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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 38, Issue 12 - Dec 2014
Volume 38, Issue 11 - Nov 2014
Volume 38, Issue 10 - Oct 2014
Volume 38, Issue 9 - Sep 2014
Volume 38, Issue 8 - Aug 2014
Volume 38, Issue 7 - Jul 2014
Volume 38, Issue 6 - Jun 2014
Volume 38, Issue 5 - May 2014
Volume 38, Issue 4 - Apr 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
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A Study on Prediction Method of Derailment Behaviors due to Cross-wind Considering Dynamic Effects of Wheel-rail Interaction
Kim, Myung Su ; Koo, Jeong Seo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 699~709
DOI : 10.3795/KSME-A.2014.38.7.699
This paper proposes a new method for predicting the derailment of a running train under cross-wind conditions, using the single wheelset derailment theory. The conventional theories used for predicting the derailment due to cross-winds were developed under the assumption that derailment will always be of the roll-over type, thus neglecting other possible types such as wheel-climbing, which may occur under special driving conditions. In addition, these theories do not consider running conditions such as dynamic wheel-rail interactions and friction effects. The new method considers the effects of dynamic wheel-rail interaction as well as those of lateral acceleration, rail cant, and cross-winds. The results of this method were compared and verified with those of the conventional methods and numerical simulations.
Dynamic Analysis of Specimen Under Ultrasonic Fatigue Using Finite Element Method
Myeong, No-Jun ; Choi, Nak-Sam ; Kwon, Hena ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 711~717
DOI : 10.3795/KSME-A.2014.38.7.711
An accelerated ultrasonic fatigue test (UFT) was used for analyzing very high cycle fatigue (VHCF,
) behaviors of a specimen with a test resonance of 20 kHz. Using the finite element method (FEM), the dynamic behaviors of the specimen was studied by calculating the stresses along its gauge portion, with displacement. The shape of gauge portion profile was assumed to be a hyperbolic according to the stress equation of the UFT. However, as the specimen used in the test had a circular arc profile, the FEM was used for studying the local stresses for two cases of the gauge profile. The results were compared with those obtain from the stress equation of the UFT. The dynamic behavior of the gauge portion could be understood for further comparison with the actual results.
Numerical Analysis of Mold Deformation Including Plastic Melt Flow During Injection Molding
Jung, Joon Tae ; Lee, Bong-Kee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 719~725
DOI : 10.3795/KSME-A.2014.38.7.719
In the present study, a numerical analysis of an injection molding process was conducted for predicting the mold deformation considering non-Newtonian flow, heat transfer, and structural behavior. The accurate prediction of mold deformation during the filling stage is important to successfully design and manufacture a precision injection mold. While the local mold deformation can be caused by various factors, a pressure induced by the polymer melt is considered to be one of the most significant ones. In this regard, the numerical simulation considering both the melt filling and the mold deformation was carried out. A mold core for a 2D axisymmetric center-gated disk was used for the demonstration of the present study. The flow behavior inside the mold cavity and temperature distribution were analyzed along with the core displacement. Also, a Taguchi method was employed to investigate the influence of the relevant parameters including flow velocity, mold core temperature, and melt temperature.
Finite Element Based Multi-Scale Ductile Failure Simulation of Full-Scale Pipes with a Circumferential Crack in a Low Carbon Steel
Han, Jae-Jun ; Bae, Kyung-Dong ; Kim, Yun-Jae ; Kim, Jong-Hyun ; Kim, Nak-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 727~734
DOI : 10.3795/KSME-A.2014.38.7.727
This paper describes multi-scale based ductile fracture simulation using finite element (FE) damage analysis. The maximum and crack initiation loads of cracked components were predicted using proposed virtual testing method. To apply the local approach criteria for ductile fracture, stress-modified fracture strain model was adopted as the damage criteria with modified calibration technique that only requires tensile and fracture toughness test data. Element-size-dependent critical damage model is also introduced to apply the proposed ductile fracture simulation to large-scale components. The results of the simulation were compared with those of the tests on SA333 Gr. 6 full-scale pipes at
, performed by the Battelle Memorial Institute.
Design of Helical Self-Piercing Rivet for Joining Aluminum Alloy and High-Strength Steel Sheets
Kim, W.Y. ; Kim, D.B. ; Park, J.G. ; Kim, D.H. ; Kim, K.H. ; Lee, I.H. ; Cho, H.Y. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 735~742
DOI : 10.3795/KSME-A.2014.38.7.735
A self-piercing rivet (SPR) is a mechanical component for joining dissimilar material sheets such as those of aluminum alloy and steel. Unlike conventional rivets, the SPR directly pierces sheets without the need for drilling them beforehand. However, the regular SPR can undergo buckling when it pierces a high-strength steel sheet, warranting the design of a helical SPR. In this study, the joining and forging processes using the helical SPR were simulated using the commercial FEM code, DEFORM-3D. High-tensile-strength steel sheets of different strengths were joined with aluminum alloy sheets using the designed helical SPR. The simulation results were found to agree with the experimental results, validating the optimal design of a helical SPR that can pierce high-strength steel sheets.
Manufacturing of High-Strength and High-Ductility Pearlitic Steel Wires Using Noncircular Drawing Sequence
Baek, Hyun Moo ; Hwang, Sun Kwang ; Joo, Ho Seon ; Im, Yong-Taek ; Son, Il-Heon ; Bae, Chul Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 743~749
DOI : 10.3795/KSME-A.2014.38.7.743
In this study, a noncircular drawing (NCD) sequence for manufacturing high-strength and high-ductility pearlitic steel wires was investigated. Multipass NCD was conducted up to the 12th pass at room temperature with two processing routes (defined as the NCDA and NCDB), and compared with the wire drawing (WD). During the torsion test, delamination fracture in the drawn wire was observed in the 10th pass of the WD whereas it was not observed until the 12th pass of the NCDB. From X-ray diffraction, the circular texture component that increases the likelihood of delamination fracture of the drawn wire was rarely observed in the NCDB. Thus, the improved ability of the multipass NCDB to manufacture high-strength pearlitic steel wires with high torsional ductility compared to the WD (by reducing the likelihood of delamination fracture) was demonstrated.
Comparison of GPU-Based Numerous Particles Simulation and Experiment
Park, Sang Wook ; Jun, Chul Woong ; Sohn, Jeong Hyun ; Lee, Jae Wook ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 751~756
DOI : 10.3795/KSME-A.2014.38.7.751
The dynamic behavior of numerous grains interacting with each other can be easily observed. In this study, this dynamic behavior was analyzed based on the contact between numerous grains. The discrete element method was used for analyzing the dynamic behavior of each particle and the neighboring-cell algorithm was employed for detecting their contact. The Hertzian and tangential sliding friction contact models were used for calculating the contact force acting between the particles. A GPU-based parallel program was developed for conducting the computer simulation and calculating the numerous contacts. The dam break experiment was performed to verify the simulation results. The reliability of the program was verified by comparing the results of the simulation with those of the experiment.
Evaluation of Shape Parameter Effect on the J-R Curve of Curved CT Specimen Using Limit Load Method
Shin, In Hwan ; Park, Chi Yong ; Seok, Chang Sung ; Koo, Jae Mean ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 757~764
DOI : 10.3795/KSME-A.2014.38.7.757
In this study, the effect of shape parameters on the J-R curves of curved CT specimens was evaluated using the limit load method. Fracture toughness tests considering the shape factors L/W and
of the specimens were also performed. Thereafter, the J-R curves of the curved CT specimens were compared using the J-integral equation proposed in the ASTM (American Society for Testing and Materials) and limit load solution. The J-R curves of the curved CT specimens were also compared with those of the CWP (curved wide plate), which is regarded to be similar to real pipe and standard specimens. Finally, the effectiveness of the J-R curve of each curved CT specimen was evaluated. The results of this study can be used for assessing the applicability of curved CT specimens in the accurate evaluation of the fracture toughness of real pipes.
Effect of the Insert Shape on the Improvement of Durability of Bolted Joints Applied to Composite Bogie Frames
Kim, JunHwan ; Shin, KwangBok ; Kim, JungSeok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 765~770
DOI : 10.3795/KSME-A.2014.38.7.765
This paper describes the study on a method for improving the structural durability of bolted joints applied to a composite bogie frame. In this study, three bolted joints with and without inserts and screw threads were selected for determining the effect of the inserts, using experiment and analysis. The structural performances of the proposed bolted joints were compared and evaluated using the test method prescribed by the ASTM D5961 standard. The results revealed that the bolted joint having an insert shape without the screw thread offered improved durability for application to a composite bogie frame. Furthermore, the structural integrity of the frame comprising the bolted joints was evaluated using finite element analysis according to the JIS E 4207 standard. The Tasi-Wu and Von-Mises failure criteria were used for determining the failure of the composite structure and bolted joints, respectively. A sub-modeling technique was introduced for investigating the performance of the bolted joints in greater detail. The analysis results demonstrated that the Tasi-Wu failure index of the composite structure near the bolted joints was reduced by approximately one-half after applying an insert without the screw thread. This implies that the structural durability of the bolted joints of a composite bogie frame could be improved by using a metal insert without the screw thread.
Film Insert Molding of Automotive Door Grip Using Injection-Compression Molding
Lee, Ho Sang ; Yoo, Young Gil ; Kim, Tae An ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 771~777
DOI : 10.3795/KSME-A.2014.38.7.771
Injection-compression molding was used for film insert molding of an automotive door grip using films with three-dimensional embossed patterns. A vacuum mold was fabricated for vacuum-assisted thermoforming of the film, and an injection-compression mold was developed for film insert molding. Three pressure transducers were installed inside the mold cavity to measure cavity pressures. Injection-compression molding experiments under various compression strokes and toggle speeds were performed to investigate their effects on the cavity pressure and heights of the embossed patterns. The compression stroke of 0.9mm and low toggle speed resulted in a higher degree of conservation of embossed patterns. Additionally, the processing conditions for the maximum heights of embossed patterns were almost similar to those for minimum integral value of cavity pressures. The injection-compression molding process presents the opportunity to impart a soft-touch feeling of plastic parts printed with embossed patterns.
Investigation of Friction Noise in Ball Joint Under Edge Loading Condition
Kang, Jaeyoung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 779~784
DOI : 10.3795/KSME-A.2014.38.7.779
This study provided the analytical model describing the friction-induced noise in the ball joint system under the edge loading condition. The frictional and conformal contact kinematics between the spherical bearing and the hemispherical socket was derived and the dynamic equations of the perturbed motion were established. The numerical results revealed that the bending modes of the ball joint system can become unstable due to friction, and the axial load and contact stiffness strongly influenced the dynamic instability. In contrast, the tilting angle of the socket was not found to significantly contribute to the dynamic instability of the ball joint.
Evaluation of EtherCAT Clock Synchronization in Distributed Control Systems
Kim, Woonggy ; Sung, Minyoung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 785~797
DOI : 10.3795/KSME-A.2014.38.7.785
Support for the precise time synchronization of EtherCAT, known as distributed clock (DC), enables the design of highly synchronized operations in distributed real-time systems. This study evaluates the performance of the EtherCAT DC through extensive experiments in a real automation system. We constructed an EtherCAT control system using Xenomai and IgH EtherCAT stack, and analyzed the clock deviation for different devices in the network. The results of the evaluation revealed that the accuracy of the synchronized clock is affected by several factors such as the number of slave devices, period of drift compensation, and type of system time base. In particular, we found that careful decision regarding the system time base is required because it has a fundamental effect on the master operation, which results in significantly different performance characteristics.
Development of Indoor Locomotion Assistive Robot, Ball-Chair, for the Elderly
Kim, Woo-Yong ; Kim, Jung-Yup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 799~807
DOI : 10.3795/KSME-A.2014.38.7.799
This paper describes the development of an indoor locomotion assistive robot, Ball-Chair, comprising a novel drive system. This robot facilitates locomotion assistive operation in narrow spaces, in which common wheelchairs cannot move easily. The Ball-Chair has two main features: its structural feature and driving mechanism. The exoskeleton frames of the Ball-Chair have been designed with octagonal shapes resembling a circle, for minimizing its volume and weight. Additionally, all its driving parts (including the ball) are mounted within of the robot to enhance its safety. The Ball-Chair features a reverse ball-mouse driving mechanism comprising two driving omni-wheels in the x- and y-axes. By controlling the speed of each omni-wheel, a holonomic driving system that can facilitate omnidirectional locomotion has been achieved using only two wheels. The effective movement of the Ball-Chair in any direction within narrow indoor spaces was experimentally verified. The paper outlines the development procedure in detail.
Investigation of Residual Stress Distributions of Induction Heating Bended Austenitic Stainless Steel (316 Series) Piping
Kim, Jong Sung ; Kim, Kyoung Soo ; Oh, Young Jin ; Chang, Hyun Young ; Park, Heung Bae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 809~815
DOI : 10.3795/KSME-A.2014.38.7.809
The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects.
Interior Noise Characteristics of the Electric Trains in Gyeongchun Line
Ann, Yong Chan ; Lee, Jung Hyeok ; Kim, Seock Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 38, issue 7, 2014, Pages 817~822
DOI : 10.3795/KSME-A.2014.38.7.817
Since the opening of the double-track railway for the Gyeongchun local electric train and the semi-high speed train ITX, floating population between Seoul and Chuncheon has rapidly increased. This is attributable to the competitiveness of the railway service in terms of punctuality and safety of operation, mass transportation and low fare. However, many passengers have expressed strong dissatisfaction and displeasure towards the interior noise and its high rate of increase, particularly in tunnel sections. In this study, the interior noise characteristics of Gyeongchun local electric train and ITX were analyzed and compared. Noise levels, frequency spectrum and sound quality indices were compared for the open land, tunnel and bridge. Finally, from the noise levels depending on the location in the vehicle compartment, the noise transmission path was determined and a basic strategy for reducing the interior noise was developed.