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Gao L.-L.,Tianjin University of Technology | Zhang C.-Q.,Tianjin University of Technology | Yang Y.-B.,Tianjin Special Equipment Inspection Institute | Shi J.-P.,Tianjin University of Technology | Jia Y.-W.,Tianjin University of Technology
Materials Science and Engineering C | Year: 2013

It is significant to investigate the depth-dependent mechanical behaviors of articular cartilage under rolling load since considerable rolling occurs for cartilage joint in activities of daily living. In this study, the rolling experiments of articular cartilage were conducted by applying an optimized digital image correlation (DIC) technique for the first time and the depth-dependent normal strain and shear strain of cartilage were analyzed. It is found that the normal strain and shear strain values of different layers increase firstly and then decrease with rolling time, and they increase with increasing compressive strains. The normal strain and shear strain values decrease along cartilage depth with constant compressive strain. The normal strain values of different normalized depth decrease with increasing rolling rates. The shear strain values of superficial layer and middle layer decrease; however there are no major changes for the shear strain values of deep layer with increasing rolling rates. The normal strain values with different rolling time increase with increasing rolling numbers and the 30.6% increase in initial normal strain is observed from 1st to 99th cycle. The fitting relationship of the normal strain and normalized depth was obtained considering the effects of compressive strain and rolling rate and the fitting curves agree with the experimental results for cartilage very well. © 2013 Elsevier B.V.

Tan W.,Tianjin University | Liu X.,Tianjin University | Liu Y.,Tianjin University | Bu Y.,Tianjin University | Wang Z.,Tianjin Special Equipment Inspection Institute
Journal of Loss Prevention in the Process Industries | Year: 2011

Computational Fluid Dynamics (CFD) approach has been successfully applied to simulate the small-scale instantaneous flashing release experiment by Pettitt. A model for dispersion of the release event is provided based on relevant theories and existing experimental data. An application of the CFD method to the dispersion simulation is illustrated. Furthermore, a new methodology based on discrete phase model for setting computational initial conditions is provided. An initial expansion and subsequent turbulence dispersion can be characteristically identified from both volume and temperature variation of the cloud obtained by the simulation. The possible mechanism for these phenomena has also been discussed and analyzed. The study deepens the understanding of the physical process of this event and provides one more reliable tool for relevant safety systems. © 2011 Elsevier Ltd.

Wei C.,Tianjin University of Technology | Wei C.,Tianjin Special Equipment Inspection Institute | Liu Y.C.,Tianjin University of Technology | Yu L.M.,Tianjin University of Technology | And 2 more authors.
Microelectronics Reliability | Year: 2010

Tensile testing of Sn-3.7Ag-0.9Zn-xAl (x = 0, 0.5 and 1.0 wt.%) solders have been performed and the failure mechanism was investigated. The results suggest that the addition of Al in the Sn-3.7Ag-0.9Zn solder decreases both the tensile strength and ductility. Moreover, a brittle fracture occurs instead of a ductile fracture with increasing Al content. The fractographs suggest that the fracture mechanism of Sn-Ag-Zn eutectic solder is microvoid coalescence fracture, and the Sn-3.7Ag-0.9Zn-xAl (x = 0.5 and 1.0) solder corresponds to quasi-cleavage crack and cleavage fracture respectively. © 2010 Elsevier Ltd. All rights reserved.

Wang H.,Tianjin University | Wang H.,Tianjin Special Equipment Inspection Institute | Wang D.,Tianjin University | Cheng F.,Tianjin University | Wang Y.,Tianjin University
Tehnicki Vjesnik | Year: 2015

In the welding process of jackets for offshore platform, transverse weld cracks occur frequently, even when welding techniques, welding materials and marine steel plates used are stringently selected. But now defect failure analysis and mechanism study on this issue are scarce. To fully study the causes of transverse weld cracks of marine thick steel plate, this research uses instruments including metalloscope, scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS) and Auger Electronic Spectrom (AES). Researchers conclude that transverse weld cracks are welding hot cracks. © 2015, Strojarski Facultet. All rights reserved.

Qi Z.,Tianjin University of Technology | Lin B.,Tianjin University of Technology | Zhang Y.,Tianjin University of Technology | Liang X.,Tianjin Special Equipment Inspection Institute | Li X.,Tianjin University of Technology
Key Engineering Materials | Year: 2015

Traditional methods of roughness characterization cannot properly reflect the characteristics of engineering ceramics surface topography. Therefore, the composite characterization using combined fractal method and wavelet method is introduced in this paper. And they are used to describe the global and local characteristics of engineering ceramics ground surface, respectively. Furthermore, a concept called topography damage ratio is proposed to describe characteristic of the deep wave trough. Finally, 3-D measurement is used to verify this method. © (2015) Trans Tech Publications.

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