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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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The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 24, Issue 12 - Dec 2000
Volume 24, Issue 11 - Nov 2000
Volume 24, Issue 10 - Oct 2000
Volume 24, Issue 9 - Sep 2000
Volume 24, Issue 8 - Aug 2000
Volume 24, Issue 7 - Jul 2000
Volume 24, Issue 6 - Jun 2000
Volume 24, Issue 5 - May 2000
Volume 24, Issue 4 - Apr 2000
Volume 24, Issue 3 - Mar 2000
Volume 24, Issue 2 - Feb 2000
Volume 24, Issue 1 - Jan 2000
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Dynamic Stability Analysis of a Spinning Disk with Angular Acceleration by Using the Uncoupled Governing Equations
Choe, Tae-Yeong ; Jeong, Jin-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1363~1370
DOI : 10.22634/KSME-A.2000.24.6.1363
Dynamic stability of a flexible spinning disk with angular acceleration is considered. To avoid the coupling between the in-plane and out-of-plane displacements, the linearized strain-displacement relations are used in the Kirchhoff plate theory. The uncoupled governing equations are derived by using Hamilton's principle with considering the angular acceleration. Numerical tests show that existence of the angular acceleration makes a spinning disk dynamically unstable.
Control of the Multi-Mode Muffler for Low Noise and Low Backpressure
Son, Dong-Gu ; Kim, Heung-Seop ; O, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1371~1378
DOI : 10.22634/KSME-A.2000.24.6.1371
To reduce backpressure for improving engine power in exhaust system, a large difference of pressure is required, but this is in conflict with the requirement for reducing exhaust noise that needs a small pressure difference. In this paper, the controllable muffler designed by simplifying the structure of the exhaust system has a low backpressure and a proper sound specification to the rotation of engine. The exhaust system in conventional studies has been designed to have maximum noise reduction over the whole driving domain, but due to its complex structure this led to increased backpressure. If the muffler is designed according to the driving frequency, which is a dominant noise component in stationary driving speed, the backpressure is reduced due to the simplified structure of the muffler. Furthermore, a multi-mode muffler able to change structure with varied driving speed was designed.
Design Process of Robotic Cell and Layout Design Tool
Guk, Geum-Hwan ; Park, Jun-Mo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1379~1389
DOI : 10.22634/KSME-A.2000.24.6.1379
In this study, a design process of robotic cell is presented. This paper focuses only on the automation of workpiece handling with robot. The presented design process enables us to analyze effectiv ely the original production system and to redesign it as an optimum production system with robots. An original production system is analyzed with respect to its economical and technological requirements for automation. If automation of the given production system is feasible, the conceptual design for automation is firstly derived. Next, the detail design is derived for the optimum conceptual design. Finally, an optimum system solution is determined after the economical and technical evaluation of all the derived detail designs. The all specifications of each element of the redesigned production system and its layout are determined at the detail design phase. This paper shows a low cost supporting tool for layout design of robotic cell with SCARA type robots.
Active Vibration Control of Acoustically Loaded Flexible Plate Enclosure Using Multi-Channel Control Algorithm
Hong, Jin-Seok ; Park, Su-Hong ; Kim, Heung-Seop ; O, Jae-Eung ; Jeong, Jin-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1390~1397
DOI : 10.22634/KSME-A.2000.24.6.1390
This paper presents the multi-channel active vibration control of a flexible plate of the acoustically loaded enclosure. The flexible plate was excited acoustically with sinusoidal and white noise input. The control was performed by two piezo ceramic actuators and two accelerometers. The experimental results were compared with the single channel control results. In the case of white noise input, 20 dB of vibration reduction was achieved below 300Hz frequency range. The experimental results demonstrate that multi-channel filtered-x LMS algorithm is effective than single-channel filtered-x LMS algorithm in active vibration control of plate.
Degradation Damage Evaluation of High Temperature Structural Components by Electrochemical Anodic Polarization Test
Yu, Ho-Seon ; Song, Mun-Sang ; Song, Gi-Uk ; Ryu, Dae-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1398~1407
DOI : 10.22634/KSME-A.2000.24.6.1398
The structural steels of power plant show the decrease of mechanical properties due to degradation such as temper embrittlement, creep damage and softening during long-term operation at high temper ature. The typical causes of material degradation damage are the creation and coarsening of carbides(M23C6, M6C) and the segregation of impurities(P, Sb and Sn) to grain boundary. It is also well known that material degradation induces the cleavage fracture and increases the ductile-brittle transition temperature of steels. So, it is very important to evaluate degradation damage to secure the reliable and efficient service condition and to prevent brittle failure in service. However, it would not be appropriate to sample a large test piece from in-service components. Therefore, it is necessary to develop a couple of new approaches to the non-destructive estimation technique which may be applicable to assessing the material degradation of the components with not to influence their essential strength. The purpose of this study is to propose and establish a new electrochemical technique for non-destructive evaluation of material degradation damage for Cr-Mo steels which is widely used in the high temperature structural components. And the electrochemical anodic polarization test results are compared with those of semi-nondestructive SP test.
A Study on the Construction of Response Surfaces for Design Optimization
Hong, Gyeong-Jin ; Jeon, Gwang-Gi ; Jo, Yeong-Seok ; Choe, Dong-Hun ; Lee, Se-Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1408~1418
DOI : 10.22634/KSME-A.2000.24.6.1408
Gradient-based optimization methods are inefficient in applications which require expensive function evaluations, and useless in applications where objective and/or constraint functions are 'noisy' due to modeling and cumulative numerical inaccuracy since gradient evaluation results cannot be reliable. Moreover, it is difficult to be integrated with commercial analysis software, and they cannot be employed when only experimental analysis results are available. In this research an optimization program based on a response surface method has been developed to overcome the aforementioned difficulties. Various methods for design of experiments and new proposed approximation models are implemented in the program. The effectiveness of the optimization program is tested on several test problems and results are discussed.
Application of Pseudospectral Method to the Dynamic Analysis of Rectangular Reissner-Mindlin Plate
Seung, Yong-Ho ; Lee, Jin-Hui ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1419~1426
DOI : 10.22634/KSME-A.2000.24.6.1419
A dynamic analysis of rectangular Reissner-Mindlin plate was carried out using pseudospectral method. The pseudospectral method is superior to the finite element method because of more rapid conver gence speed of approximate solutions. Especially, the improvement in accuracy of the pseudospectral method is remarkable. Numerical examples demonstrate the excellent performance and robustness of the pseudospectral method with respect to thickness ratio of rectangular Reissner-Mindlin plate. The natural frequencies of rectangular Reissner-Mindlin plate calculated with the pseudospectral method are more reliable than those calculated with other numerical methods.
Modal Synthesis of a Car Body Structure Using an Improved Experimental Free-Interface Method
Jang, Gyeong-Jin ; Park, Yeong-Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1427~1437
DOI : 10.22634/KSME-A.2000.24.6.1427
In the authors＇ preceeding paper, an improved component mode synthesis (CMS) technique in which experimental data as well as finite-element data are available in sub-systems has been proposed. Thi s technique, called an improved experimental free-interface method (IEFIM), has been proved to be more accurate and more efficient than the conventional experimental CMS method based on McNeal's formulation. It is due to the facts that dynamic residual terms as well as static ones are compensated from experimentally obtained FRFs and that FRFs measured on any frequencies can be used for the compensation. In this paper, the technique is applied to the component mode synthesis of a car body structure. As a result, the applicability of the technique to a large structure is demonstrated.
A Program Development for Dynamic Characteristics of Material in SHPB with Explicit Finite Element Method
Lee, Seung-U ; Hong, Seong-In ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1438~1445
DOI : 10.22634/KSME-A.2000.24.6.1438
To determine dynamic characteristics of materials, a program was developed under base of stress wave propagation theory for SHPB with explicit finite element method. Through the program, all kinds of quasi-static stress-strain curves can be directly converted to dynamic stress-strain curves at any strain rate. This simulation results were compared with experimental results in the references and they are in a good agreement with each other.
Behavior of Fatigue Crack Initiation and Propagation under Cyclic Tensile or Torsional Loading with Superimposed Static Biaxial Load
Heo, Yong-Hak ; Park, Hwi-Rip ; Gwon, Il-Beom ; Kim, Jin-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1446~1455
DOI : 10.22634/KSME-A.2000.24.6.1446
Fatigue crack initiation and propagation behavior under cyclic biaxial loading has been investigated using thin-walled tubular specimen with a hole. Two types of biaxial loading system, i.e. cyclic tensile loading with super-imposed static torsional load and cyclic torsional loading with superimposed static tensile load, with various values of the biaxial loading ratio,
s) were employed. Fatigue tests show that fatigue crack near the hole initiates and propagates at 900 and 450 direction to the longitudinal direction of the specimen under cyclic tensile and torsion loading with static biaxial stress, respectively, and the static biaxial stress doesn't have any great influence on fatigue crack initiation and growth direction. Stress analysis near the hole of the specimen shows that the crack around the hole initiates along the plane of maximum tangential stress range. Fatigue crack growth rates were evaluated as functions of equivalent stress intensity factor range, strain energy density factor range and crack tip opening displacement vector, respectively. It is shown that the biaxial mode fatigue crack growth rates can be relatively consistently predicted with these cyclic parameters.
Failure Mechanism of Metal Matrix Composites Subject to Transverse Loading
Ham, Jong-Ho ; Lee, Hyeong-Il ; Jo, Jong-Du ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1456~1469
DOI : 10.22634/KSME-A.2000.24.6.1456
Mechanical behaviors of uniaxially fiber-reinforced metal matrix composites under transverse loading conditions were studied at room and elevated temperatures. A mono-filament composite was selecte d as a representative analysis model with perfectly bonded fiber/matrix interface assumption. The elastic-plastic and visco-plastic models were investigated by both theoretical and numerical methods. The product of triaxiality factor and effective strain as well as stress components and strain energy was obtained as a function of location to estimate the failure sites in fiber-reinforced metal matrix composite. Results showed that fiber/ matrix interfacial debond plays a key role for local failure at the room temperature, while void creation and growth in addition to the interfacial debond are major concerns at the elevated temperature. It was also shown that there would be an optimal diameter of fiber for the strong fiber-reinforced metal matrix composite.
Analysis of Actuating and Joint Reaction Forces for Various Drivings in Multibody Systems with Closed-Loops
Lee, Byeong-Hun ; Choe, Dong-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1470~1478
DOI : 10.22634/KSME-A.2000.24.6.1470
Analysis of actuating forces and joint reaction forces are essential to determine the capacity of actuators, to control the system and to design the components. This paper presents an algorithm tha t calculates actuating forces(or torques) depending on the various driving types to produce a given system motion. The joint reaction forces(or torques) of multibody systems with closed-loops are analyzed in the Cartesian coordinate space using the inverse velocity transformation technique. Two numerical examples were carried out to verify the algorithm proposed.
Analysis and Design of a Motor Driven Tilt/Telescopic Steering Column for Safety Improvement
Sin, Mun-Gyun ; Hong, Seong-U ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1479~1490
DOI : 10.22634/KSME-A.2000.24.6.1479
The design process of the motor driven tilt/telescopic steering column is established by axiomatic design approach in conceptual design stage. By selecting independent design variables for improvin g performance of the steering system, each detailed design can be carried out independently. In the detailed design, the safety in crash environment and vibration reduction are considered. An occupant analysis code SAFE(Safety Analysis For occupant crash Environment) is utilized to simulate the body block test. Segments, contact ellipsoids and spring-damper elements are used to model the steering column in SAFE. The model is verified by the result of the body block test. After the model is validated, the energy absorbing components are designed using an orthogonal array. Occupant analyses are performed for the cases of the orthogonal array. Final design is determined for the minimum occupant injury. For vibrational analysis, a finite element model of the steering column is defined for the modal analysis. The model is validated by the vibration experiment. Size and shape variables are selected for the optimization process. An optimization is conducted to minimize the weight subjected to various constraints
The Application of AE for a Drilling Damage Process Monitoring in [0/90 0 ]s CFRP Composites
Yun, Yu-Seong ; Gwon, O-Heon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1491~1498
DOI : 10.22634/KSME-A.2000.24.6.1491
In recent years, CFRP composite materials have been increasingly used in various fields of engineering because of a high specific strength and stiffness properties. Drilling is one of the most impo rtant cutting processes that are generally carried out on CFRP materials owing to the need for the structural integration. However, delamination are often occurred as one of the drilling damages. Therefore, there are needs studying for the relationships between CFRP drilling and delamination in order to avoid low strength of the structures and inaccuracies of the integration. In this study, AE signals and thrust forces were used for the evaluations of the delamination from a drilling process in [0/900]s CFRP materials. And the drilling damage processes were observed and measured by a real time monitoring technique with a video camera. From the results, we found that the relationships between the delamination from drilling and AE characteristics and drill thrust forces for [0/900]s CFRP composites. Also, we proposed the monitoring method for a visual analysis of drilling damages.
A Study on Virtual Manufacturing for Total Auto-Body Panel Stamping Processes
Jeong, Dong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1499~1512
DOI : 10.22634/KSME-A.2000.24.6.1499
The dynamic explicit finite element method and the static implicit finite element method are applied effectively to analyze total auto-body panel stamping processes, which include the forming stage , the trimming stage and the spring-back stage.\The explicit time integration method has better merits in the forming stage including highly complicated three-dimensional contact conditions. On the contrary, the implicit time integration method is better for analyzing spring-back since the complicated contact conditions are removed and the computing time to get the final static state is short. In this work, brief descriptions of the formulation and the factor study are presented. Further, the simulated results for the total auto-body panel stamping processes are shown and discussed. The formability and the weld line movement in stamping with Tailor Welded Blanks were investigated through QTR-OTR-FRT.
Control of Biped Robots Based on Impedance Control and Computed-Torque Control
Jeong, Ho-Am ; Park, Jong-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1513~1519
DOI : 10.22634/KSME-A.2000.24.6.1513
This paper proposes a hybrid control method of using impedance control and the computed-torque control for biped robot locomotion. Computed torque control is used for supporting (constrained) leg. For the free leg, the impedance control is used, where different values of impedance parameters are used depending on the gait phase of the biped robot. To reduce the magnitude of an impact and guarantee a stable footing when a foot contacts with the ground, this paper proposes to increase the damping of the leg drastically and to modify the reference trajectory of the leg. Computer simulations with a 3 -dof environment model for which a combination of a nonlinear and a linear compliant models is used, show that the proposed controller is superior to the computed-torque controllers in reducing impacts and stabilizing the footing.
An Analysis of Dynamic Characteristics of Air-Lubricated Slider Bearing by Using Perturbation Method
Gang, Tae-Sik ; Choe, Dong-Hun ; Jeong, Tae-Geon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1520~1528
DOI : 10.22634/KSME-A.2000.24.6.1520
This study presents a method for determining bearing stiffness and damping coefficients of air-lubricated slider bearing, and shows influences of air-bearing surface geometry(recess depth, crown an d pivot location) on flying attitude and dynamic characteristics. To derive the dynamic lubrication equation, the perturbation method is applied to the generalized lubrication equation which based on linearized Boltzmann equation. The generalized lubrication equation and the dynamic lubrication equation are converted to a control volume formulation, and then, the static and dynamic pressure distributions are calculated by finite difference method. The recess depth and crown of the slider show significantly influence on flying attitude and dynamic characteristics comparing with those of pivot location.
A Study on the Optimization Method using the Genetic Algorithm with Sensitivity Analysis
Lee, Jae-Gwan ; Sin, Hyo-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1529~1539
DOI : 10.22634/KSME-A.2000.24.6.1529
A newly developed optimization method which uses the genetic algorithm combined with the sensitivity analysis is presented in this paper. The genetic algorithm is a probabilistic method, searching the optimum at several points simultaneously, requiring only the values of the object and constraint functions. It has therefore more chances to find global solution and can be applied various problems. Nevertheless, it has such shortcomings that even it approaches the optimum rapidly in the early stage, it slows down afterward and it can't consider the constraints explicitly. It is only because it can't search the local area near the current points. The traditional method, on the other hand, using sensitivity analysis is of great advantage in searching the near optimum. Thus the combination of the two techniques makes use of the individual advantages, that is, the superiority both in global searching by the genetic algorithm and in local searching by the sensitivity analysis. Application of the method to the several test functions verifies that the method suggested is very efficient and powerful to find the global solutions, and that the constraints can be considered properly.
Finite Element Analysis of Nonlinear Behavior of a Column Type Sensing Element for Load Cell According to Design Parameters
Lee, Chun-Yeol ; Gang, Dae-Im ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1540~1546
DOI : 10.22634/KSME-A.2000.24.6.1540
Recently, force measurement systems are commonly used in many industrial fields and the precision of the measurement system is getting more important as the industry needs more precise tools and in struments to make high quality products. However, a high precision force measurement system is hard to make unless we know precisely the causes, quality and quantity of measurement errors in advance. In this work, many possible mechanical causes of measurement errors are reviewed including ratio of length to diameter of sensing part, radius of contact area, radius of bearing part, ratio of material properties and change of boundary conditions. Also, the measurement errors are analyzed by nonlinear finite element method and the nonlinear behavior of the errors are investigated. The results can be used to design force measurement systems and expected to be very useful especially for compact type load cells.
Analyses of Stress Intensity Factors and Evaluation of Fracture Toughness in Adhesively Bonded DCB Joints
Jeong, Nam-Yong ; Lee, Myeong-Dae ; Gang, Sam-Geun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1547~1556
DOI : 10.22634/KSME-A.2000.24.6.1547
In this paper, an evaluation method of fracture toughness to apply interfacial fracture mechanics was investigated in adhesively bonded double-cantilever beam (DCB) joints. Four types of adhesively bonded DCB joints with an interface crack were prepared for analyses of the stress intensity factors using boundary element method(BEM) and the fracture toughness test. From the results of BEM analysis and fracture toughness experiments, it is found that the stress intensity factor, K1 is a parameter driving the fracture of adhesively bonded joints. Also, the evaluation method of fracture toughness by separated stress intensity factors of mixed mode cracks was proposed and the influences of mode components for its fracture toughness are investigated in adhesively bonded DCB joints.
Dynamic Stress Intensity Factors of the Half Infinite Crack in the Orthotropic Material Strip with a Large Anisotropic Ratio
Baek, Un-Cheol ; Hwang, Jae-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1557~1564
DOI : 10.22634/KSME-A.2000.24.6.1557
When the half infinite crack in the orthotropic material strip with a large anisotropic ratio(E11>>E22) propagates with constant velocity, dynamic stress component
y occurre d along the
axis is derived by using the Fourier transformation and Wiener-Hopf technique, and the dynamic stress intensity factor is derived. The dynamic stress intensity factor depends on a crack velocity, mechanical properties and specimen hight. The normalized dynamic stress intensity factors approach the maximum values when normalized time(=Cs/a) is about 2. They have the constant values when the normalized time is greater than or equal to about 2, and decrease with increasing a/h(h: specimen hight, a: crack length) and the normalized crack propagation velocity( = c/Cs, Cs: shear wave velocity, c: crack propagation velocity).
Crack Analysis under Fretting Condition by Rounded Punch
Kim, Hyeong-Gyu ; Jeong, Yeon-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1565~1574
DOI : 10.22634/KSME-A.2000.24.6.1565
Surface edge crack subjected to contact stresses is analysed. A punch with corner radii is considered to press the semi-infinite plane. Partial slip problem is solved when a shear force is applied to the punch. Dislocation density function method is used to solve the present mixed mode crack problem. The crack length of positive K1 is examined, which is affected by the ratio of the flat portion to the total width of the punch. Surface traction during one cycle of the shear force is evaluated to simulate the fretting condition. The compliance change of the contact surface is also investigated during the shear cycle. It is found that the crack grows during only a part of the cycle, which may be termed as effective period of crack growing. A design method for restraining the fretting failure is discussed, from which recommendable geometry of the punch is suggested.
Numerical Simulation of the Sandwich Injection Molding Process
Mun, Jong-Sin ; Sin, Hyo-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1575~1583
DOI : 10.22634/KSME-A.2000.24.6.1575
Recently, the sandwich injection molding has drawn attention because it offers the flexibility of using the optimal properties of two different but compatible polymers and is also one of the most p romising methods in connection with recycling of thermoplastics. In this paper, a new particle tracing algorithm is presented in order to describe the advancement of core polymer melt during filling stage. The main advantage of this algorithm is the use of identity field information rather than tracking a set of fluid particles. In addition, to model the process accurately, especially to detect the possible
Initiation and Growth Behavior of Small Surface Fatigue Cracks on SiC Whisker Reinforced Aluminum Composite
Choe, Yeong-Geun ; Lee, Taek-Sun ; Kim, Sang-Tae ; Seo, Chang-Min ; Lee, Mun-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1584~1592
DOI : 10.22634/KSME-A.2000.24.6.1584
Reversed plane bending fatigue tests were conducted on SiC whisker reinforced aluminum composite which were consolidated by squeeze casting process. Initiation and growth of small surface fatigue c racks were investigated by means of a plastic replica technique. The fatigue crack initiated in the vicinity of SiC whisker/matrix interface. It was found that a fatigue crack deflected along SiC whisker and grew in a zig-zag manner microscopically, although the crack propagated along the direction normal to the loading axis macroscopically. The coalescence of micro-cracks was observed in the tests conducted at high stress levels, but were not evident in tests in which lower levels of stress were applied. Due to the coalescence, a higher crack growth rate of small cracks rather than those of long cracks was recognized in da/dn -ΔK realtionship.
Nonlinear System Parameter Identification Using Finite Element Model
Kim, Won-Jin ; Lee, Bu-Yun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1593~1600
DOI : 10.22634/KSME-A.2000.24.6.1593
A method based on frequency domain approaches is presented for the nonlinear parameters identification of structure having nonlinear joints. The finite element model of linear substructure is us ed to calculating its frequency response functions needed in parameter identification process. This method is easily applicable to a complex real structure having nonlinear elements since it uses the frequency response function of finite element model. Since this method is performed in frequency domain, the number of equations required to identify the unknown parameters can be easily increased as many as it needed, just by not only varying excitation amplitude but also selecting excitation frequencies. The validity of this method is tested numerically and experimentally with a cantilever beam having the nonlinear element. It was verified through examples that the method is useful to identify the nonlinear parameters of a structure having arbitary nonlinear boundaries.
Determination of Intensity Factors in Piezoelectric Ceramic Strip with Impermeable Crack
Gwon, Jong-Ho ; Gwon, Sun-Man ; Sin, Jeong-U ; Lee, Gang-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1601~1607
DOI : 10.22634/KSME-A.2000.24.6.1601
Using the theory of linear piezoelectricity, we consider the problem of piezoelectric ceramic infinite strip containing a finite crack with free surface traction and surface charge under anti-plane shear. The crack is symmetrically parallel to the edges of infinite strip. Fourier transforms are used to reduce the problem to two pairs of dual integral equations, which are then expressed in terms of Fredholm integral equations of the second kind. Numerical results for PZT-5H ceramic are obtained and discussed.
Track Tension Monitoring in the Longitudinal Traveling of Tracked Vehicles
Heo, Geon-Su ; Jo, Byeong-Hui ; Seo, Mun-Seok ; Seo, Il-Seong ; Park, Dong-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1608~1615
DOI : 10.22634/KSME-A.2000.24.6.1608
The track tension is closely related to the maneuverability of tracked vehicles and the durability of tracks and suspension systems. In order to minimize the excessive load on the tracks and to pre vent the peal-off of tracks from the road wheels, it is required to maintain the optimum track tension throughout the maneuver. However, the track tension cannot be easily measured due to the limitation in the sensor technology, harsh environment, etc. In this paper an indirect track tension monitoring system is developed based on idler assembly models, a geometric relation around the idler, and the tractive force estimated by using the Extended Kalman Filter. The performance of the tension monitoring system is verified with the results obtained from the Multi-Body Dynamics model.
Finite Element Analysis and Optimal Design of Automobile Clutch Diaphragm Spring
Lee, Chun-Yeol ; Chae, Yeong-Seok ; Gwon, Jae-Do ; Nam, Uk-Hui ; Kim, Tae-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1616~1623
DOI : 10.22634/KSME-A.2000.24.6.1616
A diaphragm spring is an important component of a clutch assembly, characteristics of which depends largely on that of a diaphragm spring. A diaphragm spring is subject to high stress concentration in driving condition, which frequently causes cracks and fracture around finger area. In this paper, behavior of a diaphragm spring is analysed by finite element method to calculate sensitivity of design parameters, which is used to perform optimal design of diaphragm spring shape. As an object function, hoop stresses are taken and minimized to improve durability. Characteristics of the diaphragm is used as equality constraint to maintain the original design purpose and sequential linear programming(SLP) is utilized as an optimization tool. With optimized design, it is verified that concentrated stress is decreased maintaining release load characteristic.
The Effect of the Drawbead Shape on the Sheet Metal Forming Process
Jeong, Dong-Won ; Lee, Sang-Je ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1624~1632
DOI : 10.22634/KSME-A.2000.24.6.1624
In the sheet metal forming process, the drawbead is used to control the flow of material during the forming process. The drawbead provides proper restraining force to the material and prevents defe cts such as wrinkling or breakage. For these reasons, many studies for designing the effective drawbead have been conducted. In this paper, the effect of the drawbead shape will be introduced. For the analysis, the numerical method called the static-explicit finite element method was used. The finite element analysis code for this method has been developed and applied to the drawbead process problems. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis methods were no longer a critical problem. Futhermore, this approach could treat the contact friction problem easily by applying very small time intervals. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.
Manipulator Joint Friction Identification using Genetic Algorithm and its Experimental Verification
Kim, Gyeong-Ho ; Park, Yun-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 24, issue 6, 2000, Pages 1633~1642
DOI : 10.22634/KSME-A.2000.24.6.1633
Like many other mechanical dynamic systems, flexible manipulator systems experience stiction or sticking friction, which may cause input-dependent instabilities. Manipulator performance can be enha nced by identifying friction but it is hard and expensive to measure friction by direct and precise sensing of contact displacements and forces. This study addresses the problem of identifying flexible manipulator joint friction. A dynamic model of a two-link flexible manipulator based upon finite element and Lagrange's method is constructed. The dynamic model includes the effects of joint compliances and actuator dynamics. Friction is also incorporated in the dynamic model to account for stick-slip at the joints. Next, the friction parameters are to be determined. The identification problem is posed as an optimization problem to be solved using nonlinear programming methods. A genetic algorithm is used to increase the convergence rate and the chances of finding the global optimum. The identified friction parameters are experimentally verified and it is expected that the identification technique is applicable to a system parameter identification problem associated with a wide class of nonlinear systems.