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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 30, Issue 12 - Dec 2006
Volume 30, Issue 11 - Nov 2006
Volume 30, Issue 10 - Oct 2006
Volume 30, Issue 9 - Sep 2006
Volume 30, Issue 8 - Aug 2006
Volume 30, Issue 7 - Jul 2006
Volume 30, Issue 6 - Jun 2006
Volume 30, Issue 5 - May 2006
Volume 30, Issue 4 - Apr 2006
Volume 30, Issue 3 - Mar 2006
Volume 30, Issue 2 - Feb 2006
Volume 30, Issue 1 - Jan 2006
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Weldability and Optimum Welding Conditions on the 4 Lap Spot Welded Joint of High Strength Steel Sheets in Automobile
Kwon Il-Hyun ; Kim Hoi-Hyun ; Baek Seung-Se ; Yang Seong-Mo ; Yu Hyo-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 481~487
DOI : 10.3795/KSME-A.2006.30.5.481
Spot-welding is a widely used manufacturing method for thin-sheet components, especially in mass-production industries such as the car industry. Automobiles are often constructed by multi-lap spot welding to secure the passenger from the accident, where optimisation of the welding conditions is a major economic consideration. This research is conducted to investigate weldability characteristics with various welding conditions on the 4-lap spot welded joint of structural steel sheets in automobile. The relationship between the tensile-shear strength and the indentation depth has been investigated to propose the optimum welding conditions. The welding current and the welding time have a greater effect on the welding characteristics than the electrode force. It was found that the electrode force has a relatively close relationship with the expulsion occurrence. The design curves for optimum welding are proposed for the 4-lap spot welded joint.
Design of Lightweight CAD Files with Dimensional Verification Capability for Web-Based Collaboration
Song In-Ho ; Chung Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 488~495
DOI : 10.3795/KSME-A.2006.30.5.488
The demand for the use of 3D CAD data over the Internet environment has been increased. However, transmission of 3D CAD data has delayed the communication effectiveness because of the CAD data size. Lightweight CAD file design methodology is required for rapid transmission in the distributed environment. In this paper, to derive lightweight CAD files from commercial CAD systems, a file translation system producing a native file is constructed first by using the InterOp and API of the ACIS kernel. Using the B-rep model and mesh data extracted from the native file, the lightweight CAD file with topological information is constructed as a binary file. Since the lightweight CAD file retains topological information, it is applied to the dimensional verification, digital mock-ups and visualization of CAD files. Effectiveness of the proposed lightweight CAD file is confirmed through various case studies.
3D Wear Analysis of Valve Assemblies by Using the Machine Vision
Park Chang-Woo ; Chung Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 496~504
DOI : 10.3795/KSME-A.2006.30.5.496
Wear of engine valves and seat inserts is a major factor affecting engine performance. In order to improve quality and life of valve assemblies, wear mechanism and 3-D surface topography should be analyzed according to operating conditions of the engine. After developing an engine simulator that generates valve speed up to 90Hz and temperature up to
as well as controls test load, wear experiments have been conducted for two different engine speeds as 10Hz and 25Hz. In order to observe the wear characteristics and monitor surface conditions of the valve assemblies, a cost-effective 3-D wear analysis system based on the shape from focus(SFF) and machine vision has been fabricated in this paper. 3-D surface topography of the valve assemblies has been analyzed to understand the wear behavior according to operating conditions of the engine. Consequently, wear volume of the valve assemblies is quantized by using the developed 3-D wear analysis system.
Limit Loads for Pipe Bends under Combined Pressure and in-Plane Bending Based on Finite Element Limit Analysis
Oh Chang-Sik ; Kim Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 505~511
DOI : 10.3795/KSME-A.2006.30.5.505
In the present paper, approximate plastic limit load solutions fur pipe bends under combined internal pressure and bending are obtained from detailed three-dimensional (3-D) FE limit analyses based on elastic-perfectly plastic materials with the small geometry change option. The present FE results show that existing limit load solutions for pipe bends are lower bounds but can be very different from the present FE results in some cases, particularly for bending. Accordingly closed-form approximations are proposed for pipe bends under combined pressure and in-plane bending based on the present FE results. The proposed limit load solutions would be a basis of defective pipe bends and be useful to estimate non-linear fracture mechanics parameters based on the reference stress approach.
Structural Layout Optimization Strategy Considering Assemblage
Choi Guk-Jin ; Kim Myung-Jin ; Kim Yoon-Young ; Jang Gang-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 512~519
DOI : 10.3795/KSME-A.2006.30.5.512
In the ground-structure-based topology optimization, beam elements are regarded to be rigidly connected to each other, and joints are assumed to have infinite stiffness. Thus the optimized topology of a structure is obtained according to the assumption of no joint effect, and the resulting structure should be manufactured in one piece if the joint effect is to be excluded as much as possible. The underlying problems are that 1) the performance of the structure might be seriously decreased if the members of the structure are connected through welding or bolting, not manufactured in one piece, and 2) the topology of the structure will be changed if the joint effect is taken into account. In the paper, the assemblage issue is considered on topology optimization, and a new formulation based on the joint stiffness-varied ground beam structure is developed. Joints of a beam structure are modeled by elastic spring elements whose stiffnesses are controlled by design variables during the optimization.
Stress Classification Using Artificial Neural Networks and Fatigue Life Assessment
Jung Sung-Wook ; Chang Yoon-Suk ; Choi Jae-Boons ; Kim Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 520~527
DOI : 10.3795/KSME-A.2006.30.5.520
The design of major industrial facilities for the prevention of fatigue failure is customarily done by defining a set of transients and performing a calculation of cumulative usage factor. However, sometimes, the inherent conservatism or lack of details as well as unanticipated transients in old plant may cause maintenance problems. Even though several famous on-line monitoring and diagnosis systems have been developed world-widely, in this paper, a new system fur fatigue monitoring and life evaluation of crane is proposed to reduce customizing effort and purchasing cost. With regard to the system, at first, comprehensive operating transient data has been acquired at critical locations of crane. The real-time data were classified, by using adaptive resonance theory that is one of typical artificial neural network, into representative stress groups. Then the each classified stress pattern was mapped to calculated cumulative usage factor in accordance with ASME procedure. Thereby, promising results were obtained fur the crane and it is believed that the developed system can be applicable to other major facilities extensively.
Using the Finite Element Method, 3 Dimensional FE Analysis of Residual Stress by Cold Expansion Method in the Plate Baying Adjacent Holes
Yang Won-Ho ; Cho Myoung-Rae ; Jang Jae-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 528~532
DOI : 10.3795/KSME-A.2006.30.5.528
In the aerospace industry, Cold expansion has been used the most important method that is retarded of crack initiation from fastener hole surface. Cold expansion method(CEM) is that a oversized tapered mandrel goes through the hole in order to develop a compressive residual stress as the passing of the mandrel around the hole. Therefore, because of characteristic of mandrel inserting, Residual Stress Distributions (RSD) are differently generated form Entry, Mid and Exit position of the plate. Also, it is respected that RSD are changed as distances between holes. In this paper, It is performed a FE analysis of RSD by CEM and it is respectively shown RSD in the Entry, Mid and Exit position. It is compared residual stress results form the cold expansion in these two cases: the concurrent CEM and the sequential CEM. From this research, it has been found that compressive residual stress of Entry position is lower than other positions. Also, the concurrent CE of adjacent holes leads to much higher compressive residual stress than the sequential CE. In addition, in the sequential CE case, a compressive RSD of 1 step`s hole around is lower than compressive RSD of 2 step`s hole around.
Estimation Method of Local Elastic-Plastic Strain at Thinning Area of Straight Pipe Under Tension Loading
An Joong-Hyok ; Kim Yun-Jae ; Yoon Kee-Bong ; Ma Young-Wha ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 533~542
DOI : 10.3795/KSME-A.2006.30.5.533
In order to assess the integrity of pipes with local thinning area, the plastic strain as well as the elastic strain at the root of thinned region are required particularly when fluctuating load is applied to the pipe. For estimating elastic-plastic strain at local wall thinning area in a straight pipe under tensile load, an estimation model with idealized fully circumferential constant depth wall thinning area is proposed. Based on the compatibility and equilibrium equations a nonlinear estimation equation, from which local elastic-plastic strain can be determined as a function of pipe/defect geometry, material and the applied strain was derived. Estimation results are compared with those from detailed elastic-plastic finite element analysis, which shows good agreements. Noting that practical wall thinning in nuclear piping has not only a circular shape but also a finite circumferential length, the proposed solution for the ideal geometry is extended based on two-dimensional and three-dimensional numerical analysis of pipes with circular wall thinning.
A Study on Bursting Properties of Short-Fiber Reinforced Chloroprene Rubber
Ryu Sang-Ryeoul ; Lee Dong-Joo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 543~549
DOI : 10.3795/KSME-A.2006.30.5.543
The bursting properties under various conditions were investigated to ascertain the optimum conditions to yield the best properties. Fiber aspect ratio (AR: length of fiber/diameter of fiber), interphase condition and fiber content were considered as variables which impact the bursting pressure, bulge constant, torsional rigidity ratio. The bursting pressure of reinforced rubber increases up to 8.73 times compared to the virgin material. The better interphase condition shows the higher bursting pressure at given AR and fiber content. The bulge constant and torsional rigidity highly decrease with increasing AR and better interphase condition at same fiber content. The bulge constant and torsional rigidity reveal the minimum of 11% and 0.6% of the matrix, respectively. The bursted shape after test shows the different patterns between unfilled and reinforced rubbers. The case of virgin rubber shows a radiating shape while that of reinforced rubber shows a fluctuating straight line. Overall, it was found that the fiber AR and interphase condition have an important effect on bursting properties.
Design and Performance Investigation of Bypass-Type MR Shock Dampers
Nam Yun-Joo ; Kim Dong-Uk ; Lee Yuk-Hyung ; Park Myeong-Kwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 550~559
DOI : 10.3795/KSME-A.2006.30.5.550
This paper presents designs and performance investigations of two bypass-type MR (magneto-rheological) shock dampers for high impulsive force systems, one of which is with single rod and the other with double rod. First of all, on the basis of the Bingham properties of the MR fluid and the magnetic field analysis of the magnetic circuit, the MR shock dampers are designed and manufactured. After experimental investigations on their magnetic field-dependent damping forces and responses characteristics, dynamic models of the proposed dampers are formulated and compared. Then, a simple 1 degree-of-freedom mass-drop system is constructed, and the effective and practical control algorithm is designed by considering dynamic characteristics of the shock control system. The shock control performances of the proposed MR shock dampers are verified through the comparison study of experiment results with simulation ones.
A Calibration and Uncertainty Analysis on the Load Monitoring System for a Low Speed Shaft and Rotor Blade of a Wind Turbine
Park Moo-Yeol ; Yoo Neung-Soo ; Nam Yoon-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 560~567
DOI : 10.3795/KSME-A.2006.30.5.560
The exact load measurements for the mechanical parts of a wind turbine are important step both fur the evaluation of a specific wind turbine design and for a certification process. A common method for a mechanical load measurement is using a strain gauge sensing. Two main problems ought to be answered in order for this method to be applied to the wind turbine project. These are strain gauge calibration and non-contact signal transmission from the strain gauge output to a load monitoring system. This paper suggests reliable solutions fer these two problems. A Bluetooth, a short range wireless data communication technology, is used to solve the second problem. The first one, the strain gauge calibration methodology for a load measurement in a wind turbine application, is fully explained in this paper. Various mechanical loadings for a strain gauge calibration in a wind turbine load measurement are introduced and analyzed. Initial experimental results which are obtained from a 1 kW small size wind turbine are analyzed, and the uncertainty problem in estimating mechanical loads using a calibration matrix is fully covered in this paper.
Plastic Limit Loads for Through-Wall Cracked Pipes Using 3-D Finite Element Limit Analyses
Huh Nam-Su ; Kim Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 568~575
DOI : 10.3795/KSME-A.2006.30.5.568
The present paper provides plastic limit load solutions of axial and circumferential through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis using elastic-perfectly-plastic behavior. As a loading condition, axial tension, global bending moment, internal pressure, combined tension and bending and combined internal pressure and bending are considered for circumferential through-wall cracked pipes, while only internal pressure is considered for axial through-wall cracked pipes. Especially, more emphasis is given for through-wall cracked pipes subject to combined loading. Comparisons with existing solutions show a large discrepancy in short through-wall crack (both axial and circumferential) for internal pressure. In the case of combined loading, the FE limit analyses results show thickness effect on limit load solutions. Furthermore, the plastic limit load solution for circumferential through-wall cracked pipes under bending is applied to derive plastic
-factor of testing circumferential through-wall cracked pipes to estimate fracture toughness. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be meaningful fur structural integrity assessment of through-wall cracked pipes.
Influence of Applied Electric Fields and Drive Frequencies on The Actuating Displacement of a Plate-type Piezoelectric Composite Actuator
Goo Nam-Seo ; Woo Sung-Choong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 576~584
DOI : 10.3795/KSME-A.2006.30.5.576
The actuating performance test of plate-type piezoelectric composite actuators having different lay-up sequences was experimentally carried out at simply supported and fixed-free boundary conditions. The actuating displacement of manufactured plate-type piezoelectric composite actuator (PCA) was measured using a non-contact laser displacement measurement system. Our results revealed that the actuating displacement with increasing applied electric field at a drive frequency of 1Hz increased non-linearly at the simply supported boundary condition whereas it almost linearly increased at the fixed-free boundary condition. On the other hand, the actuating displacement of piezoelectric composite actuator depended on the applied electric field in a drive frequency range from 1Hz to 10Hz, but its behavior was different in higher drive frequencies beyond 15Hz due to the occurrence of resonance. On the basis of the above experimental results, the bending characteristics of PCAs revealed different behavior depending on applied electric fields, drive frequencies as well as boundary conditions. Therefore, by investigating drive frequencies together with applied electric fields, actuating performance can be easily controlled and PCAs which were fabricated for this study will be sufficiently applied to pumping devices.
Structural Optimization of a Joined-Wing Using Equivalent Static Loads
Lee Hyun-Ah ; Kim Yong-Il ; Park Gyung-Jin ; Kang Byung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 585~594
DOI : 10.3795/KSME-A.2006.30.5.585
The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing are joined together in a joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performance and reduction of the structural weight. In this research, dynamic response optimization of a joined-wing is carried out by using equivalent static loads. Equivalent static loads are made to generate the same displacement field as the one from dynamic loads at each time step of dynamic analysis. The gust loads are considered as critical loading conditions and they dynamically act on the structure of the aircraft. It is difficult to identify the exact gust load profile. Therefore, the dynamic loads are assumed to be (1-cosine) function. Static response optimization is performed for the two cases. One uses the same design variable definition as dynamic response optimization. The other uses the thicknesses of all elements as design variables. The results are compared.
Topology Optimization for a Knuckle Using Design Space Adjustment and Refinement
Yu Yong-Gyun ; Kwak Byung-Man ; Jang In-Gwun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 595~601
DOI : 10.3795/KSME-A.2006.30.5.595
Design space optimization using design space adjustment and refinement is used to optimize a knuckle in the suspension system of an automobile. This approach is a new efficient method for large-scale topology optimization by virtue of two reasons. First, design space adjustment including design space expansion and reduction is suitable for large-scale problems. Second, the design space refinement can be done globally or locally where and when necessary and thus is very effective in obtaining a target resolution with much less number of elements. Compliance minimization for a knuckle is considered with a realistic working condition to show the effectiveness and superiority of the new approach.
Residual Stress of the Lower Control Arm Subjected to Cyclic Loading
Kim Gi-Hoon ; Kang Woo-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 602~608
DOI : 10.3795/KSME-A.2006.30.5.602
Vehicle components such as lower control arm are usually affected by heat during the welding process. As a result, residual stress is generated, which has much effect on mechanical performances such as crashworthiness and durability. In this study, the residual stress in lower control arm has been measured by the x-ray diffraction method and been analyzed by finite element methods. Heat transfer during seam weld process has been calculated and used in calculating thermal deformation with temperature dependent material properties. High residual stress has been found at vertical wall both by measurement and simulation. The simulation also showed the residual stress re-distribution when the component is subjected to cyclic loading condition.
Development of a Linear Motor Dynamometer for Positioning Control Performance Test
Roh Chang-Yul ; Rho Myung-Hwan ; Kim Ju-Kyung ; Park Jong-Jin ; Lee Eung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 30, issue 5, 2006, Pages 609~614
DOI : 10.3795/KSME-A.2006.30.5.609
Recently linear motor has been used mainly for high speed feeding performance of machine tools. The advantages of linear motor are not only high speed but high accuracy, because it is not required the coupling and ballscrew for converting rotary to liner motion. Before applying in different moving system, the dynamometer is necessary to test the performance. In Korea, the linear motor is producing in a couple of company However, the liner motor dynamometer is not commercialized yet, like as rotary motor dynamometer. In this paper, a linear motor dynamometer is designed and manufactured using a MR damper. The dynamometer system developed in this study could be used for testing the positioning accuracy fur different loading conditions, traction forces, dynamic performance and so on.