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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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Joint Module with Joint Torque Sensor Having Disk-type Coupling for Torque Error Reduction
Min, Jae-Kyung ; Kim, Hwi-Su ; Song, Jae-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 133~138
DOI : 10.3795/KSME-A.2016.40.2.133
Force control and collision detection for a robot are usually conducted using a 6-axis force/torque sensor mounted at the end-effector. However, this scheme suffers from high-cost and the inability to detect collisions at the robot body. As an alternative, joint torque sensors embedded in each joint were used, which also suffered from various errors in torque measurement. To resolve this problem, a robot joint module with an improved joint torque sensor is proposed in this study. In the proposed torque sensor, a cross-roller bearing and disk-type coupling are added to prevent the moment load from adversely affecting the measurement of the joint torque under consideration. This joint design also aims to reduce the stress induced during the assembly process of the sensor. The performance of the proposed joint torque sensor was verified through various experiments.
Study of Mechanical and Hygroscopic Characteristics of Nanoclay/Epoxy Nanocomposites
Kim, Do Hyoung ; Kim, Jung Kyu ; Kim, Hak Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 139~145
DOI : 10.3795/KSME-A.2016.40.2.139
In this study, the moisture related hygroscopic characteristics and mechanical properties of epoxy-clay nanocomposites were investigated by experiments as a function of the weight fraction of nanoclay. The hygroscopic and mechanical properties including the moisture saturation amount, moisture diffusivity, adhesive strength, and tensile properties were obtained by moisture absorption test and various tensile tests, respectively. Also, the molecular dynamics (MD) simulation was devised to study of hygroscopic characteristics of nanocomposites and the results were compared to experimental results as a function of the nanoclay content. It was demonstrated that the proposed MD simulation technique can be successfully used for the prediction of the effects of the nanoclay on the moisture diffusion characteristics.
Optimization of Lightened Fiber-Reinforced Composite City & Trekking Bicycle Frame
Yoon, Won Sok ; Kim, Do Hyung ; Kim, Hak Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 147~156
DOI : 10.3795/KSME-A.2016.40.2.147
In this paper, optimal designs of bicycle frame were studied for weight reduction of bicycle using carbon-fiber-reinforced plastic (CFRP), glass-fiber-reinforced plastic (GFRP) and Kevlar-fiber-reinforced plastic (KFRP), respectively. Based on the anisotropic properties of FRP material, stacking angle and thickness optimization were performed under the safety reference of European committee for standardization (CEN) to ensure the stability of bicycle frame. Finally, performances of FRP bicycle frame was evaluated by digital logic method based on the optimized results of weight, strength properties and cost. Then, the optimized bicycle frame composed of each FRPs were evaluated and ranked by total performance values.
Simplified Model of Wheel Type Dog-Horse Robot to Reduce Dynamic Analysis Time
Kim, Young Jin ; Jung, Samuel ; Kim, Tae Yun ; Yoo, Wan Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 157~165
DOI : 10.3795/KSME-A.2016.40.2.157
In wartime conditionsmilitary combat vehicles are required to be driven on rough roads that have significant obstacles. A wheel type dog-horse robot with a rotary suspension system was applied to overcome the obstacles. To achieve real-time analysis, a simplified model was proposed by using velocity transformations. Through comparison with the multi-body dynamics model, the efficiency and accuracy of the proposed modeling was proven.
Development of Finite Element Ductile Tearing Simulation Model Considering Strain Rate Effect
Nam, Hyun Suk ; Kim, Ji Soo ; Kim, Jin Weon ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 167~173
DOI : 10.3795/KSME-A.2016.40.2.167
This paper proposes ductile failure simulation under high strain rate conditions using finite element (FE) analyses. In order to simulate a cracked component under a high strain rate condition, this paper applies the stress-modified fracture strain model combined with the Johnson/Cook model. The stress-modified fracture strain model determines the incremental damage in terms of stress triaxiality (
) and fracture strain (
) for a dimple fracture using the tensile test results. To validate the stress-modified fracture strain model under dynamic loading conditions, the parameters are calibrated using the tensile test results under various strain rates and the fracture toughness test results under quasi-static conditions. The calibrated damage model predicts the CT test results under a high strain rate. The simulated results were then compared with the experimental data.
A Study of Structural Stress Technique for Fracture Prediction of an Auto-Mobile Clutch Snap-Ring
Kim, Ju Hee ; Myeong, Man Sik ; Oh, Chang Sik ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 175~183
DOI : 10.3795/KSME-A.2016.40.2.175
The endurance reliability assessment of a highly complex mechanism is generally predicted by the fatigue life based on simple stress analysis. This study discusses various fatigue life assessment techniques for an automobile clutch snap ring. Finite element analyses were conducted to determine the structural stress on the snap ring. Structural stress that is insensitive in regards to the mesh size and type definition is presented in this study. The structural stress definition is consistent with elementary structural mechanics theory and provides an effective measure of a stress state that pertains to fatigue behavior of welded joints in the form of both membrane and bending components. Numerical procedures for both solid models and shell or plate element models are presented to demonstrate the mesh-size insensitivity when extracting the structural stress parameters. Conventional finite element models can be used with the structural stress calculations as a post-processing procedure. The two major implications from this research were: (a) structural stresses pertaining to fatigue behavior can be consistently calculated in a mesh-insensitive manner regardless of the types of finite element models; and (b) by comparing with the clutch snap-ring fatigue test data, we should predict the fatigue fractures of an automobile clutch snap ring using this method.
Investigation of Error Factors from an Impact Hammer Test for Developing a Statistic Based Technique for Model Updating
Lee, Su ; Lee, Jin Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 185~198
DOI : 10.3795/KSME-A.2016.40.2.185
In this work, experimental errors from an impact hammer test were investigated to develop a statistic-based technique for updating a finite element model. Digital signal processing was analyzed by using theoretical models and experiments when errors occurred during the experimental procedure. First, the duration time and peak level of the excitation signal, the stiffness and position of elastic springs connecting the specimen as well as the support, position and mass of the accelerometer were considered as error factors during the experiment. Then the picket fence effect, leakage, and exponential window function were considered as candidate error factors during the digital signal processing. Finally, methods to reduce errors are suggested.
Formulation of Friction Forces in LM Ball Guides
Oh, Kwang-Je ; Khim, Gyungho ; Park, Chun-Hong ; Chung, Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 199~206
DOI : 10.3795/KSME-A.2016.40.2.199
Linear motion (LM) ball guides with rolling contact are core units of feed-drive systems. They are widely applied for precision machinery such as machine tools, semiconductor fabrication machines and robots. However, the friction force induced from LM ball guides generates heat, which deteriorates positioning accuracy and incurs changes of stiffness and preload. To accurately analyze the effects and apply the results to precision machine design, mathematical modeling of the friction force is required. In this paper, accurate formulation of the friction force due to rolling, viscous, and slip frictions is conducted for LM ball guides. To verify the reliability of the developed friction model, experiments are performed under various assembly, load and velocity conditions. Effects of frictional components are analyzed through the formulated friction model.
An Optimal Frequency Condition for An Induction Hardening for An Axle Shaft using Thermal-Electromagnetic Coupled Analysis
Choi, Jin Kyu ; Nam, Kwang Sik ; Kim, Jae Ki ; Choi, Ho Min ; Lee, Seok Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 207~212
DOI : 10.3795/KSME-A.2016.40.2.207
High-frequency induction hardening (HFIH) is used in many industries and has a number of advantages, including reliability and repeatability. It is a non-contact method of providing energy-efficient heat in the minimum amount of time without using a flame. Recently, HFIH has been actively studied using the finite-element method (FEM), however, these studies only focused on the accuracy of the analysis. In this paper, we analyzed HFIH by using a variable frequency based on the conditions of the same shape and input power then comparing the analysis results to experimental results. The analysis and experimental results indicate that the hardening depths are approximately the same using the optimal frequency of 3kHz.
Passive Maglev Carrier Control with Consideration of Pitch Motion
Lee, Younghak ; Kim, Chang-Hyun ; Ha, Chang-Wan ; Park, Doh-Young ; Yang, Seok-Jo ; Lim, Jaewon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 213~220
DOI : 10.3795/KSME-A.2016.40.2.213
This research aims to develop core technologies for passive carrier (no power in carrier itself) transfer system. The technologies are passive levitation, propulsion, and guidance, which can be great benefits for semiconductor and display manufacturing industries. Passive maglev carrier is necessary to precise position control for quiet and stable transfer operation. However, the structural characteristics of carrier and the installation errors of gap sensors cause the pitch motion. Hence, the controller design in consideration of pitch motion is required. This study deals with the reduction control of carrier pitch motion. PDA controller and PDA controller with pitch control are proposed to compare the pitch angle analysis. The pitch angle and the levitation precision are measured by experiment. Finally, the optimized design of pitch controller is presented and the effects are discussed.
Study on Manufacturing Process of Hollow Main Shaft by Open Die Forging
Kwon, Yong Chul ; Kang, Jong Hun ; Kim, Sang Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 221~227
DOI : 10.3795/KSME-A.2016.40.2.221
The main shaft is one of the key components connecting the rotor hub and gear box of a wind power generator. Typically, main shafts are manufactured by open die forging method. However, the main shaft for large MW class wind generators is designed to be hollow in order to reduce the weight. Additionally, the main shafts are manufactured by a casting process. This study aims to develop a manufacturing process for hollow main shafts by the open die forging method. The design of a forging process for a solid main shaft and hollow shaft was prepared by an open die forging process design scheme. Finite element analyses were performed to obtain the flow stress by a hot compression test at different temperature and strain rates. The control parameters of each forging process, such as temperature and effective strain, were obtained and compared to predict the suitability of the hollow main shaft forging process. Finally, high productivity reflecting material utilization ratio, internal quality, shape, and dimension was verified by the prototypes manufactured by the proposed forging process for hollow main shafts.
Accuracy of Fire of a Mortar via Multibody Dynamics Analysis
Jin, Jae Hoon ; Jung, Samuel ; Kim, Tae Yoon ; Kim, Young Ku ; Ahn, Chang Gi ; Yoo, Wan Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 229~236
DOI : 10.3795/KSME-A.2016.40.2.229
For this research, the trajectory of a projectile was simulated via the multibody dynamics analysis of a self-propelled mortar. The dynamic model was composed of a mortar model and a vehicle model, and was simulated using the RecurDyn program. Interior ballistic was applied to the mortar model, and exterior ballistic was conducted by Matlab using the simulation results of the interior trajectory. Through repetitive Monte-Carlo simulations, the accuracy of the mortar was analyzed by considering variations in the aiming angle and vehicle dynamic response.
Study on the Linear Static Structural Analysis Error of Helical Compression Springs
Jang, Sang Chan ; Kang, Jung Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 2, 2016, Pages 237~244
DOI : 10.3795/KSME-A.2016.40.2.237
Helical compression springs have been widely used in industries. The springs should be verified through experiment whether the inherent characteristics of the spring can be maintained during the manufacturing process. Considerable time and expense is spent in the manufacturing process. Therefore, in this study, the structural integrity evaluation of a spring was conducted using linear static structural analysis. Verification and comparison of the experimental data were carried out using a variety of international industrial standards with the intent to prove the validity of this study. The spring model did not consider coil ends. As a result of conducting the structural analysis, the quality of the mesh was improved and the time needed to create an analytical model was reduced. The study indicated that Poisson's ratio had little influence on the result of the structural analysis. Additionally, the possibility of verifying the structural integrity evaluation by structural analysis was confirmed.