Free vibration analysis of functionally graded coupled circular plate with piezoelectric layers

Based on classical plate theory (CLPT), free vibration analysis of a circular plate composed of functionally graded material (FGM) with its upper and lower surfaces bounded by two piezoelectric layers was performed. Assuming that the material properties vary in a power law manner within the thickness of the plate the governing differential equations are derived. The distribution of electric potential along the thickness direction in piezoelectric layers is considered to vary quadratically such that the Maxwell static electricity equation is satisfied. Then these equations are solved analytically for two different boundary conditions, namely clamped and simply supported edges. The validity of our analytical solution was checked by comparing the obtained resonant frequencies with those of an isotropic host plate. Furthermore, for both FGM plate and FGM plate with piezoelectric layers, natural frequencies were obtained by finite element method. Very good agreement was observed between the results of finite element method and the method presented in this paper. Then for the two aforementioned types of boundary conditions, the values of power index were changed and its effect on the resonant frequencies was studied. Also, the effect of piezoelectric thickness layers on the natural frequencies of FGM piezoelectric plate was investigated. This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim Saeed Jafari Mehrabadi received his B.S. in mechanical Engineering from Azad University, Arak, Iran, in 1992. He then received his M.S. from Azad University, Tehran, Iran in 1995. Now he is a faculty member of the department of mechanical engineering in Azad university of Arak, Iran and PhD student of Azad University, Science and Research Campus, Pounak, Tehran, Iran. His interests include computational methods and solid mechanics such as vibration, buckling.     

Free vibration of multi-layered circular cylindrical shell with cross-ply walls,including shear deformation by using spline function method

The spline function technique is used to analyze the vibration of multi-layered circular cylindrical shells with cross-ply walls including first-order shear deformation theory. Both antisymmetric and symmetric cross-ply laminations are considered in this analysis. The governing equilibrium equations are obtained in terms of displacement and rotational functions. A system of coupled ordinary differential equations in terms of displacement and rotational functions are obtained by assuming the solution in a separable form. These functions are approximated by using Bickley-type splines of suitable order to obtain the generalized eigenvalue problem by applying point collocation techniques with appropriate boundary conditions. Parametric studies are performed to analyze the frequency response of the shell with reference to the material properties, number of layers, fiber orientation, thickness to radius ratio, length to radius ratio and circumferential node number. Reasonable agreement is found with existing results obtained by FEM and other methods. Valuable results are presented as graphs and discussed. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Dr. K. K. Viswanathan was born in 1962 in Vellore District, India. He received his B.Sc. in Mathematics from University of Madras and M.Sc. in 1992 and Ph.D. in 1999 from Anna University, India. Later he was a Project Associate in Indian Institute of Science, Bangalore. He served as lecturer in Crescent Engg. College and as Asst. Professor in SRM University, India. He did his post doctoral research in Korea for three years. At present he serves as Professor in the Dept. of Naval Architecture, Inha University, Incheon, Korea. His research areas of interest includes vibration of plates, shells and the application of numerical techniques in Engineering problems. Dr. Kyung Su Kim was born in Korea in 1954. He is a professor in Naval Architecture and Ocean Engineering at Inha University, Korea. He obtained his B.Sc. degree in Naval Architecture and Ocean Engineering from Seoul National University, Korea, in 1981. He worked for KR (Korean Register of Shipping) from 1981 to 1983. He obtained M.Sc. degree in Naval Architecture and Ocean Engineering in 1986, and Ph.D. degree in Structural Mechanics in 1991 from Rheinisch — Westfaelische Technische Hoch-schule Aachen, Germany. From 1986 to 1992, he was a Post Doctoral Research Engineer of Engineering Research Institute at Rheinisch — Westfaelische Technische Hochschule Aachen. He was appointed as a professor of Inha University, Korea, in 1994. His major area of study is Impact and Fatigue Fracture. Dr. Jang Hyun Lee was born in Korea in 1969. Currently, he is an Assistant professor of the Department of Naval Architecture and Ocean Engineering at Inha University, Korea. He obtained his B.Sc., M.Sc. and Ph.D. degrees in Naval Architecture and Ocean Engineering from Seoul National University, Korea, in 1993, 1995 and 1999 respectively. From 1999 to 2002, he was a Post Doctoral Research Engineer of Engineering Research Institute at Seoul National University. He joined the Inha University in 2005 after holding the Chief Technology Officer at Xinnos for four years. His research interests include press forming of thick plates and shells, computational welding mechanics and Product Lifecycle Management.     

An enhanced real-time dynamic imbalance correction for precision rotors

Even a moderate mass imbalance of a high-precision rotor produces a significant level of vibration when it spins at high revolutionary speed such as 10,000 rpm or faster. As a result, many attempts have been made for the development of dynamic rotor balancing methods mostly by the precision mechanical system industry; however, intensive studies about the fundamental principles from a theoretical point of view should be carried out further. In the present paper, a new dual axes dynamic imbalance correction method is introduced and tested through simulations. The proposed method is more efficient and effective than its predecessors. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Jung Kwan Lee is currently a masteral student in the School of Mechanical Engineering at Sungkyunkwan University Korea. He received his B.S. degree from Sungkyunkwan University. His primary research interests are rotor design, analysis, and rotor dynamics. Hyungpil Moon received his Ph.D. degree in mechanical engineering from the University of Michigan in 2005. He was a postdoctoral fellow at Carnegie Mellon University. He joined the faculty of the School of Mechanical Engineering at Sungkyunkwan University in 2008. Dongho Oh received his Ph.D. degree from KAIST in 1996. He worked as a Principal En-gineer of Samsung Electronics and SAIT. Dr. Oh is currently an Associate Professor at the Department of Mechanical Engineering at Chungnam National University. Ja Choon Koo is an associate professor of the School of Mechanical Engineering at Sungkyunkwan University Korea. He was an engineer at IBM Corporation, San Jose, California. He received his Ph.D from the University of Texas at Austin. His primary research interests are analysis, and control of dynamic systems, mechatronics, sensors, and actuators.     

Development of rapid mask fabrication technology for micro-abrasive jet machining

Micro-machining of a brittle material such as glass or silicon is important in micro fabrication. Particularly, micro-abrasive jet machining (μ-AJM) has become a useful technique for micro-machining of such materials. The μ-AJM process is mainly based on the erosion of a mask which protects brittle substrate against high velocity of micro-particles. Therefore, fabrication of an adequate mask is very important. Generally, for the fabrication of a mask in the μ-AJM process, a photomask based on the semi-conductor fabrication process was used. In this research a rapid mask fabrication technology has been developed for the μ-AJM. By scanning the focused UV laser beam, a micro-mask pattern was fabricated directly without photolithography process and photomask. Therefore, rapid and economic mask fabrication can be possible for the micro-abrasive jet machining. Two kinds of mask patterns were fabricated by using SU-8 and photopolymer (Watershed 11110). Using fabricated mask patterns, abrasive-jet machining of Si wafer was conducted successfully. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Seung Pyo Lee is a research engineer of GM Daewoo Auto & Technology. He receives his Ms degree in Precision Mechanical Engineering at the Chungbuk National University in 2007. Hyun-Wook Kang is currently a Ph.D. candidate in the Department of Mechanical Engineering at POSTECH, Korea. He received his B.S. degree in the Department of Mechanical Engineering from POSTECH. His current research interests are in the solid freeform fabrication technology for the engineered tissue construction. Seung-Jae Lee received the M.S. degree from the Dept. of Me-chanical Engineering from the POSTECH in 2002, and his Ph.D. degree in Dept. of Mechanical Engineering from POSTECH in 2007. His Ph.D research is the study of Microfabrication and Tissue engineering. In Hwan Lee is a professor of School of Mechanical Engineering at Chungbuk National University, Korea. He receives his Ph.D. degree in Mechanical Engineering from the POSTECH in 2003. His research is focused on micro-manufacturing and bio-system. Tae Jo Ko is a professor of mechanical engineering at Yeungnam University, Korea. Also, he is responsible for the Gyoungbuk Hybrid Technology Institute that is regional research innovation center and initiates the idea for hybrid manufacturing. He earned Ph.D in mechanical engineering from POSTECH, Korea, in 1994. He worked for Doosan Infracore Co. Ltd. (formerly Daewoo) from 1985 to 1995. His research interests include machine tools, metal cutting as well as nontraditional machining. Dong-Woo Cho is a professor in the Department of Mechanical Engineering at the POSTECH. He received his Ph.D. degree in Mechanical Engineering from the University of Wisconsin-Madison in 1986. His research focuses on the manufacturing system for Tissue Engineering.     

Geometrically nonlinear vibration analysis of piezoelectrically actuated FGM plate with an initial large deformation

A theoretical model for geometrically nonlinear vibration analysis of piezoelectrically actuated circular plates made of functionally grade material (FGM) is presented based on Kirchhoff’s-Love hypothesis with von-Karman type geometrical large nonlinear deformations. To determine the initial stress state and pre-vibration deformations of the smart plate a nonlinear static problem is solved followed by adding an incremental dynamic state to the pre-vibration state. The derived governing equations of the structure are solved by exact series expansion method combined with perturbation approach. The material properties of the FGM core plate are assumed to be graded in the thickness direction according to the power-law distribution in terms of the volume fractions of the constituents. Control of the FGM plate’s nonlinear deflections and natural frequencies using high control voltages is studied and their nonlinear effects are evaluated. Numerical results for FG plates with various mixture of ceramic and metal are presented in dimensionless forms. In a parametric study the emphasis is placed on investigating the effect of varying the applied actuator voltage as well as gradient index of FGM plate on vibration characteristics of the smart structure. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin Farzad Ebrahimi received his B.S. and M.S. degree in Mechanical Engineering from University of Tehran, Iran. He is currently working on his Ph.D. thesis under the title of “Vibration analysis of smart functionally graded plates” at Smart Materials and Structures Lab in Faculty of Mechanical Engineering of the University of Tehran. His research interests include vibration analysis of plates and shells, smart materials and structures and functionally graded materials.     

Computational study on aerodynamics of long-span bridges

A numerical procedure for aerodynamic load analysis of long span bridges is presented. The preconditioned Reynolds averaged Navier-Stokes equations are adopted to compute flows over the bridges. To capture the turbulent characteristics of the flows, two equation turbulence models, Coakley’s q − ω model and Menter’s k − ω SST model, are used to compute the turbulent viscosity. A dual time stepping method in conjunction with the AF-ADI method is used to advance the solution in time. A loosely coupled method of the preconditioned RANS equations with the turbulence model equations is employed for fast computation without losing numerical stability. The numerical method for the aerodynamic load analysis is verified against well-known benchmark problems. Aerodynamic loads of two real bridges are computed with the method to demonstrate the usefulness of the method. This paper was recommended for publication in revised form by Associate Editor Kyung-Soo Yang Ilyong Yoo is a Ph.D. candidate in Aerodynamic Analysis and Design Laboratory at Inha University. He received his B.S. and M.S. degrees in Aerospace Engineering from Inha University in 2004 and 2006, respectively. His research area includes computational fluid dynamics, and its application to active flow control using MEMS devices. Einkeun Kwak is a Ph.D. candidate in Aerodynamic Analysis and Design Laboratory at Inha University. He holds B.S. and M.S. degrees in Aerospace Engineering from Inha University. His research area includes computational fluid dynamics, and its application to supersonic inlet analysis and design. Seungsoo Lee is a professor in Aerospace Engineering at Inha University. Prior to joining the faculty at Inha University, he was a senior research engineer at the Agency for Defense Development. He earned his Ph.D. degree from the Pennsylvania State University in 1990. He also holds B.S. and M.S degrees in Aeronautical and Astronautical Engineering from Seoul National University. Dr. Lee’s research interests are in the area of computational fluid dynamics, overset grid method, and applied aerodynamics. Beom Soo Kim received his B.S. and M.S degrees in Aeronautical and Astronautical Engineering from Seoul National University in 1974 and 1977, respectively. He earned his Ph.D. degree from University of Oklahoma in 1983. Dr. Kim is currently a Professor at the Department of Aerospace Engineering at Inha University. Dr. Kim’s research interests are in the area of hypersonic aerodynamics, and wind tunnel testing. Si Hyong Park is a developer in the applied analysis team of MidasIT Co. Ltd, Korea. He received the Bachelor, the Master and the Ph.D degree in Aerospace Engineering from Seoul National University in 1996, in 1998 and in 2003, respectively. His research interest is currently development of CAE software including FEM, CFD and Multi-physics simulation.     

Optimal operating points of PEM fuel cell model with RSM

The output power efficiency of the fuel cell system mainly depends on the required current, stack temperature, air excess ratio, hydrogen excess ratio, and inlet air humidity. Therefore, the operating conditions should be optimized to get maximum output power efficiency. In this paper, a dynamic model for the fuel cell stack was developed, which is comprised of a mass flow model, a gas diffusion layer model, a membrane hydration, and a stack voltage model. Experiments have been performed to calibrate the dynamic Polymer Electrolyte Membrane Fuel Cell (PEMFC) stack model. To achieve the maximum output power and the minimum use of hydrogen in a certain power condition, optimization was carried out using Response Surface Methodology (RSM) based on the proposed PEMFC stack model. Using the developed method, optimal operating conditions can be effectively selected in order to obtain minimum hydrogen consumption. This paper was recommended for publication in revised form by Associate Editor Tong Seop Kim Dong-Ji Xuan received his B.S. degree in Mechanical Engineering from Harbin Engineering University, China in 2000. He then received his M.S. degree in Mechanical Engineering from Chonnam National University, South Korea in 2006. Currently, he is a Ph.D. candidate of the Department of Mechanical Engineering, Chonnam National University, South Korea. His research interests include control and optimization of PEM fuel cell system, dynamics and control, and mechatronics. Zhen-Zhe Li received his B.S. degree in Mechanical Engineering from Yanbian University, China in 2002. He then received his M.S. degree in Aerospace Engineering from Konkuk University, South Korea in 2005 and his Ph.D. degree in Mechanical Engineering from Chonnam National University, South Korea in 2009. Dr. Li is currently a Researcher of the Department of Mechanical Engineering in Chonnam National University, South Korea. Dr. Li’s research interests include applied heat transfer, fluid mechanics, and optimal design of thermal and fluid systems. Jin-Wan Kim received his B.S. degree in Aerospace Engineering from Chosun University, South Korea in 1990. He then received his M.S. degree in Aerospace and Mechanical Engineering from Korea Aerospace University, South Korea in 2003 and his Ph.D degree in Mechanical Engineering from Chonnam National University, South Korea in 2008. He is currently a Post Doctor of the Department of Mechanical Engineering in Chonnam National University, South Korea. His research interests include control of hydraulic systems, dynamics and control, and mechatronics. Young-Bae Kim received his B.S. degree in Mechanical Design from Seoul National University, South Korea in 1980. He then received his M.S. degree in Mechanical Engineering from the Korean Advanced Institute of Science and Technology (KAIST), South Korea in 1982 and his Ph.D. degree in Mechanical Engineering from Texas A&M University, USA in 1990. Dr. Kim is currently a Professor of the School of Mechanical and Systems Engineering in Chonnam National University, South Korea. Dr. Kim’s research interests include mechatronics, dynamics and control, and fuel cell hybrid electric vehicle (FCHEV) systems.     

The influence on the contact condition and initial fixation stability of the main design parameters of a self-expansion type anterior cruciate ligament fixation device

This paper proposes a self-expansion type anterior cruciate ligament fixation device. The proposed fixation device provides graft fixation force by maintaining contact with the bone tunnel. Since the device maintains contact with the bone tunnel by the force that expands by the self-driven elastic force of the device, the main design parameters that determine the performance of this device are the ring thickness and expansion angle. This paper develops the three-dimensional finite element models of the fixation device and bone. By simulation with the developed finite element model, this paper studies the influence of the main design parameters of the device on the maximum stress around the ring when grasping the fixation device. Through the analysis of the stress on the bone tunnel wall when the fixation device comes in contact with the bone tunnel, this paper shows the influence of the main design parameters of the fixation device on the contact condition. In addition, through the analysis of the migration that occur upon application of the pull-out force, this paper studies the influence of the main design parameters on the initial fixation stability of the fixation device. This paper was recommended for publication in revised form by Associate Editor Young Eun Kim Jong-Dae KIM received the B.S. and M.S. degrees in Precision Mechanical Engineering from Chonbuk National University, Korea in 1993 and 1995, respectively. He then received his Ph.D. degree in Bionano System Engineering from Chonbuk National University, Korea in 2008. He worked at DAEWOO Electronic Components Co., Ltd., Korea for eight years from 1995. He is currently a full-time lecturer at the Department of Mechanical and Automotive Engineering in Jeonju University, Korea. Dr. Kim’s research interests are in the area of biomechanics and robotics for rehabilitation. Chae-Youn OH received the B.S. degree in Mechanical Engineering from Chonbuk National University, Korea, in 1982. He then received his M.S. and Ph.D. degrees in Mechanical Engineering from Iowa State University, U.S.A., in 1987 and 1990, respectively. He is currently a Professor at the Division of Mechanical System Engineering at Chonbuk National University in Jeonju, Korea. Dr. OH’s research interests are in the area of biomechanics and haptics. Cheol-Sang KIM received his B.S. and M.S. degrees in Mechanical Engineering from Chonbuk National University in Korea in 1980 and 1982, respectively. He then received a Ph.D. degree in Material Science at Universite de Louis Pasteur in Strasbourg, France in 1988. He spent two years at the Department of Bioengineering at University of Pennsylvania (U.S.A) as a Post Doc. fellow. Dr. Kim is currently an Associate Professor at the Division of Mechanical Engineering at Chonbuk National University in Korea. Dr. Kim’s research interests are in the area of biomaterials for hard tissue replacements, design and analysis of implants and artificial organs, and anti-biofouling technology.     

Micro machining of an STS 304 bar by magnetic abrasive finishing

A magnetic abrasive finishing process is a method of non-traditional precision machining in which the finishing process is completed using magnetic force and magnetic abrasives. In this research, a STS 304 cylindrical workpiece was finished using a magnetic abrasive finishing process at 30,000 rpm, and the roughness, roundness, and changes in the micro-diameter were investigated. The study showed that it is possible to control the micro-diameter and weight of the STS 304 cylindrical workpiece by using a near linear approach. Surface roughness as fine as 0.06 μm (Ry) and roundness as fine as 0.12 μm (LZS) were achievable by using a diamond paste with 1 μm particles. Vibrational motion applied to the workpiece improved the surface roughness. The improvement of the surface roughness was achieved because the vibrational motion effectively removes unevenness in the rotational direction and the direction orthogonal to it. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.recommended for publication in revised form by Associate Editor Dae-Eun Kim Ik-Tae Im received the B.S., M.S. and Ph.D. degrees in Mechanical Engineering from Hanyang University, Seoul, Korea, in 1993, 1995 and 1999, respectively. He has been a visiting scientist at the Department of Materials Engineering, the University of Tokyo, Japan, where he studied on the film growth during the MOCVD process. His research interests include the numerical modeling on the transport phenomena in various materials processing. He is a professor at the Division of Mechanical Design Engineering at Chonbuk National University in Jeonju, Korea. Sang Don Mun received the B.S. degree and M.S. in Precision Mechanical Engineering from Chonbuk National University, Korea, in 1991 and 1993, respectively. He then received the Ph.D. in Precision Mechanical Engineering at the same university in 1997. Dr. Mun is currently a Professor at the Division of Mechanical Design Engineering at Chonbuk National University in Jeonju, Korea. His research interests include magnetic abrasive finishing, tool wear, and micro machining. Seong Mo Oh received his B.S. degree in Mechanical Engineering from Wonkwang University, Korea, in 1992. He then received his M.S. and Ph.D. degrees from Wonkwang in 1994 and 2000 respectively. Dr. Oh is currently a Lecturer at the Division of Mechanical and Automotive Engineering at Wonkwang University in Jeonbuk, Korea. Dr. Oh’s research interests include tribology, functional surfaces, and micromachining.     

Approximate velocity scale for primary and secondary dual-inlet side-dump flows

Effects of the bulk inlet velocity on the characteristics of dual-inlet side-dump flows are numerically investigated. Non-reacting subsonic turbulent flow is solved by a preconditioned Reynolds-averaged Navier-Stokes equation system with low-Reynolds number k − ɛ turbulence model. The numerical method is properly validated with measured velocity distributions in the head dome and the combustor. With substantial increase in the bulk inlet velocity, general profiles of essential primary and secondary flows normalized by the bulk inlet velocity are quantitatively invariant to the changes in the bulk inlet velocity. This paper was recommended for publication in revised form by Associate Editor Do Hyung Lee Seung-chai Jung received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2001. He then received his M.S. degree in Mechanical Engineering from Yonsei University, Korea, in 2005. Mr. Jung is currently a Ph. D. candidate at Yonsei University, where he is majoring in Mechanical Engineering. Mr. Jung’s research interests include propulsion system and particle-surface collision dynamics. Byung-Hoon Park received his B.S. degree in Mechanical Design and Production Engineering from Yonsei University in 2003. He is currently a Ph.D. candidate in Yonsei University in Seoul, Korea. His research interests include performance design of propulsion systems and nu-merical analysis of instability in multiphase turbulent reacting flow-fields. Hyun Ko received his B.S. degree in Aerospace Engineering from Chonbuk National University, Korea, in 1996. He then received his M.S. degree in Mechanical Design from Chonbuk National University, Korea, in 1998. In 2005, he obtained his Ph.D. degree from Yonsei University, where he majored in mechanical engineering. Dr. Ko is currently a Principal Research Engineer of the MicroFriend Co., Ltd. in Seoul, Korea. His research interests include propulsion related systems and computational fluid dynamics. Woong-sup Yoon received his B.S. degree in Mechanical Engineering from Yonsei University, Korea, in 1985. He then received his M.S. degree from University of Missouri-Rolla in 1989. In 1992, he obtained his Ph.D. degree from the University of Alabama in Huntsville, where he majored in mechanical and aerospace engineering. Dr. Yoon is currently a professor at the School of Mechanical Engineering at Yonsei University in Seoul, Korea. His research interests include propulsion system and particle-related environmental/ thermal engineering.     

Topology optimization with displacement-based nonconforming finite elements for incompressible materials

This investigation is concerned with the topology optimization using displacement-based nonconforming finite elements for problems involving incompressible materials. Although the topology optimization with mixed displacement-pressure elements was performed, a displacement-based approach can be an efficient alternative because it interpolates displacement only. After demonstrating the Poisson locking-free characteristics of the employed nonconforming finite elements by a simple patch test, the developed method is applied to solve the design problems of mounts involving incompressible solid or fluid. The numerical performance of the nonconforming elements in topology optimization was examined also with existing incompressible problems. This paper was recommended for publication in revised form by Associate Editor Tae Hee Lee Gang-Won Jang received his M.S. degree in 2000, and Ph.D. degree in 2004, both from the School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Korea. He is currently an Assistant Professor at the School of Mechanical and Automotive Engineering, Kunsan National University, Jeonbuk, Korea. His current interest concerns topology optimization of multiphysics problems and thin-walled beam analysis. Yoon Young Kim received his B.S. and M.S degrees from Seoul National University, Seoul, Korea, and the Ph.D. degree from Stanford University, Palo Alto, CA, in 1989. He has been on the faculty of the School of Mechanical and Aerospace Engineering, Seoul National University, since 1991. He is also the Director of the National Creative Research Initiatives Center for Multiscale Design. His main research field is the optimal design of multiphysics systems, mechanisms, and transducers. He has served as an editor of several Korean and international journals, and as an organizing committee member of several international conferences.     

A study on cooling efficiency using 1-d analysis code suitable for cooling system of thermoforming

Thermoforming is one of the most versatile and economical processes available for polymer products, but cycle time and production cost must be continuously reduced in order to improve the competitive power of products. In this study, water spray cooling was simulated to apply to a cooling system instead of compressed air cooling in order to shorten the cycle time and reduce the cost of compressed air used in the cooling process. At first, cooling time using compressed air was predicted in order to check the state of mass production. In the following step, the ratio of removed energy by air cooling or water spray cooling among the total removed energy was found by using 1-D analysis code of the cooling system under the condition of checking the possibility of conversion from 2-D to 1-D problem. The analysis results using water spray cooling show that cycle time can be reduced because of high cooling efficiency of water spray, and cost of production caused by using compressed air can be reduced by decreasing the amount of the used compressed air. The 1-D analysis code can be widely used in the design of a thermoforming cooling system, and parameters of the thermoforming process can be modified based on the recommended data suitable for a cooling system of thermoforming. This paper was recommended for publication in revised form by Associate Editor Dongsik Kim Zhen-Zhe Li received his B.S. degree in Mechanical Engineering from Yanbian University, China, in 2002. He then received his M.S. degree in Aerospace Engineering from Konkuk University, South Korea, in 2005. He then received his Ph.D. degree in Mechanical Engineering from Chonnam National University, South Korea, in 2009. Dr. Li is currently a Researcher of the Department of Mechanical Engineering, Chonnam National University, South Korea. Dr. Li’s research interests include applied heat transfer, fluid mechanics and optimal design of thermal and fluid systems. Kwang-Su Heo received his B.S. degree in Mechanical Engineering from Chonnam National University, South Korea, in 1998. He then received his M.S. and Ph.D. degrees in Mechanical Engineering from Chonnam National University, South Korea, in 2003 and 2008, respectively. Dr. Heo is currently a Post-doctorial Researcher of the Department of Mechanical Engineering, KAIST(Korean Advanced Institute of Science and Technology), South Korea. Dr. Heo’s research interests include applied heat transfer, fluid mechanics and thermal analysis of superconductor. Dong-Ji Xuan received his B.S. degree in Mechanical Engineering from Harbin Engineering University, China, in 2000. He then received his M.S. degree in Mechanical Engineering from Chonnam National University, South Korea, in 2006. He is currently a Ph.D. candidate of the Department of Mechanical Engineering, Chonnam National University, South Korea. His research interests include control & optimization of PEM fuel cell system, dynamics & control, mechatronics. Seoung-Yun Seol received his B.S. degree in Mechanical Design from Seoul National University, South Korea, in 1983. He then received his M.S. degree in Mechanical Engineering from KAIST(Korean Advanced Institute of Science and Technology), South Korea, in 1985. He then received his Ph.D. degree in Mechanical Engineering from Texas Tech University, USA, in 1993. Dr. Seol is currently a Professor of the School of Mechanical and Systems Engineering, Chonnam National University, South Korea. Dr. Seol’s research interests include applied heat transfer, fluid mechanics and thermal analysis of superconductor.     

A second-order time-accurate finite element method for analysis of conjugate heat transfer between solid and unsteady viscous flow

A fractional four-step finite element method for analyzing conjugate heat transfer between solid and unsteady viscous flow is presented. The second-order semi-implicit Crank-Nicolson scheme is used for time integration and the resulting nonlinear equations are linearized without losing the overall time accuracy. The streamline upwind Petrov-Galerkin method (SUPG) is applied for the weighted formulation of the Navier-Stokes equations. The method uses a three-node triangular element with equal-order interpolation functions for all the variables of the velocity components, the pressure and the temperature. The main advantage of the method presented is to consistently couple heat transfer along the fluid-solid interface. Five test cases, which are the lid-driven cavity flow, natural convection in a square cavity, transient flow over a heated circular cylinder, forced convection cooling across rectangular blocks, and conjugate natural convection in a square cavity with a conducting wall, are selected to evaluate the efficiency of the method presented. This paper was recommended for publication in revised form by Associate Editor Kyung-Soo Yang Atipong Malatip received his B.S. degree in Mechanical Engineering from King Mongkut’s University of Technology North Bangkok, Thailand, in 2002. He then received his M.S. degree in Mechanical Engineering Chulalongkorn University, Thailand, in 2005. He is currently pursuing a Ph.D. degree in Mechanical Engineering at Chulalongkorn University. His research interests include computational fluid dynamics and fluid-thermal-structural interaction. Niphon Wansophark received his B.S., M.S., and Ph.D. degrees in Mechanical Engineering from Chulalongkorn University, Thailand in 1996, 2000, and 2007, respectively. He is an Assistant Professor of Mechanical Engineering at Chulalongkorn University, Bangkok, Thailand. His research interests are numerical methods and finite element method. Pramote Dechaumphai received his B.S. degree in Industrial Engineering from Khon-Kaen University, Thailand, in 1974, M.S. degree in Mechanical Engineering from Youngstown State University, USA in 1977, and Ph.D. in Mechanical Engineering from Old Dominion University, USA in 1982. He is currently a Professor of Mechanical Engineering at Chula-longkorn University, Bangkok, Thailand. His research interests are numerical methods, finite element method for thermal stress and computational fluid dynamics analysis.     

Development of rapid mixing fuel nozzle for premixed combustion

Combustion in high-preheat and low oxygen concentration atmosphere is one of the attractive measures to reduce nitric oxide emission as well as greenhouse gases from combustion devices, and it is expected to be a key technology for the industrial applications in heating devices and furnaces. Before proceeding to the practical applications, we need to elucidate combustion characteristics of non-premixed and premixed flames in high-preheat and low oxygen concentration conditions from scientific point of view. For the purpose, we have developed a special mixing nozzle to create a homogeneous mixture of fuel and air by rapid mixing, and applied this rapidmixing nozzle to a Bunsen-type burner to observe combustion characteristics of the rapid-mixture. As a result, the combustion of rapid-mixture exhibited the same flame structure and combustion characteristics as the perfectly prepared premixed flame, even though the mixing time of the rapid-mixing nozzle was extremely short as a few milliseconds. Therefore, the rapid-mixing nozzle in this paper can be used to create preheated premixed flames as far as the mixing time is shorter than the ignition delay time of the fuel. This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon Masashi Katsuki received his B.E. degree in Mechanical Engineering from Osaka University, Japan, in 1965. He received his Dr. Eng. from O. U. in 1985. Dr. Katsuki is currently a Visiting Professor at the Department of Environmental Engineering at Hoseo University in Chungnam, Korea. He was a Vice President of the Japan Society of Mechanical Engineers. Dr. Katsuki’s research interests include combustion, computational thermo-fluid dynamics, and molecular dynamics. Jin-Do Chung received his B. S., M.S. and Ph.D. degrees in Mechanical Engineering from Chungnam University, Korea in 1983, 1985 and 1990. He then received another Ph.D. in Environmental Engineering from Kanazawa University, Japan in 1996. After that he worked as Post-doc researcher for 1,6 year at KIMM and Senior researcher for 6years at KEPCO Research Center. Dr. Chung is currently a Professor at the Department of Environmental Engineering at Hoseo University in Asan, Korea. Dr. Chung’s research interests include thermal-fluid and environmental engineering. Jang-Woo Kim received his B. S. degree in Mechanical Engineering from Chungnam University, Korea, in 1990. He then received his M. S. and Ph. D. degrees from Kyushu University, Japan in 1994 and 1998, respectively. Dr. Kim is currently a Professor at the School of Display Engineering at Hoseo University in Asan, Korea. Dr. Kim’s research interests include CFD, aerodynamics, and display equipment technology. Seung-Min Hwang received the Ph.D. degree in Mechanical Engineering at Osaka University in 2005. After that he worked as visiting researcher for 3 years at CRIEPI (central research institute of electric power industry) and Osaka University in Japan. He is currently a Professor at the Graduate School of Venture at Hoseo University in Korea. His major research is thermal-fluid, energy issue and environment. Seung-Mo Kim received his Ph. D. degrees in Mechanical engineering from Osaka University, Japan, in 2004. Dr. Kim is currently a research Professor at Pusan Clean Coal Center at Pusan National University in Pusan, South Korea. Dr. Kim’s research interests include coal combustion, oxy-fuel combustion, coal gasification, coal de-watering, power generation plant system and energy issues. Chul-Ju Ahn received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 1998. He then received his M.S. and Ph.D. degrees from Osaka University, Japan, in 2001 and 2006, respectively. Dr. Ahn is currently a Senior Research Engineer at Samsung Techwin CO. LTD. in Changwon, Korea. Dr. Ahn’s research interests include gas turbine engine, biomass gasification, and power system.     

Effect of imperfections on the mechanical behavior of wire-woven bulk kagome truss PCMs under shear loading

Wire-woven bulk kagome (WBK) materials are a new class of cellular metallic structures possessing desired mechanical performance and can be fabricated easily by assembling metallic wires. In previous studies, the WBK materials were shown to have high strength and weak sensitivity on imperfections under compressive loads. In this paper, we present numerical simulation results on the mechanical performance of WBK and its sensitivity on imperfections under shear loads. Two types of statistical imperfections on geometry and material property were introduced in the simulation models as likewise the previous studies. The simulation results were compared with the experimental measurement on the WBK made of stainless wire (SUS304). The WBK were shown to have a good isotropic mechanical strength under various orientations of shear loadings. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Sangil Hyun received his B.S. and M.S. degrees in physics from Seoul National University, Korea, in 1986 and 1989. He received his Ph.D. degree in solid state theory from Michigan State Uni-versity in 1998. Dr. Hyun is currently a senior researcher at the simulation center in Korea Inst. of Ceramic Eng. & Tech. (KICET). He is mainly working on computational studies on multifunctional cha-racteristics of fine ceramics, metals, and composites. He also develops a multiscale modeling on nanotribology and nanofluidics. Ji-Eun Choi received her B.S. and M.S degrees in Mechanical Engineering from Chosun University, Korea, in 1999 and 2001. Ms. Choi is currently an associate research engineer at the automobile research center in Chonnam National University. She is mainly working on the theoretical and numerical analyses on truss PCMs (Periodic Cellular Metals). Ki-Ju Kang received his B.S. degree in Mechanical Engineering from Chonnam National University, Korea, in 1981. He then received his M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology in 1983 and 1988, respectively. Dr. Kang is currently a Professor at the School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea. Prof. Kang’s lab is designated as a national research Lab. His research interests include the optimal designs and manufacturing technologies of various types of porous cellular metals and mechanical behaviors of a thermally grown oxide at high temperature.     

Research on transmission paths of a coupled beam-cylindrical shell system by power flow analysis

A power flow analysis based on a substructure approach is performed to exhibit vibration transmission in a complex coupled beam-cylindrical shell system. The system is divided into a shell substructure and a beam substructure, which are coupled by three spring-dampers. The theoretical receptance function of each substructure with a free-free interface condition is formulated by modal analysis to describe the dynamical behavior. On the basis of the receptance functions of the two substructures as well as synthesis through the geometrical compatibility and force balance conditions at the coupling interfaces, the dynamic characteristics of the coupled system are calculated. Both the input and transmitted powers within the system are estimated, and the influences of the excitation locations, the stiffness and loss factor of the spring-dampers on the vibration transmission are investigated as well. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin G.P. Feng received his Ph.D. from the School of Mechanical Engineering at Shanghai Jiao Tong University. His research interests include vibration analysis, control and sound radiation, etc. Z.Y. Zhang received his Ph.D. from the School of Mechanical Engineering at Shanghai Jiao Tong University. Dr. Zhang is currently a Professor at the School of Mechanical Engineering at Shanghai Jiao Tong University in Shanghai, China. Y. Chen received his Ph.D. from the School of Mechanical Engineering at Shanghai Jiao Tong University. His research interests include vibration and shock analysis. H.X. Hua received his Ph.D. at the University of Brussels in Belgium. Dr. Hua is currently a Professor and Doctoral Supervisor at the School of Mechanical Engineering at Shanghai Jiao Tong University in Shanghai, China. His research interests include modal parameter identification, and analysis of vibration and shock.     

Analysis of the vibration behavior of FGM cylindrical shells including internal pressure and ring support effects based on Love-Kirchhoff theory with various boundary conditions

This paper presents the study on vibration behavior of functionally graded material (FGM) cylindrical shell with the effects of internal pressure and ring support. The FGM properties are graded along the thickness direction of the shell. The FGM shell equations with internal pressure and ring support are established based on strain-displacement relationship using Love-Kirchhoff shell theory. The governing equations of motion were solved by using energy functional and by applying Ritz method. The boundary conditions represented by end conditions of the FGM cylindrical shell are simply supported-simply supported (SS-SS), clamped-clamped (C-C), free-free (F-F), clamped-free (C-F), clamped-simply supported (C-SS), free-simply supported (F-SS), free-sliding (F-SL) and clamped-sliding (C-SL). To check the validity and accuracy of the present method, the results obtained are compared with those available in the literature. The influence of internal pressure, ring support position and the effect of the different boundary conditions on natural frequencies characteristics are studied. These results presented can be used as important benchmark for researchers to validate their numerical methods when studying natural frequencies of shells with internal pressure and ring support.     

The kinematic design of a planar-cam type pick-and-place device

The planar-cam type pick-and-place device can clearly and effectively achieve the desired curvilinear motion of its end effector, and it can be designed and fabricated easily. By employing the concept of velocity instant center, the cam profiles, the paths of cutters, the pressure angles and the radii of curvature of the dual cams of the planar-cam type pick-and-place device can be expressed parametrically. The cam profiles may have concave portions, and each minimum radius of curvature of the concave portion of the dual cam profiles is the upper bound of the grinding-wheel radius that may not cause undercutting. This paper was recommended for publication in revised form by Associate Editor Jeonghoon Yoo Wen-Tung Chang received his Bachelor and Master degrees in Mechanical and Marine Engineering from Nation Taiwan Ocean University in 2000 and 2002, respectively. He then went on to receive his Ph.D. degree in Power Mechanical Engineering from National Tsing Hua University in 2007. Dr. Chang is currently a Postdoctoral Researcher of Opto-Mechatronics Technology Center at National Taiwan University of Science and Technology in Taipei, Taiwan. His research interests include kinematics and dynamics of machinery, mechanism and machine design, and opto-mechatronic system. Long-Iong Wu received his Ph.D. degree in Mechanical Engineering from National Cheng Kung University in 1987. Dr. Wu is currently a Professor of Department of Power Mechanical Engineering at National Tsing Hua University in Hsinchu, Taiwan. His research interests include kinematics of machinery, mechanism design, and precision machine design. His main research activities in his laboratory are linkage mechanism design and cam mechanism design. In the past, Dr. Wu has worked for China Steel Corp., and San Shing Fastech Corp. where he was responsible for designing high speed nut formers. Chun-Hsien Liu received his Master degree in Mechanical Engineering from Nation Chiao Tung University in 1996. He is currently a Lecturer and also a Ph.D. Candidate of Department of Power Mechanical Engineering at National Tsing Hua University in Hsinchu, Taiwan. Mr. Liu has worked for over twenty years at Industrial Technology Research Institute (ITRI), where he was responsible for designing packaging equipments in semiconductor and flat panel display industry. He is currently the Deputy Director of Intelligent Systems Engineering Division of Mechanical and Systems Research Laboratories at ITRI.     

Tolerance effects on natural frequencies of multibody systems undergoing constant rotational motion

A general multi-body formulation to analyze the tolerance effects on the statistical property variations of natural frequencies of multi-body systems undergoing constant rotational motion is proposed in this paper. To obtain the tolerance effects, Monte-Carlo simulation method is conventionally employed. However, the Monte-Carlo simulation has serious drawbacks; spending too much computation time for the simulation and achieving very slow convergence around some dynamically unstable regions. To resolve such problems, a method employing analytical sensitivity information is suggested in this paper. To obtain the sensitivities of natural frequencies the eigenvalue problem should be differentiated with respect to a design variable. The sensitivities of mass and stiffness matrices should be calculated at the dynamic equilibrium. By employing the sensitivities of natural frequencies along with the tolerance of the design variable, the statistical property variations of the natural frequencies can be calculated. This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim Seung Man Eom graduated from the Department of Mechanical Engineering at Incheon University in 2005 and received his master degree from the Department of Mechanical Engineering at Hanyang University in 2007. He is currently working as a Researcher of Aircraft Development Team in KIAT(Korea Institute of Aerospace Technology, Koreanair), DaejeonDeajeon, Korea. Bum Suk Kim graduated from the School of Mechanical Engineering at Hanyang University in 2006 and received his master degree from the same department in 2008. He is currently working as a Ph.D. student in the School of Mechanical Engineering in Hanyang University, Seoul, Korea. Hong Hee Yoo graduated from the Department of Mechanical Design and Production Engineering at Seoul National University in 1980 and received his master degree from the same department in 1982. He received his Ph.D. degree in 1989 from the Department of Mechanical Engineering and Applied Mechanics in the University of Michigan at Ann Arbor, U.S.A. He is currently working as a professor in the School of Mechanical Engineering in Hanyang University, Seoul, Korea.     

Reliability design of preventive maintenance scheduling for cumulative fatigue damage

As the cumulative running times of a locomotive truck increases, degradation such as fatigue, wear, and deterioration occur. Particularly the container train and uncovered freight train, their maintenance cost during their lifetime is three times more than the manufacturing cost. Generally, for the freight train, corrective maintenance to repair a bad part after a breakdown is not adapted; however, preventive maintenance that fixes a bad part before a breakdown is. Therefore, it is important and necessary to establish a system of optimal preventive maintenance and exact maintenance period. This study attempts to propose a preventive maintenance procedure that predicts a repair period using reliability function and instantaneous failure rate based on fatigue test and load history data. Additionally, this method is applied to the end beam of an uncovered freight train, which is the brake part, and its usefulness is examined and analyzed. This paper was recommended for publication in revised form by Associate Editor Chongdu Cho Seok-Heum Baek received a B.S. and M.S. degree in Mechanical Engineering from the Dong-A University in 2001 and 2003, respectively. He is currently a Ph.D. student at the School of Mechanical Engineering at Dong-A University in Busan, Korea. Student Baek works on ceramic composite design and robust and reliability-based design, and his research interests are in the areas of trade-off analysis in multicriteria optimization, design under uncertainty with incomplete information, and probabilistic design optimization. Seok-Swoo Cho received a B.S. degree in Mechanical Engineering from Dong-A University in 1991. He then went on to receive his M.S. from Dong-A University in 1993 and Ph.D. degree from Dong-A University in 1997. Dr. Cho is currently a Professor at the Vehicle Engineering at Kangwon National University in Kangwon-do, Korea. Dr. Cho works on crack growth modeling and composite design and optimization, and his research interests are in the areas of structural optimization and inverse and identification problems, and X-ray diffraction, brittle collapse and crack propagation, fatigue fracture phenomena. Hyun-Su Kim received a B.S. degree in Mechanical Engineering from Seoul National University in 1978. He then went on to receive his M.S. from KAIST in 1980 and Ph.D. degree from University of Iowa in 1989. Dr. Kim is currently a Professor at the Mechanical Engineering at Dong-A University in Busan, Korea. His research interests are in the area of high temperature creep fatigue, bio-engineering, design using the finite element method, optimization, and MEMS. Won-Sik Joo received a B.S. degree in Mechanical Engineering from Dong-A University in 1968. He then went on to receive his M.S. from Dong-A University in 1978 and Ph.D. degree from Kookmin University in 1988. Dr. Joo is currently a Professor at the Mechanical Engineering at Dong-A University in Busan, Korea. His research interests are in the area of creep and fatigue in high temperature alloy, fatigue design, and strength evaluation.