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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 31, Issue 12 - Dec 2007
Volume 31, Issue 11 - Nov 2007
Volume 31, Issue 10 - Oct 2007
Volume 31, Issue 9 - Sep 2007
Volume 31, Issue 8 - Aug 2007
Volume 31, Issue 7 - Jul 2007
Volume 31, Issue 6 - Jun 2007
Volume 31, Issue 5 - May 2007
Volume 31, Issue 4 - Apr 2007
Volume 31, Issue 3 - Mar 2007
Volume 31, Issue 2 - Feb 2007
Volume 31, Issue 1 - Jan 2007
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Nonlinearity of Biodynamic Response to Shock-Type Vertical Whole-Body Vibration
Ahn Se-Jin ; Griffin Michael J. ; Yoo Wan-Suk ; Jeong, Weui-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 145~151
DOI : 10.3795/KSME-A.2007.31.2.145
Impulsive excitation on vehicle produces shock-type vibration on the seat, which has major frequencies and damping ratios dependent on the characteristics of the suspension, the tire, the seat cushion and so on. The response of single degree of freedom model to a half-sine force input was considered as simple shock-type vibration signal. Quasi-apparent-mass for fifteen subjects was measured with the shock-type vibration generated on a rigid seat mounted on the simulator, so its nonlinearity was apparently found over 6.3 Hz according to the difference of magnitude of the shock.
Vibration and Stability Control of Rotating Composite Shafts via Collocated Piezoelectic Sensing and Actuation
Jeong, Nam-Heui ; Kang, Ho-Shik ; Yoon, Il-Sung ; Song, Oh-Seop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 152~159
DOI : 10.3795/KSME-A.2007.31.2.152
A study on the control of free vibration and stability characteristics of rotating hollow circular shafts subjected to compressive axial forces is presented in this paper. Both passive structural tailoring technique and active control scheme via collocated piezoelectric sensing and actuation are used in the study Gyroscopic and centrifugal forces combined with the compressive axial force contribute to the occurrence of divergence and flutter instabilities of the rotating shaft. The dual methodology based on the passive and active control schemes shows a high degree of efficiency toward postponement of these instabilities and expansion of the domain of stability of the system. The structural model of the shaft is based on an advanced thin-walled beam structure that includes the non-classical effects of transverse shear, anisotropy of constituent materials and rotatory inertia.
Creep-Life Prediction and Its Error Analysis by the Time Temperature Parameters and the Minimum Commitment Method
Yin, Song-Nan ; Ryu, Woo-Seog ; Yi, Won ; Kim, Woo-Gon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 160~165
DOI : 10.3795/KSME-A.2007.31.2.160
To predict long-term creep life from short-term creep life data, various parametric methods such as Larson-Mille. (L-M), Orr-Sherby-Dorn (O-S-D), Manson-Haferd (M-H) parameters, and a Minimum Commitment Method (MCM) were suggested. A number of the creep data were collected through literature surveys and experimental data produced in KAERI. The polynomial equations for type 316LN SS were obtained by the time-temperature parameters (TTP) and the MCM. Standard error (SE) and standard error of mean (SEM) values were obtained and compared with the each method for various temperatures. The TTP methods showed good creep-life prediction, but the MCM was much superior to the TTP ones at
. It was found that the MCM were lower in the SE values when compared to the TTP methods.
Static and Fatigue Fracture Assessment of Hybrid Composite Joint for the Tilting Car Body
Jung, Dal-Woo ; Kim, Jung-Seok ; Seo, Sueng-Il ; Jo, Se-Hyun ; Choi, Nak-Sam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 166~173
DOI : 10.3795/KSME-A.2007.31.2.166
Fatigue fracture behavior of a hybrid bolted joint was evaluated in comparison to the case of static fracture. Two kinds of specimens were fabricated for the mechanical tests; a hybrid bolted joint specimen for the shear test and a hybrid joint part specimen applied in the real tilting car body for the bending test. Characteristic fracture behaviors of those specimens under cyclic toads were obviously different from the case under static loads. For the hybrid bolted joint specimen, static shear loading caused the fracture of the bolt body itself in a pure shear mode, whereas cyclic shear loading brought about the fracture at the site of local tensile stress concentration. For the hybrid joint part specimen, static bend loading caused the shear deformation and fracture in the honeycomb core region, while cyclic bend loading did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.
Dynamic Constitutive Equations of Auto-Body Steel Sheets with the Variation of Temperature (I) - Dynamic Material Characteristics with the Variation of Temperature -
Lee, Hee-Jong ; Song, Jung-Han ; Park, Sung-Ho ; Huh, Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 174~181
DOI : 10.3795/KSME-A.2007.31.2.174
This paper is concerned with the thermo-mechanical behavior of steel sheet for an auto-body including temperature dependent strain rate sensitivity. In order to identify the temperature-dependent strain rate sensitivity of SPRC35R, SPRC45E and TRIP60, uniaxial tensile tests are performed with the variation of the strain rates from 0.001/sec to 200/sec and the variation of environmental temperatures from
. The thermo-mechanical response at the quasi-static state is obtained from the static tensile test and that at the intermediate strain rate is obtained from the high speed tensile test. Experimental results show that the variation of the flow stress and fracture elongation becomes sensitive to the temperature as the strain rate increases. It is observed that the dynamic strain aging occurs with TRIP60 at the temperature above
. Results also indicate that the flow stress and tincture elongation of SPRC35R are more dependent on the changes of strain rates and temperature than those of SPRC45E and TRIP60.
Dynamic Constitutive Equations of Auto-body Steel Sheets with the Variation of Temperature (II) - Flow Stress Constitutive Equation -
Lee, Hee-Jong ; Song, Jung-Han ; Park, Sung-Ho ; Huh, Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 182~189
DOI : 10.3795/KSME-A.2007.31.2.182
This paper is concerned with the empirical flow stress constitutive equation of steel sheets for an auto-body with the variation of temperature and strain rate. In order to represent the strain rate and temperature dependent behavior of the flow stress at the intermediate strain rates accurately, an empirical hardening equation is suggested by modifying the well-known Khan-Huang-Liang model. The temperature and strain rate dependent sensitivity of the flow stress at the intermediate strain rate is considered in the hardening equation by coupling the strain, the strain rate and the temperature. The hardening equation suggested gives good correlation with experimental results at various intermediate strain rates and temperatures. In order to verify the effectiveness and accuracy of the suggested model quantitatively, the standard deviation of the fitted result from the experimental one is compared with those of the other two well-known empirical constitutive models such as the Johnson-Cook and the Khan-Huang-Liang models. The comparison demonstrates that the suggested model gives relatively well description of experimental results at various strain rates and temperatures.
Structural Vibration Analysis Caused by Piping Resonance
Gu, Dong-Sik ; Kim, Hyo-Jung ; Jeong, Han-Eol ; Kim, Hak-Eun ; Choi, Byeong-Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 190~196
DOI : 10.3795/KSME-A.2007.31.2.190
A few intake stations have vibration problems caused by pumps, motors and pipes. The vibration transferred from pumps, motors and pipes excites building severely. Therefore, the crack is generated on building wall and people who work at intake station are damaged. In this paper, the vibration has been measured and analyzed for pumps, motors, pipes and building at intake station. Also, the cause of vibration is identified. Finally, the solution of structural vibration is established using the results of measurement.
Fretting Fatigue Behavior of High Strength Aluminum Alloys
Choi, Sung-Jong ; Lee, Hak-Sun ; Lee, Cheol-Jae ; Kim, Sang-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 197~204
DOI : 10.3795/KSME-A.2007.31.2.197
Fretting is a contact damage process that occurs between two contact surfaces. Fretting fatigue reduces fatigue strength of the material due to low amplitude oscillatory sliding and changes in the contact surfaces of strongly connected machine and structure such as bolt, key, pin, fixed rivet and connected shaft, which have relative slip of repeatedly extreme low frequency amplitude. In this research, the fretting fatigue behavior of 2024-T3511 and 7050-T7451 aluminum alloys used mainly in aircraft and automobile industry were experimentally estimated. Based on this experimental wort the following results were obtained: (1) A significant decrease of fatigue lift was observed in the fretting fatigue compared to the plain fatigue. The fatigue limit of 2024-T3511 aluminum alloy decreased about 59% while 7050-T7451 aluminum alloy decreased about 75%. (2) In 7050-T7451 specimen using ATSI4030 contact pad, crack was initiated more early stage than using 2024-T3511 contact pad. (3) In all specimens, oblique cracks were initiated at contact edge. (4) Tire tracks and rubbed scars were observed in the oblique crack region of fracture surface.
Property Evaluation of Reaction Sintered SiC/SiC Composites Fabricated by Melt Infiltration Process
Lee, Sang-Pill ; Shin, Yun-Seok ; Kohyama, Akira ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 205~210
DOI : 10.3795/KSME-A.2007.31.2.205
SiC/SiC composites and monolithic SiC materials have been fabricated by the melt infiltration process, through the creation of crystallized SiC phase by the chemical reaction of C and Si. The reinforcing material used in this system was a braided Hi-Nicalon SiC fiber with double interphases of BN and SiC. The microstructures and the mechanical properties of RS-SiC based materials were investigated through means of SEM, TEM, EDS and three point bending test. The matrix morphology of RS-SiS/SiC composites was greatly composed of the SiC phases that the chemical composition of Si and C is different. The TEM analysis showed that the crystallized SiC phases were finely distributed in the matrix region of RS-SiC/SiC composites. RS-SiC/SiC composites also represented a good flexural strength and a high density, accompanying a pseudo failure behavior.
Iterated Improved Reduced System (IIRS) Method Combined with Sub-Structuring Scheme (I) - Undamped Structural Systems -
Choi, Dong-Soo ; Kim, Hyun-Gi ; Cho, Maeng-Hyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 211~220
DOI : 10.3795/KSME-A.2007.31.2.211
This work presents an iterated improved reduced system (IIRS) procedure combined with sub-structuring scheme for large structures. Iterated IRS methods are usually more efficient than others because the dynamic condensation matrix is updated repeatedly until the desired convergent values are obtained. However, using these methods simply for large structures causes expensive computational cost and even makes analyses intractable because of the limited computer storage. Therefore, the application of sub-structuring scheme is necessary. Because the large structures are subdivided into several (or more) sub-domains, the construction of dynamic condensation matrix does not require much computation cost in every iteration. This makes the present method much more efficient to compute the eigenpairs both in lower and intermediate modes. In Part I, iterated IRS method combined with sub-structuring scheme for undamped structures is presented. The validation of the proposed method and the evaluation of computational efficiency are demonstrated through the numerical examples.
Iterated Improved Reduced System (IIRS) Method Combined with Sub-Structuring Scheme (II) - Nonclassically Damped Structural Systems -
Choi, Dong-Soo ; Kim, Hyun-Gi ; Cho, Maeng-Hyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 221~230
DOI : 10.3795/KSME-A.2007.31.2.221
An iterated improved reduced system (IIRS) procedure combined with sub-structuring scheme for nonclassically damped structural systems is presented. For dynamic analysis of such systems, complex eigenproperties are required to incorporate properly the nonclassical damping effect. In complex structural systems, the equations of motion are written in the state space from. Thus, the number of degrees of freedom of the new equations of motion and the size of the associated eigenvalue problem required to obtain the complex eigenvalues and eigenvectors are doubled. Iterated IRS method is an efficient reduction technique because the eigenproperties obtained in each iteration step improve the condensation matrix in the next iteration step. However, although this reduction technique reduces the size of problem drastically, it is not efficient to apply this technique to a single domain finite element model with degrees of freedom over several thousands. Therefore, for a practical application of the reduction method, accompanying sub-structuring scheme is necessary. In the present study, iterated IRS method combined with sub-structuring scheme for nonclssically damped structures is developed. Numerical examples demonstrate the convergence and the efficiency of a newly developed scheme.
The Effect of Series Center on the Convergence of the Solution in Vibration Analysis by Differential Transformation Method(DTM)
Shin, Young-Jae ; Yun, Jong-Hak ; Yoo, Yeong-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 231~236
DOI : 10.3795/KSME-A.2007.31.2.231
This paper presents the effect of the center of the series on convergence in solving vibration problems by Differential Transformation Method(DTM) to the transverse vibration of the Euler-Bernoulli beam under varying axial force. The governing differential equation of the transverse vibration of the Euler-Bernoulli beam under varying axial force is derived. The concepts of DTM were briefly introduced. Numerical calculations are carried out and compared with previously published results. The effect of the center of the series on convergence in solving the problem by DTM is discussed.
Molecular Dynamics Simulation for the Mechanical Properties of CNT/Polymer Nanocomposites
Yang, Seung-Hwa ; Cho, Maeg-Hyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 237~244
DOI : 10.3795/KSME-A.2007.31.2.237
In order to obtain mechanical properties of CNT/Polymer nano-composites, molecular dynamics simulation is performed. Overall system was modeled as a flexible unit cell in which carbon nanotubes are embedded into a polyethylene matrix for N
T ensemble simulation. COMPASS force field was chosen to describe inter and intra molecular potential and bulk effect was achieved via periodic boundary conditions. In CNT-polymer interface, only Lennard-Jones non-bond potential was considered. Using Parrinello-Rahman fluctuation method, mechanical properties of orthotropic nano-composites under various temperatures were successfully obtained. Also, we investigated thermal behavior of the short CNT reinforced nanocomposites system with predicting glass transition temperature.
A New Method to Fabricate Bulk PCMs from Continuous Wires and the Mechanical Behaviors
Lee, Yong-Hyun ; Choi, Ji-Eun ; Jeon, In-Su ; Kang, Ki-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 245~252
DOI : 10.3795/KSME-A.2007.31.2.245
Since the new millennium, truss PCMs(Periodic Cellular Metals) have drawn attention because of their superior specific stiffness, strength and multi-functionality. Prior studies have focused on the structural design and optimization. Kagome truss PCM has been proved to have the higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. In this study, we introduce a new idea to fabricate multi-layered Kagome truss PCM from continuous wires which can gain high strength as in piano wires and can be controlled to be defect free owing to drawing process. The relative density, the stiffness and the strength under bending and compressive load are estimated through elementary mechanics and compared with the results from experiments and FEA. The failure mechanisms are analyzed, and also mechanical performance and production are discussed.
Design and Construction of a High Temperature Creep Tester for Thin Film Specimens
Ko, Gyoung-Dek ; Lee, Sang-Shin ; Kang, Ki-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 253~259
DOI : 10.3795/KSME-A.2007.31.2.253
A new material tester has been developed to measure mechanical properties of thin film specimens at high temperature. It is useful for observing oxide film growth or local deformation on the surface, and for measuring creep strength. Main characteristics of the tester is as follows; First, high temperature is achieved by Joule heating generated by electricity passing through the specimen, which does not need to enclose the specimen by a furnace or a heating chamber. The exposed specimen enables one to observe the surface during the test. Because the overall size of the test rig is compact, the whole test rig can be placed in a chamber for environmental controlled tests. The loading device is from a level scales. Not only static load with fixed counter weight, but also variable load by moving counter weight controlled remotely can be applied for an ordinary creep test and creep-fatigue test, respectively. The detail of the construction, operation principle, and the specification are described. And also, an example of test result obtained using the creep tester is presented.
Geometric Kernel Design of the Web-Viewer for the PDM Based Assembly DMU
Song, In-Ho ; Chung, Sung-Chong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 260~268
DOI : 10.3795/KSME-A.2007.31.2.260
Demand for the use of 3D CAD DMU systems over the Internet environment has been increased. However, transmission of commercial 3D kernels has delayed the communication effectiveness due to the kernel size. Light weight CAD geometric kernel design methodology is required for rapid transmission in the distributed environment. In this paper, an assembly data structure suitable for the top-down and bottom-up assembly models has been constructed. Part features are stored without a hierarchy so that they are created and saved in no particular order. In particular, this paper proposes a new assembly representation model, called multi-level assembly representation (MAR), for the PDM based assembly DMU system. Since the geometric kernel retains assembly hierarchy and topological information, it is applied to the web-viewer for the PDM based DMU system. Effectiveness of the proposed geometric kernel is confirmed through various case studies.
Shape Optimal Design to Minimize the Weight of the Pedal Arm of an Automotive Clutch
Lee, Boo-Youn ; Lee, Hyun-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 269~276
DOI : 10.3795/KSME-A.2007.31.2.269
Optimal thickness and shape of the pedal arm of an automotive clutch is determined, using the numerical optimization technique, by solving the size and shape optimization problems to minimize its weight. For the optimization problems, two cases of stress and displacement constraints are considered: one from the vertical, and the other from the transverse stiffness test condition. The result of the transverse case is shown to be more conservative than that from the vertical case, being determined as the final optimum.
Restrained Bending Effect by the Support Plate on the Steam Generator Tube with Circumferential Cracks
Kim, Hyun-Su ; Jin, Tae-Eun ; Kim, Hong-Deok ; Chung, Han-Sub ; Chang, Yoon-Suk ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 31, issue 2, 2007, Pages 277~284
DOI : 10.3795/KSME-A.2007.31.2.277
The steam generator in a nuclear power plant is a large heat exchanger that uses heat from a reactor to generate steam to drive the turbine generator. Rupture of a steam generator tube can result in release of fission products to environment outside. Therefore, an accurate integrity assessment of the steam generator tubes with cracks is of great importance for maintaining the safety of a nuclear power plant. The steam generator tubes are supported at regular intervals by support plates and rotations of the tubes are restrained. Although it has been reported that the limit load for a circumferential crack is significantly affected by boundary condition of the tube, existing limit load solutions do not consider the restraining effect of support plate correctly. In addition, there are no limit load solutions for circumferential cracks in U-bend region with the effect of the support plate. This paper provides detailed limit load solutions for circumferential cracks in top of tube sheet and the U-bend regions of the steam generator tube with the actual boundary conditions to simulate the restraining effect of the support plate. Such solutions are developed based on three dimensional finite element analyses. The resulting limit load solutions are given in a polynomial form, and thus can be simply used in practical integrity assessment of the steam generator tubes.