The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Te-hua Fang - One of the best experts on this subject based on the ideXlab platform.
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Mechanical characteristics of copper indium gallium diselenide compound nanopillars using in situ transmission electron microscopy compression
Scripta Materialia, 2015Co-Authors: Te-hua Fang, Yu-jen Hsiao, Shao-hui KangAbstract:Abstract The critical-stress and strain-induced structural variations of the copper indium gallium diselenide (CIGS) compound nanopillars were estimated using in situ transmission electron microscopy (TEM) compression experiments. The Young’s modulus values of nanopillars with diameters of 200–400 nm were 29–75 GPa. The nanopillars exhibited the superelasticity effect at diameters of 90 and 150 nm. The Plastic Deformation Energy and the elastic Deformation Energy values were 0.04–0.13 × 10 −12 J and 0.05–5.41 × 10 −12 J, respectively, for nanopillars with diameters of 200–400 nm.
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Size effect on compression properties of GaN nanocones examined using in situ transmission electron microscopy
Journal of Alloys and Compounds, 2014Co-Authors: Shao-hui Kang, Te-hua FangAbstract:Abstract Mechanical property measurements of single nanocones are challenging because the small scale of the nanostructures. In this study, critical-stress- and strain-induced structural variations of GaN nanocones are estimated using in situ transmission electron microscopy (TEM) compression experiments. For single GaN nanocones with a diameter of 100–350 nm, the Young’s modulus, Plastic Deformation Energy ( W p ), and elastic Deformation Energy ( W e ) values were 190–290 GPa, 0.02–1.65 × 10 −11 J, and 0.04–3.85 × 10 −11 J, respectively. Raman spectra were used to measure GaN indentation. The E 2 peak was red-shifted, indicated increased compressive stress in the indented area.
Shao-hui Kang - One of the best experts on this subject based on the ideXlab platform.
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Mechanical characteristics of copper indium gallium diselenide compound nanopillars using in situ transmission electron microscopy compression
Scripta Materialia, 2015Co-Authors: Te-hua Fang, Yu-jen Hsiao, Shao-hui KangAbstract:Abstract The critical-stress and strain-induced structural variations of the copper indium gallium diselenide (CIGS) compound nanopillars were estimated using in situ transmission electron microscopy (TEM) compression experiments. The Young’s modulus values of nanopillars with diameters of 200–400 nm were 29–75 GPa. The nanopillars exhibited the superelasticity effect at diameters of 90 and 150 nm. The Plastic Deformation Energy and the elastic Deformation Energy values were 0.04–0.13 × 10 −12 J and 0.05–5.41 × 10 −12 J, respectively, for nanopillars with diameters of 200–400 nm.
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Size effect on compression properties of GaN nanocones examined using in situ transmission electron microscopy
Journal of Alloys and Compounds, 2014Co-Authors: Shao-hui Kang, Te-hua FangAbstract:Abstract Mechanical property measurements of single nanocones are challenging because the small scale of the nanostructures. In this study, critical-stress- and strain-induced structural variations of GaN nanocones are estimated using in situ transmission electron microscopy (TEM) compression experiments. For single GaN nanocones with a diameter of 100–350 nm, the Young’s modulus, Plastic Deformation Energy ( W p ), and elastic Deformation Energy ( W e ) values were 190–290 GPa, 0.02–1.65 × 10 −11 J, and 0.04–3.85 × 10 −11 J, respectively. Raman spectra were used to measure GaN indentation. The E 2 peak was red-shifted, indicated increased compressive stress in the indented area.
L. A. Carlsson - One of the best experts on this subject based on the ideXlab platform.
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Influence of fibre volume fraction on mode II interlaminar fracture toughness of glass/epoxy using the 4ENF specimen
Composites Science and Technology, 2005Co-Authors: Peter Davies, Pascal Casari, L. A. CarlssonAbstract:Glass reinforced composites are used in many structural applications. Their fibre content can vary considerably according to the manufacturing route, typically from 30% to 70% by volume. This paper presents results from an experimental study of the influence of fibre volume fraction on the mode II interlaminar fracture toughness, G(IIc), using the 4ENF (four point end notched flexure) specimen. Results show that G(IIc) increases with decreasing fibre content. This effect is caused by Plastic Deformation Energy dissipation in the thicker resin-rich interlaminar layer in lower fibre content composites.
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Influence of fibre volume fraction on mode II interlaminar fracture toughness of glass/epoxy using the 4ENF specimen
Composites Science and Technology, 2005Co-Authors: Peter Davies, Pascal Casari, L. A. CarlssonAbstract:International audienceGlass reinforced composites are used in many structural applications. Their fibre content can vary considerably according to the manufacturing route, typically from 30% to 70% by volume. This paper presents results from an experimental study of the influence of fibre volume fraction on the mode II interlaminar fracture toughness, G(IIc), using the 4ENF (four point end notched flexure) specimen. Results show that G(IIc) increases with decreasing fibre content. This effect is caused by Plastic Deformation Energy dissipation in the thicker resin-rich interlaminar layer in lower fibre content composites
Xing Ai - One of the best experts on this subject based on the ideXlab platform.
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investigations of critical cutting speed and ductile to brittle transition mechanism for workpiece material in ultra high speed machining
International Journal of Mechanical Sciences, 2015Co-Authors: Guosheng Su, Qinghua Song, Xing Ai, Bing WangAbstract:Abstract This paper investigates the brittle removal mechanism of ductile materials in ultra-high speed machining (UHSM). Firstly, a predictive model of critical cutting speed for UHSM is proposed with the theory of stress wave propagation. The predicted critical cutting speed for ductile-to-brittle transition of ductile materials is then validated by machining experiments of 7050-T7451 aluminum alloy at the cutting speeds ranging from 50 m/min to 8000 m/min. The experimental results show that fragmented chips are produced above the critical cutting speed of 5000 m/min for 7050-T7451 aluminum alloy. The scanning electron microscopic (SEM) images of chips, chip roots and finished workpiece surfaces are observed and analyzed. Large amounts of brittle cracks and cleavage steps are observed on the fragmented chip surface obtained under the ultra-high cutting speed. Due to the remained brittle cracks, the finished surface quality obtained with UHSM is worse than that obtained with high speed machining. Secondly, the specific Energy models for the chip formation are proposed and validated by experiments under ductile regime machining and brittle regime machining, respectively. The specific energies consumed for continuous and serrated chip formation mainly include Plastic Deformation Energy located in the primary shear zone, the friction work between the tool–chip interface, and the chip kinetic Energy. The Plastic Deformation Energy accounts for the largest proportion among the total specific Energy. Comparatively, the specific Energy consumed during fragmented chip formation mainly includes the local kinetic Energy of fragments and fracture surface Energy. When the chip morphology evolves from serrated to fragmented one, the specific Energy consumed reduces substantially, which demonstrates that the UHSM is beneficial for the Energy saving. Lastly, taking both of the material removal efficiency and machined surface quality into consideration, the UHSM is recommended to be applied in rough machining or semi-finishing, while high speed machining is recommended to be applied in finishing process. This research firstly reveals the control mechanism for ductile-to-brittle transition of ductile materials under critical cutting speed (i.e. critical strain rate) considering solid mechanics and metal cutting principles as well as Energy consumption simultaneously. This paper is enticing from both engineering and analytical perspectives aimed at revealing the mechanism of UHSM and instructing the optimization of machining parameters.
Krzysztof Gołacki - One of the best experts on this subject based on the ideXlab platform.
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Quantity assessment of Plastic Deformation Energy under impact loading conditions of selected apple cultivars
Postharvest Biology and Technology, 2016Co-Authors: Zbigniew Stropek, Krzysztof GołackiAbstract:This paper presents a new method for Plastic Deformation Energy calculation under impact loading conditions. It consisted in determination of the difference between the values of the absorbed Energy from both force-Deformation course and the formulae for kinetic Energy before and after the impact. Using a high speed camera and a piezoelectric force sensor as two independent measuring systems made it possible. This enabled direct recording of Deformation and force response during the apple impact against a rigid, flat surface. For the tested cultivars the increasing relationship between the Plastic Deformation Energy and the impact velocity was obtained. The coefficient of restitution was an appropriate parameter which allowed to determine the initial apple bruising. The increase of apple bruise susceptibility with the increasing impact velocity was also found.