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Yanru Zhao,Xiaohui Sun,Tiande Wen,Rui Chen,Liping Huang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.8
As a completed decomposed product of granite rock, the granite residual soil widely distributes in South China with a special soil structure that can be easily damaged under external disturbance. Therefore, studying the evolution of soil cracks during the loading process is important for engineering practice that needs to evaluate the soil shear strength, such as slope stability analysis. The purpose of this study is to investigate the micro-structure for the intact granite residual soil under external loading base on X-ray computed tomography (CT) through global and local scanning (with resolutions of 180 μm and 26.7 μm, respectively). The micro-structural evolution of the cross-sections of soil column extracted from a granite residual soil layer under axial loading was investigated by CT scanning with a 0.5 mm slice thickness. The number of cracks (including macro-cracks and meso-cracks), area ratios and porosity corresponding to varying loading stages (initial, peak-stress and failure) were analyzed based on the cross-sectional CT images. Test results shows that the structure strength of the soil was mainly subject to macro-cracks. In addition, the increase of the porosity is mainly attributed to the generation and expansion of the cracks along sandy particle under external loading. This study can provide theoretical support and data support for understanding the micro-structural evolution of granite residual soil that is commonly encountered in civil engineering.
Abnormal residual stress in nanostructured Al thin films grown on Ti/glass substrates
샤르마,김득영 한국물리학회 2013 Current Applied Physics Vol.13 No.9
The residual stress and micro-structural properties of nanostructured Al thin films prepared by electron beam evaporator are studied. The films were grown on Ti/glass substrates at normal and oblique angles of inclination. The average aspect ratio of Al nanorods produced at an oblique angle of incidence of 85,increased from 2.2 to 6.0, as the thickness of the films increased from 100 nm to 600 nm. The column tilt angle of Al nanorods was observed to be in close agreement with the theoretical value. The XRD pattern of nanostructured Al thin films showed (111) planes oriented parallel to the substrate surface. The crystallite size was observed to be w9 nm for all the films produced at oblique angle deposition (OAD). Abnormal residual stresses were determined in the films produced at OAD. The nanocrystalline films produced at normal angle, exhibited tensile residual stress, while, the residual stresses in the films produced at oblique angles of inclination (a¼65, 75), were observed to be compressive. Residual stress-free nanocolumnar Al films (Al nanorod films) were observed, when they were grown at an oblique angle of inclination of 85.
Abnormal residual stress in nanostructured Al thin films grown on Ti/glass substrates
Sharma, S.K.,Kim, D.Y. Elsevier 2013 CURRENT APPLIED PHYSICS Vol.13 No.9
The residual stress and micro-structural properties of nanostructured Al thin films prepared by electron beam evaporator are studied. The films were grown on Ti/glass substrates at normal and oblique angles of inclination. The average aspect ratio of Al nanorods produced at an oblique angle of incidence of 85<SUP>o</SUP>, increased from 2.2 to 6.0, as the thickness of the films increased from 100 nm to 600 nm. The column tilt angle of Al nanorods was observed to be in close agreement with the theoretical value. The XRD pattern of nanostructured Al thin films showed (111) planes oriented parallel to the substrate surface. The crystallite size was observed to be ~9 nm for all the films produced at oblique angle deposition (OAD). Abnormal residual stresses were determined in the films produced at OAD. The nanocrystalline films produced at normal angle, exhibited tensile residual stress, while, the residual stresses in the films produced at oblique angles of inclination (α = 65<SUP>o</SUP>, 75<SUP>o</SUP>), were observed to be compressive. Residual stress-free nanocolumnar Al films (Al nanorod films) were observed, when they were grown at an oblique angle of inclination of 85<SUP>o</SUP>.
석한길 三陟大學校 産業科學技術硏究所 2004 産業科學技術硏究論文集 Vol.9 No.1
In this study, productivity elevation of horizontal fillet welding process using the auto carriage was investigated. And we studied micro-structures of grooves in various welding processes. Furthermore, it was performed the elasto-plastic finite element analysis in welding residual stress field to evaluate the fatigue strength of structure steel for bridge. Residual stress that happen on weld line direction affects greatly in weld zone fatigue strength because it is overlapped each other with external force. That is, if welding residual stresses is the bigger, fatigue strength is fallen.
김철희,김전하,강명창,김정석 한국공작기계학회 2001 한국공작기계학회 춘계학술대회논문집 Vol.2001 No.-
In this study, residual stress was investigated to evaluate damaged layer in high speed machining through simulation. In machining steel(STD11), residual stress remaining in machined surface was mainly appeared as compressive stress. The scale of this damaged layer more depends on feed per tooth and radial depth than spindle speed. Damaged layer was measured by optical microscope and hardness method. The micro-structure of damaged layer was a marten site because of cutting force and cutting temperature. Thickness of damaged layer is increased with incresing of feed per tooth and radial depth.
Tensile Property and Residual Stresses in Dissimilar Aluminiums Friction Stir Welding
Kelimu Tulugan,WonJun Lee,HanKi Yoon,SunChul Huh,WonJo Park 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
Friction stir welding has the advantage that many of the welding parameters, eg. tool design, rotation speed and travelling speed, can be contralled in a precise manner, thus controlling the energy input into the system. Therefore, the micro-structure of the welding aluminium were tested, the residual stresses induced by the friction stir welding process conducted with 500rpm and 100mm/min was also measured. The stresses in the test specimen peaked at -9Mpa and had the conventional "M" profile.
Sarkar, Swapan Kumar,Lee, Byong Taek Materials Research Society of Korea 2013 한국재료학회지 Vol.23 No.9
This paper investigates the effect of prolonged high temperature exposure on concentric laminated $Al_2O_3-ZrO_2$ composites. An ultrafine scale microstructure with a cellular 7 layer concentric lamination with unidirectional alignment was fabricated by a multi-pass extrusion method. Each laminate in the microstructure was $2-3{\mu}m$ thick. An alternate lamina was composed of 75%$Al_2O_3$-(25%m-$ZrO_2$) and t-$ZrO_2$ ceramics. The composite was sintered at $1500^{\circ}C$ and subjected to $1450^{\circ}C$ temperature for 24 hours to 72 hours. We investigated the effect of long time high temperature exposure on the generation of residual stress and grain growth and their effect on the overall stability of the composites. The residual stress development and its subsequent effect on the microstructure with the edge cracking behavior mechanism were investigated. The residual stress in the concentric laminated microstructure causes extensive micro cracks in the t-$ZrO_2$ layer, despite the very thin laminate thickness. The material properties like Vickers hardness and fracture toughness were measured and evaluated along with the microstructure of the composites with prolonged high temperature exposure.