• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.458-462
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• 2011

The strength of ceramic was improved by lamination by suppressing the propagation of cracks with compressive residual stress in the face layer of the laminate. Hot pressed SiAlON+SiC/SiC/SiAlON+SiC laminate discs were fabricated for tailored residual stress. The residual stress in this laminate was studied by X-ray diffraction (XRD). There was considerable compressive residual stress in the face layer. A Finite Element Analysis (FEA) was performed to support the measured XRD results and to determine the stress field in the laminate. The residual stress measured by XRD had satisfactory agreement with the analytically calculated and FEA values. The measured value by XRD was -385 ${\pm}$ 20 MPa over most of the face layer. The calculated and FEA values were -386 MPa and -371MPa, respectively. FEA also showed significantly modified stresses and the maximum tensile stress near the edge region which are possible crack generators in the presence of flaws or contact damage.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.1
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• pp.67-73
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• 2011

In this study, the manufacturing technology of a folding blind rivet was developed through finite element analysis(FEA). Numerical simulations of the folding blind rivet used to join two components have been performed with the finite element method for the forging process design. To minimize the process and manufacture the folding blind rivet without defects, a variety of design rules were proposed. From the results of FEA applied process design rules, an optimal six-stage process was proposed. The finite element simulation results such as shape of the forged rivet, strain distribution and forging load were investigated for the usefulness of the forging process of the blind rivet. In addition, the experiments have been implemented and their results were compared to the analytic results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.24-30
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• 2008

The laminate IPMC actuator have been developed with a commercial Nafion film and platinum electrodes. Equivalent beam and equivalent bimorph beam models for IPMC(Ionic Polymer-Metal Composite) actuators are described. By using a beam equation with estimated physical properities and actuation displacements of a cantilevered IPMC actuator are estimated. And Finite element analysis(FEA) was done by ANSYS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1455-1460
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• 2006

The relationship between fatigue crack growth behavior and cyclic crack tip opening displacement is studied. An elastic-plastic finite element analysis (FEA) is performed to examine the growth behavior of fatigue crack, where the contact elements are used in the mesh of the crack tip area. We investigate the relationship between the reversed plastic zone size and the changes of the cyclic crack tip opening displacement along the crack growth. We investigate the effect of the element size when predict fatigue crack opening behavior using the cyclic crack tip opening displacement obtained from FEA. The cyclic crack tip opening displacement is related to fatigue crack opening behavior.

• Journal of the Korea Society for Simulation
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• v.11 no.3
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• pp.13-22
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• 2002

This paper describes an automated evaluation of electrostatic field for micro motors whose sizes range 10 to 103um. Electric field modeling in micro motors has been generally restricted to in-plane two-dimensional finite element analysis (FEA). In this paper, the actual three-dimensional geometry of the micro motor is considered. An automatic FE mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry techniques, is incorporated in the system, together with one of commercial FE analysis codes and one of commercial solid modelers. The system allows a geometry model of concern to be automatically converted to different FE models, depending on physical phenomena to be analyzed, electrostatic analysis and stress analysis and so on. The FE models are then exported to the FE analysis code, and then analyses are peformed. Then, analytical analysis and FE analysis about the torque generated by electrostatic micro motor are performed. The starting torque is proportional to $V^2$, the calculated starting torque from the two-dimensional analytical solutions are three times larger than those from the three-dimensional FE solutions.

• Structural Engineering and Mechanics
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• v.42 no.6
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• pp.849-866
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• 2012

Single span historic bridges often contain non-prismatic members identified with a varying depth along their span lengths. Commonly, the symmetric parabolic height variations having the constant haunch length ratio of 0.5 have been selected to lower the stresses at the high bending moment points and to maintain the deflections within the acceptable limits. Due to their non-prismatic geometrical configuration, their assessment, particularly the computation of fixed-end horizontal forces (FEFs) and fixed-end moments (FEMs) becomes a complex problem. Therefore, this study aimed to investigate the behavior of non-prismatic beams with symmetrical parabolic haunches (NBSPH) having the constant haunch length ratio of 0.5 using finite element analyses (FEA). FEFs and FEMs due to vertical loadings as well as the stiffness coefficients and the carry-over factors were computed through a comprehensive parametric study using FEA. It was demonstrated that the conventional methods using frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. Despite the robustness of FEA, the generation of FEFs and FEMs using the nodal outputs of the detailed finite element mesh still remains an intricate task. Therefore, this study advances to propose effective formulas and dimensionless estimation coefficients to predict the FEFs, FEMs, stiffness coefficients and carry-over factors with reasonable accuracy for the analysis and re-evaluation of the NBSPH. Using the proposed approach, the fixed-end reactions due to vertical loads, and also the stiffness coefficients and the carry-over factors of the NBSPH can be determined without necessitating the detailed FEA.

• Journal of IKEEE
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• v.13 no.3
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• pp.24-31
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• 2009

The computation time of FEA(finite element analysis) for one model may range from a few seconds up to several hours according to the complexity of the simulated model. If these FEA is used to calculate the objective and the constraint functions during the optimal solution search, it causes very excessive execution time. To resolve this problem, the distributed computing technique using internet web service is proposed in this paper. And the dynamic load balancing mechanisms are established to advance the performance of distributed computing. To verify its validity, this method is applied to a traditional mathematical optimization problem. And the proposed FEA-based optimization using internet distributed computing is applied to the optimal design of the permanent magnet dc motor(PMDCM) for automotive application.

• Computers and Concrete
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• v.2 no.5
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• pp.389-409
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• 2005

The Finite Element Analysis (FEA) is evidently a powerful tool for the analysis of structural concrete having nonlinearity and brittle failure properties. However, the result of FEA of structural concrete is sensitive to two modeling factors: the shear transfer coefficient (STC) for an open concrete crack and force convergence tolerance value (CONVTOL). Very limited work has been done to find the optimal FE Modeling (FEM) methodologies for structural concrete members strengthened with externally bonded FRP sheets. A total of 22 experimental deep beams with or without FRP flexure or/and shear strengthening systems are analyzed by nonlinear FEA using ANAYS program. For each experimental beams, an FE model with a total of 16 cases of modeling factor combinations are developed and analyzed to find the optimal FEM methodology. Two elements the SHELL63 and SOLID46 representing the material properties of FRP laminate are investigated and compared. The results of this research suggest that the optimal combination of modeling factor is STC of 0.25 and CONVTOL of 0.2. A SOLID 46 element representing the FRP strengthening system leads to better results than a SHELL 63 element does.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.115-121
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• 2005

Micromachines are extremely novel artifacts with a variety of special characteristics. Utilizing their tiny dimensions ranging roughly from 10 to $10^3$ micro-meters, the micromachines can perform tasks in a revolutionary manner that would be impossible for conventional artifacts. Micromachines are in general related to various coupled physical phenomena. They are required to be evaluated and designed considering the coupled phenomena. This paper describes finite element analysis (FEA) simulation of practical behaviors for the micro actuator. Especially, electric field modeling in micro actuators has been generally restricted to in-plane two-dimensional finite element analysis because of the complexity of the micro actuator geometry. However, in this paper, the actual three-dimensional geometry of the micro actuator is considered. The starting torque obtained from the in-plane two-dimensional analytical solutions were compared with that of the actual three-dimensional FE analysis results. The starting torque is proportional to $V^2$, and that the two-dimensional analytical solutions are larger than the three- dimensional FE ones. It is found that the evaluation of micro actuator has to be considered electrical leakage phenomenon.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.63-69
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• 2013

In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However in the most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleigh-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculates the optimal thickness and the thickness ratio of individual elements of the 2-D plane element through a parallel algorithm method which satisfy the design constraint of natural frequency. As a result this method of optimization for natural frequency by using finite element method can determine the optimal size or its ratio of geometrically complicated shape and large scale structure.