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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
Editor in Chief :
Volume & Issues
Volume 25, Issue 12 - Dec 2001
Volume 25, Issue 11 - Nov 2001
Volume 25, Issue 10 - Oct 2001
Volume 25, Issue 9 - Sep 2001
Volume 25, Issue 8 - Aug 2001
Volume 25, Issue 7 - Jul 2001
Volume 25, Issue 6 - Jun 2001
Volume 25, Issue 5 - May 2001
Volume 25, Issue 4 - Apr 2001
Volume 25, Issue 3 - Mar 2001
Volume 25, Issue 2 - Feb 2001
Volume 25, Issue 1 - Jan 2001
Selecting the target year
Development of Robust Adaptive Learning Control for Nonlinear System
Yu, Yeong-Sun ; Ha, Hwan-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1895~1902
DOI : 10.22634/KSME-A.2001.25.12.1895
This paper gives an overview of the relationships between methods of loaming and adaptive control. It is the objective of this paper to develop adaptive learning control algorithms that combine the advantages of adaptive control with those of leaning control to the extent possible for the type of system model used. The robustness of this adaptive loaming control with respect to reinitialization errors and fluctuation of dynamics from disturbance is analyzed extensively. Simulation results have shown to verify the effectiveness of the proposed control algorithm.
A Study on the Evaluation Method of Mechanical Properties by Ball Indentation Method
Seok, Chang-Seong ; Kim, Jeong-Pyo ; Song, Seong-Jin ; Kim, Hun-Mo ; Kim, Jae-Won ; Kim, Su-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1903~1910
DOI : 10.22634/KSME-A.2001.25.12.1903
The BI(Ball Indentation) method has a potential to assess the mechanical properties and to replace conventional fracture tests. In this study, the BI test system has been developed to evaluate material properties. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed by the system using four classes of thermally aged specimens. The results of the BI tests were in good agreement with fracture characteristics from a standard fracture test method.
A Study on Test Variables Effected on Grain Boundary Etching Test
Baek, Seung-Se ; Na, Seong-Hun ; Lee, Hae-Mu ; Yu, Hyo-Seon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1911~1918
DOI : 10.22634/KSME-A.2001.25.12.1911
Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However, during in-serviced GEM test there are a lot of variables such as the changes of temperature and concentration of etching solution, the roughness condition of surface polished etc.. The purpose of this paper is to investigate the influences of these test variables on GEM test results in order to establish a reliable and sensitive of GEM evaluation technique. The experiments are conducted in various solution temperatures, 10
, and 25
and in 70% and 100% concentrations of that, and in various surface roughnesses polished by #800, #2000, and 0.3㎛ alumina powder. Through the test with variables, it is verified that the decrease of temperature and concentration of etching solution and the coarsened surface roughness by not using polishing cloth and powder induce some badly and/or greatly influences on GEM test results like grain boundary etching width(W
GB) and intersecting point ratio(N
0/). Therefore, to get reliable and good GEM test results, it must be prepared the surface of specimen polished by polishing cloth and 0.3㎛ alumina powder and the saturated picric acid solution having 25
and be maintained the constant temperature(25
) during GEM test.
The Modelling and Position Control of Overhead Cranes
Lee, Jong-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1919~1925
DOI : 10.22634/KSME-A.2001.25.12.1919
Overhead cranes consist of trolley, girder, rope, objects, trolley motor, girder motor, and hoist motor. If objects are regarded as mass point, and the acceleration of hoisting motion for objects is neglected, analytical model of overhead cranes becomes a nonlinear model because the length of a rope changes. Equations of motion this model is derived of simultaneous differential equations fur motors and object. Positions of the model are controlled by optimal inputs which obtain from a nonlinear optimal control method. From the results of computer simulation, even if initial states of objects suing, it is founded that position of overhead cranes is controlled, and that swing of objects is suppressed.
Development of Algorithm for Two Dimensional Automatic Mesh Generation and Remeshing Technique Using Bubble Packing Method (II) - Nonlinear Analysis -
Jeong, Sun-Wan ; Kim, Seung-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1926~1932
DOI : 10.22634/KSME-A.2001.25.12.1926
In this second part of the paper, the automatic mesh generation and remeshing algorithm using bubble packing method is applied to the nonlinear problem. The remeshing/refinement procedure is necessary in the large deformation process especially because the mesh distortion deteriorates the convergence and accuracy. To perform the nonliear analysis, the transfer of state variables such as displacement and strain is added to the algorithm of Part 1. The equilibrium equation based on total Lagrangian formulation and elasto-viscoplastic model is used. For the numerical experiment, the upsetting process including the contact constraint condition is analyzed by two refinement criteria. And from the result, it is addressed that the present algorithm can generate the refined meshes easily at the largely deformed area with high error.
Micromechanical Superplastic Model for the Analysis of Inhomogeneous Deformation in Heterogeneous Microstructure
Kim, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1933~1943
DOI : 10.22634/KSME-A.2001.25.12.1933
A micromechanical model is presented for superplasticity in which heterogeneous microstructures are coupled with deformation behavior. The effects of initial distributions of grain size, and their evolutions on the mechanical properties can be predicted by the model. Alternative stress rate models such as Jaumann rate and rotation incremental rate have been employed to analyze uniaxial loading and simple shear problems and the appropriate modeling was studied on the basis of hypoelasticity and elasto-viscoplasticity. The model has been implemented into finite element software so that full process simulation can be carried out. Tests have been conducted on Ti-6Al-4V alloy and the microstructural features such as grain size, distributions of grain size, and volume fraction of each phase were examined for the materials that were tested at different strain rates. The experimentally observed stress-strain behavior on a range of initial grain size distributions has been shown to be correctly predicted. In addition, the effect of volume fraction of the phases and concurrent grain growth were analyzed. The dependence of failure strain on strain rate has been explained in terms of the change in mechanism of grain growth that occurs with changing strain rate.
Microstructure and Cutting Characteristics of SiC-
Ceramic Cutting Tool
Gwon, Won-Tae ; Kim, Yeong-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1944~1949
DOI : 10.22634/KSME-A.2001.25.12.1944
ceramic cutting tools with different composition have been fabricated by hot-pressing. Correlations among the annealing time, the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The fracture toughness and the grain size of both SiC and Si
composites increased with the annealing time. 1\`he hardness of SiC-Si
composites was relatively independent of the grain size and the sintered density. These ceramic cutting tools were tested under various cutting conditions and compared with the commercial Si
ceramic cutting tools. The experimental results were compared in terms of tool life and cutting force. The performance of SiC-Si
ceramic cutting tool shows the possibility to be a new ceramic tool.
Active Vibration Control of a Cylindrical Rod Transmitting Axial Load
Choe, Seung-Ju ; Park, Hyeon-Cheol ; Hwang, Un-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1950~1959
DOI : 10.22634/KSME-A.2001.25.12.1950
An active control of the vibration transmitted by longitudinal load in flight control system is investigated numerically. The flight control system is modeled as a finite, thin shell cylinder with constant thickness. A vibration source is generated by exterior monopole source. Distributed piezoelectric actuator is used to control of the vibration. Thin shell theory is used to formulate the numerical models. The amplitude of vibration at discrete location and power transmission are minimized by analytical optimization method. Genetic algorithm is used as numerical optimization method to search optimal actuator position and size which amplitude of vibration is minimized.
Optimal Design for the Thermal Deformation of Disk Brake by Using Design of Experiments and Finite Element Analysis
Lee, Tae-Hui ; Lee, Gwang-Gi ; Jeong, Sang-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1960~1965
DOI : 10.22634/KSME-A.2001.25.12.1960
In the practical design, it is important to extract the design space information of a complex system in order to optimize the design because the design contains huge amount of design conflicts in general. In this research FEA (finite element analysis) has been successfully implemented and integrated with a statistical approach such as DOE (design of experiments) based RSM (response surface model) to optimize the thermal deformation of an automotive disk brake. The DOE is used for exploring the engineer's design space and for building the RSM in order to facilitate the effective solution of multi-objective optimization problems. The RSM is utilized as an efficient means to rapidly model the trade-off among many conflicting goals existed in the FEA applications. To reduce the computational burden associated with the FEA, the second-order regression models are generated to derive the objective functions and constraints. In this approach, the multiple objective functions and constraints represented by RSM are solved using the sequential quadratic programming to archive the optimal design of disk brake.
Construction of System Jacobian in the Equations of Motion Using Velocity Transformation Technique
Lee, Jae-Uk ; Son, Jeong-Hyeon ; Kim, Gwang-Seok ; Yu, Wan-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1966~1973
DOI : 10.22634/KSME-A.2001.25.12.1966
The Jacobian matrix of the equations of motion of a system using velocity transformation technique is derived via variation methods to apply the implicit integration algorithm, DASSL. The concept of generalized coordinate partitioning is used to parameterize the constraint set with independent generalized coordinates. DASSL is applied to determine independent generalized coordinates and velocities. Dependent generalized coordinates, velocities, accelerations and Lagrange multipliers are explicitly retained in the formulation to satisfy all of the governing kinematic and dynamic equations. The derived Jacobian matrix of a system is proved to be valid and accurate both analytically and through solution of numerical examples.
Control of a 3-Phase VR Type Self-Bearing Step Motor
Kim, Dae-Gon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1974~1980
DOI : 10.22634/KSME-A.2001.25.12.1974
The control algorithm of a new type self-bearing step motor is presented. The motor actuator is used for both motor and bearing functionality without any redundant coil windings or redundant electromagnets. The self
bearing step motor layout and its control method are described. A linearized farce-current-displacement relationship is derived. As the result of the unbalance response approach, the constant torque production is possible fur the supply current regulation algorithm. And even if the bearing functionality is added in the motor functionality, no additional current for bearing functionality is possible, and this leads to minimize the net power loss. Also, the unbalance response shows the independent bearing force and motor torque.
Effect of Aluminum Treatment by Plasma on the Bonding Strength Between Aluminum and CFRP Composites
Lee, Gyeong-Yeop ; Yang, Jun-Ho ; Choe, Nak-Sam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1981~1987
DOI : 10.22634/KSME-A.2001.25.12.1981
This paper documents the effect of surface treatment of aluminum on the bonding strength of aluminum/CFRP composites. The surface of aluminum panel was treated by DC plasma. The optimal treatment condition of the aluminum was determined by measuring the contact angle and T-peel strength as functions of mixture ratio of acetylene gas to nitrogen gas. The mixture ratios used were 1:9, 3:7, 5:5, 7:3, and 9:1 Lap shear tests and T-peel tests were performed using surface-treated alumiunm/CFRP composites and regular alumiunm/CFRP composites. The results showed that the contact angle was minimized and the T-peel strength was maximized iota the mixture ratio of 5:5. The results also showed that the shear strength of surface-treated alumiunm/CFRP composites was 34% greater than that of regular alumiunm/CFRP composites. The T-peel strength of surface-treated alumiunm/CFRP composites was also 5 times greater than that of regular alumiunm/CFRP composites.
A Study on the Thermal Properties of Glass for Effective Salvage Process of Flat Cathode-ray Tube
Park, Sang-Hu ; Lee, Bu-Yun ; Kim, Won-Jin ; Heo, Bo-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1988~1994
DOI : 10.22634/KSME-A.2001.25.12.1988
The CRT(Cathode-ray Tube) of salvage is a process of separating the panel and funnel to recycle a cathode-ray tube. In this paper, the thermal properties of glass for CRT were studied to improve its recycling ratio. In the salvage process, several patterns of breakage, as called 'comer pull', were easily generated on the sealing surface of panel or funnel glass due to the residual tensile stress, which had correlations with some parameters of the manufacturing process of CRT and the initial material properties of glass. Finite element analyses and experimental approaches on the flit sealing process were carried out to obtain the major characteristic of glass related to the residual stress. From this study, it was identified that the thermal expansion coefficient of glass had much influence on the residual stress of panel glass after frit sealing process. Therefore, the optimal conditions of thermal properties for CRT glass were proposed to achieve an effective salvage process. By using these optimal conditions, the size of comer pull on the panel and funnel glass was reduced to 10% level compared with the original size, and the recycling ratio of CRT was increased in the salvage process.
Development of Evaluation Technique of High Temperature Creep Characteristics by Small Punch-Creep Test Method (I) - Boiler Superheater Tube -
Baek, Seung-Se ; Na, Seong-Hun ; Na, Ui-Gyun ; Yu, Hyo-Seon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 1995~2001
DOI : 10.22634/KSME-A.2001.25.12.1995
In this study, a small punch creep(SP-Creep) test using miniaturized specimen(10
0.5mm) is described to develop the new creep test method for high temperature structural materials. The SP-Creep test is applied to 2.25Cr-lMo(STBA24) steel which is widely used as boiler tube material. The test temperatures applied for the creep deformation of miniaturized specimens are between 550∼600
. The SP-Creep curves depend definitely on applied load and creep temperature, and show the three stages of creep behavior like in conventional uniaxial tensile creep curves. The load exponent of miniaturized specimen decreases with increasing test temperature, and its behavior is similar to stress exponent behavior of uniaxial creep test. The creep activation energy obtained from the relationship between SP-Creep rate and test temperature decreases as the applied load increases. A predicting equation or SP-Creep rate for 2.25Cr-lMo steel is suggested. and a good agreement between experimental and calculated data has been found.
Nonlinear Vibrations of Piezoelectric Microactuators in Hard Disk Drives
Jeong, Deok-Yeong ; Lee, Seung-Yeop ; Kim, Cheol-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2002~2008
DOI : 10.22634/KSME-A.2001.25.12.2002
Nonlinear vibration characteristics of a piezoelectric-type micro actuator used for hard disk drives are experimentally studied. The nonlinear characterisitics include hysteresis, superharmonic resonance, jump phenomenon, and shifting of natural frequencies. The vibration modes and frequencies of the commercial actuator of the Hutchinson's Magnum series are measured using a laser vibrometer. From harmonic excitation to the PZT acturator, we observe interesting hysteresis patterns with 3 times input frequency. It is shown that the micro actuator has the typical 3 times superhamonic resonances coupled to the first torsional and sway modes of the suspension.
Offsetting a Region Including Islands for Tool-Path Generation
Park, Sang-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2009~2018
DOI : 10.22634/KSME-A.2001.25.12.2009
This paper presents a region offsetting algorithm for tool-path generation. The proposed region offsetting algorithm is developed by expanding the 'PWID offset algorithm [Choi and Park, 1999]'designed to offset a simple polygon. The PWID offset algorithm has three important steps; 1) remove 'local invalid ranges'by invoking a PWID test, 2) construct a raw offset owe and 3) remove 'global invalid ranges'by finding self-intersections of the raw offset cure. To develop a region offsetting algorithm, we modified the PWID offset algorithm by expanding the concept of the 'global invalid range'in the third step. The time complexity of the proposed algorithm is approximately Ο(n), where n is the number of points, and it is free of numerical errors for practical purposes. The proposed algorithm has been implemented and tested with various real regions obtained by intersecting a sculptured surface with a plane.
Development of Differentially Driven Inpipe Inspection Robot for Underground Gas Pipeline
No, Se-Gon ; Ryu, Seong-Mu ; Choe, Hyeok-Ryeol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2019~2029
DOI : 10.22634/KSME-A.2001.25.12.2019
Up to now a wide variety of researches on inpipe inspection robots have been introduced, but it still seems to be difficult to construct a robot providing mobility sufficient to navigate inside the complicated configuration of underground pipelines. This paper introduces a robot called MRINSPECT IV(Multifunctional Robotic Crawler for inpipe inSPECTion IV) for the inspection of urban gas pipelines with a nominal 4-inch inside diameter. The proposed robot can freely move along the basic configuration of pipelines such as along horizontal or vertical pipelines. Moreover it can travel along reducers, elbows, and steer in the branches by modulating the speeds of driving modules. Especially, its capability for steering in tile three-dimensional pipeline configuration has a competative edge over the other ones and provides excellent mobility in navigation. Its critical points in the design and construction are introduced and results of experiments are given.
Development of Inpipe Inspection Robot System
Baek, Sang-Hun ; Ryu, Seong-Mu ; No, Se-Gon ; Choe, Hyeok-Ryeol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2030~2039
DOI : 10.22634/KSME-A.2001.25.12.2030
Recently, various inpipe inspection robots are developed and its effective values are increased in industrial use. However, it is so difficult to make a inpipe inspection robot system which has flexible mobility and accuracy of inspection in pipelines. Especially, it is very important to know the exact crack position. In this paper, we are to present a lately developed inpipe inspection robot system which can resolve the above Problems. The robot is configured as an articulated structure like a snake. Two active driving vehicles are located in front and rear of the inspection robot respectively and passive modules such as a nondestructive testing module and a control module are chained between the active vehicles. Special feature of the robot system is a ground interface, which is able to show informations of robot and pipelines. By using this, so called virtual map in this paper, user is able to know the pipelines'feature and crack position.
Analytic Solution to the Spatial Propagation of the Flexible Structures
Seok, Jin-Yeong ; Jeong, Eun-Tae ; Kim, Yu-Dan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2040~2047
DOI : 10.22634/KSME-A.2001.25.12.2040
In this paper, a singularity problem of the state transition matrix is investigated in the spatial propagation when the spatial matrix differential equation is constructed via time finite element analysis. A parametric study shows that the degree of singularity of the state transition matrix depends on the degree of flexibility of the structures. As an alternative to avoid the numerical problems due to the singularity, an analytic solution fur spatial propagation of the flexible structures is proposed. In the proposed method, the spatial properties of the structure are analytically expressed by a combination of transcendental functions. The analytic solution serves fast and accurate results by eliminating the possibility of the error accumulation caused by the boundary condition. Several numerical examples are shown to validate the effectiveness of the proposed methods.
A Study on the Estimation of the Ride Quality of a Large-Sized Truck Using a Computer Model
Mun, Il-Dong ; O, Jae-Yun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2048~2055
DOI : 10.22634/KSME-A.2001.25.12.2048
This paper develops a computational model for estimating the ride quality of a cabover type large-sized truck in a double wheel bumpy ride test. The computational model is developed using ADAMS. To verify the developed model, an actual vehicle double wheel bumpy ride test is performed. In the test, the vehicle maintains a straight course with a constant velocity such that the front two wheels are passed the bump at the same time. The bump has the height of 60mm, and the width of 550mm. In the test, four velocities are used. They are 10kph, 20kph, 30kph and 40kph. Since the large-sized truck's center of gravity location is high, and its weight is heavy, it is a quite severe test condition to perform the test with more than 30kph velocity. In the test, vertical accelerations on the floor of the cab are measured. The measured accelerations are compared to the simulation results. From the comparison, it is shown that the developed model can predict not only the measured acceleration's tendency but also peak accelerations quite well. In this paper, the validated model is utilized to compare the ride quality between a vehicle with a multi-leaf spring and a vehicle with a tapered leaf spring in the front suspension system in a double bumpy ride test.
An Overstress Model for Non-proportional Loading of Nylon 66
Ho, Gwang-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2056~2061
DOI : 10.22634/KSME-A.2001.25.12.2056
Non-proportional loading tests of Nylon 66 at room temperature exhibit path dependent behavior and plasticity-relaxation interactions. The uniaxial formulation of the viscoplasticity theory based on overstress (VBO), which has been used to reproduce the nonlinear strain rate sensitivity, relaxation, significant recovery and cyclic softening behaviors of Nylon 66, is extended to three-dimensions to predict the response in strain-controlled, comer-path tests. VBO consists of a flow law that is easily written for either the stress or the strain as the independent variable. The flow law depends on the overstress, the difference between the stress and the equilibrium stress that is a state variable in VBO. The evolution law of the equilibrium stress in turn contains two additional state variables, the kinematic stress and the isotropic stress. The simulations show that the constitutive model is competent at modeling the deformation behavior of Nylon 66 and other solid polymers.
Crack Identification Based on Synthetic Artificial Intelligent Technique
Sim, Mun-Bo ; Seo, Myeong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2062~2069
DOI : 10.22634/KSME-A.2001.25.12.2062
It has been established that a crack has an important effect on the dynamic behavior of a structure. This effect depends mainly on the location and depth of the crack. To identify the location and depth of a crack in a structure, a method is presented in this paper which uses synthetic artificial intelligent technique, that is, Adaptive-Network-based Fuzzy Inference System(ANFIS) solved via hybrid learning algorithm(the back-propagation gradient descent and the least-squares method) are used to learn the input(the location and depth of a crack)-output(the structural eigenfrequencies) relation of the structural system. With this ANFIS and a continuous evolutionary algorithm(CEA), it is possible to formulate the inverse problem. CEAs based on genetic algorithms work efficiently for continuous search space optimization problems like a parameter identification problem. With this ANFIS, CEAs are used to identify the crack location and depth minimizing the difference from the measured frequencies. We have tried this new idea on a simple beam structure and the results are promising.
A Study on Fatigue Crack Growth of Composite Patching Repaired on Cracked Thick Plate
Jeong, Gi-Hyeon ; Yang, Won-Ho ; Go, Myeong-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2070~2077
DOI : 10.22634/KSME-A.2001.25.12.2070
An experimental investigation of the effect of composite patching repair was conducted to characterize the fatigue crack growth behavior in thick A16061-T6 (6mm) panels with single bonded patch by fiber reinforced composite patch. Four patch lengths and no patch plate were examined. An analytical procedure, involving three-dimensional finite element method having three layers to model cracked aluminum plate, epoxy by adhesive and composite Patch, is calculated the stress intensity factors. From the calculated stress intensity factors, the fatigue crack growth rates are obtained. At the single patching type, different fatigue crack growth ratios through the palate thickness were investigated by using the experimental and analytical results. The results demonstrated that there was a definite variation in fatigue life depending on the size of composite patch. While crack reached the patch end, retardation of crack growth was also revealed in the bonded repair.
Precise Position Synchronous Control of Two Axes Rotating Systems by Cooperative Control
Jeong, Seok-Gwon ; Kim, Yeong-Jin ; Yu, Sam-Sang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2078~2090
DOI : 10.22634/KSME-A.2001.25.12.2078
This paper deals with a precise position synchronous control by a cooperative control method of two axes rotating systems. First, the system's dynamics including motor drives described by a motor circuit equation and Newton's kinetic formulation about rotating system. Next, based on conventional PID(Proportional, Integral, Derivative) control law, current and speed controller are designed very simply to follow up reference speed correctly under some disturbances. Also, position synchronous controller designed to minimize position errors according to integration of speed errors between two motors. Then, the proposed control enables the distributed drives by a software control algorithm to behave in a way as if they are mechanically hard coupled in axes. Further, the stabilities and robustness or the proposed system are investigated. Finally, the proposed system presented here is shown to be more precise position synchronous motion than conventional systems through some simulations and experiments.
A Study on Fatigue Crack Growth Analysis of Inclined Cracked Plate with Composite Patched Repair
Jeong, Gi-Hyeon ; Yang, Won-Ho ; Kim, Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2091~2099
DOI : 10.22634/KSME-A.2001.25.12.2091
Fatigue crack growth behavior of inclined cracked Al 6061-T6 thick aluminum plate(6mm) repaired with the bonded composite patch was studied. A 0°inclined crack bonded reinforced composite patch and 15°, 30°, 45°, 60°inclined crack plates were tested. The effect of patch and inclined angle were studied and compared to each other. Also we investigated to the crack propagation direction and debonding behavior during the fatigue crack growth test. In this paper. a study was con(ducted to get an fatigue life, fatigue crack growth ratio and crack growth direction. Finally, the effectiveness of composite patch on inclined cracked plate was investigated. The results demonstrated thats there was a definite variation in fatigue life and fatigue crack growth behavior depending on the inclined crack angle.
A Study on the Characteristics of Edgetones by High-Speed Plane Jets
Gwon, Yeong-Pil ; Lee, Geun-Hui ; Jang, Uk ; Kim, Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2100~2108
DOI : 10.22634/KSME-A.2001.25.12.2100
The impinging tones by high-speed plane jets are experimentally investigated to study the edgetone characteristics. Experiment used a slit nozzle and a wedge system to generate edgetones. The jet in the experiment is varied from low to high subsonic speed to obtain the effect of the speed on the frequency characteristics of impinging tones. The experimental data obtained previously fur edgetones and platetones by various nozzles are compared with the present edgetone data. And the condition of tone generation, the frequency ranges, the effective source point and the sound pressure level are compared and discussed. It is found that the jet speed has no diect influence on the impinging tone characteristics. Regardless of the jet speed, the effective source point is about a quarter wavelength downstream from the edge tip. With increase in jet speed, the influence of the nozzle configuration is decreased and the operating frequencies show good coincidences by normalized parameters based on the slit thickness.
Normalization of DBTT Size Effect far Aged 1Cr-lMo-0.25V Steel
Nam, Seung-Hun ; Kim, Eom-Gi ; Lee, Dae-Yeol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2109~2115
DOI : 10.22634/KSME-A.2001.25.12.2109
Miniaturized specimen technology is useful to characterize the mechanical behavior when it is difficult to sample the material enough for the test. In this study, two kinds of miniaturized Charpy impact specimens(i.e., miniaturized specimen with side groove and without side groove) of aged 1Cr- lMo-0.25V steel were prepared and tested. The relationship between the extent of degradation in terms of ductile brittle transition temperature(DBTT) and the fracture stress of 1Cr-1Mo-0.25V steel was established. The fracture stress obtained from miniaturized specimen without side groove turned out to be linearly related with the DBTT of standard specimen. Therefore the fracture toughness of aged turbine rotor steel might be evaluated by the fracture stress. In addition, the correlation between DBTT of standard specimen and that of miniaturized specimen was investigated. As the results of normalizing DBTT by maximum elastic tensile stress, the normalized DBTT of miniaturized specimen without side groove allows one to estimate that of standard specimen.
A Study on the Evaluation of Material Degradation of 1Cr-lMo-0.25V Steel using Ultrasonic Techniques
Kim, Jeong-Pyo ; Seok, Chang-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 12, 2001, Pages 2116~2124
DOI : 10.22634/KSME-A.2001.25.12.2116
It's required mechanical properties of in-service facilities to maintain safety operation in power plants as well as chemical plants. In this studdy the four classes of the thermally aged 1Cr-lMo-0.25V specimens were prepared using an artificially accelerated aging method at 630
. Ultrasonic tests, tensile tests, K
IC/ tests and hardness tests were performed in order to evaluate the degree of degradation of the material. The mechanical properties were decreased as degraded, but the attenuation coefficient and the harmonic generation level of a ultrasonic signal were increased. Expecially the nonlinear parameter derived from the harmonic generation level is sensitive and will be a good parameter to evaluate the material degradation.