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Material Removal Model Considering Influence of Curvature Radius in Bonnet Polishing Convex Surface

Chinese Journal of mechanical engineering 2015年第6期28卷 1109-1116页

作者： SONG Jianfeng YAO Yingxue College of mechanical engineering Yanshan University Digital manufacturing Laboratory of Mechatronicas engineering College Harbin Institute Technology

The bonnet tool polishing is a novel, advanced and ultra-precise polishing process, by which the freeform surface can be polished. However, during the past few years, not only the key technology of calculating the dwell time and controlling the surface form in the bonnet polishing has been little reported so far, but also little attention has been paid to research the material removal function of the convex surface based on the geometry model considering the influence of the curvature radius. Firstly in this paper, for realizing the control of the freeform surface automatically by the bonnet polishing, on the basis of the simplified geometric model of convex surface, the calculation expression of the polishing contact spot on the convex surface considering the influence of the curvature radius is deduced, and the calculation model of the pressure distribution considering the influence of the curvature radius on the convex surface is derived by the coordinate transformation. Then the velocity distribution model is built in the bonnet polishing the convex surface. On the basis of the above research and the semi-experimental modified Preston equation obtained from the combination method of experimental and theoretical derivation, the material removal model of the convex surface considering the influence of the curvature radius in the bonnet polishing is established. Finally, the validity of the model through the simulation method has been validated. This research presents an effective prediction model and the calculation method of material removal for convex surface in bonnet polishing and prepares for the bonnet polishing the free surface numerically and automatically.

关键词： bonnet polishing convex surface material removal model curvature radius

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Liquid Phase Bonding of 316L Stainless Steel to AZ31 Magnesium Alloy

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Journal of Materials Science & technology 2011年第1期27卷 22-28页

作者： Waled Elthalabawy Tahir Khan Department of mechanical and manufacturing engineering University of Calgary

The excellent corrosion resistance,formability and strength make stainless steels versatile for diverse ***,its high specific strength and good crashworthiness make it suitable for transportation and aerospace *** the other hand,the need to reduce the weight of vehicle and aerospace components has created renewed interest in the use of magnesium *** to their differences in physical and metallurgical properties,bonding of the 316L steel and AZ31 magnesium alloy using conventional fusion welding methods encountered many ***,the use of liquid phase forming interlayers is required to overcome the differences in their properties,eliminates the need for a high bonding pressure to achieve intimate contact between the bonded *** Cu and Ni interlayers successively formed a eutectic phase with *** formation of intermetallics and Mg diffusion caused the eutectic phase to isothermally solidify with increasing bonding *** formation of ternary intermetallic phases（λ1 and B2） impaired the bond shear strength particularly at the end of the isothermal solidification stage where no eutectic phase was ***,the joints showed a higher shear strength value of 57 MPa when bonding with Cu interlayer at 530℃ for 30 min compared to 32 MPa when Ni interlayer was used at 510℃ for 20 min.

关键词： Magnesium alloy Stainless steel Eutectic bonding Microstructure Shear strength

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Tailor-made high elasticity and low-hysteresis hydrogels based on asymmetric H-bonding crosslinking for wearable applications

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Science China Chemistry 2025年

作者： Xiaofang Shi Nan Shi Miaomiao Dang Chengyu Ji Yingjie Li Peiyi Wu Zhiguo Hu Collaborative Innovation Centre of Henan Province for Green manufacturing of Fine Chemicals Henan Engineering Laboratory of Chemical Pharmaceutical and Biomedical Materials School of Chemistry and Chemical Engineering Henan Normal University State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Chemistry Chemical Engineering and Biotechnology & Center for Advanced Low-dimension Materials Donghua University

The conventional method of fabricating hydrogels constantly confronts the conflict between elasticity and toughness, limiting their repetitive application. Achieving the desired elasticity through a simple and low-cost approach is a significant challenge for hydrogels, particularly through rational molecular design. Here, low-hysteresis and high-toughness hydrogels are developed from the design of a new feature monomer, N-acryloylethylsemicarbazide (NACE). Based on a concept of “asymmetric Hbonding design”, the unique double and triple H-bonding of NACE can result in a novel asymmetric crosslinking polymer with alternating strong and weak H-bonding regions. The NACE is copolymerized with acrylamide (AM) to regulate the mechanical properties of hydrogel via H-bonding density. The P(NACE-AM) ionic hydrogels are obtained simply and rapidly via one-step photopolymerization without a chemical cross-linking agent. The P(NACE-AM) hydrogels combine superb mechanical elasticity and toughness, and excellent ionic conductivity, showing great potential as durable ionic conductive devices for wearable utilization.

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Finite element modeling of chip separation in machining cellular metals

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Advances in manufacturing 2015年第1期3卷 54-62页

作者： R.Guerra Silva U.Teicher A.Nestler A.Brosius School of mechanical engineering Central University of Venezuela Institute of manufacturing technology Dresden University of Technology

Cellular metals and metal foams belong to a young material group. Although it is desired to manufac- ture near-net-shape parts of cellular metals by primary shaping processes, additional secondary machining opera- tions are often unavoidable to obtain the required geome- tries and quality demands. Nevertheless, conventional machining of cellular metals leads to undesirable surface damage and poor precision. Furthermore, the chip forma- tion and the mechanism description of the surface damage are still unclear. A mesoscopic finite element model was developed to simulate the chip formation process in machining cellular metals. Experimental data of orthogonal machining tests were used to validate the finite element model. The cutting and thrust forces, as well as the images of the chip formation process of both experiments and simulations were compared and analysed. The model enabled the analysis of the chip formation and the surface defect mechanisms. The rake angle and cutting conditions affected the chip formation process, but the cell arrange- ment was detected as a decisive factor in the chip forma- tion and the resulting surface damage.

关键词： Cellular metals. Metal foams - MachiningFinite element modeling - Orthogonal cutting

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Analysis of Electrical Characteristics of Inter-wire Arc in Cross-Coupling Arc

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Chinese Journal of mechanical engineering 2019年第2期32卷 203-211页

作者： Zhenyang Lu Shanwen Dong Fan Jiang Cheng Li College of mechanical engineering and Applied Electronics technology Ministry of Education Engineering Research Center of Advanced Manufacturing Technology for Automotive Components Beijing University of Technology

As a new composite welding heat source introduced in recent years, the cross-coupling arc uses a non-consumable electrode arc(plasma arc) and a consumable electrode arc(inter-wire arc) in cross-coupling, in which the plasma arc is the main arc and the inter-wire arc is the vice arc, to realize the separate control of the heat input to the workpiece,arc force, and droplet transfer. To reveal the electrical characteristics of the inter-wire arc under the action of the plasma arc, in this study, rotating probes are used to sweep across the plasma arc. When the probes rotate into the plasma arc, a circuit is formed, and the electrical characteristics of the inter-wire arc are indirectly analyzed according to the circuit: the probe centering current and input voltage are used as the physical quantities. The results show that at a certain wire feed rate, the inter-wire arc current increases with increasing input voltage. When the input voltage is low, the wire feed rate has no obvious e ect on the inter-wire arc current. At a higher input voltage, where the wire feed rate is high, the inter-wire arc current decreases. With the increase in the plasma arc current, the inter-wire arc current first increases quickly and then increases slowly, and simultaneously, the striking arc time becomes *** the increase in the interval between the nozzle and the workpiece, the inter-wire arc current increases, but when the arc length increases to a certain limit, the slope of the welding current clearly declines.

关键词： Inter-wire arc Circuit Input voltage Inter-wire arc current

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Design method and vibration testing of a reconfigurable multi-process combined turn-milling machine tool

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Journal of Beijing Institute of technology 2011年第3期20卷 351-358页

作者：范徐笑张之敬金鑫孙需要郭娜 Micro-manufacturing technology Laboratory School of Mechanical EngineeringBeijing Institute of Technology

To provide a good machining method in remanufacturing for the repaired parts with various forms, the design method of reconfigurable multi-process combined machining system and its implementation technology for remanufacturing are systematically proposed. The key technologies include reconfigurable structure design method of multi-process combined machining, man-machine coordination parameter programming and control system technology with self-maintenance function. A turn-milling machine tool based on this design method is developed. Natural frequency and corresponding vibration modes of the machine tool were analyzed by using both FEA and vibration test. Stiffness tests and machining experiments show that the rapid machining of most processes for the repaired work pieces can be successfully realized.

关键词： reconfigurable design method reconfigurable machine tool modal analysis dynamiccharacteristics

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NONLINEAR DYNAMICS OF A FGM PLATE WITH TWO CLAMPED OPPOSITE EDGES AND TWO FREE EDGES

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Acta Mechanica Solida Sinica 2014年第4期27卷 394-406页

作者： Y.X.Hao W.Zhang J.Yang College of mechanical engineering Beijing Information Science and Technology University College of mechanical engineering Beijing University of technology School of Aerospace Mechanical and Manufacturing Engineering RMIT University PO Box 71Bundoora VIC 3083 Australia

This paper deals with the nonlinear forced vibration of FGM rectangular plate with a boundary of two edges clamped opposite and the other two free. The plate is subjected to transversal and in-plane excitations. The present research treats the material properties of the FGM plates as temperature-dependent and graded continuously throughout the thickness direction, following the volume fraction of the constituent materials according to the power law. The temperature is assumed to be constant in the plane and varied only in the thickness direction of the plate. In the framework of geometrical nonlinearity the plate is modeled and the equations of motion are obtained on Hamilton＇s principle. With the help of Galerkin discretization, the nonlinear ordinary differential equations describing transverse vibration of the plate are proposed. By the numerical method, the nonlinear dynamical responses of the FGM plate with two clamped opposite and two free edges are analyzed.

关键词： functionally graded materials plate clamped bifurcation

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Microstructure transformations and improving wear resistance of austenitic stainless steel additively fabricated by arc-based DED process

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Defence technology（防务技术） 2024年第8期38卷 194-204页

作者： Ashish Yadav Manu Srivastava Prashant K.Jain Sandeep Rathee Hybrid Additive manufacturing Laboratory Mechanical Engineering DepartmentPDPM Indian Institute of Information TechnologyDesign&ManufacturingJabalpur482005Madhya PradeshIndia FFF Laboratory Mechanical Engineering DepartmentPDPM Indian Institute of Information TechnologyDesign&ManufacturingJabalpur482005Madhya PradeshIndia Department of mechanical engineering National Institute of TechnologySrinagarIndia

In this study, austenitic stainless steel(ASS) was additively fabricated by an arc-based direct energy deposition(DED) technique. Macrostructure, microstructure, mechanical characteristics at different spatial orientations(0°, 90°, and 45°), and wear characteristics were evaluated at the deposited structure top, middle, and bottom regions. Results show that austenite(γ) and delta-ferrite(δ) phases make up most of the microstructure of additively fabricated SS316LSi steel. Within γ matrix, δ phase is dispersed both(within and along) grain boundaries, exhibiting a fine vermicular morphology. The bottom, middle,and top regions of WAAM deposited ASS exhibit similar values to those of wrought SS316L in the tensile and impact test findings. Notably, a drop in hardness values is observed as build height increases. During SEM examinations of fractured surfaces from tensile specimen, closed dimples were observed, indicating good ductility of as-built structure. Wear test findings show signs of mild oxidation and usual adhesive wear. By depositing a mechanically mixed composite layer, an increase in the oxidation percentage was discovered to facilitate healing of worn surfaces. The findings of this study will help in design, production and renovation of products/components that are prone to wear. WAAM-deposited ASS has remarkable strength and ability to withstand impacts;it can be used in the production of armour plates for defence applications, mainly military vehicles and aircraft.

关键词： Metal additive deposition Defence applications Arc-based DED Characterization Wear behaviour Fractography

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Vision-based adaptive control of a 3-RRR parallel positioning system

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Science China(Technological Sciences) 2018年第8期61卷 1253-1264页

作者： YAO Sheng LI Hai ZENG Lei ZHANG XianMin Guangdong Key Laboratory of Precision Equipment and manufacturing technology School of Mechanical and Automotive EngineeringSouth China University of Technology

The macro positioning stage with high-precision and rapid positioning ability plays a crucial role in the macro-micro combination positioning system. In this paper, we develop a practical method for the control of a 3-RRR planar positioning system using online vision measurement as feedback. In this method, a monocular vision system is established to accomplish highprecision online pose measurement for the 3-RRR manipulator. Additionally, a robust and operable adaptive control algorithm,which incorporates a fuzzy controller and a PI controller, is employed to achieve precise and rapid positioning of the 3-RRR positioning system. A series of experiments are conducted to verify the positioning performances of the proposed method, and a conventional PI control algorithm is utilized for comparison. The experimental results indicate that using the proposed control approach, the parallel positioning system obtains high precision and shows higher efficiency and robustness, especially for the time-varying positioning system.

关键词： adaptive positioning control 3-RRR planar parallel manipulator machine vision-aided system full-closed loop control

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Submicron particle sizing by aerodynamic dynamic focusing and electrical charge measurement

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Particuology 2015年第1期13卷 105-111页

作者： Zhongchao Tan Raheleh Givehchi Alena Saprykina Department of mechanical & Mechatronics engineering University of Waterloo Department of mechanical and manufacturing engineering University of Calgary

Principles of a novel submicron particle sizing technology are first introduced followed by experimental validation. The sizing was accomplished by coupling aerodynamic particle focusing and maximum ion measurement. Experimental results showed that the prototype could detect particle sizes down to 40 nm in diameter. Comparison between the prototype and a scanning mobility particle sizer using identical polydisperse particles showed that the measurements agreed well for the tested particles.

关键词： Submicron particle Particle sizing Aerodynamic focusing Particle charging

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