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Optimized constitutive equation of material property based on inverse modeling for aluminum alloy hydroforming simulation

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Transactions of Nonferrous Metals Society of China 2006年第6期7卷 1379-1385页

作者：郎利辉李涛周贤宾 B.E.KRISTENSEN J.DAN CKERT K.B.NIELSEN School of mechanical Engineering and Automation Beihang University department of Production Aalborg University

By using aluminum alloys,the properties of the material in sheet hydroforming were obtained based on the identification of parameters for constitutive models by inverse modeling in which the friction coefficients were also considered in 2D and 3D *** consideration of identified simulation parameters by inverse modeling,some key process parameters including tool dimensions and pre-bulging on the forming processes in sheet hydroforming were investigated and *** on the optimized parameters,the sheet hydroforming process can be analyzed more accurately to improve the robust *** proves that the results from simulation based on the identified parameters are in good agreement with those from experiments.

关键词： hydromechanical deep drawing inverse modeling aluminum alloy simulation

Precipitation Characteristics and Mechanism of Vanadium Carbides in a V-Microalloyed Medium-Carbon Steel

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Acta Metallurgica Sinica(English Letters) 2018年第11期31卷 1197-1206页

作者： Xiao-Lin Pan Minoru Umemoto School of Metallurgy Northeastern University department of mechanical Engineering Toyohashi University of Technology

The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650℃ in aV-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electronmicroscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at differentnucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoidand pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the γ/α interface, and the fine needles ofinterphase precipitates are perpendicular to the 7/ct interface. The vanadium carbides of long or short fibers, coarse particlesand fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions andorientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modeswere proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.

关键词： Microalloyed steels Carbide precipitation Isothermal transformation Precipitation sequence Orientation relationship

Machine-vision-based electrode wear analysis for closed loop wire EDM process control

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Advances in Manufacturing 2022年第1期10卷 131-142页

作者： P.M.Abhilash D.Chakradhar department of mechanical Engineering Indian Institute of Technology PalakkadKerala 678557India

The purpose of this study was to develop a closed-loop machine vision system for wire electrical discharge machining(EDM)process *** wire wear leading to wire breakage is the primary cause of wire EDM process *** process interruptions are undesirable because they affect cost efficiency,surface quality,and process *** developed system monitors wire wear using an image-processing algorithm and suggests parametric changes according to the severity of the wire *** images of the wire electrode coming out from the machining zone are fed to the system as raw *** the proposed method,the images are preprocessed and enhanced to obtain a binary image that is used to compute the wire wear ratio(WWR).The input parameters that are adjusted to recover from the unstable conditions that cause excessive wire wear are pulse off time,servo voltage,and wire feed *** algorithm successfully predicted wire breakage *** addition,the alternative parametric settings proposed by the control algorithm were successful in reducing the wire wear to safe limits,thereby preventing wire breakage interruptions.

关键词： Wire electrical discharge machining(WEDM) Machine vision Image processing Wire wear Wire electrode Wire breakage Inconel 718Process control

Paper-based aqueous Al ion battery with water-in-salt electrolyte

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Green Energy & Environment 2023年第5期8卷 1380-1388页

作者： Yifei Wang Wending Pan Kee Wah Leong Yingguang Zhang Xiaolong Zhao Shijing Luo Dennis Y.C.Leung School of mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518055China department of mechanical Engineering The University of Hong KongHong KongChina

Low-cost,flexible and safe battery technology is the key to the widespread usage of wearable electronics,among which the aqueous Al ion battery with water-in-salt electrolyte is a promising *** this work,a flexible aqueous Al ion battery is developed using cellulose paper as *** water-in-salt electrolyte is stored inside the paper,while the electrodes are either printed or attached on the paper surface,leading to a lightweight and thin-film battery ***,this battery can tolerate a charge and discharge rate as high as 4 A g^(-1) without losing its storage *** charge voltage is around 2.2 V,while the discharge plateau of 1.6–1.8 V is among the highest in reported aqueous Al ion batteries,together with a high discharge specific capacity of~140 mAh g^(-1).However,due to the water electrolysis side reaction,the faradaic efficiency can only reach 85%with a cycle life of 250 due to the dry out of *** from using flexible materials and aqueous electrolyte,this paper-based Al ion battery can tolerate various deformations such as bending,rolling and even puncturing without losing its *** two single cells are connected in series,the battery pack can provide a charge voltage of 4.3 V and a discharge plateau as high as 3–3.6 V,which are very close to commercial Li ion *** a cheap,flexible and safe battery technology may be widely applied in low-cost and large-quantity applications,such as RFID tags,smart packages and wearable biosensors in the future.

关键词： Al ion battery Aqueous electrolyte Water-in-salt Paper battery Flexible battery

Effect of wall temperature modulation on the heat transfer characteristics of droplet-train flow inside a rectangular microchannel

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Chinese Journal of Chemical Engineering 2020年第3期28卷 685-697页

作者： Vivekanand S.V.B.,Raju V.R.K. department of mechanical Engineering National Institute of TechnologyWarangalTelangana 506004India

The numerical studies of water–oil two-phase slug flow inside a two-dimensional vertical microchannel subjected to modulated wall temperature boundary conditions have been discussed in the present *** researchers have contributed their efforts in exploring the characteristics of Taylor flows inside microchannel under constant wall heat flux or isothermal wall ***,there is no study available in the literature which discusses the impact of modulated thermal wall boundary conditions on the heat transfer behavior of slug flows inside ***,to bridge this gap,an effort has been made to understand the heat transfer characteristics of the flow under sinusoidal wall temperature ***,a single phase flow and heat transfer study was performed in microchannels,and the results of the fully developed velocity profile and heat transfer rate were validated with benchmark analytical *** an optimal selection of the combination of sinusoidal thermal wall boundary conditions has been made for the two-phase slug flow ***,the effects of amplitude(0 bεb 0.03)and frequency(0 bωb 750πrad·s-1)of the sinusoidal wall temperature profile on the heat transfer have been studied using the optimal combination of the wall boundary *** results of the numerical study using modulated temperature conditions on channel walls showed a significant improvement in the heat transfer over liquid-only flow by approximately 50%as well as over two-phase flow without wall temperature *** non-dimensional temperature contours obtained for different cases of temperature modulation clearly explain the root cause of such improvement in the heat ***,the results based on the hydrodynamics of the flow have also been reported in terms of variation of droplet shapes and film *** influence of Capillary number on the film thickness as well as heat transfer rates has also been *** addition,the measured fil

关键词： Heat transfer Microchannel Modulation Surface tension Taylor flow

Regression model for civil aero-engine gas path parameter deviation based on deep domainadaptation with Res-BP neural network

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Chinese Journal of Aeronautics 2021年第1期34卷 79-90页

作者： Xingjie ZHOU Xuyun FU Minghang ZHAO Shisheng ZHONG department of mechanical Engineering Harbin Institute of Technology at WeihaiWeihai 264209China

The variations in gas path parameter deviations can fully reflect the healthy state of aeroengine gas path components and units;therefore,airlines usually take them as key parameters for monitoring the aero-engine gas path performance state and conducting fault *** the past,the airlines could not obtain deviations *** present,a data-driven method based on an aero-engine dataset with a large sample size can be utilized to obtain the ***,it is still difficult to utilize aero-engine datasets with small sample sizes to establish regression models for deviations based on deep neural *** obtain monitoring autonomy of each aero-engine model,it is crucial to transfer and reuse the relevant knowledge of deviation modelling learned from different aero-engine *** paper adopts the Residual-Back Propagation Neural Network(Res-BPNN)to deeply extract high-level features and stacks multi-layer Multi-Kernel Maximum Mean Discrepancy(MK-MMD)adaptation layers to map the extracted high-level features to the Reproduce Kernel Hilbert Space(RKHS)for discrepancy *** further reduce the distribution discrepancy of each aero-engine model,the method of maximizing domain-confusion loss based on an adversarial mechanism is introduced to make the features learned from different domains as close as possible,and then the learned features can be *** the above methods,domain-invariant features can be extracted,and the optimal adaptation effect can be ***,the effectiveness of the proposed method is verified by using cruise data from different civil aero-engine models and compared with other transfer learning algorithms.

关键词： Civil aero-engine Deep domain adaptation Domain confusion Neural networks Transfer learning

Evaluation of different Krylov subspace methods for simulation of the water faucet problem

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Nuclear Science and Techniques 2021年第5期32卷 1-16页

作者： Hong-Yang Wei Kevin Briggs Victor Quintanilla Yi-Tung Chen department of mechanical Engineering University of NevadaLas VegasNV 89154USA

In this study,a one-dimensional two-phase flow four-equation model was developed to simulate the water faucet *** performance of six different Krylov subspace methods,namely the generalized minimal residual(GMRES),transpose-free quasi-minimal residual,quasi-minimal residual,conjugate gradient squared,biconjugate gradient stabilized,and biconjugate gradient,was evaluated with and without the application of an incomplete LU(ILU)factorization preconditioner for solving the water faucet *** simulation results indicate that using the ILU preconditioner with the Krylov subspace methods produces better convergence performance than that without the ILU *** the GMRES demonstrated an acceptable convergence performance under the Krylov subspace methods without the *** velocity and pressure distribution in the water faucet problem could be determined using the Krylov subspace methods with an ILU preconditioner,while GMRES could determine it without the need for a ***,there are significant advantages of using an ILU preconditioner with the GMRES in terms of *** different Krylov subspace methods showed similar performance in terms of computational efficiency under the application of the ILU preconditioner.

关键词： Water faucet problem Krylov subspace methods ILU preconditioner

A Dislocation-based Model for the Dynamics of Sliding Precursors

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Acta Mechanica Solida Sinica 2021年第5期34卷 624-631页

作者： Yiran Li Ganyun Huang department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China

The onset of dynamic friction plays an important role in the study of sliding ***,the sliding precursors in the form of crack-like defects have been detected in experiments and their strain fields have been measured to be comparable to those of moving *** the present work,we considered the dynamics of sliding precursors by solving the elastic problem due to a moving dislocation in a half-plane and the transient emission of a dislocation at the *** has been found that both the strain field of a moving dislocation and the spatiotemporal evolution agree well with those of a sliding precursor detected in *** results may cast new light to the dynamics of sliding onset.

关键词： Sliding precursor Crack-like defects Moving dislocations Dislocation emission

Quantitative Evaluation for Drawability of Sheet Metal

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Journal of Materials Science & Technology 2005年第5期21卷 763-766页

作者： Zhiqing XIONG and Xuemei YANGdepartment of mechanical Engineering, Nanjing Institute of Technology, Nanjing 210013, China department of mechanical Engineering Nanjing Institute of Technology Nanjing 210013 China

The theoretical evaluating method is given for the drawability of the sheet with normal anisotropy. The general solution on the cracking load of deep-drawing is deduced, which is based on three kinds of hardening curve of materials most in use. The distributions of stress and strain in the deformed region and the drawing force are obtained by the numerical method. The limiting drawing ratio is calculated through computer-aided simulating test. The experiments of deep-drawing to four kinds of sheet metals express that the relative errors between the predictive and the experimental results about the cracking load and the limiting drawing ratio are within 5%. The drawability of common sheet metals can be quantitatively evaluated in precise terms by means of the theory and the method advanced in this paper.

关键词： Sheet forming Deep-drawing Formability Drawability