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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 25, Issue 12 - Dec 2001
Volume 25, Issue 11 - Nov 2001
Volume 25, Issue 10 - Oct 2001
Volume 25, Issue 9 - Sep 2001
Volume 25, Issue 8 - Aug 2001
Volume 25, Issue 7 - Jul 2001
Volume 25, Issue 6 - Jun 2001
Volume 25, Issue 5 - May 2001
Volume 25, Issue 4 - Apr 2001
Volume 25, Issue 3 - Mar 2001
Volume 25, Issue 2 - Feb 2001
Volume 25, Issue 1 - Jan 2001
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Development of a Piping Integrity Evaluation Simulator Based on the Hardware-in-the-Loop Simulation
Kim, Yeong-Jin ; Heo, Nam-Su ; Cha, Heon-Ju ; Choe, Jae-Bung ; Pyo, Chang-Ryul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1031~1038
DOI : 10.22634/KSME-A.2001.25.7.1031
In order to verify the analytical methods predicting failure behavior of cracked piping, full-scale pipe tests are crucial in nuclear power plant piping. For this reason, series of international test programs have been conducted. However, full-scale pipe tests require expensive testing equipment and long period of testing time. The objective of this paper is to develop a test system which can economically simulate the full-scale pipe test regarding the integrity evaluation. This system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system was developed for the integrity evaluation of nuclear piping based on the methodology of hardware-in-the-loop (HiL) simulation. Using this simulator, the piping integrity can be evaluated based on the elastic-plastic behavior of full-scale pipe, and the high cost full-scale pipe test may be replaced with this economical system.
Development of the Non-Contact Torque Sensor for EPAS Using Maluss Polarization Law
No, Byeong-Ok ; Park, Ho ; Gang, Pan-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1039~1046
DOI : 10.22634/KSME-A.2001.25.7.1039
Among the automotive steering systems, an Electric Power Assisted steering (EPAS) system utilizes an electronically controlled electric motor to provide steering assistance to the driver. The key components of the EPAS system are torque sensor, ECU (Electronic Control Unit), and DC Motor. The most important component of the EPAS is the torque sensor. The conventional torque sensor has complicated mechanical mechanism of torque detection. However, we suggest a non-contact torque sensor for EPAS using Maluss polarization law. It was found that the sensor exhibited not only excellent linearity but also superior characteristics of hysteresis, temperature and vibration.
Nano-Scale Observation of Fatigue Striations for Aluminum Alloy
Choe, Seong-Jong ; Gwon, Jae-Do ; Ishii, Hitoshi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1047~1054
DOI : 10.22634/KSME-A.2001.25.7.1047
Atomic Force Microscope (AFM) was used to study cross sectional profiles and dimensions of fatigue striations in 2017-T351 aluminum alloy. Their widths(SW) and heights (SH, SH(sub)h, SH(sub)ι) were measured from the cross sectional profiles of three-dimension AFM images. The following results that will be helpful to understand the fatigue crack growth mechanism were obtained. (1) The relation of SH=
(SW)(sup)1.2 was obtained. (2) The ratio of the striation height to its width SH/SW, SH(sub)h/SW and SH(sub)ι/SW did not depend on the stress intensity factor range ΔK and the stress ratio R( =P(sub)min/P(sub)max = K(sub)min/K(sub)max). (3) Effect of precipitate on the morphology of striation was changed by the relative dimensional difference between the striation width SW and the precipitates. From these results, the applicability of the AFM to nano-fractography is discussed.
Development of the Dynamic Photoelastic Hybrid Method for Propagating Interfacial Crack of Isotropic/Orthotropic Bi-materials
Hwang, Jae-Seok ; Sin, Dong-Cheol ; Kim, Tae-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1055~1063
DOI : 10.22634/KSME-A.2001.25.7.1055
When the interfacial crack of isotropic/orthotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for the bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid developed in this research are valid. Separating method of stress components is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 69∼71% of Rayleigh wave velocity of epoxy resin. The near-field stress components of bonded interface of bimaterial are similar with those of pure isotopic material and two dissimilar isotropic bimaterials under static or dynamic loading, but very near-field stress components of bonded interface of bimaterial are different from those.
Program Development for Material Degradation Evaluation Using Grain Boundary Etching Method
Yu, Hyo-Seon ; Baek, Seung-Se ; Na, Seong-Hun ; Kim, Jeong-Gi ; Lee, Hae-Mu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1064~1072
DOI : 10.22634/KSME-A.2001.25.7.1064
It is very important to evaluate material degradation like temper and carbide embrittlements to secure the reliable and efficient operational conditions and to prevent brittle failure in service. The extent of material deterioration can be accurately evaluated by mechanical test such as impact test or creep test. But it is almost impossible to sample a large specimen from in-service plants. Thus, the material degradation evaluation by a non-destructive method is earnestly required. Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However the program for material degradation evaluation using the grain boundary etching method(GEM) in Windows 98 domain doesnt be developed now. The aims of this paper are to develop the program and to complete the new master curve equations for the evaluation of material degradation on in-serviced high temperature components.
High-Strain-Rate Deformation of Fe-6.5wt.%Si Alloys using a Split Hopkinson Pressure Bar Technique
Yun, Yeong-Gi ; Yun, Hui-Seok ; Umakoshi, Yukichi ; Yasuda, Hiroyuki Y. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1073~1081
DOI : 10.22634/KSME-A.2001.25.7.1073
Many researches have published numerous papers about the high-strain-rate obtained from Split Hopkinson Pressure Bar(SHPB) tests. And 6.5wt%Si steel is widely known as an excellent magnetic material because its magnetostriction is nearly zero. Single crystals are prepared by the Floating Zone(FZ) method, which melts the alloy by the use of a high temperature electron beam in a pure argon gas condition. In this paper, the fracture behavior of the poly crystals and single crystals (DO
phase) of Fe-6.5wt%Si alloy by SHPB test is observed. The comparison of high-strain-rate results with static results was done. Obtained main results are as follows: (1) Fe-6.5wt%Si alloy has higher strength at high-strain-rate tensile. SHPB results of polycrystal are twice as high as static results. (2) From the fractography, the cleavage steps are remarkably reduced in the SHPB test compared with the static test.
A Study on Deformation and Strength of High-Strength Polymer Composites Using Automobiles
Im, Jae-Gyu ; Sin, Jae-Hun ; Park, Han-Ju ; Shoji, T. ; Takeda, H. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1082~1088
DOI : 10.22634/KSME-A.2001.25.7.1082
Nowadays study on recycling disused plastics for automobiles was lively progressed. Rubber and talcum powder was added to retrieve degradation of physical properties caused by recycling disused polypropylene. The effect of the temperature, the fatigue load and the loading speed on DEN(double edged notch) specimen which was made by the pp-rubber composites during fracture was studied by. DEN specimen was made on PP-rubber composites through the injection molding. With increasing temperature the fracture strength was linearly decreased and the fracture energy was increased by
and after that decreased. In the same temperature the fracture strength during increasing the notch radius was hardly increased. The fracture behaviour at low and high loading speed was different entirely. At high loading speed plastic region was small and fracture behaviour was seen to brittle fracture tendency. With increasing fatigue load fracture energy was first rapidly decreased and subsequently steady when radius of notch tip was 2mm, but Maximum load during fracture scarcely varied. The deformation mechanism of polypropylene-rubber composites during fracture was studied by SEM fractography. A strong plastic deformation of the matrix ahead of the notch/crack occurred. The deformation seem to be enhanced by a thermal blunting of the notch/crack.
Fatigue Life Predication of Impacted Laminates Under Block Loading
Kim, Jeong-Gyu ; Gang, Gi-Won ; Yu, Seung-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1089~1096
DOI : 10.22634/KSME-A.2001.25.7.1089
This paper presents the fatigue behavior of composite materials with impact-induced damage under 2 level block loading. For this purpose, the 2 level block loading fatigue tests were performed on the impacted composite laminate. The fatigue life of the laminate under the block loading is greatly influenced by the impact damage; the effect of impact damage can be characterized by the present impact damage parameter. Based on this parameter, the model is developed to predict the fatigue life under block loading and the results by this model agree well with experimental results regardless of applied impact energy. Also, stochastic model is established to describe the variation of cumulative damage behavior and fatigue life due to the material nonhomogeneity.
Vibration Control of Telescopic Handler Using Time Delay Control and Commandless Input Shaping Technique
Jang, Pyeong-Hun ; Park, Jun-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1097~1106
DOI : 10.22634/KSME-A.2001.25.7.1097
A telescopic handless is a kind of construction machinery for loading, carrying and unloading various cargos. A residual vibration of the boom, however, is often caused in carrying cargos to high workplace, especially in small motion and unloading operations, even when an expert of this machine handless the boom. To solve this vibrational problem, we applied TDC and newly proposed Commandless IST to the telescopic handler, and confirmed their effectiveness through experiments. These promising results show that the proposed control schemes can improve productivity, safety and ride comfort of the telescopic handler.
Prediction of Forming Limit Diagram Dependent on Strain History in Sheet Metal Forming
Kim, Nak-Su ; Choe, Gwang-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1107~1118
DOI : 10.22634/KSME-A.2001.25.7.1107
The forming limit diagram introduced by Keeler and Goodwin has been used generally to analyze the formability of sheet metal. However, path dependent forming limit curves based on the state of strain can be explained only by a single criterion which is based on the state. In this study, experimental forming limits in strain space of some metal sheets are transformed into forming limit curves in stress space. Effects of yield criterion are investigated in transforming the forming limit curves. Some important design aspects which are based on the close prediction of movements in forming limit curves during sheet forming are concluded.
Nonlinear Vibration Analysis of a Rotating Ring
Jeong, Jin-Tae ; Kim, Seon-Gyeong ; Lee, Su-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1119~1124
DOI : 10.22634/KSME-A.2001.25.7.1119
Nonlinear Vibration of a flexible circular ring is studied in this paper. Based upon the von Karman strain theory, the nonlinear governing equations are derived, in which the in-plane bending and extension displacements as well as the out-of-plane bending displacement are fully coupled. After discretizing the governing equations by the Galerkin approximation method, we obtain the linearlized equation by using the pertubation method. The results from the linearlized equations show that the in-plane displacement has effects on the natural frequencies of the out-of-plane displacement.
Dynamic Analysis of an Automatic Dynamic Balancer in a Rotor with the Bending Flexibility
Jeong, Jin-Tae ; Bang, In-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1125~1130
DOI : 10.22634/KSME-A.2001.25.7.1125
Dynamic behaviors of an automatic dynamic balancer are analyzed by a theoretical approach. Using the polar coordinates, the non-linear equations of motion for an automatic dynamic balancer equipped in a rotor with the bending flexibility are derived from Lagrange equation. Based on the non-linear equation, the stability analysis is performed by using the perturbation method. The stability results are verified by computing dynamic response. The time responses are computed from the non-linear equations by using a time integration method. We also investigate the effect of the bending flexibility on the dynamics of the automatic dynamic balancer.
Development of Vehicle Members with Spot Welded Thin-wall Section for Optimum Impart Characteristic -Based on Collapse Characteristics on the Varied Impact Velocities-
Yang, In-Yeong ; Cha, Cheon-Seok ; Gang, Jong-Yeop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1131~1138
DOI : 10.22634/KSME-A.2001.25.7.1131
This paper concerns the crashworthiness of the widely used vehicle structure, the spot welded hat and double hat shaped section members, which are excellent on the point of the energy absorbing capacity and low production cost. The target of this paper is to analyze the energy absorption capacity of the structure against the front-end collision, and to obtain useful information for designing stage. Changing the spot weld pitches on the flanges, the hat and double hat shaped section members were tested on the axial collapse loads in impact velocities of 4.72m/sec, 6.54m/sec, 7.19m/sec and 7.27m/sec. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA3D. The solutions are compared with results from the impact collapse experiments.
A Study on the Integrity Evaluation Method of Subclad Crack Under Pressurized Thermal Shock
Kim, Yeong-Jin ; Kim, Jin-Su ; Gu, Bon-Geol ; Choe, Jae-Bung ; Park, Yun-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1139~1146
DOI : 10.22634/KSME-A.2001.25.7.1139
The reactor pressure vessel(RPV) is usually cladded with stainless steel to prevent corrosion and radiation embrittlement, and a number of subclad cracks have been found during an in-service-inspection. These subclad cracks should be assured for a safe operation under normal conditions and faulted conditions such as pressurized thermal shock(PTS). Currently available integrity assessment procedure for an RPV, ASME Code Sec. XI, are built on the basis of linear fracture mechanics (LEFM). In PTS condition, however, thermal stress and mechanical stress give rise to high tensile stress at the cladding and elastic-plastic behavior is expected in this area. Therfore, ASME Code Sec. XI is overly conservative in assessing the structural integrity under PTS condition. In this paper, the fracture parameter (stress intensity factor, K, and RT(sub)NDT) from elastic analysis using ASME Sec. XI and finite element method were validated against 3-D elastic-plastic finite element analyses. The difference between elastic and elastic-plastic analysis became significant with increasing crack depth. Therfore, it is recommended to perform elastic-plastic analysis for the accurate assessment of subclad cracks under TPS which causes plastic deformation at the cladding.
Development of the DCPD Method Based on Finite Element Analysis for Measuring Semi-Elliptical Surface Cracks
Kim, Yeong-Jin ; Sim, Do-Jun ; Choe, Jae-Bung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1147~1154
DOI : 10.22634/KSME-A.2001.25.7.1147
One of major problems in analyzing failure mechanism of real components is the accurate measurement of crack size and shape. The DCPD(Direct Current Potential Drop) method has been widely used for the crack measurement of a structure and finite element analysis has been used for the derivation of calibration equations, which relates the potential drop with the crack depth. In this paper, finite element analyses were performed for semi-elliptical surface cracks with various crack shapes(a/c) and crack depths(a/t). As a result, a calibration equation has been derived for the measurement of a semi-elliptical surface crack in wide plates. Analytical results are compared with experimental results to evaluate the validity and the applicability of the derived equation. The proposed method is expected to provide efficient and accurate measurement of a surface crack during crack growth.
Ambiguity of Minimum Strain Energy Density Criterion and Maximum Minimum Strain Energy Density Criterion
Gu, Jae-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 7, 2001, Pages 1155~1162
DOI : 10.22634/KSME-A.2001.25.7.1155
Sihs minimum strain energy density criterion(SED) often used in the mixed mode problem has the ambiguity of the choice of minimum values. In this paper, as the method to solve the problem of SED, maximum minimum strain energy density criterion is proposed that the crack propagates in the direction of having the maximum among the minimum values of modified strain energy density factor(MS), i.e., sign(