Browsing by Author "Huang, EW"

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    Development of crystallographic-orientation-dependent internal strains around a fatigue-crack tip during overloading and underloading
    (Elsevier Science Inc, 2013-05-01) Lee, SY; Huang, EW; Wu, W; Liaw, PK; Paradowska, AM
    In-situ neutron diffraction was employed to directly measure the crystallographic-orientation-dependent (i.e. hkl) internal strains as a function of distance from the crack tip on the pre-cracked Hastelloy C-2000 compact-tension specimen. Both in-plane (IP) and through-thickness (TT) strain evolutions for various grain orientations were examined during tensile overloading and compressive underloading cycles. After overloading, underloading and their combination loadings were applied and unloaded, the significantly different {hkl} residual strain profiles were obtained in the vicinity of the crack tip. The load responses of the {200} grain orientation in both the IP and TT directions were more significant than those of any other orientations. It is suggested that the different orientation-dependent strain distributions around the crack tip are caused by the combined effects of elastic and plastic anisotropy of each {hkl} reflection upon loading and the subsequent development of residual stresses generated near the crack tip during unloading as a result of the plastic deformation. © 2013, Elsevier Ltd.
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    Diffraction-based residual stress mapping of a stress frame of gray iron via vibratory stress relief method
    (Frontier Media S.A., 2022-04-07) Chen, SW; Huang, EW; Chiu, SM; Reid, M; Wu, CY; Paradowska, AM; Lam, TN; Wu, YH; Lee, SY; Lu, SC; Chen, SA; Lin, YG; Weng, SC
    The role of residual stress is critical, particularly for machine tools demanding accuracy below 1 µm. Although minor stresses are subjected to a tiny area, the applied force can cause devastating distortions on the precision components at this length scale. In this research, we systematically investigated the residual stress in a stress frame of the gray iron used in machine tools using synchrotron X-ray and neutron sources. Through the combination of these techniques, the residual stresses on the surface, inside the bulk, and in average were presented. Comprehensive analysis results shed light on the vibratory stress relief technique, which reduced the residual stresses and stabilized them, even materials undergoing cycling heating. Although compressive stresses are not effectively reduced, this technique is useful in improving the mechanical stability of the materials in machine tools. © 2022 Chen, Huang, Chiu, Reid, Wu, Paradowska, Lam, Wu, Lee, Lu, Chen, Lin and Weng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).