnetic field or abrupt shearing loading. In this paper, we fabricated a combined phase of Magneto-rheological Shear Thickening Fluid (MRSTF), where the 25 wt% STF is applied as medium phase with the addition of varied fractions of iron particle. The investigation of the dynamic behavior of this novel material under oscillatory shear was launched in a parallel-plate rheometer. The relevance of the dynamic behavior to strain amplitude, frequency and external magnetic field were investigated and discussed. A four-parameter viscoelastic model was applied to reconstruct the mechanical behavior of the MRSTF under different working conditions, and the parameters were identified within the Matlab optimization algorithm. The comparison between the experimental data and the model prediction results indicated that the four-parameter model could predict viscoelastic material with desired accuracy. The MRSTF exhibits features of both components, while prone more to MRF with the inception of external field excitations.

Experimental and modelling study of the effect of temperature on shear thickening fluids

Tongfei Tian,Gang Rou Peng,Weihua Li,Jie Ding,Masami Nakano 한국유변학회 2015 Korea-Australia rheology journal Vol.27 No.1

This paper is a study of the effect that temperature has on a shear thickening fluid made from ethylene glycol and fumed silica, with 20%-26% weight fractions. Three typical temperatures, ranging from 20oC to 60oC, were selected to study the shear rate dependence of viscosity. The temperature tests showed that a high temperature increased the critical shear rate and lowered the shear thickening ratio. A viscosity function was proposed to represent the three characteristic regions in typical shear thickening fluid and to predict viscosity at different temperatures

Bond Distortion and Electron States in Charged $C_{60}{^2-}$

Fu, Rong-Tang,Fu, Rou-Li,Lee, Kee-Hag,Sun, Xin,Ye, Hong-Juan Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.6

By considering both electron-electron and electron-lattice interactions, the effect of charge transfer on the bond structure and electronic states of $C_{60}$ is studied without configuration limitation. The results show that the electron-electron interaction does not eliminate the layer structure of the bond distortion and the self-trapping of transferred electrons. For charged ${C_{60}}^{2-}$, there exist two localized electronic states, which possess laminar wave functions, and four nonequivalent groups of carbon atoms, which induce a fine-structure in the NMR spectrum line.

Study on the flexural behavior of corroded built-up cold-formed thin-walled steel beams

Zongxing Zhang,Shanhua Xu,Han Li,Rou Li,Biao Nie 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.3

Eight cold-formed thin-walled steel beams were performed to investigate the effect of corrosion damage on the flexural behavior of steel beams. The relationships between failure modes or load-displacement curves and corrosion degree of steel beams were investigated. A series of parametric analysis with more than forty finite element models were also performed with different corrosion degrees, types and locations. The results showed that the reduction of cross-section thickness as well as corrosion pits on the surface would lead to a decline in the stiffness and flexural capacity of steel beams, and gradually intensified with the corrosion degree. The yield load, ultimate load and critical buckling load of the corroded specimen IV-B46-4 decreased by 22.2%, 26% and 45%, respectively. The failure modes of steel beams changed from strength failure to stability failure or brittle fracture with the corrosion degree increasing. In addition, thickness damage and corrosion pits at different locations caused the degradation of flexural capacity, the worst of which was the thickness damage of compression zone. Finally, the method for calculating flexural capacity of corroded cold-formed thin-walled steel beams was also proposed based on experimental investigation and numerical analysis results.

Seismic response of combined retaining structure with inclined rock slope

Yu-liang Lin,Jie Jin,Zhi-hao Jiang,Wei Liu,Hai-dong Liu,Rou-feng Li,Xiang Liu 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.5

A gravity wall combined with an anchoring lattice frame (a combined retaining structure) is adopted at a typical engineering site at Dali-Ruili Railway Line China. Where, the combined retaining structure supports a soil deposit covering on different inclined rock slopes. With an aim to investigate and compare the effects of inclined rock slopes on the response of combined retaining structure under seismic excitation, three groups of shaking table tests are conducted. The rock slopes are shaped as planar surfaces inclined at angles of 20°, 30°, and 40° with the horizontal, respectively. The shaking table tests are supplemented by dynamic numerical simulations. The results regarding the horizontal acceleration response, vertical acceleration response, permanent displacement mode, and axial anchor force are comparatively examined. The acceleration response is more susceptible to outer structural profile of combined retaining structure than to inclined angle of rock slope. The permanent displacement decreases when the inclined angle of the rock slope increases within a range of 20°-40°. A critical inclined angle of rock slope exists within a range of 20°-40°, and induces the largest axial anchor force in the combined retaining structure.