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Study on Theory and Application of the Energy Method used for Analyzing Compressive Instability in Sheet Forming

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厦门大学学报（自然科学版） 2002年第S1期41卷 126-127页

作者： XIONG Zhi-qing 1, XIE Lan-sheng 2 (1. Department of mechanical engineering, Nanjing Institute of Techno logy, Nanjing 210013, china 2. college of mechanical and electrical engineering, Nanjing University of Aer onautics and Astronautics, Nanjing 210016, china)

It is pointed out that there was serious weakness w he n using the energy method for studying compressive plastic instability in sheet forming in the past. Where applying the deduced instability strengths to relativ e engineering analysis, theoretical solutions were away from practices. Its basi c reason is that simplified process in mathematical analysis of elastic bending energy was completely applied to that of plastic bending energy. Where the cambe r expressed by function of displacement normal to a plate was approximated to re alistic deflective camber, the displacement of deflected plate to compressed dir ection was neglected. With the aid of the improved instability strengths, the pr edictions on both critical buckling dimension of blank in cup deep-drawing with out blankholder through cylindrical die or conical die and the minimum blankhold er pressure to prevent buckling under constant load are universally in agreement with both experimental results and experiential data. On the bases of above-mentioned improvement, the approximate expressions for bo th the curvature and the twist used in equation of the energy of elastic bending are also ameliorated. Thus the obtained general equations for both the energy a nd the work done by internal force in plastic bending of a plate are more precis e than before. In the analyses of plastic buckling of shell with bending moment, the effect of bending moment is considered through the work done by simulative bending for ce. The method proposed in this paper can not only simplify analyses but also ge t practical result.

关键词： sheet forming deep-drawing buckling energy me thod

Diffusion and Oxidation Wear of PCBN Tool based on Thermodynamics

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Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 265-271页

作者：邵芳 Binzhou Vacational college School of mechanical engineering Shandong University

The rules of diffusion wear and oxidation wear for PCBN cutting tools were analyzed based on thermodynamics theory. Dissolution concentrations in typical normal workpice materials of PCBN tool material at different temperature were then calculated. Diffusion reaction rules in high temperature were developed and analyzed using the Gibbs free energy criterion. The machining tests were conducted using the PCBN tools at different cutting speeds of 50, 95,100 and 180 m/min, feed of 0.1, 0.2 and depth of cut of 0.1, 0.8, 1, and 1.5 mm respectively on a PUMA300LM numerically-controlled lathe. It was found that the theoretical results were uniform with the experimental data, and the results will provide useful references for tool material design and selection.

关键词： thermodynamics PCBN tool diffusion wear oxidation wear

Multivariate Image Analysis in Gaussian Multi-Scale Space for Defect Detection

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Journal of Bionic engineering 2009年第3期6卷 298-305页

作者： Dong-tai Liang~1 Wei-yan Deng~2 Xuan-yin Wang~1 Yang Zhang~11.State Key Laboratory of Fluid Power Transmission and Control Zhejiang University,Hangzhou 310027,P.R.china2.college of mechanical and electrical engineering,china Jiliang University,Hangzhou 310018,P.R.china [a]State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 P. R. China [b]College of Mechanical and Electrical Engineering China Jiliang University Hangzhou 310018 P. R. China

Inspired by the coarse-to-fine visual perception process of human vision system,a new approach based on Gaussian multi-scale space for defect detection of industrial products was *** selecting different scale parameters of the Gaussian kernel,the multi-scale representation of the original image data could be obtained and used to constitute the multi- variate image,in which each channel could represent a perceptual observation of the original image from different *** Multivariate Image Analysis (MIA) techniques were used to extract defect features *** MIA combined Principal Component Analysis (PCA) to obtain the principal component scores of the multivariate test *** Q-statistic image, derived from the residuals after the extraction of the first principal component score and noise,could be used to efficiently reveal the surface defects with an appropriate threshold value decided by training *** results show that the proposed method performs better than the gray histogram-based *** has less sensitivity to the inhomogeneous of illumination,and has more robustness and reliability of defect detection with lower pseudo reject rate.

关键词： defect detection scale-space Gausslan multi-scale representahon principal component analysis multivariate image anaIysis

External synchronization of two dynamical systems with uncertain parameters

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Science china(Technological Sciences) 2010年第3期53卷 731-740页

作者： HAN QingKai 1,SUN XiaoYu 2,YANG XiaoGuang 3 &WEN BangChun 1 1 School of mechanical engineering&Automation,Northeastern University,Shenyang 110004,china 2 School of electrical engineering,Shenyang University of Technology,Shenyang 110023,china 3School of mechanical engineering,The University of Birmingham,Birmingham,B15 2TT,UK 1. School of mechanical engineering & Automation Northeastern University Shenyang 110004 China2. School of Electrical Engineering Shenyang University of Technology Shenyang 110023 China3. School of Mechanical Engineering The University of Birmingham Birmingham B15 2TT UK

External synchronization is addressed as two or more dynamical systems with synchronous motions,which is also regarded as master-slave *** this paper,two dynamical systems,one employs a hysteretic term to model the friction phenomenon,the other involves a hardening stiffness component with the third order of displacement due to flexible deformation,are controlled to converge to the same *** control strategy is extended from feedback control for all parameters known to adaptive control for linear parameters unknown and all parameters *** slave system can keep synchronous motions with the movements of master via the designed control strategy even all the parameters are not *** stability of synchronization error,the transient process into synchronization and the effects of parameters on the designed controller using different control strategies are *** simulation results unfold the feasibility and effectiveness of this synchronization method.

关键词： controlled synchronization uncertain parameters hysteretic system Duffing system

Effects of rapid solidification on the microstructure and microhardness of a lead-free Sn-3.5Ag solder

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Rare Metals 2006年第4期25卷 365-370页

作者： SHEN Jun LIU Yongchang Han Yajing GAO Houxiu college of mechanical engineering Chongqing University Chongqing 400044 China college of Materials Science and engineering Tianjin University Tianjin 300072 China

A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （IMCs） in Ag-rich zone, yielding fine Ag3Sn nanoparticulates with spherical morphology in the matrix of the solder. The large amount of tough homogeneously-dispersed IMCs helps to improve the surface area per unit volume and obstructs the dislocation lines passing through the solder, which fits with the dispersion-strengthening theory. Hence, the rapidly-solidified Sn-3.5Ag solder exhibits a higher rnicrohardness when compared with a slowly-solidified Sn-3.5Ag solder.

关键词： lead-free solder nanoparticulate rapid solidification intermetallic compounds dispersion-strengthening effect

Analysis on ignition and extinction of n-heptane in homogeneous systems

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Science china(Technological Sciences) 2005年第5期48卷 556-569页

作者： LIU Yongfeng1 & PEI Pucheng2 1. mechanical and electrical engineering Department, Beijing Institute of Civil engineering and Architec-ture, Beijing 100044, china 2. State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, china 1. mechanical and electrical engineering Department Beijing Institute of Civil Engineering and Architecture 100044 Beijing China 2. State Key Laboratory of Automotive Safety and Energy Tsinghua University 100084 Beijing China

To calculate ignition delay times, the governing equations about species and temperature, which are in a closed volume based on the theory of thermal explosion and in a continuously stirred flow reactor, are deducted. The method referred to steady state assumptions is based on the observation that due to very fast chemical processes in combustion problems many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. The steady state solution of the reactor equations describes the three ignition temperature regimes and get “S-shaped curve”. The reduced simplified 4-step mechanism for n-heptane from 1011 elementary reactions leads with the steady state assumptions to linear differential equations, which is solved. The simulation results of the 4-step reduced mechanism for n-heptane are fitted well with the experiment data. At last, two important parameters are discussed thoroughly and the temperature perturbation is given. It reduces the computational efforts considerably without losing too much accuracy and further supplies numerical methods for turbulent combustion in the diesel engine.

关键词： ignition delay times, thermal runaway, steady state assumptions, continuously stirred flow reactor.

Tribological Properties of PVA-H Composites Reinforced by Nano-HA Particles

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Journal of Wuhan University of Technology(Materials Science) 2007年第3期22卷 490-493页

作者：吴刚 School of mechanical engineering Shanghai Jiaotong University

The friction and wear behaviors of tribological mechanical components were studied on a four-ball tester under dry conditions, and the wear mechanism was analyzed by observed worn surface using a scanning electron microscope （SEM）. It was found that the friction and wear properties were improved by the addition ofnano HA particles. The composite containing 1 wt% nano HA had the optimum friction coefficient. It is also found that the addition of nano HA increases the wear resistance of oure PVA-H and PVA-H composites.

关键词： articular cartilage composites wear friction coefficient corrosion-abrasion

Feature Based Machining Process Planning Modeling and Integration for Life Cycle engineering

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武汉理工大学学报 2006年第S2期28卷 633-636页

作者： LIU Changyi (college of mechanical and electrical engineering,Nanjing University of Aeronautics & Astronautics,Nanjing 210016,china college of mechanical and electrical engineering Nanjing University of Aeronautics & AstronauticsNanjing 210016China

Machining process data is the core of computer aided process planning application *** is also provides essen- tial content for product life cycle *** character of CAPP that supports product LCE and virtual manufacturing is an- *** structure and content of machining process data concerning green manufacturing is also examined.A logic model of Machining Process Data has been built based on an object oriented approach,using UML technology and a physical model of machin- ing process data that utilizes XML *** realize the integration of design and process,an approach based on graph-based volume decomposition was ***,to solve the problem of generation in the machining process,case-based reasoning and rule-based reasoning have been applied ***,the integration framework and interface that deal with the CAPP integration with CAD,CAM,PDM,and ERP are discussed.

关键词： computer aided process planning feature life cycle engineering modeling integration

Energy-Based Prediction of Low Cycle Fatigue Life of High-Strength Structural Steel

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Journal of Iron and Steel Research International 2012年第10期19卷 47-53页

作者： LUO Yun-rong1,2, HUANG Chong-xiang1, GUO Yi2, WANG Qing-yuan1 (1. college of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan, china 2. college of mechanical engineering, Sichuan University of Science and engineering, Zigong 643000, Sichuan, china) [a] college of Architecture and Environment. Sichuan University Chengdu 610065 Sichuan China [b] college of mechanical engineering. Sichuan University of Science and engineering Zigong 643000 Sichuan China

Energy-based models for predicting the low-cycle fatigue life of high-strength structural steels are presented. The models are based on energy dissipation during average of cycles, cycles to crack propagation and total cycles to failure. Plastic strain energy per cycle was determined and found as an important characteristic for initiation and propagation of fatigue cracks for high-strength structural steels. Fatigue strain-life curves were generated using plastic energy dissipation per cycle (loop area) and compared with the Coffin-Manson relation. Low cycle fatigue life was found similar from both methods. The material showed Masing-type behavior. The cyclic hysterisis energy per cycle was calculated from cyclic stress-strain parameters. The fracture surfaces of the fatigue samples were characterized by scanning electron microscope and the fracture mechanisms were discussed.

关键词： low cycle fatigue high-strength steel energy-based model fatigue life