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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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Fracture Mechanics Assessment for Different Notch Sizes Using Finite Element Analysis Based on Ductile Failure Simulation
Bae, Keun Hyung ; Jeon, Jun Young ; Han, Jae Jun ; Nam, Hyun Suk ; Lee, Dae Young ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 693~701
DOI : 10.3795/KSME-A.2016.40.8.693
In this study, notch defects are evaluated using fracture mechanics. To understand the effects of notch defects, FE analysis is conducted to predict the limit load and J-integral for middle-cracked and single-edge cracked plates with various sizes of notch under tension and bending. As the radius of the notch increases, the energy release rate also increases, although the limit load remains constant. The values of fracture toughness(
) of SM490A are determined for various notch radii through FE simulation instead of conducting an experiment. As the radius of the notch increases, the energy release rate also increases, together with a more significant increase in fracture toughness. To conclude, as the notch radius increases, the resistance to crack propagation also increases.
Kalman Filter-based Sensor Fusion for Posture Stabilization of a Mobile Robot
Jang, Taeho ; Kim, Youngshik ; Kyoung, Minyoung ; Yi, Hyunbean ; Hwan, Yoondong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 703~710
DOI : 10.3795/KSME-A.2016.40.8.703
In robotics research, accurate estimation of current robot position is important to achieve motion control of a robot. In this research, we focus on a sensor fusion method to provide improved position estimation for a wheeled mobile robot, considering two different sensor measurements. In this case, we fuse camera-based vision and encode-based odometry data using Kalman filter techniques to improve the position estimation of the robot. An external camera-based vision system provides global position coordinates (x, y) for the mobile robot in an indoor environment. An internal encoder-based odometry provides linear and angular velocities of the robot. We then use the position data estimated by the Kalman filter as inputs to the motion controller, which significantly improves performance of the motion controller. Finally, we experimentally verify the performance of the proposed sensor fused position estimation and motion controller using an actual mobile robot system. In our experiments, we also compare the Kalman filter-based sensor fused estimation with two different single sensor-based estimations (vision-based and odometry-based).
A Study on Prediction of Overriding Behavior Leading Vehicle in Train Collision
Kim, Jun Woo ; Koo, Jeong Seo ; Kim, Geo Young ; Park, Jeong Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 711~719
DOI : 10.3795/KSME-A.2016.40.8.711
In this study, we derived an theoretical equation, using a simplified spring-mass model for the rolling stock, to obtain the overriding behavior of a leading vehicle, which is considered as the main factor in train accidents. To verify the derived equation, we created a simple 2D model based on the theoretical model, and a simple 3D model considering the characteristics of the power bogie. We then compared the theoretical results with the simulation results obtained using LS-DYNA. The maximum relative derivations in the vertical displacements at the first end-buffer, which is the most important point in overriding, were 3.5 [%] and 1.7 [%] between the two results. Further, we evaluated collision-induced overriding displacements using the theoretical equation for a rubber draft gear, a hydraulic buffer under various collision conditions. We have suggested a theoretical approach for the realization of overriding collision accidents or the energy absorption design of the front end of trains.
Development of Dual Sensor for Prognosticating Fatigue Failure of Mechanical Structures
Baek, Dong-Cheon ; Park, Jong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 721~724
DOI : 10.3795/KSME-A.2016.40.8.721
Because of the inherent uncertainties caused by the manufacturing process variations, future loading conditions, and incomplete damage models, the lifetimes of mechanical structures under field conditions are significantly different from the results obtained in the laboratories. In this study, a dual sensor was developed to prognosticate the fatigue failure of structures under these uncertain conditions, and its effectiveness was demonstrated on a rectangular columnar structure under repeated uni-axial loading. The dual sensor is a slightly weaker structure embedded in the target structure, so that failure occurs in the sensor earlier than in the target structure. From the signal differences in the strain gauges in the embedded dual sensor, it is possible to differentiate between the normal status and warning status, even under variable loads.
A Study on Increasing Reliability of Braking Force Inspection During Regular Inspection of Vehicles
Oh, Sang Yeob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 725~729
DOI : 10.3795/KSME-A.2016.40.8.725
The regular inspection of vehicles that are in service in domestic country, i.e., vehicle safety and emission gas inspection have been forced by the korea transportation safety authority and a private servicing enterprise according to the vehicle administration law (1995). In the safety inspection process, which is developed by a compatible inspection system and method, every effort is made to increase the reliability of vehicle safety and the service quality, and to protecting national health. In this study, the reliability of the braking force inspection method in the current regular vehicle inspection was studied statistically by comparing the dynamic braking force inspection method with the static braking force inspection method. Further, the problems and characteristics of the current braking force inspection methods were analyzed. Form the results for the dynamic braking force inspection equipment (H), a mean correction factor (y=18.61+2.18x) was obtained for the axle braking force ratio according to vehicle entering velocity.
Hybrid UV Lithography for 3D High-Aspect-Ratio Microstructures
Park, Sungmin ; Nam, Gyungmok ; Kim, Jonghun ; Yoon, Sang-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 731~736
DOI : 10.3795/KSME-A.2016.40.8.731
Three-dimensional (3D) high-aspect-ratio (HAR) microstructures for biomedical applications (e.g., microneedle, microadhesive, etc.) are microfabricated using the hybrid ultraviolet (UV) lithography in which inclined, rotational, and reverse-side UV exposure processes are combined together. The inclined and rotational UV exposure processes are intended to fabricate tapered axisymmetric HAR microstructures; the reverse-side UV exposure process is designed to sharpen the end tip of the microstructures by suppressing the UV reflection on a bottom substrate which is inevitable in conventional UV lithography. Hybrid UV lithography involves fabricating 3D HAR microstructures with an epoxy-based negative photoresist, SU-8, using our customized UV exposure system. The effects of hybrid UV lithography parameters on the geometry of the 3D HAR microstructures (aspect ratio, radius of curvature of the end tip, etc.) are measured. The dependence of the end-tip shape on SU-8 soft-baking condition is also discussed.
Hydrophobic and Hydrophilic PDMS Sponges Prepared Through Physicochemical Treatments
Nam, Kyungmok ; Park, Sungmin ; Kim, Jonghun ; Yoon, Sang-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 737~742
DOI : 10.3795/KSME-A.2016.40.8.737
An elastomer (especially PDMS) sponge is considered to be a promising selective absorber in cleaning up oil spills. The performance of a PDMS sponge in capturing and separating oil from (sea) water depends on several parameters such as surface roughness, physicochemical treatments, and hydrostatic stability. Here, we first present a method of fabricating the PDMS sponges having numerous micro-sized pores that act as absorption and storage spaces for the target material, and then we report an experimental effort undertaken to control the surface physicochemistry (i.e., hydrophobicity or hydrophilicity) of the PDMS sponges by adjusting the size of the pores and the concentration of the surfactant (i.e., silwet L-77). From the experimental results, we develop an in-depth understanding of the mechanism for controlling the surface physicochemistry of PDMS using water-soluble micro-sized particles and a surfactant. The surface energy and absorbing behavior of the PDMS sponges are also extensively discussed.
Effect of Horizontal Load on the Performance of Track Roller
Kang, Bo-Sik ; Lee, Choong-Sung ; Kim, Yong-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 743~750
DOI : 10.3795/KSME-A.2016.40.8.743
Track rollers are the key parts that support the weight applied to the caterpillar track of construction machinery. The operating conditions of construction machinery are harsh; hence, the track rollers exposed to these conditions can experience failures such as oil leakage and breakdown of the machine, because of impacts during driving. The failure of track-rollers has a major effect on the operation of the construction machinery. Therefore, each manufacturer tries to evaluate the performance of their products by conducting a self-test. However, only the vertical loads applied to the track rollers are considered in most of the self-tests. This method has the problem of ignoring the horizontal loads that are applied to the track rollers while rotary driving, and hence it does not create the practical operating condition of the construction machinery. In this study, we have determined the experimental conditions that effectively consider the magnitudes of the vertical and horizontal loads. The results of simulations and experiments conducted to assess the influence of horizontal loads on the failure of track rollers are presented in this paper.
Prediction of Reliability of Fatigue Limit of S34MnV Steel for Marine Diesel Engine Crank Throw Components
Kim, Seon Jin ; Kong, Yu Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 751~757
DOI : 10.3795/KSME-A.2016.40.8.751
The aim of this study is to estimate the reliability of fatigue limit of the material used for crank throw components according to the staircase method. The material used for crank throw components is forged S34MnV grade steel, which is heat treated by normalizing and tempering. In this work, to predict the reliability of the design fatigue strength, axially loaded constant amplitude fatigue testing was conducted. The test specimens were loaded with an axial push/pull load with a mean stress of 0 MPa, which corresponds to a stress ratio of R=-1. The fatigue test results were evaluated by Dixon-Mood formulas. The values of mean fatigue strength and standard deviation predicted by the staircase method were 296.3 MPa and 10.6 MPa, respectively. Finally, the reliability of the fatigue limit in some selected probability of failure is predicted. The proposed method can be applied for the determination of fatigue strength for design optimization of the forged steel.
Development Test for Flexible PTO Shaft Made of Ti Alloy for Aircraft
Lee, Joo Hong ; Kang, Bo Sik ; Yu, Hyun Seok ; Lee, Ji Man ; Cho, Hae Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 40, issue 8, 2016, Pages 759~765
DOI : 10.3795/KSME-A.2016.40.8.759
The PTO (Power Take-Off) shaft for aircraft, with welded construction using multiple thin membranes, was developed in the 1950s to improve the elasticity of the part. As it is lightweight, stable at high speeds, and has good flexibility, it is used in most of the fighter aircraft. It connects the AMAD (aircraft mounted accessory drive) gearbox with the EMAD (engine mounted accessory drive) gearbox and transmits the rotational power between them. It operates in the high speed range of 10,000-18,000 rpm. In this study, the safety of the PTO shaft made of Ti alloy was investigated using finite element analysis, and the ability to transmit power was demonstrated through a high-cycle fatigue test conducted in a laboratory. Further, the life of the ball joints of the aircraft under high-cycle fatigue test conditions was predicted, and the wear characteristics were analyzed.