• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.4
• /
• pp.625-642
• /
• 1993

Whether stress-absorbing elements are functional in an implant system has been an issue of interest in oral implantology. The unique feature of the IMZ implant system is the planned imitation of the stress-distributing function of the structural unit of the tooth, periodontium, and alveolar bone through the use of an intramobile element(IME). The purpose of this study was to compare the difference in the displacement and the stress distibutions of IMZ implant with a polyoxymethylene(POM) or a titanium IME under static load. Two dimensional finite element analysis(FEA) was applied for this study and two finite element models were created. PATRAN program(DPA Co.,USA), a software for FEA, and SUN-SPARC2GX(SUN Co., USA), a workstation computer, were used. $1Kg/mm^2$ of static load was loaded individually on each three point of crown of implant prosthesis ; central fossa(load 1), mesial cusp tip(load 2), distal cusp tip(load 3), The displacements of X- and Y-axis and total displacement were measured at mesial and distal cusp tips, mesial and distal points between crown and IME, and implant apex. The von Mises stress was measured at mesial and distal points between crown and IME, mesial and distal points between IME and TIE, mesial and distal alveolar crest, the mesial and distal midpoints of implant, and implant apex. The difference in resultant values were compared and evaluated statistically using paired t-test. The results were as follows : 1. Under the load 1, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except total and Y-axis displacement at implant apex. And the differences in stress distributions with POM and titanium were varied. 2. Under the load 2, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except X-axis displacement at distal cusp tip. And the differences in stress distributions were varied. 3. Under the load 3, all the displacement of implant with titanium IME at 5 measuring points was larger than that of with POM IME except Y-axis displacement at mesial cusp tip. And the differences in stress distributions were varied. 4. For the displacement, there was significant difference statistically only in total displacement (P<0.1), but was no significant difference in X- and Y-axis displacement(P>0.1). For the stress, there was no significant difference among the compared values.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.2
• /
• pp.163-173
• /
• 2012

A connection composed of a circular hollow structural section (HSS) has complicated details, and exhibits a very complex local deformation when it reaches the yield stress. Given these circumstances, proposing a simple design equation considering local deformation is difficult. The design equations of the Korea Building Code (KBC 2009) for HSS joints are simple and are very similar to those of the AISC. These design equations limit the maximum yield stress up to 360MPa and yield ratio (yield strength/tensile strength) up to 0.8. This means that the material with yield strength exceeding 360MPa could be used after verification based on the test or rational analysis for the similar connection. This paper introduces an experimental program and finite element analysis (FEA) for the circular hollow section (CHS) with a transverse gusset plate made of high-strength steel (HSB600) or structural steel (SS400) when the joints are subjected to lateral force. Comparison of the design equations with the results of FEA and test may be used for the modification of the design equations.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.2
• /
• pp.95-102
• /
• 2014

In this paper, a coupling scheme for applying finite element analysis(FEA) programs, such as, LS-DYNA and MIDAS/Civil, to a nonlinear soil structure interaction analysis by the boundary reaction method(BRM) is presented. With the FEA programs, the structure and soil media are discretized by linear or nonlinear finite elements. To absorb the outgoing elastic waves to unbounded soil region as much as possible, the PML elements and viscous-spring elements are used at the outer FE boundary, in the LS-DYNA model and in MIDAS/Civil model, respectively. It is also assumed that all the nonlinear elements in the problem are limited to structural region. In this study, the boundary reaction forces for the use in the BRM are calculated using the KIESSI-3D program by solving soil-foundation interaction problem subjected to incident seismic waves. The effectiveness of the proposed approach is demonstrated with a linear SSI seismic analysis problem by comparing the BRM solution with the conventional SSI solution. Numerical comparison indicates that the BRM can effectively be applied to a nonlinear soil-structure analysis if motions at the foundation obtained by the BRM for a linear SSI problem excluding the nonlinear structure is conservative.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.11a
• /
• pp.317-322
• /
• 2004

In this study the structural design of conveyor frame was carried out for the high efficiency gantry crane which can improve the productivity of the container transportation job by reducing cycle time. When the gantry crane was operated, the conveyor frame was deflected largely by its deadload and the total weight of containers placed on it. Therefore thicknesses of conveyor frame to minimize its deadload were designed by the size optimization using ANSYS program as the bending stress and the deflection of frame due to this simulation satisfied their required values.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.18 no.1
• /
• pp.13-20
• /
• 2005

Since High Tensile Steel has been widely used to thin plate on the steel structure and marine structure, It has increased possibility of buckling. Especially, initial deflection of ship structure is mainly caused by heat processing of welding or cutting etc. This initial deflection has negative effect to thin plate, which would incur a complicated nonlinear behavior accompanied with secondary buckling. If idealized initial deflection is considered in early marine structure design of secondary buckling, accuracy and reliability will be improved considerably. The measurement data of initial deflection from experiment is applied to finite element series analysis. For FEA(ANSYS), Applied nonlinear buckling analysis is used by Newton-Raphson method & Arc-length method included in this program.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.7
• /
• pp.642-652
• /
• 2009

Most of lap jointed aircraft structures encounter the fretting damages, which provoke fretting cracks prematurely and lead to significant reduction of fatigue life. In the case of ageing aircrafts especially, this fretting fatigue problem is a fatal threat for the safety and airworthiness. Recently, as the service life extension program(SLEP) of ageing aircrafts has become a hot issue, the prediction of fretting fatigue life is also indispensable. On these backgrounds, a series of experimental tests of fretting fatigue on bolted lap joint specimens, were performed. And the fretting crack initiation and propagation life of each specimen were evaluated using existing and newly proposed prediction models with the fretting parameters obtained from the FEA results for elasto-plastic contact stress analyses. The validations of prediction models were also discussed, comparing the prediction results with experimental test ones.

• Journal of Korean Society of Steel Construction
• /
• v.26 no.3
• /
• pp.219-229
• /
• 2014

The experiment and FE analysis of ultimate behavior of GFRP cylindrical shell structure stiffened by steel pipe ring instead of rectangular cross-section ring was presented. Four kinds of test models were designed and flexural failure experiment was performed to investigate ultimate behavior characteristic according to the size of cross section of steel pipe ring and diameter of GFRP shell. Material properties of specimens were experimented by bending, tensile and compressive test. Displacements and strains were measured to evaluate failure behavior of steel pipe ring and GFRP shell structure. The experimental results were compared with the FEA results by commercial program ABAQUS. It is observed that GFRP shell structure stiffened by steel ring have enough ductility to bending failure, and an increase of bending rigidity of steel ring is very effective to increase of failure strength of GFRP shell structure.

• Korean Journal of Optics and Photonics
• /
• v.21 no.5
• /
• pp.214-223
• /
• 2010

Optimization of a 30 cm lightweight mirror was proposed with the best optical performance under various loads of gravity and thermal loads with proper boundary conditions. A pattern for a lightweight mirror was generated based on the best optical performance combined with ease of manufacturing for proper design parameters of physical properties of face sheet, back sheet, rib, and web. Evaluation of the optical performances of a telescope mirror was obtained by using the finite element analysis program, NX I-DEAS. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were calculated by using Zernike polynomials. The proposed telescope mirror meets well the opto-mechanical design consideration of RMS surface error less than 16 nm.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.1 s.94
• /
• pp.227-237
• /
• 1999

As the interface bonding phenomenon between the matrix and the reinforcements has a large effect on the mechanical properties of MMCs, a sugestion of the strength analysis technique considering the residual stress and the interface bonding phenomenon is very important for the design of pans and the estimation of fatigue behavior. In this paper the three dimensional finite element anaysis is performed during the elasto-plastic deformation of the particulate reinforced metal matrix composites. It was analyzed with the volume fractions in view of microscale. Bonding strength. interface separation and matrix void growth between the matrix and the reinforcements will be predicted on deformation under tensile loading. An interface seperation is estimated by the fracture criterion which is a critical value of generalized plastic work per unit volume. The shape of the reinforcement is assumed to be a perfect sphere. And the type of the reinforcement distribution is assumed as FCC array. The thermal residual stress in MMCs is induced by the heat treatment. It is included at the simulation as an initial residual stress. The element birth and death method of the ANSYS program is used for the estimation of the interface bonding strength, void generation and propagation. It is assumed that the fracture in the matrix region begin to occur under the external loading when the plastic work per unit volume is equal to the critical value. The fracture strain will be defined. The experimental data of the extruded $SiC_p$>/606l Al composites are compared with the theoretical results.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.7
• /
• pp.105-111
• /
• 2009

This study was carried out to evaluate structural stability of the suspended plastic pedal used in vehicles and to predict its fatigue life with the results obtained from finite element analysis. And also shape optimization was performed to reduce its weight. Structural analysis of the suspended plastic pedal was based on the evaluation tests such as static test, stiffness test, and fatigue test in the actual field, which were frequently carried out in the companies manufacturing plastic pedals. The evaluation for the plastic pedal was carried out by structural and fatigue analyses using a commercial FEA program and according to it, maximum stress and strain and fatigue life of the pedal satisfied all the requirements in the evaluation tests. The results of structural analysis of the suspended plastic pedal were used in the fatigue analysis. Fatigue test was performed to verify validity of the theoretical fatigue life of the plastic pedal. And the life by theoretical calculation was in good agreement with that by the experiment. Object function for optimizing shape of the plastic pedal is its volume, and total volume of the plastic pedal was reduced to about 11.7% through shape optimization.