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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
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 23, Issue 11 - Nov 1999
Volume 23, Issue 7 - Jul 1999
Volume 23, Issue 6 - Jun 1999
Volume 23, Issue 11 - 00 1999
Selecting the target year
Monitoring of Grinding Force in Plunge Grinding Process
Park, Jong-Chan ; Park, Cheol-Woo ; Lee, Sang-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 881~894
DOI : 10.22634/KSME-A.19126.96.36.1991
Cylindrical plunge grinding is widely used for final machining process of precision parts such as automobile, aircraft, measurement units. But in order to make parts which have high precision accuracy and high surface integrity, it is necessary to consider grinding characteristics due to accumulation phenomena of grinding wheel in plunge grinding process. In this study, in order to examine closely plunge grinding process, grinding power, grinding force, real depth of cut are monitored in transient state, steady state and spark out state. As the result, it is shown that grinding power and force are affected by dressing condition, depth of cut and speed ratio and that there exist threshold grinding force and it also affected by dressing condition. Also considered effects of grinding conditions on surface roughness and roundness of workpiece
Finite Element Analysis of the Contact Stress Characteristics in Scraper Seals
Kim, Chung-Kyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 895~902
DOI : 10.22634/KSME-A.19188.8.131.525
This paper deals with a numerical study of the tribological contact stress distributions of elastomeric lip seals for oscillating shafts when the sealing interference and band width between the lip ease or contact seals and the shaft are present. Using the finite element method the contact stress and band width of scraper seals are analyzed for the sealing interference including some nonlinearities such as geometrical nonlinearity, material nonlinearity and nonlinear contact boundary condition. The FEM results showed that the contact stress concentrated on the contacting lip zone between the contacting edge of lip and the shaft for the increased interference. In double lip scraper seals, ole maximum contact stress of the dust lip, which is used to exclude foreign contaminants is six times higher than that of the primary sealing lip, which is used to contain lubricants.
Model-Based Control System Design and Sliding Mode Control of Stewart Platform Manipulator
Lee, Chong-Won ; Kim, Nag-In ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 903~911
DOI : 10.22634/KSME-A.19184.108.40.2063
A high speed tracking control system for 6-6 Stewart platform manipulator is designed for performing the model based joint-axis sliding mode control. Because of the complex dynamics and kinematics of the Stewart platform manipulator, two computer systems, consisting of a PC and a DSP, are adopted, so that real time tasks are run in synchronous and asynchronous modes. It is experimentally proven that the proposed control system makes the convenience in implementation of model based tracking control, so that it can achieve effective tracking control under relatively high speed and additional payload conditions.
The Effects of Wall Elasticity on Wall Shear Rate of a Divergent Tube (Vascular Graft)
Rhee, Kye-Han ; Lee, Sang-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 912~921
DOI : 10.22634/KSME-A.19220.127.116.112
Shear stress acting on the arterial wall by blood flow is an important hemodynamic factor influencing blocking of blood vessel by thickening of an arterial wall. In order to study the effects of wall elasticity on the wall shear rate distribution in an artery-divergent graft anastomosis, a rigid and a elastic model are manufactured. These models are placed in a pulsatile flow loop, which can generate the desired flow waveform. Flow visualization method using a photochromic dye is used to measure the wall shear rate distribution. The accuracy of measuring technique is verified by comparing the measured wall shear rate in the straight portion of a model with the theoretical solution. Measured wall shear rates depend on the wall elasticity and flow waveform. The mean and maximum shear rate in the elastic model are lower than those in rigid model, and the decreases are more significant near the end of a divergent tube. The reduction of mean and maximum of wall shear rate in an elastic model are up to 17 percent.
A Real-time Distributed AGC System for a Hot Strip Mill
Lee, Ho-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 922~930
DOI : 10.22634/KSME-A.1918.104.22.1682
This paper describes a new 14-CPU real-time distributed automatic gauge control (AGC) system for POSCO's No. 2 Hot Strip Mill at Pohang Works. The new AGC system has adopted gaugemeter AGC, Monitor AGC, and roll gap disturbance compensators. The computer system for the new AGC system has been developed based on VMEbus computer systems and a commercial real-time operating system. A VMEbus computer system is also used for the position servo control of hydraulic cylinders. All the application programs and input/output signals have been reasonably distributed over the control computer systems for the maximum reliability and effectiveness of the system. The new AGC system has been successfully used for the No. 2 Hot Strip Mill.
A Study on a 4WS Vehicle Using Fuzzy Logic and Model Following Control
Baek, Seung-Ju ; Oh, Chae-Youn ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 931~942
DOI : 10.22634/KSME-A.1922.214.171.1241
This paper develops a 3 DOF vehicle model which includes lateral, roll and yaw motion to study a 4WS vehicle. The model is used for the simulation of a 4WS vehicle behavior, and to derive a control algorithm for rear wheel steering. This paper uses a feedforward plus feedback control scheme to compute a rear wheel steering angle. The feedforward control scheme for computing the first rear wheel steering angle uses a gain which is acquired by multiplying a proper value on a gain to maintain a zero sideslip angle. The feedback control scheme for computing the second rear wheel steering angle uses fuzzy logic and model following control scheme. A linear 2 DOF model is used as a reference model for model following control, and is derived from the developed 3 DOF model by neglecting sprung mass roll motion. A reference state variable is yaw rate, and is computed using the linear 2 DOF model. J-turn and lane change maneuver simulation are performed to show the effectiveness of the developed control scheme. The simulation results show that the 4WS vehicle with the developed control scheme has much better performance in yaw rate, lateral acceleration, roll angle, and sideslip angle than the 2WS vehicle. Also, the results show that the performance of the developed control is close to the one of an optimal control which assumes all states are perfect.
Effect of Residual Stress in Al5083 TIG Weld Region on Fatigue Crack Propagation Behavior
Lee, Ouk-Sub ; Park, Chan-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 943~951
DOI : 10.22634/KSME-A.19126.96.36.1993
The welded structure unnecessarily remains residual stress due to the very high heating of local region and lastly cooling. The residual stress sometimes causes fracture initiation of welded structures. In this paper, distribution and magnitude of tensile and compressive residual stresses in the TIG(Tungsten Inert Gas) welded aluminum alloy such as Al5083-H112 are measured by using the hole-drilling method. Furthermore, the effects of residual stresses in the TIG welded aluminum CCT(Center Crack Tension) and SEN(Single Edge Notched) Specimens on the fatigue crack propagation behavior are analyzed. The fatigue cracks initiated at residual stresses region are influnced by tensile and compressive residual stresses. However, the effects are found to be released fast for both cases according to the cyclic loads and extension of crack length.
Effects of Binder on the Mechanical Properties of Preform and MMCs
Nam, Hyun-Wook ; Min, Byung-Ryoul ; Lee, Jong-Hae ; Han, Kyung-Seop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 952~960
DOI : 10.22634/KSME-A.19188.8.131.522
The effects of binder on the mechanical properties of the preforms and metal matrix composites (MMCs) were studied. Fibers were
, HTZ and
fibers(Saffil) and binders were organic binder, inorganic binder, polyacrylamide under various PH conditions. Compressive strength of the preform increased with the addition of inorganic binder. The polyacrylamide did not improve the permeability of the preforms. PH of the slurry should be controlled because it affects the viscosity of the slurry. Good preforms were obtained under following conditions : 3 wt% inorganic binder, 0.1 wt% organic binder, 0.1 wt% polyacrylamide and PH 9. Tensile tests of MMCs were conducted at
using MTS(100KN USA). Wear tests were conducted under various sliding speeds. High temperature(
) tensile strengths of Alborex/Saffil/AC8A and HTZ/AC8A are 80% and 75% of the room temperature tensile strengths respectively. The tensile and wear properties of the Alborex/Saffil/AC8A are superior to that of the HTZ/AC8A. The wear behavior of HTZ/AC8A shows more orthotropic characteristic than that of Alborex/Saffil/AC8A.
Mode III Stress Intensity Factors for Orthotropic Layered Material with Internal Center Crack Under Uniform Anti-Plane Shear Loading
Lee, Kang-Yong ; Joo, Sung-Chul ; Kim, Sung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 961~967
DOI : 10.22634/KSME-A.19184.108.40.2061
A model is constructed to evaluate the mode III stress intensity factor(SIF) for orthotropic three-layered material with a center crack subjected to uniform anti-plane shear loading. A mixed boundary value problem is formulated by Fourier integral transform method and a Fredholm integral equation of the second kind is derived. The integral equation is numerically analyzed to evaluate the effects of the ratio of shear modulus, strength of each layer and crack length to layer thickness on the stress intensity factor.
Long Wavelength Scattering Approximations for the Effective Elastic Parameters of Spherical Inclusion Problems
Jeong, Hyun-Jo ; Kim, Jin-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 968~978
DOI : 10.22634/KSME-A.19220.127.116.118
The effective elastic properties of materials containing spherical inclusions were calculated by the elastic wave scattering theory. In the formulation additional scattering fields by the presence of random multiple scatterers that affects the effective properties were found by the single scattering approximation. In calculating the scattering fields the ensemble average on the displacements and strains inside the scatterer was found from the static approximation at long wavelength limit. The displacements were assumed to be equal to the incident field, while the strains were calculated by Eshelby's equivalent inclusion principle on the single inclusion problem. Four different models were considered and they reflected different degrees of multiple scattering effects based on the approximation introduced in the process of embedding the inclusion in the matrix. The expressions for the effective elastic constants were given in each model, and their relations to the results obtained from other scattering theory and elasticity theory were discussed. The theoretical predictions were compared with experimental results on the epoxy matrix composites containing tungsten particles of different sizes and volume fractions
Specific Cutting Force Coefficients Modeling of End Milling by Using Neural Network
Lee, Sin-Young ; Lee, Jang-Moo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 979~987
DOI : 10.22634/KSME-A.1918.104.22.1689
In a high precision vertical machining center, the estimation of cutting forces is important for many reasons such as prediction of chatter vibration, surface roughness and so on, and cutting forces are difficult to predict because they are very complex and time variant. In order to predict the cutting forces of end-milling process for various cutting conditions, a mathematical model is important and this model is based on chip load, cutting geometry, and the relationship between cutting forces and chip loads. Specific cutting force coefficients of the model have been obtained as interpolation function types by averaging farces of cutting tests. In this paper, the coefficients are obtained by neural network and the results of the conventional method and those of the proposed method are compared. The results show that the neural network method gives more correct values than the function type and that in teaming stage as the omitted numbers of experimental data increases the average errors increase.
Hybrid Full-field Stress Analysis around a Circular Hole in a Tensile Loaded Plate using Conformal Mapping and Photoelastic Experiment
Baek, Tae-Hyun ; Kim, Myung-Soo ; Rhee, Ju-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 988~1000
DOI : 10.22634/KSME-A.1922.214.171.1248
An experimental study is presented for the effect of number of terms of a pewee series type stress function on stress analysis around a hole in tensile loaded plate. The hybrid method coupling photoelastsic data inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width tensile plate. In order to measure isochromatic data accurately, actual photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. For qualitative comparison, actual fringes are compared with calculated ones. For quantitative comparison, percentage errors and standard deviations with respect to percentage errors are caculated for all measured points by changing the number of terms of stress function. The experimental results indicate that stress concentration factors analyzed by the hybrid method are accurate within three percent compared with ones obtained by theoretical and finite element analysis.
Thermo-Mechanical Behavior of Short SMA Reinforced Polymeric Composite Using Shear tag Theory
Jeong, Tae-Heon ; Lee, Dong-Joo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1001~1010
DOI : 10.22634/KSME-A.19126.96.36.1991
Thermo-mechanical behavior of discontinuous shape memory alloy(SMA) reinforced polymeric composite has been studied using modified shear lag theory and finite element(FE) analysis with 2-D multi-fiber model. The aligned and staggered models of short-fiber arrangement are employed. The effects of fiber overlap and aspect ratio on the thermomechanical responses such as the thermal expansion coefficient are investigated. It is found that the increase of both tensile stress(resistance stress) in SMA fiber and compressive stress in polymer matrix with increasing aspect ratio is the main cause of low thermal deformation of the composite.
A Study on the Monitoring of Grinding Stability Using AE Sensor in Electrolytic In-Process Dressing Grinding
Kim, Tae-Wan ; Lee, Jong-Ryul ; Lee, Deug-Woo ; Song, Ji-Bok ; Choi, Dae-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1011~1017
DOI : 10.22634/KSME-A.19188.8.131.521
Electrolytic in-process dressing grinding technique which enables application of metal bond wheels with fine superabrasives in mirror surface grinding operations has developed. It is possible to make efficient precision machining of hard and brittle material such as ceramic and hard metal by the employment of this technique. However, in order to ensure the success of performances such as efficient machining, surface finish, and surface quality, it is important to sustain the insulating layer that has sharply exposed abrasives in wheel surface. Using AE(Acoustic Emission) sensor, this paper will show whether the insulating layer sustains stably or not in real grinding time. And by comparing AErms value and surface roughness their thresholds for stable electrolytic in-process dressing grinding will be determined.
Formulation of a Singular Finite Element and Its Application
Kim, Myung-Sik ; Lim, Jang-Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1018~1025
DOI : 10.22634/KSME-A.19184.108.40.2068
For the effective analysis of two dimensional plane problems with geometrical discontinuities, singular finite element has been proposed. The element matrix equation was formulated on the basis of hybrid variational principle and Trefftz function sets derived consistently from the complex theory of plane elasticity by introducing a conformal mapping function. In order to suggest the accuracy characteristics of the proposed singular finite element, typical plane problems were analyzed and these results were compared with exact solutions. The singular finite element gives the comparatively exact values of stress concentration factors or stress intensity factors and can be effectively used for the analysis of mechanical structures containing various geometrical discontinuities.
Effect of Crack Propagation Directions on the Interlaminar Fracture Toughness of Carbon/Epoxy Composite Materials
Hwang, Jin-Ho ; Hwang, Woon-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1026~1038
DOI : 10.22634/KSME-A.19220.127.116.116
Interlaminar fracture toughness of carbon/epoxy composite materials has been studied under tensile and flexural loading by the use of width tapered double cantilever beam(WTDCB) and end notched flexure(ENF) specimens. This study has significantly examined the effect of various interfacial ply orientation,
and crack propagation direction,
in terms of critical strain energy release rate through experiments. Twelve differently layered laminates were investigated. The data reduction for evaluating the fracture energy is based on compliance method and beam theory. Beam theory is used to analyze the effect of crack propagation direction. The geometry and lay-up sequence of specimens are considered various conditions such as skewness parameter, beam volume, and so on. The results show that the fiber bridging occurred due to the non-midplane crack propagation and causes the difference of fracture energy evaluated by both methods. For safer and more reliable composite structures, we obtain the optimal stacking sequence from initial fracture energy in each mode.
Fracture Criterion and Fatigue Crack Growth Behavior of Rail Steel Under Mode I & Mixed Mode Loading
Kim, Jung-Kyu ; Lee, Jong-Sun ; Kim, Chul-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1039~1047
DOI : 10.22634/KSME-A.1918.104.22.1689
It is necessary to evaluate the fatigue behavior of rail steel under the multi-axial stress state to assure the railway vehicle's safety. For this purpose, the stress analysis to investigate the crack initiation criteria, static failure and fatigue behavior under mixed-mode are performed. The stress analysis results show that the initiation of the transverse fissure depends on the maximum shear stress below the surface. For the mixed mode, the fatigue crack growth behavior which is represented by the projection crack length and comparative S.I.F,
, shows the more conservative results. Also, its rate is lower than that of the case of the mode I, and this difference decreases with increasing the stress ratio, R.
Performance Evaluation on the Reinforcing Material of Plastic Composites for the Electromagnetic Shielding
Kim, Dong-Jin ; Murakami, Ri-ichi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1048~1054
DOI : 10.22634/KSME-A.1922.214.171.1248
It is important to study the shielding effectiveness(SE) of reinforcing material of plastic composite materials against the electromagnetic(EM) waves. In this paper, SE of the shielding material of EM waves was investigated with actual experiments. The materials used in this study were made up of film, fiber and powder of conductive materials - Cu, Al, CF etc. Also, The resin film was used as matrix. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that copper, aluminum and carbon fiber were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of interval of wires on the SE were studied when the orientation and the space of Cu wires were changed. The SE strongly depended on the. orientation and the space of the Cu wire. SE decreased as the space of the Cu wires was increasing.
Performance Comparison Between ER and MR Clutches with Same Gap Size
Hong, Sung-Ryong ; Choi, Seung-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 23, issue 6, 1999, Pages 1055~1064
DOI : 10.22634/KSME-A.19126.96.36.1995
In this wort ER(electro-rheological) clutch and MR(magneto-rheological) clutch are devised and their performance characteristics such as response time and controllability are compared. As a first step, field-dependent yield stresses of ER and MR fluids are distilled in shear mode. For reasonable comparison between two clutches, a nondimensional design model is established by choosing same design parameters of gap size and number. Following the manufacturing of two clutches, field-dependent torque level, response time to step input, mechanical Power generation to electric power consumption are experimentally measured and compared. In addition, in order to investigate torque controllability of the clutches a sliding mode controller is formulated and experimentally realized. Control bandwidths of two clutches are identified and tracking control responses for desired torque trajectories are presented.