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Author

Yejun Zhu

Other affiliations: Nanjing Agricultural University
Bio: Yejun Zhu is an academic researcher from Nanjing University of Aeronautics and Astronautics. The author has contributed to research in topics: Grinding & Abrasive. The author has an hindex of 14, co-authored 41 publications receiving 665 citations. Previous affiliations of Yejun Zhu include Nanjing Agricultural University.

Papers
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TL;DR: A state-of-the-art review on monolayer electroplated and brazed cubic boron nitride (CBN) superabrasive wheels for grinding metallic materials has been provided in this paper.

107 citations

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TL;DR: In this paper, the effects of wheel speed vs on grinding temperature and power consumption were investigated, and the minimum grinding forces and specific grinding energy are obtained at vs of 120m/s and the grinding temperature is less than 100°C at this moment.
Abstract: As a kind of typical difficult-to-cut metallic material, Inconel 718 nickel-based superalloy has been widely applied in aero-engines. High speed grinding experiments of Inconel 718 have been carried out using a vitrified cubic boron nitride (CBN) superabrasive wheel in the current study. The effects of wheel speed vs on grinding temperature and power consumption were investigated. Meanwhile, the grinding performance was also analyzed from the viewpoint of undeformed chip thickness. The results obtained show that, the minimum grinding forces and specific grinding energy are obtained at vs of 120 m/s and the grinding temperature is less than 100 °C at this moment. The lost grinding power reaches the maximum value when vs is 140 m/s, which accounts for about 55%–65% of the total grinding power; however, the minimum values, such as about 20%–30%, are obtained at a conventional wheel speed. Finally, the wheel speeds in grinding Inconel 718 are optimized at 100–120 m/s under the given experimental conditions, with which not only the surface roughness Ra below 0.4 μm is obtained, but also the distorted lattice or elongated grain cannot be formed in the ground surface/subsurface layer.

100 citations

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TL;DR: In this paper, the authors provide a state-of-the-art review on the investigations into the residual stresses in metallic structural materials generated by grinding, including steels, titanium alloys, and nickel-based superalloys.
Abstract: This paper provides a state-of-the-art review on the investigations into the residual stresses in metallic structural materials generated by grinding. The materials covered include steels, titanium alloys, and nickel-based superalloys. The formation mechanisms of the residual stresses and their impacts are specifically discussed. Some major influential factors on the residual stresses formation in grinding, such as grinding wheel characteristics, dressing techniques, grinding parameters, cooling conditions, and properties of workpiece materials, are analyzed in detail. These include experimental measurement, modeling, simulation, knowledge-based monitoring, and fuzzy analysis. Finally, the paper highlights some important aspects of grinding-induced residual stresses for further investigation.

98 citations

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TL;DR: In this paper, an ultrasonic vibration plate device enabling the longitudinal full-wave and transverse half-wave (L2T1) vibration mode for UVAG was proposed, and the characteristics of coupled vibration in different directions were analyzed on the basis of apparent elastic method and finite element method.

75 citations

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TL;DR: In this paper, a detailed investigation on the effects of TiX addition on the microstructure and strength of Ag-Cu-Ti/TiX bonding layer was made based on the evaluation of some fundamental performance.

60 citations


Cited by
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TL;DR: In this paper, a generalization of the Local Density Approximation (LDA) method for the systems with strong Coulomb correlations is presented which gives a correct description of the Mott insulators.
Abstract: The generalization of the Local Density Approximation (LDA) method for the systems with strong Coulomb correlations is presented which gives a correct description of the Mott insulators. The LDA+U method is based on the model hamiltonian approach and allows to take into account the non-sphericity of the Coulomb and exchange interactions. parameters. Orbital-dependent LDA+U potential gives correct orbital polarization and corresponding Jahn-Teller distortion. To calculate the spectra of the strongly correlated systems the impurity Anderson model should be solved with a many-electron trial wave function. All parameters of the many-electron hamiltonian are taken from LDA+U calculations. The method was applied to NiO and has shown good agreement with experimental photoemission spectra and with the oxygen Kα X-ray emission spectrum.

376 citations

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TL;DR: In this paper, a surface grinding experiment was conducted under three lubricating conditions (cryogenic air, minimum quantity lubrication, and cryogenic air nanofluids minimum quantity lubrication) with Ti 6Al 4V as the workpiece material.

300 citations

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TL;DR: In this article, a minimum chip thickness (h min ) model that considers lubrication conditions (represented by frictional angle β ) is developed according to strain gradient, as well as geometry and kinematics analyses.

296 citations

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TL;DR: In this article, the processing characteristics of different vegetable oil-based nanofluid MQL for grinding various workpiece materials were evaluated in terms of force ratio, specific grinding energy, and G ratio.
Abstract: Minimum quantity lubrication (MQL) is an efficient, green, and eco-friendly method of applying cutting fluids in machining processes. This study presents the processing characteristics of different vegetable oil-based nanofluid MQL for grinding various workpiece materials. The performance of three lubricant types (i.e., pure palm oil, MoS2 nanofluid, and Al2O3 nanofluid) of good lubrication performance and three types of materials (i.e., Inconel 718, ductile cast iron, and AISI 1045 steel) was evaluated in terms of force ratio, specific grinding energy, and G ratio. The optimal processing combination of lubricants and workpiece materials under the same experimental conditions was obtained using orthogonal experiment. Optimization results were verified by evaluating the morphology of the workpiece surface and grinding debris. Experimental results show the different processing characteristics of materials when various workpieces are processed using dissimilar MQL lubricants. MoS2 nanofluid MQL is suitable for machining soft medium carbon steels, such as 45 steel, while Al2O3 nanofluid is suitable for machining materials of high strength and hardness, such as nickel-based alloys.

239 citations

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TL;DR: In this article, the authors used six nanofluids, namely, MoS 2, SiO 2, diamond, carbon nanotubes (CNTs), Al 2 O 3, and ZrO 2, to select the kind of nanoparticles with optimum lubrication performance in grinding nickel alloy GH4169.

208 citations