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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 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
A Fast Forward Kinematic Analysis of Stewart Platform
Ha, Hyeon-Pyo ; Han, Myeong-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 339~352
DOI : 10.22634/KSME-A.2001.25.3.339
The inverse kinematics problem of Stewart platform is straightforward, but no closed form solution of the forward kinematic problem has been presented. Since we need the real-time forward kinematic solution in MIMO control and the motion monitoring of the platform, it is important to acquire the 6 DOF displacements of the platform from measured lengths of six cylinders in small sampling period. Newton-Raphson method a simple algorithm and good convergence, but it takes too long calculation time. So we reduce 6 nonlinear kinematic equations to 3 polynomials using Nairs method and 3 polynomials to 2 polynomials. Then Newton-Raphson method is used to solve 3 polynomials and 2 polynomials respectively. We investigate operation counts and performance of three methods which come from the equation reduction and Newton-Raphson method, and choose the best method.
The Prediction Modelling on the Stress Intensity Factor of Two Dimensional Elastic Crack Emanating from the Hole Using Neural Network and Boundary element Method
Yun, In-Sik ; Lee, Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 353~361
DOI : 10.22634/KSME-A.2001.25.3.353
Recently the boundary element method has been developed swiftly. The boundary element method is an efficient and accurate means for analysis of two dimensional elastic crack problems. This paper is concerned with the evaluation and the prediction of the stress intensity factor(SIF) for the crack emanating from the circular hole using boundary element method-neural network. The SIF of the crack emanating from the hole was calculated by using boundary element method. Neural network is used to evaluate and to predict SIF from the results of boundary element method. The organized neural network system (structure of four processing element) was learned with the accuracy 99%. The learned neural network system could be evaluated and predicted with the accuracy of 83.3% and 71.4% (in cases of SIF and virtual SIF). Thus the proposed boundary element method-neural network is very useful to estimate the SIF.
Study on the Dynamic Modeling of a MCCB Mechanism Including Electro-Magnetic Force Effect
Gang, Gyeong-Rok ; Yu, Hong-Hui ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 362~368
DOI : 10.22634/KSME-A.2001.25.3.362
To design a limiting MCCB (Molded Case Circuit Breaker) mechanism, a dynamic modeling of the mechanism in which the electro-magnetic force effects are incorporated needs to be developed. Conventionally, electro-magnetic effects were considered separately for the design of the mechanism. In this paper, an electro-magnetic force that is induced by limited current is identified and included in the dynamic modeling of the mechanism. Thus, the electro-magnetic which is defined as a external force and the mechanical effects are simultaneously considered for the design of the mechanism which is composed of contactor, spring , link, latch and so on.
Optimal Design of Composite Laminated Plates with the Discreteness in Ply Angles and Uncertainty in Material Properties Considered
Kim, Tae-Uk ; Sin, Hyo-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 369~380
DOI : 10.22634/KSME-A.2001.25.3.369
Although extensive efforts have been devoted to the optimal design of composite laminated plates in recent years, some practical issues still need further research. Two of them are: the handling of the ply angle as either continuous or discrete; and that of the uncertainties in material properties, which were treated as continuous and ignored respectively in most researches in the past. In this paper, an algorithm for stacking sequence optimization which deals with discrete ply angles and that for thickness optimization which considers uncertainties in material properties are used for a two step optimization of composite laminated plates. In the stacking sequence optimization, the branch and bound method is modified to handle discrete variables; and in the thickness optimization, the convex modeling is used in calculating the failure criterion, given as constraint, to consider the uncertain material properties. Numerical results show that the optimal stacking sequence is found with fewer evaluations of objective function than expected with the size of feasible region taken into consideration; and the optimal thickness increases when the uncertainties of elastic moduli considered, which shows such uncertainties should not be ignored for safe and reliable designs.
A Study on the Characteristic of Fracture Toughness in the Multi-Pass Welding Zone for Nuclear Piping
Park, Jae-Sil ; Seok, Chang-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 381~389
DOI : 10.22634/KSME-A.2001.25.3.381
The objective of this paper is to evaluate the fracture resistance characteristics of SA508 Cl.1a to SA508 Cl.3 welds manufactured for the reactor coolant loop piping system of nuclear power plants. The effect of the crack plane orientation to the welding process orientation and the preheat temperature on the fracture resistance characteristics were discussed. Results of the fracture resistance test showed that the effect of the crack plane orientation to the welding process orientation of the fracture toughness is significant, while that of preheat temperature on the fracture toughness is negligible. The micro Vickers hardness test, the metallographic observation and the fractography analysis were conducted to analyse the crack jump phenomenon on the L-R crack plane orientation in the multi-pass welding zone. As these results, it is shown that the crack jump phenomenon was produced because of the inhomogeneity between welding beads and the crack plane orientation must be considered for the safety of the welding zone in the piping system.
A Study on the Analysis of Residual Stress in Weldment by Considering the Phase Transformation of Carbon Steel
Jo, Si-Hun ; Kim, Jae-Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 390~398
DOI : 10.22634/KSME-A.2001.25.3.390
Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper suggests new analysis method to predict welding residual stress by considering solid phase transformation during welding process. Using the method, analysis is performed for medium and low carbon steel. The analysis result for medium carbon steel reveals that case considering phase transformation has compressive residual stress in contrast with the case neglecting phase transformation because of martensite formation. However, for the case of low carbon steel, residual stress shows little difference between the case considering phase transformation and the other case, because it has small transformation strain and recovers rapidly stress after phase transformation.
Improvement of the Accuracy in Cornering Cut Using End Mill
Kim, Yong-Hyeon ; Go, Seong-Rim ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 399~407
DOI : 10.22634/KSME-A.2001.25.3.399
The Surface, generated by end milling operation, is deteriorated by tool runout, vibration, friction, tool deflection, etc. Especially in cornering cut, surface accuracy is usually determined by varying cutting forces, which causes tool deflections. Cutting conditions like feed rate is usually kept constant during machining a part, which causes dimensional error in severe cutting. Cornering cut is a typical example of deterioration of surface accuracy when constant feed rate is applied. Therefore it becomes important to develop NC post processor module to determine optimal cutting conditions in various cutting situations. In this paper, cutting force is predicted in cornering cut with flat end mill and feed rate is determined by constraining constantly resultant force. Also some control characteristics of CNC machining center are evaluated.
A Study on the Vibration Characteristics of Stiffened Cylinder
Kim, Gwang-Rae ; Jang, Yong-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 408~414
DOI : 10.22634/KSME-A.2001.25.3.408
The structural characteristics of the stiffened double cylinder was investigated through experiment and analysis. The outside cylinder was excited with piezoelectric actuator and the mode shape of the cylinder with stiffening T frame was obtained by using holographic interferometry. Finite element method was applied for further modal investigation of the stiffened cylinder. The experimental results showed that the mode shape of cylinder was dependent on the exciting frequencies and the T frame showed salient effect of damping at most of the resonent frequencies. In particular frequencies, the T frame worked as a transmitter. FFM showed similar results with the experiments. This paper showed that the laser-based method such as holographic interferometry is well suited for investigation of the whole-field mode shapes and FEM has good performance to estimate the medal characteristics of the mechanical structure.
Detection of Interface Crack Using Ultrasonic Method in Adhesively Bonded Joints
Jeong, Nam-Yong ; Park, Seong-Il ; Lee, Myeong-Dae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 415~423
DOI : 10.22634/KSME-A.2001.25.3.415
In is well recognized that the ultrasonic method is one of the most common and reliable nondestructive testing(NDT) methods for the quantitative estimation of defects in welded structures. However, NDT techniques applying for adhesively bonded joints have not been clearly established yet. In this paper, the detection of interface crack by the ultrasonic method was applied for the measurement of interface crack length in the adhesively bonded joints of double-cantilever beam(DCB). The optimum condition of transmission coefficients and experimental accuracy by the ultrasonic method in the adhesively bonded joints have been investigated. The experimental values are in good agreement with the computed results by boundary element method(BEM) and Riplings equation.
Laterally-Driven Electrostatic Repulsive-Force Microactuator
Lee, Gi-Bang ; Jo, Yeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 424~433
DOI : 10.22634/KSME-A.2001.25.3.424
We present a new electrostatic repulsive-force microactuator using a lateral repulsive force induced by an asymmetric distribution of electrostatic field. The lateral repulsive force has been characterized by a simple analytical equation, derived from a finite element simulation. A set of repulsive force polysilicon microactuators has been designed and fabricated by a 4-mask surface-micromachining process. Static and dynamic micromechanical behavior of the fabricated microactuators has been measured at the atmospheric pressure for a varying bias voltage. The static displacement of the fabricated microactuator, proportional to the square of the DC bias voltage, is obtained as 1.27
for the DC bias voltage of 140V. The resonant frequency of the repulsive-force microactuator increases from 11.7 kHz to 12.7 kHz when the DC bias voltage increases from 60V to 140V. The measured quality-factor varies from 12 to 13 for the bias volatge range of 60V∼140V. The characteristics of the electrostatic repulsive-force have been discussed and compared and compared with those of the conventional electrostatic attractive-force.
A Study on the Development of the Dynamic Photoelastic Hybrid Method for Two Dissimilar Isotropic Bi-Materials
Sin, Dong-Cheol ; Hwang, Jae-Seok ; Gwon, O-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 434~442
DOI : 10.22634/KSME-A.2001.25.3.434
When the interfacial crack of two dissimilar isotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid method developed in this research are valid. Separating method of stress component is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 80∼85% (in case of aluminum, 24.3∼25.9%) of Rayleigh wave velocity of epoxy resin. The near-field stress components of crack-tip are similar with those of pure isotropic material under static or dynamic loading, but very near-field stress components of crack-tip are different from those.
On-Line Scheduling Method for Track Systems in Semiconductor Fabrication
Yun, Hyeon-Jung ; Lee, Du-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 443~451
DOI : 10.22634/KSME-A.2001.25.3.443
This paper addresses an on-line scheduling method for track systems in semiconductor fabrication. A track system is a clustered equipment performing photolithography process in semiconductor fabrication. Trends toward high automation and flexibility in the track systems accelerate the necessity of the intelligent controller that can guarantee reliability and optimize productivity of the track systems. This paper proposes an-efficient on-line scheduling method that can avoid deadlock inherent to track systems and optimize the productivity. We employ two procedures for the on-line scheduling. First, we define potential deadlock set to apply deadlock avoidance policy efficiently. After introducing the potential deadlock set, we propose a deadlock avoidance policy using an on-line Gantt chart, which can generate optimal near-optimal schedule without deadlock. The proposed on-line scheduling method is shown to be efficient in handling deadlock inherent to the track systems through simulation.
Concurrent Optimization of Design and Machining Tolerances with Accumulated Scrap Cost Model(ASCM)
Choe, Min-Seok ; Lee, Du-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 452~460
DOI : 10.22634/KSME-A.2001.25.3.452
Most of researches of tolerance optimization have used a simple sum of tolerance-cost functions with several constraint equations as an optimization model. However, if there is a machining sequence with more than one processes to complete a part, and machining failure, i.e., out-of-tolerance occurs at one of the intermediate processes, the tolerance-cost of this process should be added by the machining cost of all the previous processes already completed on the part. In this study, an accumulated scrap cost model(ASCM) is proposed considering the scrapped machining cost, and applied to a simple assembly example. The result of tolerance optimization using ASCM is compared with that of using a traditional optimization model to confirm its effectiveness.
A Stereo Matching Algorithm with Projective Distortion of Variable Windows
Kim, Gyeong-Beom ; Jeong, Seong-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 461~469
DOI : 10.22634/KSME-A.2001.25.3.461
Existing area-based stereo algorithms rely heavily on rectangular windows for computing correspondence. While the algorithms with the rectangular windows are efficient, they generate relatively large matching errors due to variations of disparity profiles near depth discontinuities and doesnt take into account local deformations of the windows due to projective distortion. In this paper, in order to deal with these problems, a new correlation function with 4 directional line masks, based on robust estimator, is proposed for the selection of potential matching points. These points is selected to consider depth discontinuities and reduce effects on outliers. The proposed matching method finds an arbitrarily-shaped variable window around a pixel in the 3d array which is constructed with the selected matching points. In addition, the method take into account the local deformation of the variable window with a constant disparity, and perform the estimation of sub-pixel disparities. Experiments with various synthetic images show that the proposed technique significantly reduces matching errors both in the vicinity of depth discontinuities and in continuously smooth areas, and also does not be affected drastically due to outlier and noise.
An Experimental Study on the Factors that Affect Fatigue Crack Growth Retardation Behavior in S45C Steel
Kim, Seon-Jin ; An, Seok-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 470~477
DOI : 10.22634/KSME-A.2001.25.3.470
Constant ΔK fatigue crack growth tests were performed by applying an intermediate multiple overload for S45C steel. The purpose of the present study is to investigate effects of specimen thickness at various baseline stress intensity factor range levels (ΔK(sub)b), overload application position (a/W) and overload application frequency (OL(sub)HZ) on fatigue crack growth retardation behavior. The principal results are summarized as follows. The amount of retardation for a given ΔK(sub)b level is increased with increasing the baseline stress intensity factor range level for all specimen thickness. The normalized minimum crack growth rate is increased with increasing the specimen thickness, except for ΔK=45MPa√m. The retardation cycle is decreased with increasing a/W and increased with OL(sub)HZ.
Dynamic Characteristic Analysis of Aerodynamic Load Simulator English
Nam, Yun-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 478~485
DOI : 10.22634/KSME-A.2001.25.3.478
A dynamic load simulator(DLS) which can reproduce on-ground the aerodynamic hinge moment of control surface is an essential rig for the performance and stability test of aircraft actuation system. By setting up load actuator as counter acting with the control surface driving actuator and designing an appropriate force control system for load actuator, DLS can be mechanized. Obtaining an accurate mathematical model for the DLS is the first step to successfully design an aerodynamic load replicati on system. Two theoretical models are presented and tested for their validities with the experimental results, which turns out to be not successful. An alternative way of using system identification approaches in investigated to develop a good nominal model for DLS dynamics, and suitable uncertainty bounds for this nominal model are proposed with the consideration of experimental results.
Real-time Dynamic Simulation Using Multibody Vehicle Model
Choe, Gyu-Jae ; No, Gi-Han ; Yu, Yeong-Myeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 486~494
DOI : 10.22634/KSME-A.2001.25.3.486
This paper presents a real-time multibody vehicle dynamic analysis method using recursive Kanes formulation and suspension composite joints. To shorten the computation time of simulation, relative coordinate system is used and the equations of motion are derived using recursive Kanes formulation. Typical suspension systems of vehicles such as MacPherson strut suspension system is modeled by suspension composite joints. The joints are derived and utilized to reduce the computation time of simulation without any degradation of kinematical accuracy of the suspension systems. Using the develop program, a multibody vehicle dynamic model is formed and simulations are performed. Accuracy of the simulation results is compared to the real vehicle field test results. It is found that the simulation results using the proposed method are very accurate and real-time simulation is achieved on a computer with single PowerPC 604 processor.
Dynamic Modeling of Bolt Joints Using Lumped Mass-Spring Model
Go, Gang-Ho ; Lee, Jang-Mu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 495~501
DOI : 10.22634/KSME-A.2001.25.3.495
In this paper, a new technique which models the joints characteristics through reduction of DOFs of structures with joints using component mode synthesis (CMS) method is proposed. Bolt joints are modeled by mass-spring systems. Also generalized mass and stiffness matrices for this models are introduced. Because bolt joints have influence on eigenvalues of structures, exact eigenvalues from modal test are used. The results show that the behaviors of structures with bolt joints depend to a large extent on the translational DOFs and not on rotational DOFs of mass and stiffness matrices of bolts. Furthermore it is confirmed that lumped mass-spring systems as models of bolt joints are effective models considering the facts that joint characteristics converged to constant values in some iterations and eignevalues from proposed method are in good agreement with ones from modal test.
Effect of Anisotropic Ratio for Rayleigh Wave of a Half-Infinite Composite Material
Baek, Un-Cheol ; Hwang, Jae-Seok ; Song, Yong-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 502~509
DOI : 10.22634/KSME-A.2001.25.3.502
In this paper, when stress waves are propagated along the reinforced direction of the composite, the characteristic equation of Rayleigh wave is derived. The relationships between velocities of stress waves and Rayleigh wave are studied for anisotropic ratios(E(sub)11/E(sub)12 or E(sub)22/E(sub)11). The increments of anisotropic ratios is made by using known material properties and being constant of basic properties. When the anisotropic ratios are increased, Rayleigh wave velocities to the shear wave velocities are almost equal to 1 with any anisotropic ratios. Rayleigh wave velocities to the longitudinal wave velocities and Shear wave velocities ratio to the longitudinal wave velocities are almost identical each other, they are between 0.12 and 0.21. When the anisotropic ration is very high, that is, E(sub)11/E(sub)22=46.88, Rayleigh wave velocities and the shear wave velocities are almost constant with Poissons ratio, longitudinal wave velocities are very slowly increased with the increments of Poissons ratios. When E(sub)11(elastic modulus of the reinforced direction)and ν(sub)12 are constant, Rayleigh wave velocities and the shear wave velocities are steeply decreased with the increments of anisotropic ratios and the velocities of longitudinal wave are almost constant with them. When E(sub)22(elastic modulus of the normal direction to the fiber) and ν(sub)12 are constant, Rayeigh wave velocities is slowly increased with the increments of anisotropic ratios, the shear wave velocities are almost constant with them, the longitudinal wave velocities are steeply increased with them.
The Strength and Fracture Behavior characteristics of Irradiated Zr-2.5Nb CANDU Pressure Tube Materials
An, Sang-Bok ; Kim, Yeong-Seok ; Kim, Jeong-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 510~519
DOI : 10.22634/KSME-A.2001.25.3.510
The tensile and fracture toughness tests have been conducted to investigate the degradations of mechanical properties induced mainly by neutron irradiations in Zr-2.5Nb CANDU pressure tube materials operated in Wolsung Unit-1. the tests were performed at room, 150, 200, 250, 300
for the irradiated and unirradiated specimens in hot cell. The specimens were directly machined from the tube retaining original curvature using specially designed electric discharge machine(EDM). From the tensile tests of the irradiated specimens, it was found that tensile strength was increased and total elongation was decreased compared to those of the unirradiated ones. The active voltages in the fracture toughness tests for the irradiated showed the discontinuous abrupt increases caused by crack jumping in lower temperature. In the crack resistance curves we found the stable crack growth in the unirradiated, whereas the unstable and three crack growth stages in the irradiated specimens due to the accumulated irradiation defects. The various fracture characteristic values in the irradiated are remarkably lower than those of the unirradiated. Through the fractography, we found in the irradiated that smaller dimple and shorter fissures than the unirradiated, and that the fractured surface had three regions that were flat, transition and slant/shear area. These can explain the difference in the crack growth characteristic values of the irradiated and the unirradiated ones.
Design, Fabrication, Static Test and Uncertainty Analysis of a Resonant Microaccelerometer Using Laterally-driven Electrostatic Microactuator
Seo, Yeong-Ho ; Jo, Yeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 520~528
DOI : 10.22634/KSME-A.2001.25.3.520
This paper investigates a resonant microaccelerometer that measures acceleration using a built-in micromechanical resonator, whose resonant frequency is changed by the acceleration-induced axial force. A set of design equations for the resonant microaccelerometer has been developed, including analytic formulae for resonant frequency, sensitivity, nonlinearity and maximum stress. On this basis, the sizes of the accelerometer are designed for the sensitivity of 10
Hz/g in the detection range of 5g, while satisfying the conditions for the maximum nonlinearity of 5%, the minimum shock endurance of 100g and the size constraints placed by microfabrication process. A set of the resonant accelerometers has been fabricated by the combined use of bulk-micromachining and surface-micromachining techniques. From a static test of the cantilever beam resonant accelerometer, a frequency shift of 860Hz has been measured for the proof-mass deflection of 4.3
; thereby resulting in the detection sensitivity of 1.10
Hz/g. Uncertainty analysis of the resonant frequency output has been performed to identify important issues involved in the design, fabrication and testing of the resonant accelerometer.
Design, Fabrication and Micromachining Error Evaluation for a Surface-Micromachined Polysilicon Capacitice Accelerometer
Kim, Jong-Pal ; Han, Gi-Ho ; Jo, Yeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 529~536
DOI : 10.22634/KSME-A.2001.25.3.529
We investigate a surface-micromachined capacitive accelerometer with the grid-type electrodes surrounded by a perforated proof-mass frame. An electromechanical analysis of the microaccelerometer has been performed to obtain analytical formulae for natural frequency and output sensitivity response estimation. A set of prototype devices has been designed and fabricated based on a 4-mask surface-micromachining process. The resonant frequency of 5.8
0.17kHz and the detection sensitivity of 0.28
0.03mV/g have been measured from the fabricated devices. The parasitic capacitance of the detection circuit with a charge amplifier has been measured as 3.34
1.16pF. From the uncertainty analysis, we find that the major uncertainty in the natural frequency of the accelerometer comes from the micromachining error in the beam width patterning process. The major source of the sensitivity uncertainty includes uncertainty of the parasitic capacitance, the inter-electrode gap and the resonant frequency, contributing to the overall sensitivity uncertainty in the portions of 75%, 14% and 11%, respectively.
Application of Soft Computing Based Response Surface Techniques in Sizing of A-Pillar Trim with Rib Structures
Kim, Seung-Jin ; Kim, Hyeong-Gon ; Lee, Jong-Su ; Gang, Sin-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 537~547
DOI : 10.22634/KSME-A.2001.25.3.537
The paper proposes the fuzzy logic global approximate optimization strategies in optimal sizing of automotive A-pillar trim with rib structures for occupant head protection. Two different strategies referred to as evolutionary fuzzy modeling (EFM) and neuro-fuzzy modeling (NFM) are implemented in the context of global approximate optimization. EFM and NFM are based on soft computing paradigms utilizing fuzzy systems, neural networks and evolutionary computing techniques. Such approximation methods may have their promising characteristics in a case where the inherent nonlinearity in analysis model should be accommodated over the entire design space and the training data is not sufficiently provided. The objective of structural design is to determine the dimensions of rib in A-pillar, minimizing the equivalent head injury criterion HIC(d). The paper describes the head-form modeling and head impact simulation using LS-DYNA3D, and the approximation procedures including fuzzy rule generation, membership function selection and inference process for EFM and NFM, and subsequently presents their generalization capabilities in terms of number of fuzzy rules and training data.
New Engineering Estimation Method of J-Integral and COD for Circumferential Through-Wall Cracked Pipes
Kim, Yun-Jae ; Heo, Nam-Su ; Kim, Yeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 3, 2001, Pages 548~553
DOI : 10.22634/KSME-A.2001.25.3.548
A new method to estimate the elastic-plastic J-integral and the crack tip opening displacement (COD) for circumferential through-wall cracked pipes under tension and under bending is proposed for Leak-Before-Break (LBB) analysis. Being based on the reference stress method with further modifications, the proposed method is simple to use and easy to be generalised in practice. Comparison of the CODs, predicted using the proposed method with published pipe test data show overall excellent agreement.