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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 36, Issue 12 - Dec 2012
Volume 36, Issue 11 - Nov 2012
Volume 36, Issue 10 - Oct 2012
Volume 36, Issue 9 - Sep 2012
Volume 36, Issue 8 - Aug 2012
Volume 36, Issue 7 - Jul 2012
Volume 36, Issue 6 - Jun 2012
Volume 36, Issue 5 - May 2012
Volume 36, Issue 4 - Apr 2012
Volume 36, Issue 3 - Mar 2012
Volume 36, Issue 2 - Feb 2012
Volume 36, Issue 1 - Jan 2012
Selecting the target year
Evaluation of Cutting Characteristics in Bulk Metallic Glasses
Shin, Hyung-Seop ; Choi, Ho-Yeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 591~598
DOI : 10.3795/KSME-A.2012.36.6.591
In this study, the cutting characteristics of bulk metallic glass (BMG) cut using a computer numerically controlled (CNC) lathe were investigated for different insert tool materials and cutting speeds. The surface roughness, chip morphology, cutting forces, and tool wear during turning of
BMG alloy were examined. Four kinds of tool materials were used to cut an 8-mm-diameter BMG. The examination of the surface roughnesses of the BMG specimens machined at each cutting speed showed that the surface roughness became better as the cutting speed increased, and the tool materials also influenced the surface roughness. The chip morphology investigations showed that the unoxidized BMG chips had serrated curled chips with adiabatic shear bands, while the oxidized chips exhibited local melting and tangling rather than the usual spiral-shaped chips. The cutting force induced during machining of the Zr-based BMG was the largest for the TiN-WC tool, followed by the polycrystalline diamond (PCD) tool. The cermet tool exerted the smallest cutting force.
A Numerical Analysis on Application of Laser Peening to Dissimilar Metal Welds in a Safety Injection Nozzle of Integral Reactor
Seo, Joong-Hyun ; Kim, Jong-Sung ; Jhung, Myung-Jo ; Ryu, Yong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 599~608
DOI : 10.3795/KSME-A.2012.36.6.599
A numerical analysis has been performed through implicit dynamic finite element analysis using the commercial package, ABAQUS in order to investigate effect of laser peening on welding residual stress mitigation of dissimilar metal welds in a safety injection nozzle of integral reactor. The implicit dynamic finite element analysis are compared with the previous experimental results. By comparison, it is identified that the implicit dynamic finite element analysis is valid for residual stress mitigation via laser peening. Implicit static finite element residual stress analysis has been performed for the dissimilar metal welds subject to inner repair welding. The analysis results represent that both axial and hoop residual stresses are tensile on inner surface of safety injection nozzle due to inner repair welding. Also Parametric study has performed to investigate effect of laser peening variables such as maximum impact pressure, duration time of pressure, spot diameter and peening direction on the welding residual stress mitigation. As a result, it is found that laser peening has the preventive maintenance effect to mitigate mainly residual stresses of region near inner surface.
Effects of Laser Source Geometry on Laser Shock Peening Residual Stress
Kim, Ju-Hee ; Kim, Yun-Jae ; Kim, Joung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 609~615
DOI : 10.3795/KSME-A.2012.36.6.609
In LSP (laser shock peening) treatment, the laser source geometries when the laser beam strikes the metal target area are diverse. The laser spot geometry affects the residual stress field beneath the treated surface of the metallic materials, which determines the characteristics of the pressure pulse. In this paper, detailed finite-element (FE) simulations on laser shock peening have been conducted in order to predict the magnitude and of the residual stresses and the depth affected in Inconel alloy 600 steel. The residual stress results are compared for circular, rectangular, and elliptical laser spot geometries. It is found that a circular spot can produce the maximum compressive residual stresses near the surface but generates tensile residual stresses at the center of the laser spot. In the depth direction, an elliptical laser spot produces the maximum compressive residual stresses. Circular and elliptical spots plastically affect the alloy to higher depths than a rectangular spot.
Compressive Deformation Behaviors of Aluminum Alloy in a SHPB Test
Kim, Jong-Tak ; Woo, Sung-Choong ; Kim, Jin-Young ; Kim, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 617~622
DOI : 10.3795/KSME-A.2012.36.6.617
Structures are often subjected to various types of loading such as static, dynamic, or impact loading. Therefore, experimental and numerical methods have been employed to find adequate material properties according to the conditions. The Split-Hopkinson pressure bar (SHPB) test has frequently been used to test engineering materials, particularly those used under high strain rates. In this study, the compressive deformation behaviors of aluminum alloy under impact conditions have been investigated by means of the SHPB test. The experimental results were then compared with those of finite element analyses. It was shown that reasonably good agreement with the true stress-strain curves was obtained at strain rates ranging from 1000
. When the strain rate increased by 30%, the peak stress in particular increased by 17%, and the strain also increased by 20%.
Path Planning Using an Information Grid Map for Safe Navigation
Jung, Min-Kuk ; Park, Joong-Tae ; Song, Jae-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 623~628
DOI : 10.3795/KSME-A.2012.36.6.623
Conventional path planning methods have focused on the generation of an optimal shortest path to the goal. However, this optimal path cannot guarantee safe navigation, because it can often lead to a narrow area. Therefore, we propose a Coulomb's law-based safe path planning method that uses an information grid map. The information grid map includes four types of information: occupied, empty, guide, and dangerous areas. A safe path can be generated away from the dangerous area and close to the guide area by repulsive and attractive forces, respectively. Experiments and simulations show that the proposed method can generate paths inside the safe region and is useful for safe navigation.
Localization of a Tracked Robot Based on Fuzzy Fusion of Wheel Odometry and Visual Odometry in Indoor and Outdoor Environments
Ham, Hyeong-Ha ; Hong, Sung-Ho ; Song, Jae-Bok ; Baek, Joo-Hyun ; Ryu, Jae-Kwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 629~635
DOI : 10.3795/KSME-A.2012.36.6.629
Tracked robots usually have poor localization performance because of slippage of their tracks. This study proposes a new localization method for tracked robots that uses fuzzy fusion of stereo-camera-based visual odometry and encoder-based wheel odometry. Visual odometry can be inaccurate when an insufficient number of visual features are available, while the encoder is prone to accumulating errors when large slips occur. To combine these two methods, the weight of each method was controlled by a fuzzy decision depending on the surrounding environment. The experimental results show that the proposed scheme improved the localization performance of a tracked robot.
Experimental Study on Fretting Wear of Inconel 690 Under High Temperatures and Pressures
Lee, Coon-Yeol ; Lee, Ju-Suck ; Bae, Joon-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 637~644
DOI : 10.3795/KSME-A.2012.36.6.637
In a nuclear power plant, fretting wear due to impact motion between U-tubes and support structures located in steam generators can cause serious problems. In order to guarantee the reliability of the steam generator, the damage due to fretting wear should be thoroughly investigated. The purpose of this study is to elucidate the fretting wear mechanism qualitatively and quantitatively. Hence, fretting wear simulation is performed for the environments to which the actual steam generators in nuclear power plants are exposed. Initial experimental results are obtained for various experimental parameters, and the effect of the work rate and temperature on fretting wear is evaluated. In water, the wear coefficients for
are found to be
, respectively. It is also found that the wear coefficient at room temperature is larger than that at low temperature in water because of the dynamic viscosity of water.
Digital Image Stabilization of Robot Buoy Using the Image of Mechanism
Im, Eun ; Myeong, Ho-Jun ; Kim, Young-Jin ; Yim, Choong-Hyuk ; Kim, Dong-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 645~651
DOI : 10.3795/KSME-A.2012.36.6.645
In this paper, we propose a new method for stabilizing the image captured from a camera mounted on a buoy robot. In this study, in order to solve the problem of cumulative errors and noise produced by a general gyro sensor measuring the orientation angle of the buoy robot, we propose new method for stabilizing the image. In this method, image processing techniques are combined with a newly designed target mounting mechanism that adapts to wave fluctuations. New target extraction and angle estimation techniques are introduced, along with the new mounting mechanism used for the camera and the target, which produce a stabilized image even if the buoy robot is on fluctuating waves.
Optimization of the Flapping Motion for the High Maneuverability Flight
Choi, Jung-Sun ; Kim, Jae-Woong ; Lee, Do-Hyung ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 653~663
DOI : 10.3795/KSME-A.2012.36.6.653
The study considers the high maneuverability flight and path optimization is conducted to investigate the appropriate generation of the lift and thrust considering the angle of the stroke plane. The path optimization problem is defined according to the various purposes of the high maneuverability flight. The flying purposes are to maximize thrust force, lift force and both lift and thrust forces. The flapping motion of the airfoil is made by a combined sinusoidal plunging and pitching motion in each problem. The optimization process is carried out by using well-defined surrogate models. The surrogate model is determined by the results of two-dimensional computational fluid dynamics analysis. The Kriging method is used to make the surrogate model and a genetic algorithm is utilized to optimize the surrogate model. The optimization results show the flapping motions for the high maneuverable flight. The effects on the generation of lift and thrust forces are confirmed by analyzing the vortex.
Antiplane Problem of Interfacial Cracks Bonded with Transversely Isotropic Piezoelectric Media
Choi, Sung-Ryul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 665~672
DOI : 10.3795/KSME-A.2012.36.6.665
Interfacial cracks bonded with dissimilar transversely isotropic piezoelectric media that are subjected to combined anti-plane mechanical and in-plane electrical loading are analyzed. The problem is formulated using complex function theory, from which the Hilbert problem is derived. By solving the Hilbert problem, the general form solution is obtained. Using this solution, closed-form solutions for one or two finite cracks as well as a semi-infinite crack are obtained, for the problem in which one concentrated mechanical and electrical load is imposed on the crack surface. This solution could be used as a Green's function to generate solutions to other problems with the same geometry but different loading conditions.
Real-Time Vehicle Mass Estimator for Active Rollover Prevention Systems
Han, Kwang-Jin ; Kim, In-Keun ; Kim, Seung-Ki ; Huh, Kun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 673~679
DOI : 10.3795/KSME-A.2012.36.6.673
Vehicle rollover is a serious kind of accident, particularly for sport utility vehicles, and its occurrence can be minimized by utilizing active rollover prevention systems. The performance of these protection systems is very sensitive to vehicle inertial parameters such as the vehicle's mass and center of mass. These parameters vary with the number of passengers and in different load situations. In this paper, a unified method for vehicle mass estimation is proposed that takes into account the available driving conditions. Three estimation algorithms are developed based on longitudinal, lateral, and vertical vehicle motion, respectively. Then, the three algorithms are combined to extract information on the vehicle's mass during arbitrary vehicle maneuvering. The performance of the proposed vehicle mass estimation method is demonstrated through real-time experiments.
Dynamic Response Simulation of a Heavy Cargo Suspended by Parallel Connected Floating Cranes
Cha, Ju-Hwan ; Ku, Nam-Kug ; Roh, Myung-Il ; Lee, Kyu-Yeul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 681~689
DOI : 10.3795/KSME-A.2012.36.6.681
In this study, we performed a simulation of the dynamic response of a multibody system to calculate the tension acting on wire ropes connecting floating cranes and a heavy cargo such as a Giga Block weighing over 5000 tons when the cargo is salvaged using parallel connected floating cranes. In this simulation, we supposed that the motion of the floating cranes, barge ship, and heavy cargo has 6 degrees of freedom and that the interaction is determined by constraints among them. In addition, we considered independent hydrostatic and hydrodynamic forces as external forces acting on the floating cranes and barge ship. The simulation result can be a basis for verifying the safety of construction methods in which heavy cargo is salvaged by parallel connected floating cranes, and it can also be used to guide the development of such construction methods.
Joining High-Strength Steel and Al6061 Sheet Using Hole Clinching Process
Ahn, Nam-Sik ; Lee, Chan-Joo ; Lee, Jung-Min ; Ko, Dae-Cheol ; Lee, Seon-Bong ; Kim, Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 691~698
DOI : 10.3795/KSME-A.2012.36.6.691
The joining of aluminum and HSS (high-strength steel) by the conventional clinching process is limited by the low formability of HSS. Defects in the clinching joint, such as necking of the upper sheet, cracks, and lack of interlocking, are produced by the different ductility properties of HSS and aluminum. In this study, we propose the hole clinching process for joining Al6061 and SPFC440, in which deformation of SPFC440 is avoided by drilling a hole in the SPFC440. The dimensions of the interlocking in the hole-clinched joint necessary to provide the required joint strength were determined. Based on the volume constant of the hole clinching process, the shapes of the tools were designed by finite element (FE)-analysis. A hole clinching experiment was performed to verify the proposed process. A cross-section of the joint showed good agreement with the results of the FE-analysis. The lap shear strength was found to be 2.56 kN, which is higher than required joint strength.
Stress Analysis and Shape Optimization of Dynamic Locking Tongue (DLT) Using FEM
Choi, Ji-Hun ; Park, Tae-Won ; Lee, Jin-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 699~705
DOI : 10.3795/KSME-A.2012.36.6.699
The role of a seat belt in a vehicle is to protect the driver from injury when a crash occurs. However when a large crash occurs, the driver slips forward and receives a strong impact. To prevent this situation, improvement of seat belts is essential. In this study, the new concept of a dynamic locking tongue (DLT) for seat belts is developed. The DLT device is used to reduce the impact to the driver's chest by tightening the webbing, so the driver is protected from severe injury in a large crash. First, a finite element model of the DLT device is created using SAMCEF and structural analysis is conducted with boundary conditions similar to those found in experiments. Then, the stress in the DLT device can be calculated. Second, the shape of the DLT device is optimized using the response surface analysis method in order to minimize the stress and weight. The validity of the optimization of the DLT device is verified using structural analysis.
Accelerated Ultrasonic Fatigue Testing Applications and Research Trends
Cho, In-Sik ; Shin, Choong-Shig ; Kim, Jong-Yup ; Jeon, Yong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 6, 2012, Pages 707~712
DOI : 10.3795/KSME-A.2012.36.6.707
Very high cycle fatigue (VHCF) behavior of aerospace components has emerged much attention due to their long service life. In this study, a piezoelectric ultrasonic fatigue testing (UFT) system has been developed by Mbrosiatec Co., Ltd. to study the high cycle fatigue (HCF) strength of Ti-6Al-4V alloy. Hourglass-shaped specimens have been investigated in the range from
cycles at room temperature under completely reversed R = -1 loading conditions,. Scanning electron microscopy (SEM) analysis revealed that failures occurred in the entire range up to the gigacycle regime, and the fractures have beenfound to be initiated from the surface, unlike in steels. However, it was found from the SEM microgprahs that microcracks transformed into intergranular fractures. Thus, it can be concluded from according to the results that this test method can be applicable to commercialized automotive and railroad parts that require high cycle fatigue strength.