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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 22, Issue 4 - Apr 1998
Volume 22, Issue 3 - Mar 1998
Volume 22, Issue 2 - Feb 1998
Volume 22, Issue 1 - Jan 1998
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A method of determining flow stress and friction factor using an inverse analaysis in ring compression test
Choi, Y ; Kim, H.K ; Cho, H.Y ; Kim, B.M ; Choi, J.C ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 483~492
DOI : 10.22634/KSME-A.19220.127.116.113
An inverse analysis been applied to obtain the flow stress of the material. In this method, a ring-shaped specimen is compressed between two flat tools. This procedure employs, as the object function of inverse analysis, the balance of measured loads and reaction forces calculated by using rigid-plastic finite element method. The balance is explicit scalar function of flow stress which is a function of some unknown constants. For minimizing the balance, Newton-Raphon scheme is used. The friction factor, m, between flat tools and the specimen is determined by using friction area-divided method. The proposed method allows an accurate identification by avoiding the usual assumptions made in order to convert experimental measures into stress-strain relation. In this paper, the proposed method is numerically tested. A commercial pure aluminum was selected, as an example, to apply the method and the results are compared with stress-strain relation obtained by experiments.
Sectional forming analysis by membrane finite elements considering bending effects
Kim, Jun-Bo ; Lee, Gwang-Byeong ; Keum, Yeong-Tak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 493~503
DOI : 10.22634/KSME-A.1918.104.22.1683
The sectional forming analysis considering bending effects from the geometrically deformed shape of two linear membrane finite elements(called super element) was performed under plane strain assumption for analyzing forming processes of an arbitrarily shaped draw-die. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the changes in the interior angle at the middle node of super element, and are agumented to the membrane stretch forces. In order to verify the validity of the bending formulation, the simulation results for the stretch, draw, and bend sections were compared with membrane analysis results and measurements.
A study on the efficient simulation methods for an automatic power transmission system applying dynamic torque constraint
Jeong, Heon-Sul ; Lee, Kyo-Ill ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 504~518
DOI : 10.22634/KSME-A.1922.214.171.1244
Degree-Of-Freedom(DOF) for most power transmission system varies according to the operation status which consists of friction elements to change the power flow or to adjust the speed ratio such as clutches, brakes or one-way clutches. To simulate the dynamic characteristics of automatic power transmission system which is a typical example of such a variable DOF systems, many sets of governing equations and complicated phase decision routines are necessary. In this paper dynamic constraint theorem is derived explaining the torque transmission characteristics during the clutch engagement process and a robust stable algorithm is developed describing this phase transition phenomenon effectively by introducing the concept of direct torque and virtual damping. Finally, applying this algorithm to a passenger car automatic transmission gear consisting of several friction elements, an efficient simulation methods for such a complex system will be suggested that is very simple and systematic.
A numerical method for dynamic analysis of cam-follower mechanism including impact, separation and elastic deformation
Lee, Gi-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 519~528
DOI : 10.22634/KSME-A.19126.96.36.1999
A numerical method is presented for the dynamic analysis of cam and follower. Contact and separation between the cam and the follower are analyzed by imposing dynamic contact condition. The correct solution is obtained without spurious oscillation by imposing the velocity and acceleration constraints as well as the displacement constraint on the possible contact point. The constraints are satisfied by iteratively reducing the constraint errors toward zero, and a simple time integration of ordinary differential equation is employed for the solution of the equation of motion. The solution procedure associated with the iterative scheme is presented, and numerical simulations are conducted to demonstrate the accuracy of the solution.
Damage mechanism of particle impact in a
plasma coated soda-lime glass
Suh, Chang-Min ; Lee, Moon-Hwan ; Hong, Dea-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 529~539
DOI : 10.22634/KSME-A.19188.8.131.529
A quantitative study of impact damage of
plasma coated soda-lime glasses was carried out and compared with that of the uncoated smooth glass specimen. The shape of cracks by the impact of steel ball was observed by stereo-microscope and the decrease of the bending strength due to the impact of steel ball was measured through the 4-point bending test. At the low velocity, cone cracks were occurred. As the impact velocity increases, initial lateral cracks were propagated on the slanting surface of a cone crack, and radial cracks were generated at the crushed site. When the impact velocity of steel ball exceeds the critical velocity, the contact site of specimen was crushed due to plastic deformation and then radial and lateral cracks were largely grown. Crack length of coated specimens was smaller than that of uncoated smooth specimen due to the effect of coating layer on the substrate surface. According to impact velocity, the bending strength of coated specimens had no significant difference, compared with that of the uncoated smooth specimen. But this represents that the bending strength of coated specimens was increased, considering the effect of sand blasting damage which was performed to increase the adhesion force of coating layer.
determination of unidirectional graphite /epoxy DCB composites from the elastic work factor approach
Rhee, Kyeong-Yeop ; Lee, Joong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 540~544
DOI : 10.22634/KSME-A.19184.108.40.2060
Compliance calibration method is frequently used to determine
from the DCB composite specimen. However, the method requires at least 4 to 5 fracture test (loading-unloading) records. In this study,
of unidirectional graphite/epoxy DCB composites was determined from the elastic work factor approach which uses a single fracture test record. In order to inspect the validity of the elastic work factor approach,
determined from the elastic work factor approach was compared to that of determined from the compliance calibration method. It was shown that
determined from the elastic work factor approach was comparable to that determined from the compliance calibration method. That is, the elastic work factor approach can be used to determine
of unidirectional graphite/epoxy DCB specimen from a single fracture record.
Development of machining apparatus for ceramic ball bearing
Aum, Ho-Sung ; Roh, Byung-Ok ; Lee, Soo-Wohn ; Jang, Tae-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 545~553
DOI : 10.22634/KSME-A.19220.127.116.115
Recently a new process known as the magnetic fluid grinding has been developed, which can remove material from the surface of ceramic balls by fifty to one hundred times more rapidly than the conventional lapping process. In this study, the ceramic balls with various compositions are made and ground by using the magnetic fluid grinding technique with various machining parameters. In order to make well-round shaped balls by using the magnetic fluid grinding technique, the fundamental research to find out the machining factors has been carried out. Developing an equipment with higher efficiency and reliability in the machining could certainly lead to the higher productivity with excellent quality of ceramic balls.
The comparision of fatigue behavior of
plug weld and resistance spot weld
Jeong, Won-Uk ; Jeong, Yeon-Su ; Kang, Seong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 554~561
DOI : 10.22634/KSME-A.1918.104.22.1684
Vehicle body structures are formed by thousands of spot welds and fatigue failure of vehicle structures occur near the spot welds after driving a long way at a durability test road. It is necessary to know accurately the reason of the fatigue failure of the spot weld in the developing stage in order to reinforce it. Many investigations have been done regarding the strength of spot welded joints, contributing to understand its fatigue strength. In developing process, a fatigue failed spot welded area can be repaired by
welding or another method to continue the test. To know the effect of reinforcing these welds, several methods of welding were analyzed and compared to spot welding. With the results of this test, the appropriate repair method can be used instead of spot welding during the development of new car and best design guide can be given for the strength. In this study, fatigue and static tensile tests are made and microstructure is investigated for the purpose of estimating the strength of welded joints by using spot welded and
plug welded specimens. The tested specimens are of two types : Tensile-shear type(TS) and L-tension type(LT).
Direct multivariable quantitative feedback theory
Park, Myoung-Soo ; Lee, Jae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 562~568
DOI : 10.22634/KSME-A.1922.214.171.1242
During the past three decades, several techniques have been suggested for robust performance design of multivariable systems within the framework of Quantitative Feedback Theory. They are all characterized and limited by the use of loop transmission inversion. A new approach within framework is described which leads to a design tehnique without loop transmission inversion. Complete sequential design algorithms are derived for performance specifications in terms of plant input disturbance, sensitivity, complimentary sensitivity and control effort.
Stress intensity factor in cracked plate reinforced with a plate under mixed mode loading
Lee, Kang-Yong ; Kim, Ok-Whan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 569~578
DOI : 10.22634/KSME-A.19126.96.36.1999
The mode I and II stress intensity factors have been calculated theoretically for the cracked plate reinforced with a plate by symmetric spot welding under remote mixed mode loading. This is the extension of authors' previous work for the reinforced cracked plate under remote normal stress. Regardless of loading types, the reinforcement effect gets better as one joining spot is closer to the crack tip and the others are closer to the crack surface, and optimum number of the joining spots can be existed. For the present model, the remote loading parallel to crack surface produces the mode I stress intensity factor.
A study on the fatigue behavior of optical fiber sensors embedded in smart composite structures
Jang, Tae-Seong ; Kim, Ho ; Lee, Jung-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 579~587
DOI : 10.22634/KSME-A.19188.8.131.529
In this study, fatigue behavior of the optical fiber sensor embedded in composite laminate was investigated. Static tensile and fatigue tests were performed for three types of laminated composite specimens with embedded optical fiber sensor in the neutral plane ; [0/sub 6//OF/0/sub 6/]/sub T/, [0/sub 2//90/sub 4//OF/90/sub 4//0/sub 2/]/sub T/ and [0/sub 3//90/sub 3//OF/90/sub 3//0/sub 3/]/sub T/. The fracture of the embedded optical fiber sensor was detected by the intensity drop off of laser signal transmitted through the optical fiber sensors embedded within laminated composite specimen. The maximum fatigue stress applied to laminated specimen was compared with the average tensile stress at which the fracture of the embedded optical fiber within the laminate occurred under static tensile loading. From the experiments, firstly it is observed that the decrease in the life of optical fiber sensors embedded within unidirectional-ply laminate by the fatigue loading is relatively small compared to that of cross-ply laminate. Secondly, the optical fiber embedded in unidirectional-ply laminate is fractured by the fatigue damage due to the growth of internal defects of optical fiber, however the optical fiber embedded in cross-ply laminate is fractured by the growth of transverse matrix crack.
Computation of equivalent material properties of woven fabric composites using homogenization technique
Jang, Ji-hyun ; Yoon, Min-woo ; Lee, Jin-hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 588~594
DOI : 10.22634/KSME-A.19184.108.40.2068
Reliable three-dimensional models of woven fabric composites had scarcely been proposed for their geometric complexity. Simplified models, mostly one- or two-dimensional, currently used are not considered effective enough because of their oversimplifications. In this paper, the equivalent thermal conductivities and elasticity properties of woven fabric composites are computed using homogenization technique. The computational results show that the strength and thermal conductivity linearly increase with fiber volume fraction and that the variations of undulation of fibers has little effect on equivalent material properties. Homogenization technique is proved useful in the study of woven fabric composites and may find a lot more applications in the area.
High temperature rupture lifetime of 304 stainless steel under multiaxial stress states
Kim, Ho-Kyung ; Chung, Kang ; Chung, Chin-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 595~602
DOI : 10.22634/KSME-A.19220.127.116.115
Specimens of 304 stainless steel were tested to failure at elevated temperatures under multiaxial stress states, uniaxial tension using smooth bar specimens, biaxial shearing using double shear bar specimens, and triaxial tension using notched bar specimens. Rupture times are compared for uniaxial, biaxial, and triaxial stress states with respect to the maximum principal stress, the von Mises effective stress, and the principal facet stress. The results indicate that the principal facet stress gives the best correlation for the material investigated, and this parameter can predict creep life data under multiaxial stress states with rupture data obtained with specimens under uniaxial stresses. The results also suggest that grain boundary cavitation, coupled with localized deformation processes such as grain boudary sliding, controls the lifetimes of the specimens.
A study on the effects of active suspension upon vehicle handling
Lee, Jung-Sup ; Kwon, Hyok-Jo ; Oh, Chae-Youn ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 603~610
DOI : 10.22634/KSME-A.1918.104.22.1683
This paper develops a 7 DOF vehicle model to study the effects of the active suspension on ride. The model is used to derive a control law for the active suspension using a full state linear optimal control technique. A wheelbase preview type active suspension is also considered in the control law derivation. The time delay between wheelbases is approximated using Pade approximation technique. The ride model is extended to a 14 DOF handling model. The 14 DOF handling model includes lateral, longitudinal, yaw and four wheel spin motions in addition to the 7 DOF ride model. A control law which is derived considering only ride related parameters is used to study the effects of the active suspension on a vehicle handling. J-turn maneuver simulation results show that the active suspension has a slower response in lateral acceleration and yaw rate, a bigger steady state lateral acceleration and an oversteer tendency. Lane changing maneuver simulation results show that the active suspension has a little bigger lateral acceleration but a much smaller roll angle and roll motion. Braking maneuver simulation results show that the active suspension has a much smaller pitch angle and pitch motion.
Delamination behavior of multidirectional laminates under the mode I loading
Choi, Nak-Sam ; Kinloch, A.J. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 611~623
DOI : 10.22634/KSME-A.1922.214.171.1241
The delamination fracture of multidirectional carbon-fiber/epoxy laminates under the Mode I condition has been studied using the modified beam analysis for a fracture mechanics approach. It was found that the variation of fracture energy
with increasing length of the propagating crack exhibited a minimum for the pure interlaminar fracture and a maximum for the intraply fracture,i.e. a rising "R-curve", which was strongly affected by the degree of fiber bridging and crack-tip splitting arising in the global delamination. The maximum
value was significantly dependent on such types of delamination as no crack jumping, crack jumping into the adjacent ply and edge-delamination. It was shown also that the value of "effective flexural modulus" estimated from the modified beam analysis increased much with the development of fiber bridging behind the crack tip.ehind the crack tip.
A study on the development of photoelastic model material with shape memory effect
Lee, Hyo-Jae ; Hwang, Jae-Seok ; Shimamoto, Akira ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 624~634
DOI : 10.22634/KSME-A.19126.96.36.1994
The photoelastic model material with shape memory effect and the molding processes for the material are developed in this research. The matrix and fiber of the photoelastic model material developed in this research are epoxy resin (Araldite to hardner 10 to 3 (weight ratio)) and wire of
shape memory alloy, respectively. It is called Ti50-Ni50 Shape Memory Alloy Fiber Epoxy Composite
Ti50-Ni50 SMA-FEC is satisfied with the requirements of the photoelastic model material and can be used as a photoelastic model material. The maximum recovering strain of
SMA-FEC is occurred at
in any prestrain of
shape memory alloy fiber and in any fiber volume ratio. Recovering strain(force) is increased with the increment of the prestrain and the fiber volume ratio. The best prestrain of
SMA-FEC is 5% for the recovering force among 1%, 3%, 5%.
Vibration analysis of the plates subject to dynamic concentrated loads by using spectral element method
Lee, Joon-Keun ; Lee, U-sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 635~643
DOI : 10.22634/KSME-A.19188.8.131.525
A spectral element method(SEM) is introduced for the vibration analysis of a rectangular plate subject to dynamic concentrated loads. First, the spectral plate element is derived from the relations between the forces and displacements along the two opposite edges of plate element. The global spectral matrix equation is then formulated by assembling two spectral plate elements so that the dynamic concentrated load is located at the connection nodal line between two plate elements. the concentrated load is then spatially Fourier transformed in the direction of the connection nodal line to transform the two-dimensional plate problem into a simplified equivalent one-dimensional beam-like problem. We may benefit from these procedures in that the spectral results from the present SEM is compared with the exact analytical solutions to prove the remarkable accuracy of the present SEM, while this is not true for conventional finite element solutions, especially at high frequency.
Quality assurance algorithm using fuzzy reasoning for resistance spot weldings
Kim, Joo-Seok ; Lee, Jae-Ik ; Lee, Sang-ryong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 644~653
DOI : 10.22634/KSME-A.19184.108.40.2064
In resistance spot weld, the assurance of weld quality has been a long-standing problem. Since the weld nuggets if resustance spot welding form between the workpieces, visual detection of defects in usually impossible. Welding quality of resistance spot welding can be verified by non destructive and destructive inspections such as X-Ray inspection and testing of weld strength. But these tests, in addition to being time-consuming and costly, can entail risks due to sampling basis. The purpose of this study is the development of the monitoring system based on fuzzy inference, aimed at diagonosis of quality in resistance spot welding. The fuzzy inference system consists of fuzzy input variables, fuzzy membership functions and fuzzy rules. For inferring the welding quality(strength), the experimental data of the spot welding were acquired in various welding conditions with the monitoring system designed. Some fuzzy input variables-maximum, slop and difference values of electrode movement signals-were extracted from the experimental data. It was confirmed that the fuzzy inference values of strength have a .
5% error in comparison with actual values for the selected welding conditions(9-10.5KA, 10-14 cycle, 250-300
). This monitoring system can be useful in improving the quality assurance and reliability of the resistance spot welding process.
Shift-transient characteristics of an automatic transmission
Chang, Hyo-Whan ; Jun, Yoon-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 654~662
DOI : 10.22634/KSME-A.19220.127.116.114
Shift quality of an automatic transmission in a vehicle is mainly affected by transient pressures in the hydraulic system during shifting. In this study, dynamic modelings of the hydraulic system and the power train of an automatic transmission are made systematically by a bond-graph method. The dynamic characteristics of the line pressures and clutch/brake pressures during shiftings are investigated by simulations and verified by experiments. The effects of clutch/brake pressures on the shift torque are also investigated through driving simulation.
Design of shift controller using learning algorithm in automatic transmission
Jun, Yoon-Sik ; Chang, Hyo-Whan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 663~670
DOI : 10.22634/KSME-A.1918.104.22.1683
Most of feedback shift controllers developed in the past have fixed control parameters tuned by experts using a trial and error method. Therefore, those controllers cannot satisfy the best control performance under various driving conditions. To improve the shift quality under various driving conditions, a new self-organizing controller(SOC) that has an optimal control performance through self-learning of driving conditions and driver's pattern is designed in this study. The proposed SOC algorithm for the shift controller uses simple descent method and has less calculation time than complex fuzzy relation, thus makes real-time control passible. PCSV (Pressure Control Solenoid Valve) control current is used as a control input, and turbine speed of the torque converter is used indirectly to monitor the transient torque as a feedback signal, which is more convenient to use and economic than the torque signal measured directoly by a torque sensor. The results of computer simulations show that an apparent reduction of shift-transient torque is obtained through the process of each run without initial fuzzy rules and a good control performance in the shift-transient torque is also obtained.
Stress intensity factor and stress distribution near crack tip for infinite body containing regid inclusion with crack shape
Lee, Kang-Young ; Kim, Jong-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 680~683
DOI : 10.22634/KSME-A.1922.214.171.1240
In case of the infinite body containing a rigid inclusion with line crack shape, stress intensity factor is determined and the relation between stress intensity factor and stress distribution near a crack tip is developed. Also, the relation between stress intensity factor and Kolosoff stress function is developed. Finally, these results are compared with those that the crack surface is under no traction.
Phase unwrapping enhancement of phase shift interferometry by using lateral scanning
Park, Do-Min ; Park, Sung-Lim ; Gweon, Dae-Gab ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 684~687
DOI : 10.22634/KSME-A.19126.96.36.1994
The biggest problem common on to all forms of Phase Shift Interferometer is unwrapping the phase. Simple phase unwrapping algorithms assume that every pixel is within radians of its neighbors. If this is true, any reasonable algorithm will return the correct unwrapped phase. If not, correct unwrapped phase will not be obtained. In rough surface, frequently, neighboring pixels have phase steps greater than. This paper proposes the new method which makes phase steps smaller than by sub-pixel movement.
AE source on-line localization on material with unknown acoustic wave propagation velocity
Jhang, Kyung-Young ; Lee, Weon-Heum ; Kim, Dal-jung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 688~694
DOI : 10.22634/KSME-A.19188.8.131.528
The ability to locate the defects in materials is one of the major attrations of the acoustic emission(AE) technique. The most conventional method for planar AE source localization is to place three or more AE sensors on the plate and to determine the source position by measuring the differences in the arrival times of the AE wave at the sensors, which is called as triangulation method. But this method can not be applied in the material of which elastic wave propagtion velocity is not known. In this paper, we propose two methods, vector method and error minimization method, for AE source location on the material with unknown AE wave velocity. In this method, it is not needed to know the propagation velocity previously, that is, we can apply this method to arbitrary material of which properties are not known exactly. Also, in this paper, the robustness to the error in the measurement of time differences are discussed for both methods. Finally, in order to evaluate the actual performances, experiments using a pencil lead break as the AE source were carried out on the aluminum plate.
Evaluation of C(t)-integral for inner cracks of steel slab during reheating process
Lee, Kang-Yong ; Kim, Jong-Sung ; Lee, Hyo-Jin ; Park, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 695~703
DOI : 10.22634/KSME-A.19184.108.40.2065
The crack problem of continuous casting slab due to the thermal stresses during the reheating process is analyzed using FEM. In this study, the C(t)-integral is calculated. As a result, the values of the C(t)-integral decrease by increasing the initial temperature of the slab and decreasing total heat flux. And those decrease by decreasing the heat flux of pre-heating zone and increasing the heat flux of heating zone.
Analysis of joint reaction forces of flexible multibody system with closed loops
Choi, Yong-Cheol ; Kim, Gwang-Seok ; Kim, Oe-Jo ; Yoo, Wan-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 3, 1998, Pages 704~713
DOI : 10.22634/KSME-A.19220.127.116.114
The analysis of dynamic forces is essential to the design of systems, stress analysis, or life prediction of part of machine. Calculation of dynamic forces has very close relations with multibody dynamics algorithm. In this paper, an algorithm which calculates joint reaction force/moment of flexible multibody dynamic systems is proposed by using inverse dynamic algorithm and velocity transformation technique.