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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 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
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A Optimal 3D FE Model for Evaluation of Peening Residual Stress Under Angled Multi-impacts
Hyun, Hong-Chul ; Kim, Tae-Hyung ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 125~135
DOI : 10.3795/KSME-A.2012.36.2.125
The FE model for shot peening often assume that shots impact vertically on the engineering parts to generate compressive residual stresses. However, the shots obliquely impact on the surface in actual peening. In this work, we propose a 3D finite element (FE) model for evaluation of residual stress under angled shot peening. Using the FE model for angled multi-impact, we examine the effects of factors such as impact angle, impact pattern and the number of shots. Plastic deformation of shot is also considered. To validate the model, we then compare the FE solution with experimental result by X-ray diffraction (XRD). The proposed model will be a base of 3D multi-impact FE model with diverse impact angles.
Welding Residual Stress Distributions for Dissimilar Metal Nozzle Butt Welds in Pressurized Water Reactors
Kim, Ji-Soo ; Kim, Ju-Hee ; Bae, Hong-Yeol ; Oh, Chang-Young ; Kim, Yun-Jae ; Lee, Kyung-Soo ; Song, Tae-Kwang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 137~148
DOI : 10.3795/KSME-A.2012.36.2.137
In pressurized water nuclear reactors, dissimilar metal welds are susceptible to primary water stress corrosion cracking. To access this problem, accurate estimation of welding residual stresses is important. This paper provides general welding residual stress profiles in dissimilar metal nozzle butt welds using finite element analysis. By introducing a simplified shape for dissimilar metal nozzle butt welds, changes in the welding residual stress distribution can be seen using a geometry variable. Based on the results, a welding residual stress profile for dissimilar metal nozzle butt welds is proposed that modifies the existing welding residual stress profile for austenitic pipe butt welds.
Calculation of Intensity Factors Using Weight Function Theory for a Transversely Isotropic Piezoelectric Material
Son, In-Ho ; An, Deuk-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 149~156
DOI : 10.3795/KSME-A.2012.36.2.149
In fracture mechanics, the weight function can be used for calculating stress intensity factors. In this paper, a two-dimensional electroelastic analysis is performed on a transversely isotropic piezoelectric material with an open crack. A plane strain formulation of the piezoelectric problem is solved within the Leknitskii formalism. Weight function theory is extended to piezoelectric materials. The stress intensity factors and electric displacement intensity factor are calculated by the weight function theory.
Heuristic Method for RAM Design of Multifunctional System
Han, Young-Jin ; Kim, Hee-Wook ; Yun, Won-Young ; Kim, Jong-Woon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 157~164
DOI : 10.3795/KSME-A.2012.36.2.157
When designing a multifunctional system consisting of many components performing many functions or missions, it is important to determine the reliability, availability, and maintainability (RAM) of the system and components, and we consider system availability to be the optimization criterion. For given intervals of mean time between failure (MTBF) and mean time to repair (MTTR) of the components, we want to determine the values of MTBF and MTTR for all components that satisfy the target availability. A heuristic method is proposed for finding near-optimal solutions through simulation. We also study numerical examples to check effects of model parameters on the optimal solutions.
Analytical Sensitivity Analysis of Geometric Errors in a Three-Axis Machine Tool
Park, Sung-Ryung ; Yang, Seung-Han ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 165~171
DOI : 10.3795/KSME-A.2012.36.2.165
In this paper, an analytical method is used to perform a sensitivity analysis of geometric errors in a three-axis machine tool. First, an error synthesis model is constructed for evaluating the position volumetric error due to the geometric errors, and then an output variable is defined, such as the magnitude of the position volumetric error. Next, the global sensitivity analysis is executed using an analytical method. Finally, the sensitivity indices are calculated using the quantitative values of the geometric errors.
Matching Technology Between Nip Roll Characteristics and Quality of Print Pattern in Roll-to-Roll Printed Electronics Systems
Choi, Jea-Won ; Shin, Kee-Hyun ; Lee, Chang-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 173~178
DOI : 10.3795/KSME-A.2012.36.2.173
Currently, active research is being performed on printing of electronic devices such as RFID devices, flexible displays, solar cells, and e-paper. This technique has several advantages over existing technologies such as lithography and etching. In particular, RFID devices, flexible displays, solar cells, and e-paper require flexibility and a mass production system. Thus, attention is being focused on the roll-to-roll process. High quality should be guaranteed in the roll-to-roll printed electronics systems, and good thickness and roughness qualities must be ensured. Experimental design was applied to this problem to analyze the main effects and interaction effects of various factors. Matching technology between the nip roll characteristics and the quality of the print pattern in roll-to-roll printed electronics systems was proposed to improve the printing quality.
Prediction of Formability of Aluminum Alloy 5454 Sheet
Kim, Chan-Il ; Yang, Seung-Han ; Kim, Young-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 179~186
DOI : 10.3795/KSME-A.2012.36.2.179
In the automobile industry, reducing the weight is the most important objective for reducing air pollution and improving the fuel efficiency. For this reason, the application of aluminum sheets is increasing. When the sheets are applied to the automobile, using inappropriate variables for the material, product design, and press processing can generate tearing, wrinkling, and spring-back problems, which are the main types of failure in the manufacturing process. Therefore, it is necessary to reduce these failures by harmonizing the many variables and strictly managing the processes. In this research, we study the theoretical plasticity instability of Al5454 and obtain the forming limit diagram (FLD) using MATLAB. Moreover, we compare the theoretical FLD with an experimental FLD obtained from a stretching test.
Hierarchical Finite-Element Modeling of SiC
/Al2124-T4 Composites with Dislocation Plasticity and Size-Dependent Failure
Suh, Yeong-Sung ; Kim, Yong-Bae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 187~194
DOI : 10.3795/KSME-A.2012.36.2.187
The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of
/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.
Development of Hole Inspection Program using Touch Trigger Probe on CNC Machine Tools
Lee, Chan-Ho ; Lee, Eung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 195~201
DOI : 10.3795/KSME-A.2012.36.2.195
According to many customers' requests, optical measurement module (OMM) applications using automatic measuring devices to measure the machined part rapidly on a machine tool have increased steeply. Touch trigger probes are being used for job setup and feature inspection as automatic measuring devices, and this makes quality checking and machining compensation possible. Therefore, in this study, the use of touch trigger probes for accurate measurement of the machined part has been studied and a macro program for a hole measuring cycle has been developed. This hole is the most common feature to be measured, but conventional methods are still not free from measuring error. In addition, the eccentricity change of the least square circle was simulated according to the roundness error in a hole measurement. To evaluate the reliability of this study, the developed hole-measuring program was executed to measure the hole plate on the machine and verify the roundness error in the eccentricity simulation result.
Fatigue Safe Life Evaluation of Rotating Swashplate of Helicopter Main Rotor Control System
Kim, Dong-Chul ; Lee, Pan-Ho ; Kang, Shin-Hyun ; Choi, Young-Don ; Kim, Tae-Joo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 203~210
DOI : 10.3795/KSME-A.2012.36.2.203
The main rotor control system is an important structural part of a helicopter that manages the thrust and control force of the helicopter. The main rotor control system consists of a swashplate assembly, scissor assembly, pitch rod assembly, guide, etc. The main rotor control system must endure various loads, such as the thrust and control force, and must meet the optimized fatigue safety life. The rotating swashplate is an important structure influenced by the pitch rod load and rotating scissor load. In this paper, the accuracy of a result about the rotating swashplate part of the main rotor control system is proven through comparison between fatigue test and FEM results. Based on this result, we estimate the lifetime and deduce the fatigue safe lifetime.
Design of Battery-Supporting Structure for Reducing Deflection of On-Line Electric Vehicles
Park, Hong-Ik ; Yoo, Ji-Sue ; Lee, Jun-Young ; Lee, Sang-Beom ; Yim, Hong-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 211~216
DOI : 10.3795/KSME-A.2012.36.2.211
This paper presents methods to reduce the deflection of the battery-supporting structure on on-line electric vehicles (OLEVs). First, by testing various battery locations, a location is found that increases the dynamic stiffness of the OLEV. Second, static analysis is conducted to analyze the maximum deflection caused by the battery weight. In order to reduce the amount of deflection, the contributions of the battery-supporting structures are analyzed, and reinforcements are inserted. Then, another static analysis is conducted to compare the results of the base model and modified model. Consequently, through the static analysis, both the base model and modified model are similarly improved in terms of deflection, but the modified model is better than the base model at reducing the mass.
Experimental Study of Internal Distribution of Temperature and Relative Humidity in Notebook LCD Module
Kim, Tae-Woo ; Kim, Gi-Bin ; Lee, Jae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 217~221
DOI : 10.3795/KSME-A.2012.36.2.217
As a part of basic research to improve screen quality, which deteriorates when strain occurs within optical sheets in LCD modules for laptop computers, a measurement system is needed to analyze the influence of heat and moisture, which are the main factors causing the strain. It is assumed that the existence of an air gap less of than 0.5 mm inside the LCD module causes humid air from outside to permeate through the module. To investigate this phenomenon, in this study a thin printed circuit board (PCB) of compact sensors that measure temperature and humidity is inserted into LCD modules, and thus, the changes in temperature and humidity can be analyzed in real time. The results can be used as basic data for simulation of the deformation behavior and structural design of LCD modules in the future.
Estimation and Application of Reliability Values for Strength of Material Following Gamma Distribution
Park, Sung-Ho ; Kim, Jae-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 223~230
DOI : 10.3795/KSME-A.2012.36.2.223
The strength of brittle material has commonly been characterized by a normal distribution or Weibull distribution, but it may fit the gamma distribution for some material. The use of an extreme value distribution is proper when the largest values of a set of stresses dominate the failure of the material. This paper presents a formula for reliability estimation based on stress-strength interference theory that is applicable when the strength of material is distributed like a gamma distribution and the stress is distributed like an extreme value distribution. We verified the validity of the equation for the reliability estimation by examining the relationships among the factor of safety, the coefficient of variation, and the reliability. The required minimum factor of safety and the highest allowable coefficient of variation of stress can be estimated by choosing an objective reliability and estimating the reliabilities obtained for various factors of safety and coefficients of variation.
DFSS-Based Design of a Hall-Effect Rotary Position Sensor
Kim, Jae-Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 231~236
DOI : 10.3795/KSME-A.2012.36.2.231
This work presents the application of the DFSS (Design for Six Sigma) methodology to optimizing both the linearity and the sensitivity of the output voltage of a Hall-effect rotary position sensor. To this end, the dimensions and relative positions of a permanent magnet with reference to a Hall sensor are selected as the design factors for a full factorial design. In order to evaluate the output voltage of the rotary position sensor at each run in the experimental design, analytical solutions to the magnetic flux density were obtained using the Biot-Savart law and the relations between the magnetic flux density and the output voltage intrinsic to a Hall sensor. Through measurements of the improved output voltage of the rotary position sensors manufactured using the optimized design factors, the proposed method is shown to be simple and practical.
Design of Two-DOF Optimal Controller for Strip Gage and Tension Control of Cold Tandem Mills Using Reference Shaping Filter and Disturbance Observer
Hong, Wan-Kee ; Kang, Hyun-Seok ; Hwang, I-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 2, 2012, Pages 237~244
DOI : 10.3795/KSME-A.2012.36.2.237
This paper studies the design of a two-DOF optimal controller for the strip gauge-tension of cold tandem mill processes, that uses a reference shaping filter and a disturbance observer. First, a mathematical model of the strip gauge and tension system is constructed using the gauge meter equation and Hooke's law, respectively. Next, a two-DOF controller considering of a feedforward controller and a feedback controller is designed. The former is based on the reference shaping filter and the disturbance observer, and the latter is based on the ILQ optimal control algorithm. Finally, it is shown through a computer simulation that the proposed optimal controller is able to improve the strip gauge accuracy and the tension variation more than the conventional MV-AGC controller.