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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 40, Issue 9 - Sep 2016
Volume 40, Issue 8 - Aug 2016
Volume 40, Issue 7 - Jul 2016
Volume 40, Issue 6 - Jun 2016
Volume 40, Issue 5 - May 2016
Volume 40, Issue 4 - Apr 2016
Volume 40, Issue 3 - Mar 2016
Volume 40, Issue 2 - Feb 2016
Volume 40, Issue 1 - Jan 2016
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An Analytical Study on Crack Behavior Inside Standard Compact Tension Specimen with Holes
Lee, Jung Ho ; Cho, Jae Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 531~537
DOI : 10.3795/KSME-A.2016.40.6.531
The damage and fracture of machine or structure are caused by the crack happened from the defect existed at the inside of material. The properties of crack propagation and growth characteristic must be considered because there are many cases at which these cracks are densely existed. Therefore, this study investigates the fracture property due to the position of crack and hole inside the standard compact tension (C. T.) specimen. When the concentrated load is applied eccentrically at the standard C. T. specimen, the fracture mechanical behavior due to the existence or non-existence and the position of hole near crack is investigated. As the result of analysis study, model 3 (in case of the distance of 2mm on the horizontal direction between the end part and hole as the specimen model existed with one hole near the crack) has the maximum deformation, stress and deformation energy of the most values among three models. As the distance between the crack and hole inside the specimen becomes nearer, the maximum stress becomes higher in cases of three models. Apart from the number of holes, it is seen that the maximum stress becomes higher near the crack when the hole exists near the crack inside the specimen. If the hole inside the machine or the mechanical structure is punctured by using the result of this study, it is thought that the occurred breakage or breakdown can be prevented by reducing the fracture stress happened at the specimen.
Evaluation of the Effect of Fracture Resistance Curve Change Owing to the Presence or Absence of Side Groove in C(T) Specimen on Finite Element Failure Model Parameter Determination
Kim, Hune-Tae ; Ryu, Ho-Wan ; Kim, Yun-Jae ; Kim, Jong-Sung ; Choi, Myung-Rak ; Kim, Jin-Weon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 539~546
DOI : 10.3795/KSME-A.2016.40.6.539
In this paper, the effect of J-R curve changes on the determination of parameters in a failure model owing to the presence or absence of a side groove in a C(T) specimen is investigated. A stress-modified fracture strain model is implemented for FE damage simulations. C(T) specimens were taken from SA508 grade 1a low-alloy steel piping material, and some of them were processed with a side groove. Fracture toughness tests were performed at room temperature and at
. The parameters of the failure model were determined by damage simulations using the J-R curves obtained from the tests. Finally, the results show that the determination of failure model parameters is not affected by variations in J-R curves owing to the presence or absence of a side groove.
A Wheel Wear Analysis of Railway Vehicle on a Curved Section
Kang, Juseok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 547~555
DOI : 10.3795/KSME-A.2016.40.6.547
The wheel wear of a railway vehicle is mainly generated when maneuvering on a curved track. The change in the wheel profile affects the dynamic stability of the vehicle. In this analysis, the wheel wear volume was calculated while changing the velocity and radius of the curve to analyze the wear characteristics of a wheel at a curved section. The wear index was calculated from a vehicle dynamic analysis based on a multibody dynamics analysis and wear volume from a wear model by British Rail Research. The wear volume at a radius of 300 m is dominant compared with other radii. The wear volume was calculated by assigning different coefficients of friction to the tread and flange of the wheel to investigate the effect of lubrication on the wear characteristics. The effect of the improvement by lubrication is calculated by varying the radius of the track, and is assessed on an actual urban railway section.
Efficiency Analysis of a Wave Power Generation System by Using Multibody Dynamics
Kim, Min Soo ; Sohn, Jeong Hyun ; Kim, Jung Hee ; Sung, Yong Jun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 557~563
DOI : 10.3795/KSME-A.2016.40.6.557
The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system.
Macro and Microscopic Investigation on Fracture Specimen of Alloy 617 Base Metal and Weldment in Low Cycle Fatigue Regime
Kim, Seon Jin ; Dewa, Rando Tungga ; Kim, Woo Gon ; Kim, Eung Seon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 565~571
DOI : 10.3795/KSME-A.2016.40.6.565
This paper investigates macro- and microscopic fractography performed on fracture specimens from low cycle fatigue (LCF) testings through an Alloy 617 base metal and weldments. The weldment specimens were taken from gas tungsten arc welding (GTAW) pad of Alloy 617. The aim of the present study is to investigate the macro- and microscopic aspects of the low cycle fatigue fracture mode and mechanism of Alloy 617 base metal and GTAWed weldment specimens. Fully axial total strain controlled fatigue tests were conducted at room temperature with total strain ranges of 0.6, 0.9, 1.2 and 1.5%. Macroscopic fracture surfaces of Alloy 617 base metal specimens showed a flat type normal to the fatigue loading direction, whereas the GTAWed weldment specimens were of a shear/star type. The fracture surfaces of both the base metal and weldment specimens revealed obvious fatigue striations at the crack propagation regime. In addition, the fatigue crack mechanism of the base metal showed a transgranular normal to fatigue loading direction; however, the GTAWed weldment specimens showed a transgranular at approximately
to the fatigue loading direction.
Reliability Assessment of Impact Tensile Testing Apparatus using a Drop-bar Striker for Intermediate Strain-rate Range and Evaluation of Dynamic Deformation Behaviors for a Carbon Steel
Bae, Kyung Oh ; Kim, Dae Woong ; Shin, Hyung Seop ; Park, Lee Ju ; Kim, Hyung Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 573~579
DOI : 10.3795/KSME-A.2016.40.6.573
Studies on the deformation behavior of materials subjected to impact loads have been carried out in various fields of engineering and industry. The deformation and fracture of members for these machines/structures are known to correspond to the intermediate strain-rate region. Therefore, for the structural design, it is necessary to consider the dynamic deformation behavior in these intermediate strain-rate ranges. However, there have been few reports with useful data about the deformation and fracture behavior at intermediate strain-rate ranges. Because the intermediate strain-rate region is located between quasi-static and high strain-rate regions, it is difficult to obtain the intermediate strain-rate using conventional reasonable test equipment. To solve this problem, in this study, the measurement reliability of the constructed drop-bar impact tensile test apparatus was established and the dynamic behavior at the intermediate strain-rate range of carbon steels was evaluated by utilizing the apparatus.
Development of a Non-contact Liquid Dispenser for High Contents Screening System
Cho, Seong J. ; Kim, Intae ; Lim, Geunbae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 581~585
DOI : 10.3795/KSME-A.2016.40.6.581
Nowadays medical treatment service increase due to ageing population and improving the quality of life. Accordingly it is predicted that drug discovery market will expansion continuously. Therefore it is necessary that profit creation by drug discovery on the global market is important. HCS(High Contents Screening) has been emerging as a potential method to solve problems of the present drug discovery. This research is about liquid dispenser for HCS. The purpose of this research is to manufacture high performance liquid dispenser for HCS. The dispenser is designed to control 5 liquids separately. The liquid contact parts are designed disposably, biocompatibly and chemically inertly. Air curtain is equipped at the side of tip to dispense very small liquid volume and to prevent hanging drop on tip. Valving is performed by just controlling the pressure of the pressure driven pump without valve.
An Efficient Constraint Boundary Sampling Method for Sequential RBDO Using Kriging Surrogate Model
Kim, Jihoon ; Jang, Junyong ; Kim, Shinyu ; Lee, Tae Hee ; Cho, Su-gil ; Kim, Hyung Woo ; Hong, Sup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 587~593
DOI : 10.3795/KSME-A.2016.40.6.587
Reliability-based design optimization (RBDO) requires a high computational cost owing to its reliability analysis. A surrogate model is introduced to reduce the computational cost in RBDO. The accuracy of the reliability depends on the accuracy of the surrogate model of constraint boundaries in the surrogated-model-based RBDO. In earlier researches, constraint boundary sampling (CBS) was proposed to approximate accurately the boundaries of constraints by locating sample points on the boundaries of constraints. However, because CBS uses sample points on all constraint boundaries, it creates superfluous sample points. In this paper, efficient constraint boundary sampling (ECBS) is proposed to enhance the efficiency of CBS. ECBS uses the statistical information of a kriging surrogate model to locate sample points on or near the RBDO solution. The efficiency of ECBS is verified by mathematical examples.
Bearing Life Evaluation of Automotive Wheel Bearing Considering Operation Loading and Rotation Speed
Lee, Seung Pyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 595~602
DOI : 10.3795/KSME-A.2016.40.6.595
An automotive wheel bearing is important part that translates rotating motion and bears vehicle weight. Recently, in accordance with the demands for
emission reduction and fuel economy regulation, the requirements for the weight reduction and miniaturization of vehicles has increased. Therefore, life evaluation technology of the bearings has increased in necessity. Since the bearing life is affected by many parameters such as bearing geometry, bearing specifications, and vehicle specifications, it is difficult to predict. In this paper, the bearing life was tested by varying the applied load and rotation speed and comparing them with the basic rating life and modified rating life that were suggested in ISO standards. From the results, it was found that there was a difference between the test life and theoretical life and modified rating life than basic rating life was to be relatively well predicted by test life.
Optimization of Down-the-Hole Hammer Using Experimental Design Method
Hwang, Un Kyoo ; Lim, Jong Hyuk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 603~611
DOI : 10.3795/KSME-A.2016.40.6.603
Research and development of mineral-resource-related products has progressed with the increased need to develop mineral resources. The DTH hammer is a resultant product. However, owing to particular work conditions of underground drilling, it is difficult to obtain direct data on the DTH hammer. A DTH drill rig requires a significant amount of money and time for actual testing. This thesis aimed to resolve this problem by using CAE. In a previous paper, the structure of the DTH hammer and its movement were analyzed, and a standard model based on simulation was proposed. Then, experimentation and comparison verification were conducted. In this paper, by using an experimental design method, we derived a control factor of the impact force and efficiency of the DTH hammer and attempted to optimize the design. As a result, the impact energy increased by 14.9%, and the efficiency increased by 3.3%.
Experimental Study of Operating Parameters for Pneumatic Control Valve in Abnormal Conditions
Kim, Yang-seok ; Kim, Dae-woong ; Lee, Byoung-oh ; Jeoung, Rae-hyuk ; Lee, Seung-ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 6, 2016, Pages 613~619
DOI : 10.3795/KSME-A.2016.40.6.613
A pneumatic control valve performs a major role in controlling the flow of a system or the level of a key tank in many power plants, and its performance should be guaranteed during the plant's lifetime. Its operation starts by supplying air to the pneumatic actuator or by exhausting the air from the actuator. To control the valve position, the amount of air supply or exhaust is adjusted by a control loop where various accessaries are equipped. In this paper, air leakage in the air supply line, changes in the valve packing force, and false adjustments of zero and the span of the positioner are simulated and analyzed using a 2-in pneumatic valve with a position control loop including an I/P converter and positioner, where the valve position is controlled within
of the control pressure at 67% opening position.