Papers by Author: Yong Ming Xing

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Authors: Heng Mao Niu, Yong Ming Xing, Yan Ru Zhao
Abstract: Engineered cementitious composites(ECC) are characterized by strain hardening and tight crack width control. Good fiber distribution can maximize fiber contribution at each stage of the crack bridging process. However, poor fiber distribution can be disadvantage to fiber contribution, even influence the robustness of strain-hardening. Combined with the latest research results, this review highlights the methods of improving fiber distribution in ECC. Good fiber distribution is based on excellent matrix fluidity, which can be determined by mineral admixtures, admixture and water/binder (w/c). Fiber included surface morphology, size and content of fiber have also an effect on fiber distribution in the ECC. Additionally, slag and sand size shape of matrix components play a surprising role on fiber distribution. Based on the reviewed methods it is argued that fiber optimization and matrix components tailoring can be used to improve fiber distribution.
Authors: Chun Wang Zhao, Yong Ming Xing
Abstract: A micro mechanical study of Carbon/Epoxy composites with internally dropped plies has been made using micro-moiré interferometry. The experimental results show that there is a stress concentration region before the dropped ply. Micro cracks were initiated and propagated in this region. Two failure mechanisms in the dropped ply region were observed.
Authors: Yong Ming Xing, Satoshi Kishimoto
Abstract: The electron moiré method uses a high frequency grating to measure microscopic deformation. Finer and finer gratings are being pursued to meet higher and higher resolution requirements in microscopic stress analysis. In this study, the techniques of fabricating electron grid by means of a scanning electron microscope are improved. The use of a low accelerating voltage shows a better effect than the high accelerating voltage in fabricating a superfine grid. A new group of parameters is suggested based on this consideration. A cross-line grid with a frequency of 10,000 lines/mm and a parallel grating with a frequency of 13,000 lines /mm have been successfully fabricated.
Authors: Xin Wei Yang, Xin Hua Ji, Yong Ming Xing, Yu Wen Qin
Abstract: Interfacial residual stresses play an important role in the mechanical properties. In this paper, the interfacial residual stresses of SCI/Epoxy composites were determined using a novel technique-microphotoelastic method. The thermal residual stress field was also numerically simulated using a finite element software MSC.MARC. The difference and the similarities between the experimental results and the simulation of FEM analysis were discussed and the availability of the method was preliminarily certified.
Authors: Satoshi Kishimoto, Yoshihisa Tanaka, Yong Ming Xing, Gyu Chang Lee
Abstract: A method for measuring the stress and strain distribution in the composite materials and residual stress at the interface in the fiber reinforced composite has been developed. The strains are measured using an electron Moiré method and then the stresses are calculated from these strains. A very fine model grid with frequencies up to 10,000lines/mm can be fabricated using the optical and electron lithography techniques on the surface of the specimen and an electron beam scan which spaces are almost same as that of model grid the can be used for master-grid. The difference of the amount of secondary electrons per a primary electron makes Moiré fringes that consists bright and dark parts. Micro-creep deformation and residual strain and stress near the fibers of composite materials were measured by this method.
Authors: Fei Liu, Pu Cun Bai, Xiao Hu Hou, Yong Ming Xing
Abstract: The strain field of η′ phase in an aged 7000 series aluminum alloy has been investigated using a combination of high resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA) technique in this paper, and strain components εxx, εyy were mapped, respectively. The results showed that the strain is mainly generated near the matrix/η′ phase interface and gradually decreases with distance increasing away from the interface. There were convergence and divergence regions of the strain within the η′ phase, and maximum strain occurred in the position where about 0.25 nm far from the interface, value of the maximum strains was about 2.54%.
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