Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 26, Issue 12 - Dec 2002
Volume 26, Issue 11 - Nov 2002
Volume 26, Issue 10 - Oct 2002
Volume 26, Issue 9 - Sep 2002
Volume 26, Issue 8 - Aug 2002
Volume 26, Issue 7 - Jul 2002
Volume 26, Issue 6 - Jun 2002
Volume 26, Issue 5 - May 2002
Volume 26, Issue 4 - Apr 2002
Volume 26, Issue 3 - Mar 2002
Volume 26, Issue 2 - Feb 2002
Volume 26, Issue 1 - Jan 2002
Selecting the target year
Axiomatic Design of a Beam Adjuster for Laser Marker
Sin, Gwang-Seop ; Lee, Jeong-Uk ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1727~1735
DOI : 10.3795/KSME-A.2002.26.9.1727
The usage of beam scanning type laser marker is rapidly increasing in the field of semiconductor equipment. A device called ″beam adjuster″ is employed to adjust the visible diode laser, which points the marking position for various setting. The device is very sensitive to manufacturing tolerance and assembly condition. Axiomatic approach has been applied to the design of the device. An existing design is analyzed based on the Independence Axiom. The existing design is found to violate the axiom. Two new designs are proposed to satisfy the Independence Axiom. The Information Axiom is utilized to evaluate the designs. A design is selected to have the minimum information content. The significance of this research is that a full cycle of axiomatic design is applied to a real engineering product.
Development of Technique Predicting of the Wear of DCI Roll Using Carbon Steel in Hot Rod Rolling Process
Kim, Dong-Hwan ; Kim, Byeong-Min ; Lee, Yeong-Seok ; Yu, Seon-Jun ; Ju, Ung-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1736~1745
DOI : 10.3795/KSME-A.2002.26.9.1736
The objective of this study is to predict the roll wear in hot rod rolling process. In this study hot rod rolling process for round and oval passes has been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the thermal softening of DCI (Ductile Cast Iron) roll according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering parameter curve. 3D wear program developed in this study might be used for adjusting the gap of rolls to set up a suitable rolling schedule for keeping dimensional tolerance of the product.
Prediction of Fatigue Life using Extreme Statistics Analysis
Lee, Dong-U ; Hong, Sun-Hyeok ; Jo, Seok-Su ; Ju, Won-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1746~1752
DOI : 10.3795/KSME-A.2002.26.9.1746
Fatigue fracture in machine components is produced by surface micro-crack from stress concentration area such as notch and material defect. It is difficult to predict the remaining fatigue lift of mechanical components because the surface micro-crack on critical area initiates and grows with statistical distribution. Plane bending fatigue tests were carried out on the plain specimen of Al 2024-T3 and the initiation and growth behavior of surface micro cracks were observed. The statistical distribution of surface length of multiple micro cracks and their maximum length were investigated. The maximum surface crack length distributions were analyzed on the basis of the statistics of extremes in order to examine the prediction of remaining life.
Stress and Displacement Fields for a Propagating Crack in a Linear Functionally Gradient Material Along X Direction
Lee, Gwang-Ho ; Jo, Sang-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1753~1763
DOI : 10.3795/KSME-A.2002.26.9.1753
Stress and displacement fields for a propagating crack in a functionally gradient material (FGM) which has shear modulus as
0/(1＋ζX) are derived. The equations of motion in FGM which is nonhomogeneous material are different from those of homogeneous material. The stress intensity factors in stress fields have influence on odd terms of γ
n/2-1/(n=1,3,5,...,) but stress at crack tip only retains term of γ
-1/2/, where the γ is a radius of cylindrical coordinates centered at crack tip. When the FGM constant ζ is zero or γ→0, the fields for FGM are almost same as the those for isotropic material.
Dynamic Analysis of the Latch Needle Cam System
Jeong, Gwang-Yeong ; Kim, Yeong-Bae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1764~1771
DOI : 10.3795/KSME-A.2002.26.9.1764
The latch needle cam system of circular knitting machines is analysed using multibody dynamics. A formulation is made to obtain the vertical stiffness between the needle and the cam. By implementing this formulation into the data of the multibody dynamics program, the motion of the needle is described and the forces and impulses between the needle and the cam are obtained.
Inference System for Complex Mechanical Design Knowledge
Cha, Ju-Heon ; Lee, In-Ho ; Park, Myeon-Ung ; Kim, Jae-Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1772~1778
DOI : 10.3795/KSME-A.2002.26.9.1772
This paper describes inference architecture of an intelligent CAD system that is to be used for design tasks in which complex and large amount of knowledge is used. In order to investigate the issue of handling huge and complex knowledge, design knowledge is categorized into four types and inference methods for them are identified respectively: original design problems are decomposed into several modules of design processes and finally into sub-problems with the four types of knowledge as basic elements in a top-down manner. We demonstrate the implementation of the architecture with the result of the machining center - a sort of machine tools - design.
Compliant Mechanism Design with Displacement Constraint
Kim, Yeong-Gi ; Min, Seung-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1779~1786
DOI : 10.3795/KSME-A.2002.26.9.1779
When the topology optimization is applied to the design of compliant mechanism, unexpected displacements of input and output port are generated since the displacement control is not included in the formulation. To devise a more precise mechanism, displacement constraint is formulated using the mutual potential energy concept and added to multi-objective function defined with flexibility and stiffness of a structure. The optimization problem is resolved by using Finite Element Method(FEM) and Sequential Linear Programming(SLP). Design examples of compliant mechanism with displacement constraint are presented to validate the proposed design method.
A Study on the Microscopic Damage Behavior and the Damage Position Evaluation of TiNi/Al6061 Share Memory Alloy Composite
Lee, Jin-Gyeong ; Park, Yeong-Cheol ; Gu, Hu-Taek ; Lee, Gyu-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1787~1794
DOI : 10.3795/KSME-A.2002.26.9.1787
TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in the matrix using shape memory effect. In order to generate compressive residual stress in TiNi/Al6061 shape memory alloy(SMA) composite, 1, 3 and 5% pre-strains were applied to the composite in advance. It was also evaluated the effect of compressive residual stress corresponding to the pre-strain variation and the volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain in TiNi/Al6061 SMA composite. The results of the microscopic damage evaluation of TiNi/Al6061 SMA composite under various pre-strain using AE technique can be divided into three stage corresponding to the AE signals. AE counts and events were useful parameters to evaluate the fracture mechanism according to the variation of pre-strain. In addition, two dimensional AE source location technique was applied for monitoring the crack initiation and propagation in composite.
Position Control of a Pneumatic Cylinder with a Nonlinear Compensator and a Disturbance Observer
Jang, Ji-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1795~1805
DOI : 10.3795/KSME-A.2002.26.9.1795
A position controller which can achieve a specified dynamic performance irrespective of the different operating position of the pneumatic cylinder is proposed. The position controller developed in this paper is composed of a nonlinear compensator and a disturbance observer. The nonlinear compensator which feeds back position, velocity and acceleration is derived from the nonlinear dominating equations of the position control system to compensate for variation of dynamic characteristics of a pneumatic cylinder according to the change of the operating position. The disturbance observer including a simplified linear model is designed to reduce the effect of model discrepancy in the low frequency range which cannot be suppressed by the nonlinear compensator. The results of the experiments show that the position control performance maintains a designed performance regardless of the variations of an operating position of the pneumatic cylinder.
Crack Identification Using Evolutionary Algorithms in Parallel Computing Environment
Sim, Mun-Bo ; Seo, Myeong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1806~1813
DOI : 10.3795/KSME-A.2002.26.9.1806
It is well known 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 classical optimization technique was adopted by previous researchers. That technique overcame the difficulty of finding the intersection point of the superposed contours that correspond to the eigenfrequency caused by the crack presence. However, it is hard to select a trial solution initially for optimization because the defined objective function is heavily multimodal. A method is presented in this paper, which uses continuous evolutionary algorithms(CEAs). CEAs are effective for solving inverse problems and implemented on PC clusters to shorten calculation time. With finite element model of the structure to calculate eigenfrequencies, it is possible to formulate the inverse problem in optimization format. 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 with high parallel efficiency over about 94%.
Parametric Modelling of Cutter Swept Surface for Z-Map Based Cutting Simulation
Park, Bae-Yong ; An, Jeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1814~1821
DOI : 10.3795/KSME-A.2002.26.9.1814
NC cutting simulation is an important factor in the development of products. The geometric modelling of cutter swept surface should be done in NC cutting simulation. A part of cutter swept surface is a ruled surface blended with silhouette curve and cutter path. Finding an intersection point between cutter swept surface and a line is one of major problems in Z-map based cutting simulation. In this paper, cutter swept surface is defined parametrically and it's intersection point with Z-map is found in an exact form. Triangular grid Z-map based 3-axis NC cutting simulation is performed.
A Decomposition Based MDO by Coordination of Disciplinary Subspace Optimization
Jeong, Hui-Seok ; Lee, Jong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1822~1830
DOI : 10.3795/KSME-A.2002.26.9.1822
The paper describes the development of a decomposition based multidisciplinary design optimization (MDO) method that coordinates each of disciplinary subspace optimization (DSO). A multidisciplinary design system considered in the present study is decomposed into a number of subspaces based on their own design objective and constraints associated with engineering discipline. The coupled relations among subspaces are identified by interdisciplinary design variables. Each of subsystem level optimization, that is DSO would be performed in parallel, and the system level coordination is determined by the first order optimal sensitivities of subspace objective functions with respect to interdisciplinary design variables. The central of the present work resides on the formulation of system level coordination strategy and its capability in decomposition based MDO. A fluid-structure coupled design problem is explored as a test-bed to support the proposed MDO method.
Warm Isostatic Pressing of Metal Powder by a Rubber Mould
Yang, Hun-Cheol ; Lee, Ji-Wan ; Kim, Gi-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1831~1841
DOI : 10.3795/KSME-A.2002.26.9.1831
The effect of a rubber mould on densification and deformation of aluminum alloy powder was investigated during warm isostatic pressing. The hyperelastic constitutive equations based on various strain energy potentials were employed to analyze deformation of rubber. The parameters in the strain energy potentials were obtained from experimental data for uniaxial and volumetric compression of Viton rubber at two warm temperatures. For elastoplastic response, the yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to predict compaction responses of metal powder during warm isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder with/without a rubber mould under warm die pressing.
Tribological Behavior of DLC Coatings at Various Humidities
Jo, Gyeong-Man ; An, Hyo-Seok ; Kim, Dae-Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1842~1848
DOI : 10.3795/KSME-A.2002.26.9.1842
Although DLC coatings have good tribological properties, these are dependant on the deposition method, the property of contact surface, and test condition. Humidity, which has little influence on tribological behavior in macro scale, is an important factor of tribological behavior in small devices like MEMS. The objective of this study is to investigate the tribological behavior of DLC coatings with particular attention to their wettability at various humidities. DLC coatings were deposited on Si substrates and tested using a reciprocating friction tester against Si
balls at various humidities. The results showed that the tribological behavior of DLC coatings was dependant on relative humidity and wettablility of DLC coatings. Friction coefficient at high relative humidity was higher thar that at low relative humidity. The tungsten-containing DLC coatings had a good wear resistance at low relative humidity whereas DLC coatings derived from argon(Ar)+cesium(Cs) gases showed a good wear resistance at high relative humidity.
A Study on the Adaptive Scheme Using Least-Squares Meshfree Method
Park, Sang-Hun ; Gwon, Gi-Chan ; Yun, Seong-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1849~1858
DOI : 10.3795/KSME-A.2002.26.9.1849
An h-adaptive scheme of first-order least-squares meshfree method is presented. A posteriori error estimates, which can be readily computed from the residual, are also presented. For elliptic problem the error indicators are further improved by applying the Aubin-Nitsche method. In the proposed refinement scheme, Voronoi cells are utilized to insert nodes at appropriate positions. Through numerical examples, it is demonstrated that the error indicators reveal good correlations with the actual errors and the adaptive first-order least-squares meshfree method is effectively applied to the localized problems such as the shock formation in fluid dynamics.
Performance Evaluation of Sliding Mode Controller with Perturbation Estimator
Choe, Seung-Bok ; Ham, Jun-Ho ; Han, Yeong-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1859~1865
DOI : 10.3795/KSME-A.2002.26.9.1859
In the conventional sliding mode control technique, a priori knowledge of the bound of external disturbances or/and parameter uncertainties is required to assure control robustness. This, however, may not be easy to obtain in practical situation. This work presents a novel methodology, a sliding mode controller with perturbation estimator, which offers a robust control performance without a priori knowledge about the perturbations (disturbances and parameter uncertainties). The proposed technique is featured by an integrated average value of the imposed perturbation over a certain sampling period. In order to demonstrate the effectiveness of the proposed methodology, a two-link robotic system is adopted and its position control performance is evaluated. In addition, a comparative work between the conventional technique and the proposed one is undertaken.
Development of an Automatic Pipe-cutting Machine by Axiomatic Approach
Sin, Chang-Ho ; Jeong, Jin-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1866~1873
DOI : 10.3795/KSME-A.2002.26.9.1866
The pipe-cutting machine developed in this study is a portable device used to cut a steel pipe. The machine, which is attached to the steel pipe by magnetic force, is moving around the pip e using four wheels. It also works for straight cutting of a steel plate. For the higher precision and labor time reduction, the automation of a pipe-cutting process is needed. However, it is not easily achieved because of vibrations and the loss of track. It is also found that the problems of the automation arise from the coupling of the functional requirements for the pipe-cutting machine. So, it is very difficult io solve the problems by a conventional design method. To overcome the difficulties the new design process for the pipe-cutting machine is established by axiomatic approach in this paper. Based on the Independence Axiom design process, a new product is designed and manufactured. Finally, it is verified by experiments that the performance of the automatic pipe-cutting machine is improved
Vibration Exciter Design for Flow Resonance with a Displacement Estimator Using Strain Gage
Nam, Yun-Su ; Choe, Jae-Hyeok ; Gang, Byeong-Ha ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1874~1881
DOI : 10.3795/KSME-A.2002.26.9.1874
Heat dissipation technology using the flow resonant phenomenon is a kind of a new concept in the heat transfer area. A vibration exciter is needed to enhance air flow mixing which has the natural shedding frequency of thermal system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator with a displacement estimator using strain gage. An analytical dynamic model for this mechanical vibration exciter is presented and its validity is checked by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. During the experimental verification phase, it turns out the high modal resonant characteristics of a vibrating plate are a major barrier against obtaining a high bandwidth vibration exciter.
A Study on the Design of Ratchet Wheel Using Automatic Design Program and Finite Element Analysis
Kim, Min-Ju ; Lee, Seung-Su ; Jeon, Eon-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1882~1887
DOI : 10.3795/KSME-A.2002.26.9.1882
This study is to develop a automatic design program of mechanical elements as the integrated system which can create automatically 3-dimensional solid and surface model using visualLISP. By the applying developed system to CAE system, the following objects are realized. At first, constructing the library of automatic design program for unexperienced design engineer, the 3-dimensional modeling of mechanical elements can be obtained easily. at second, the 3-dimensional model for ratchet wheel design is created by finete element model of CAE system and the optimal design condition of key way.
NURBS Surface Interpolator for Constant Cutting Forces in Ball-End Milling
Ji, Seong-Cheol ; Gu, Tae-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1888~1896
DOI : 10.3795/KSME-A.2002.26.9.1888
This study presents a new type of CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter contact (CC) path scheduling and CC path interpolator. Especially in this study, a new interpolator module to regulate cutting forces is developed. This propose algorithm utilizes variable-feedrate commands along the CC path according to the curvature of machined surfaces during the interpolation process. Additionally, it proposes an OpenGL graphic library for computer graphics and animation of interpolated tool-position display. The proposed interpolator is evaluated and compared with the existing method based on constant feedrates through computer simulations.
Low Cycle Fatigue Characteristics of Duplex Stainless Steel with Degradation under Pure Torsional Load
Gwon, Jae-Do ; Park, Jung-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1897~1904
DOI : 10.3795/KSME-A.2002.26.9.1897
Monotonic torsional and pure torsional low cycle fatigue(LCF) test with artificial degradation were performed on duplex stainless steel(CF8M). CF8M is used in pipes and valves in nuclear reactor coolant system. It was aged at 430
for 3600hrs. Through the monotonic and LCF test, it is found that mechanical properties(i.e., yield strength, strain hardening exponent, strength coefficient etc.) increase and fatigue life(N
f/) decreases with degradation of material. The relationship between shear strain amplitude(
f/ was proposed.
Finite Element Analysis for Time Response of a Flexible Spinning Disk with Translating Misalignment
Heo, Jin-Uk ; Jeong, Jin-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1905~1913
DOI : 10.3795/KSME-A.2002.26.9.1905
Using the finite element method, this study investigates the dynamic time responses of a flexible spinning disk of which axis of rotation is misaligned with the axis of symmetry. The misalignment between the axes of symmetry and rotation is one of the major vibration sources in optical disk drives such as CD-ROM, CD-R, CD-RW and DVD drives. Based upon the Kirchhoff plate theory and the von-Karman strain theory, three coupled equations of motion for the misaligned disk are obtained: two of the equations are for the in-plane motion while the other is for the out-of-plane motion. After transforming these equations into two weak forms for the in-plane and out-of-plane motions, the weak forms are discretized by using newly defined annular sector finite elements. Applying the generalized-
time integration method to the discretized equations, the time responses and the displacement distributions are computed and then the effects of the misalign ment on the responses and the distributions are analyzed. The computation results show that the misalignment has an influence on the magnitudes of the in-plane displacements and it results in the amplitude modulation or the beat phenomenon in the time responses of the out-of-plane displacement.
Experimental Study for the Durability Enhancement of Plastic Spur Gear
Kim, Chung-Hyeon ; An, Hyo-Seok ; Jeong, Tae-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1914~1922
DOI : 10.3795/KSME-A.2002.26.9.1914
Operating test of power-transmission plastic spur gears were performed inspecting both characteristics of friction-wear and endurance, and suggesting endurance improvement method that either drills internal holes of tooth or inserts metallic pin in the internal hole of tooth and verifying this newly-provided method. In case of acetal gears, amount of friction-wear is observed to increase by development of plastic deformation and increase of tooth stiffness due to brittle material property of acetal. To the contrary, in case of nylon gears, suggested method is shown to drop down the tooth temperature for about 3∼10
than original gear, thus amount of wear is reduced by over 30% and operating lift prolonged by more than 200%. Hence, suggested method is proved to be practically applicable to the plastic gears made by soft polymers such as Nylon.
Modeling and Simulation of Microlens Fabricated by Modified LIGA Process
Kim, Dong-Seong ; Lee, Seong-Geun ; Yang, Sang-Sik ; Gwon, Tae-Heon ; Lee, Seung-Seop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1923~1930
DOI : 10.3795/KSME-A.2002.26.9.1923
In this paper, we present modeling and simulation of microlens formation by means of a deep X-ray lithography followed by a thermal treatment of a PMMA (Polymethylmethacrylate) sheet. According to this modeling, X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. In this modeling, the free volume theory including the relaxation process during the cooling process was considered. The simulation results indicate that the modeling in this study is able to predict the fabricated microlens shapes and the variation pattern of the maximum heights of microlens which depends on the conditions of the thermal treatment. The prediction model could be applied to optimization of microlens fabrication process and to designing a micro mold insert for micromolding processes.
Robust Design in Terms of Minimization of Sensitivity to Uncertainty and Its Application to Design of Micro Gyroscopes
Han, Jeong-Sam ; Gwak, Byeong-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1931~1942
DOI : 10.3795/KSME-A.2002.26.9.1931
In this paper a formulation of robust optimization is presented and illustrated by a design example of vibratory micro gyroscopes in order to reduce the effect of variations due to uncertainties in MEMS fabrication processes. For the vibratory micro gyroscope considered it is important to match the resonance frequencies of the vertical (sensing) and lateral (driving) modes as close as possible to attain a high sensing sensitivity. A deterministic optimization in which the difference of both the sensing and driving natural frequencies is minimized as an objective function results in highly enhanced performance but apt to be very sensitive to fabrication errors. The formulation proposed is to attain robustness of the performance by including the sensitivity of the response with respect to uncertain variables as a term of objective function to be minimized. This formulation is simple and practically applicable since no detail statistical information on fabrication errors is required. The geometric variables, beam width, length and thickness of vibratory micro gyroscopes are adopted as design variables and at the same time considered as uncertain variables because here occur the fabrication errors. A robustness test in terms of a percentage yield by using the Monte Carlo simulation has shown that the robust optimum produces twice more acceptable designs than the deterministic optimum. Improvement of robustness becomes bigger as the amount of fabrication errors is assumed larger. Considering that the magnitude of fabrication errors and uncertainties in a MEMS structure are comparatively large, the present method is illustrated to be a viable approach for a robust MEMS design.
Analysis of Thermal Stress and Deformation of Casting Roll in Twin Roll Strip Casting Process
Park, Cheol-Min ; Kim, Wan-Su ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 26, issue 9, 2002, Pages 1943~1951
DOI : 10.3795/KSME-A.2002.26.9.1943
The casting roll design is one of the most important requirements in twin roll strip casting process. Coupled analyses of heat transfer and deformation for the cast roll are carried out by use of the finite element program MARC to examine the thermal stress and deformation. The effects of several factors on thermal stress and deformation are also investigated. The amount of thermal stress increases when the ni thickness increases and when the casting speed and the copper sleeve thickness decrease.