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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
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
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
Influence of Flexible Pin for Planets on Service Life of Wind Turbine Gearboxes
Park, Young-Jun ; Lee, Geun-Ho ; Nam, Yong-Yun ; Kim, Jeong-Kil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 953~960
DOI : 10.3795/KSME-A.2012.36.9.953
An overhung mounted carrier with flexible pins is applied to the planetary gear train of a wind turbine gearbox to investigate the influence of the self-aligning effect by means of the deflection of the planet spindle and the flexible pin on the lifetime of the planet gear for a wind turbine gearbox. To analyze the load distribution of planet gears, both Euler theory and commercial software are employed. By applying an overhung mounted carrier with flexible pins in the wind turbine gearbox, we can improve the misalignment performance, face load factor, and service life of the planet gears. In particular, it was confirmed that a service life of more than 20 years could be realized for wind turbine gearboxes by applying a flexible pin to the overhung mounted carrier.
Load Bearing Capacity of Welded Joints between Dissimilar Pipelines with Unequal Wall Thickness
Baek, Jong-Hyun ; Kim, Young-Pyo ; Kim, Woo-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 961~970
DOI : 10.3795/KSME-A.2012.36.9.961
The behavior of the load bearing capacity of a pipeline with unequal wall thickness was evaluated using finite element analyses. Pipelines with a wall thickness ratio of 1.22-1.89 were adopted to investigate plastic collapse under tensile, internal pressure, or bending stress. A parametric study showed that the tensile strength and moment of a pipeline with a wall thickness ratio less than 1.5 were not influenced by the wall thickness ratio and taper angle; however, those of a pipeline with a wall thickness ratio more than 1.5 decreased considerably at a low taper angle. The failure pressure of a pipeline with unequal wall thickness was not influenced by the wall thickness ratio and taper angle.
Mechanical Properties of The CO
Free Vacuum Carburized in SCM415H
Byun, Jae-Hyuk ; Ro, Seung-Hoon ; Lee, Jong-Hyung ; Lee, Chang-Hun ; Yang, Seong-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 971~978
DOI : 10.3795/KSME-A.2012.36.9.971
Vacuum carburizing is supposed to be the superior process to the gas carburizing. However, the vacuum carburizing has the stage in which hydrocarbon gas is supplied into the furnace to be pyrolysis, and consequently the stable heat treatment is hard to achieve due to the soot from the hydrocarbon pyrolysis. Recently, many studies have been made which utilize acetylene gas to overcome this defects. In this paper, the carburizing and the diffusion periods have been selected based on the Harris experimental formula, and the mechanical properties of the vacuum carburized specimen have been compared with those of the gas carburized SCM415H specimen to identify the feasibility of the
free vacuum carburizing process. The result showed that the vacuum carburized materials used have no oxidization of the grain boundaries, and show the 29.8% higher effective hardness depth and the acceptable tensile strength.
Development of Torsion Bar for Antiroll-Bar Assembly for Express Train
Tominaga, Yasutoshi ; Pyun, Young-Sik ; Kim, Dong-Il ; Choe, Do-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 979~984
DOI : 10.3795/KSME-A.2012.36.9.979
An antiroll-bar assembly is a precision component that is designed to control the rolling of railway cars. It is important for ensuring a safe and comfortable ride. A torsion bar is the main part of the antiroll-bar assembly. Now, this part is classified as a consumable, and it is imported into Korea from France. Therefore, there is a strong need to domestically develop a torsion bar suitable for Korean conditions and to reduce cost and improve quality. In this study, an antiroll bar is developed, and it is analyzed and tested by using a road histogram measured on Korean railroads. This bar shows satisfactory results in a comparison with the imported bar. It has a novel design featuring a ring cover made of SUS steels to prevent the corrosion of the torsion bar. Its safety is examined through CAE analysis and wear tests. It is found that its design does not result in a significant difference in static and fatigue safety. Two different SUS steels were investigated in terms of their wear resistance, and the best one was adopted.
Unsteadily Propagating Permeable Mode III Crack in Piezoelectric Materials
Lee, Kwang-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 985~996
DOI : 10.3795/KSME-A.2012.36.9.985
An unsteadily propagating permeable crack in piezoelectric materials (PMs) under anti-plane shear mechanical loading and in-plane electric loading is studied. The equilibrium equations for a transiently propagating crack in a PM are developed, and the solutions on the stress and displacement fields for a permeable crack though an asymptotic analysis are obtained. The influences of piezoelectric constant, dielectric permittivity, time rate of change of the crack tip speed and time rate of change of stress intensity factor on the stress and displacement fields at the transiently propagating crack tip are explicitly clarified. By using the stress and displacements, the characteristics of the stress and displacement at a transiently propagating crack tip in a PM are discussed.
FE Simulation of Axial Crushing Test for AZ31 Tube Considering Tension-Compression Asymmetry
Yoon, Jong-Hun ; Lee, Jung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 997~1002
DOI : 10.3795/KSME-A.2012.36.9.997
With the increasing demand for lightweight materials to reduce fuel consumption, especially in the transportation industry, magnesium alloys are being widely studied. However, there are several limitations to the large-scale application of magnesium alloys in a structure because of their low formability and strong anisotropy. In order to take into account both the strong anisotropy and tension-compression asymmetry of AZ31 sheet alloy, the Cazacu-Plunkett-Barlat yield criterion (Cazacu, 2006) was adopted in material modeling. The variation of the anisotropic coefficients that describe the yield surface evolution of AZ31 is optimized using an interpolation function based on specific calibration results. It generates continuous yield surfaces, which makes it possible to describe different hardening rates in tension and compression as well as the tension-compression asymmetry of magnesium alloys. The performance of the CPB06 yield criterion for simulating an axial crushing test was tested and compared with that of the Hill (1948) yield criterion.
Real-Time Dynamic Analysis of Vehicle with Experimental Vehicle Model
Yoo, Wan-Suk ; Na, Sang-Do ; Kim, Kwang-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1003~1008
DOI : 10.3795/KSME-A.2012.36.9.1003
The paper presents an Experimental Vehicle Model (EVM), that utilizes the kinematic characteristics of suspensions from SPMD test data. The relative displacement and orientation of a wheel with respect to the body are represented as a function of the vertical displacement of the wheel. The equations of motion of the vehicle are formulated in terms of local coordinates that do not require coordinate transformation, which improves the efficiency of dynamic analysis. The EOM was modularized for each suspension model, and a
vehicle model was obtained by combining six suspensions. The analysis results were compared with ADAMS to verify the accuracy of the EVM. This study also verifies the feasibility of real-time simulation with the developed EVM. For a vehicle simulation for 1 ms, the real simulation time required within 20% of the prescribed time. This result shows that the EVM meets the real-time simulation requirements.
Theoretical Seismic Analysis of Butterfly Valve for Nuclear Power Plant
Han, Sang-Uk ; Ahn, Jun-Tae ; Lee, Kyung-Chul ; Han, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1009~1015
DOI : 10.3795/KSME-A.2012.36.9.1009
Valves are one of the most important components of a pipeline system in a nuclear power plant, and it is important to ensure their structural safety under seismic loads. A crucial aspect of structural safety verification is the seismic qualification, and therefore, an optimal shape design and experimental seismic qualification is necessary in case the configuration of the valve parts needs to be modified and their performance needs to be improved. Recently, intensive numerical analyses have been performed before the experimental verification in order to determine the appropriate design variables that satisfy the performance requirements under seismic loads. In this study, static and dynamic numerical structural analyses of a 200A butterfly valve for a nuclear power plant were performed according to the KEPIC MFA. The result of static analysis considering an equivalent static load under SSE condition gave an applied stress of 135 MPa. In addition, the result of dynamic analysis gave an applied stress of 183 MPa, where the CQC method using response spectrums was taken into account. These values are under the allowable strength of the materials used for manufacturing the butterfly valve, and therefore, its structural safety satisfies the requirements of KEPIC MFA.
Development of Frozen Shoulder Rehabilitation Robot Based On Motion Capture Data
Yang, Un-Je ; Kim, Jung-Yup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1017~1026
DOI : 10.3795/KSME-A.2012.36.9.1017
In this study, an exoskeleton-type robot is developed to assist frozen shoulder rehabilitation in a systematic and efficient manner for humans. The developed robot has two main features. The first is a structural feature: this robot was designed to rehabilitate both shoulders of a patient, and the three axes of the shoulder meet at one point to generate human-like ball joint motions. The second is a functional feature that is divided into two rehabilitation modes: the first mode is a joint rehabilitation mode that helps to recover the shoulder`s original range of motion by moving the patient`s shoulder according to patterns obtained by motion capture, and the second mode is a muscle rehabilitation mode that strengthens the shoulder muscles by suitably resisting the patient`s motion. Through these two modes, frozen shoulder rehabilitation can be performed systematically according to the patient`s condition. The development procedure is described in detail.
Strength Analyses of New 2- and 3-Axis-Type Small Multiplying Gears in Dental Hand-Pieces
Kim, Cheol ; Kim, Ju-Yeong ; Lee, Jung-Ho ; Kwak, Se-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1027~1032
DOI : 10.3795/KSME-A.2012.36.9.1027
Two types of very small multiplying gears and arrays have been developed for new dental hand-pieces, and the increased speed ratios, modules, number of teeth, gear diameters, and gear types were calculated based on the dynamics of the machinery. The contacting and bending strengths were evaluated for gear teeth with two design concepts using AGMA equations and finite element analyses, and the contacting stresses on teeth with and without DLC (diamond-like-carbon) coating layers were calculated. Fatigue and tension tests were performed to obtain an S-N curve, the Young`s modulus, and the strength of the gear material, and these were utilized in the analyses. Slightly larger stresses were found for 2-axis-type gears than for other types of gears, and the S-N curves showed that a gear lifetime of 109 cycles was satisfied. The contacting stresses in gears coated with DLC were reduced by 30%. A new prototype model of a hand-piece with small gears was successfully fabricated and tested.
Stability Test of Artificial Joint for Hip Joint
Seok, Sung-Fie ; Park, Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1033~1039
DOI : 10.3795/KSME-A.2012.36.9.1033
Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.
Estimation of Hardness and Compressive Strength of SP-100 Aluminum Powder Epoxy
Han, Jeong-Young ; Kim, Myung-Hun ; Kang, Sung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1041~1046
DOI : 10.3795/KSME-A.2012.36.9.1041
In this study, we performed experimental tests on five SP-100 aluminum powder epoxy specimens with several after-curing conditions in order to estimate their hardness with temperature and compressive strength. In the surface hardness test, it was found that the higher the after-curing temperature, the higher was the hardness. In particular, it was found that the hardness of the specimens in cases 3 and 4 was much higher than in the other cases. In addition, in the compression tests carried out to evaluate the compressive strength, it was found that the specimens showed relatively similar stiffness and strength with after-curing, and specimens with no after-curing showed compression stress-strain curves similar to those of thermoplastic resins.
Evaluation of PWSCC at Dissimilar Metal Butt Welds in NPP
Lee, Sung-Ho ; Lee, Kyoung-Soo ; Oh, Chang-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1047~1052
DOI : 10.3795/KSME-A.2012.36.9.1047
Primary water stress corrosion cracking (PWSCC) instances have been reported in the Alloy 600 reactor pressure vessel head penetration nozzle and the Alloy 82/182 dissimilar metal butt weld nozzle in several PWRs. Therefore, in-service inspection programs have been adopted worldwide to prevent failure at the weld region. If a PWSCC is observed at the dissimilar metal weld region during inspection, its structural integrity should be evaluated; however, this requires considerable time and effort, and this might lead to a decrease in the plant utilization coefficient. To prevent this, KHNP-CRI have established integrity assessment criteria and developed a computer program for the fast evaluation and judgment of PWSCC. In this paper, the results and current status of the same are presented. Through this study, criteria for the structural integrity evaluation of PWSCC have been established, and a computer program has been developed to realize technical means for the evaluation of PWSCC structural integrity.
Temperature-Dependency of Tensile Properties of GFRP Composite for Wind Turbine Blades
Huh, Yong-Hak ; Kim, Jong-Il ; Kim, Dong-Jin ; Lee, Gun-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1053~1057
DOI : 10.3795/KSME-A.2012.36.9.1053
In this study, the temperature-dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson`s ratio of the tensile specimen manufactured from uniaxial (
) and triaxial (
) laminate composite plates were measured at four different testing temperatures-room temperature,
. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson`s ratio changed slightly with a change in the testing temperature.
Estimation of Tensile Properties of Pipe Bends Manufactured by Cold-Bending
Kim, Jin-Weon ; Lee, Mi-Yeon ; Lee, Sa-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1059~1064
DOI : 10.3795/KSME-A.2012.36.9.1059
In this study, tensile tests were performed on specimens that simulated the cold-bending and heat-treatment of pipe bends to understand the mechanical properties of pipe bends manufactured by cold-bending followed by heat-treatment for relieving residual stress. The strength and ductility of cold-worked materials were respectively found to be higher and lower than those of the parent material although heat-treatment was carried out to relieve residual stress. In addition, the increase in strength and decrease in ductility were proportional to the applied strain levels for cold-working. It was thus inferred that the intrados and extrados regions of pipe bends that were cold-bended and heat-treated show higher strength and lower ductility compared to the parent straight pipe and that the mechanical properties at the crown region are nearly the same as those of the parent straight pipe.
Optimization of Wind Turbine Pitch Controller by Neural Network Model Based on Latin Hypercube
Lee, Kwangk-Ki ; Han, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1065~1071
DOI : 10.3795/KSME-A.2012.36.9.1065
Wind energy is becoming one of the most preferable alternatives to conventional sources of electric power that rely on fossil fuels. For stable electric power generation, constant rotating speed control of a wind turbine is performed through pitch control and stall control of the turbine blades. Recently, variable pitch control has been implemented in modern wind turbines to harvest more energy at variable wind speeds that are even lower than the rated one. Although wind turbine pitch controllers are currently optimized using a step response via the Ziegler-Nichols auto-tuning process, this approach does not satisfy the requirements of variable pitch control. In this study, the variable pitch controller was optimized by a genetic algorithm using a neural network model that was constructed by the Latin Hypercube sampling method to improve the Ziegler-Nichols auto-tuning process. The optimized solution shows that the root mean square error, rise time, and settle time are respectively improved by more than 7.64%, 15.8%, and 15.3% compared with the corresponding initial solutions obtained by the Ziegler-Nichols auto-tuning process.
Comparative Study on Description Schemes to Perform Finite Element Analysis in Incremental Forming Process
Park, Jun-Soo ; Byon, Sang-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1073~1080
DOI : 10.3795/KSME-A.2012.36.9.1073
Incremental forming is a cold working process in which a small part of the material is being deformed and the area of local deformation is moving over the entire material. In this paper, we study description schemes to perform finite element analysis for the incremental forming. The selected description schemes to examine are the Lagrangian description and the arbitrary Lagrangian-Eulerian (ALE) description. The sliding boundary scheme coupled with ALE is also examined to overcome the distortion problems of elements on the contact surface. Results show that the ALE description with the sliding boundary scheme is most favorable in overcoming the distortion of elements. This description leads to make the simulation continued to the final stage of the incremental forming. On the other hand, the Lagrangian description as well as the original ALE description makes the elements much distorted and the analysis is stopped long before arriving at the final shape of deformation.
Hardness Evaluation of Spot Welding Using Instrumented Indentation Technique
Jin, Ji-Won ; Kwak, Sung-Jong ; Yoo, Dong-Ok ; Kim, Tae-Seong ; Kang, Ki-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1081~1086
DOI : 10.3795/KSME-A.2012.36.9.1081
This study deals with hardness evaluation for spot welding by using an instrumented indentation technique to improve the quality of the inspection methodology. First, an instrumented indentation test and a Rockwell hardness test were performed for normal and abnormal spot welding. The hardness to indentation force-displacement curve obtained using each of the tests was compared. Furthermore, an analysis was conducted using the hardness obtained by the instrumented indentation technique. A quality control standard based on reliability was this evaluated for spot welding.
Structural Integrity of Small Wind Turbine Composite Blade Using Structural Test and Finite Element Analysis
Jang, Yun-Jung ; Lee, Jang-Ho ; Kang, Ki-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1087~1094
DOI : 10.3795/KSME-A.2012.36.9.1087
This study deals with structural analysis and testing under loading conditions calculated by computational fluid dynamics for a small composite blade that is utilized in a dual rotor wind turbine system. First, the aerodynamic forces were analyzed at the rated and cutout wind speed to identify the bending moment distribution along the blade length in previous research. Then, full-scale structural tests were conducted according to IEC 61400-2 to evaluate the structural integrity of the composite blade. These results were compared with finite element analysis to identify the accuracy of the structural analysis. Based on these results, it was revealed that the existing blade has a very high safety margin. Then, the layup of the composite blade was redesigned and analyzed using finite element analysis to achieve structural integrity and economic efficiency.
Macroscopic High-Temperature Structural Analysis of PHE Prototypes Considering Weld Material Properties
Song, Kee-Nam ; Hong, Sung-Deok ; Park, Hong-Yoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1095~1101
DOI : 10.3795/KSME-A.2012.36.9.1095
A process heat exchanger (PHE) in a nuclear hydrogen system is a key component that transfers the large amount of heat generated in a very high temperature reactor (VHTR) to a chemical reaction that yields a large quantity of hydrogen. A performance test on a small-scale and a medium-scale PHE prototype made of Hastelloy
-X is being conducted on in a small-scale nitrogen gas loop at the Korea Atomic Energy Research Institute. Previous research on the macroscopic high-temperature structural analysis of PHE prototypes had been performed using base material properties owing to a lack of weld material properties. In this study, macroscopic high-temperature structural analyses considering the weld material properties were performed and the results were compared with those of a previous study.
Structural Integrity Evaluation of Large Main Steam Piping by Water Hammering
Jo, Jong-Hyun ; Lee, Young-Shin ; Kim, Yeon-Whan ; Jin, Hai Lan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 9, 2012, Pages 1103~1108
DOI : 10.3795/KSME-A.2012.36.9.1103
A main steam pipe system is a branch pipe that connects a boiler with a turbine. Water hammering analysis is very important for limiting the damage caused to pipe systems by operation conditions. Water hammering created by an unsteady flow in pipeline systems can cause excessive change in pressure, vibration, and noise. The main steam pipe structure should be designed to safely maintain the pressure pulsation and several vibrations under operation environments. This study evaluated the structural integrity of a main steam pipe during suspended and normal operation by using the ASME fatigue life methodology and finite element analysis. In the analysis, water hammering was used for transient analysis. The calculated alternating stress and fatigue stress were compared with the applicable limits of ASME fatigue life. All the evaluation results satisfied the requirements of the ASME fatigue life.