• Journal of Biomedical Engineering Research
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• v.37 no.6
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• pp.215-221
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• 2016

Conformity between the femoral component and tibial insert within the knee replacement may be measured in frontal or sagittal view, and shows differences in the curvature radius of the femoral component depending on the flexion angle, i.e., curvature radius has a complex effect on contact stress. Therefore, it is essential to confirm how the curvature radius effects contact stress, and provide an important variable to reduce contact stress. This study correlated contact stress with curvature radius measured in frontal and the sagittal views and confirmed the effect of curvature radius for assessment of the Newly Designed Unicompartment Knee Replacement (NDUKR). Finite element models were constructed for NDUKR and $Zimmer^{(R)}$ Unicompartment High Flex Knee Replacement system (ZUKR), incorporating the curvature radius as measured in either frontal or sagittal view. The femoral component had 1200N of compressive load applied approximately 1.65xbody weight. Contact stress was predicted at flexion angles $0^{\circ}C$, $30^{\circ}C$, $60^{\circ}C$, $90^{\circ}C$ and $120^{\circ}C$, for NDUKR: 42, 47.7, 47.7, 51.2, and 54.1 MPa, and ZUKR: 41.2, 49.5, 53.2, 54.3, and 57.4 MPa, respectively. Correlation analysis showed the influence of curvature radius measured from the sagittal view was larger than for frontal view.

• Journal of the Korea Convergence Society
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• v.8 no.4
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• pp.189-197
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• 2017

In the design of an automotive structural component, one of the more important tasks for a design engineer is to determine the life of the component and to ensure that the component will not fail prematurely. In order to accomplish this, a design engineer will first use simple section analysis to come up with a section shape in the concept design stage and use more advanced analysis for stress level. At this stage, the analysis should focus on understanding overall behavior in terms of load paths and gross stress levels. A model that is adequate for a stiffness analysis of the structure will usually provide an adequate level of stress information in the design process. To perform a detailed stress analysis, the structure models must have the detailed local areas such as stress concentrations or force(or displacement) distributions. This paper is to present the design considerations for the stress analysis of automotive structure.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.385-402
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• 1996

The purpose of this study was to analyze how the stability of the implant prostheses and the loosening of the fastening screw was affected when the various types of Hex structure provided for the effect of anti-rotation of the single prostheses were given. Three dimensional finite element model was designed with which the implants with the external hex type of 0.75mm, 1.5mm and the implant with the internal hex type of 0.75mm, 1.5mm and the implant with the external hex type of $15^{\circ}$ tapered shape of 0.75mm were supposed to completely osseointegrate to the mandible. After fininshing the finite element model, the preload of 10N at the fastening screw was applied and then the vertical and $30^{\circ}$ lateral load of 200N was applied respectively at the cusp tips of the prostheses. The following results were obtained : 1. In case of displacement, the amount of displacement was increased at the internal hex type(model C, D) than at the external hex type(model A, B, E) when the vertical and lateral load was applied. 2. Less equivalent stress was represented at the model B with increased external hex height than at the model A when the vertical and lateral load was applied. 3. Much stress was represented at the model E with increased hex angle than at the model A in case of the stress happened to the implant body and the fastening screw when the vertical and lateral load was applied. 4. Much equivalent stress was represented at the model D with deepened internal hex height than at the model C when vertical and lateral load was applied. 5. The least stress was taken at the model B and the most stress was taken at the model D in case of the stress happened to the implant when the vertical and lateral load was applied. 6. The least stress was taken at the model C at the vertical load. And the least stress was taken at the model B at lateral load in case of the stress happened to the fastening screw. As a results of this study, the good lateral stability of prostheses and less stress of the component of implant was taken when the external hex height was increased, and the risk of neck fracture of implant and fastening screw was increased when the internal hex height was deepned because of long screw neck portion and thin implant neck portion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1257-1264
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• 2014

Efforts are presently underway for developing an optimal design methodology for GEN-IV nuclear reactors based on target failure probabilities. A typical example is the system-based code, in which the results are represented in the form of partial safety factors (PSFs). Thus, a PSF is one of the crucial elements in either component design or integrity assessment based on target failure probabilities during the operation period. In the present study, a procedure for calculating the PSF of a circumferential through-wall cracked pipe based on the elastic-plastic crack initiation criterion is established, in which the importance of each input variable is assessed. Elastic-plastic J-integrals are calculated using the GE/EPRI and reference stress methods, and the PSF values are calculated using both first- and second-order reliability methods. Moreover, the effect of statistical distributions of assessment variables on the PSF is also evaluated.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.45-53
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• 2009

In this study, Finite Element Analysis (FEA) was used to decide three kinds of material property of vibration proof rubber with the unique characteristic of non-linear and large deformation. As well, three types of hardness (Hs 50, 55, 60) were compared with the result of fatigue tests, fatigue life was able to be predicted. The request for fatigue life becomes strict more and more as increasing stress under conditions like a compaction, high load and high temperature for parts because it is main characteristics of rubber mount for automotive. Regarding to the fatigue life under dynamic deformation condition, it can be predicted as checking forced deformation extends and its frequency and its strain-life curve. As for material property tests of uniaxial tension test, uniaxial compression test, pure shear test, Ogden model was used for FEA by observing relations between stress and strain's rate as curve fitting. As a result of FEA, fatigue life for rubber mount was predicted and accorded well with the experimental data of fatigue test with hourglass specimens. In addition, its property of the predictable fatigue life method suggested in this study was accorded well with the experimental data by comparing the predicted fatigue life of FEA with the result of fatigue test for rubber component of engine rubber mount.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.342-351
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• 2010

During the operation of a hydro turbine the fluid mechanical pressure loading on the turbine blades provides the driving torque on the turbine shaft. This fluid loading results in a structural load on the component which in turn causes the turbine blade to deflect. Classically, these mechanical stresses and deflections are calculated by means of finite element analysis (FEA) which applies the pressure distribution on the blade surface calculated by computational fluid dynamics (CFD) as a major boundary condition. Such an approach can be seen as a one-way coupled simulation of the fluid structure interaction (FSI) problem. In this analysis the reverse influence of the deformation on the fluid is generally neglected. Especially in axial machines the blade deformation can result in a significant impact on the turbine performance. The present paper analyzes this influence by means of fully two-way coupled FSI simulations of a propeller turbine utilizing two different approaches. The configuration has been simulated by coupling the two commercial solvers ANSYS CFX for the fluid mechanical simulation with ANSYS Classic for the structure mechanical simulation. A detailed comparison of the results for various blade stiffness by means of changing Young's Modulus are presented. The influence of the blade deformation on the runner discharge and performance will be discussed and shows for the configuration investigated no significant influence under normal structural conditions. This study also highlights that a two-way coupled fluid structure interaction simulation of a real engineering configuration is still a challenging task for today's commercially available simulation tools.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.40-46
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• 2021

An automatic transmission of automobiles enables comfortable driving experience with lower transmission shifting jerks. However, the assembly structure is more complicated and requires additional components with lower efficiency than the manual transmission system. Extensive research has been conducted to improve the overall transmission efficiency by optimizing each component of the automatic transmission assembly. This study focuses on enhancing the friction torque of double angular contact ball bearings used in automatic transmission. The friction torque of the bearing varies with the operating conditions such as the operational load and rotating speed. Since reducing the friction torque of the bearing tends to deteriorate the durability of the bearing, it is necessary to design the bearing having a minimum required friction torque by determining the durability life of an automatic transmission assembly, In this study, the theoretical life and friction torque of conventional and newly-developed bearings are calculated. The difference in the friction torque between the new and existing bearings are also evaluated.

• Journal of Technologic Dentistry
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• v.46 no.2
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• pp.21-27
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• 2024

Purpose: This study aimed to analyze the stress distribution and deformation in implant abutments made from titanium (Ti-6Al-4V), zirconia, and polyetheretherketone (PEEK), including their screws and fixtures, under various loading conditions using finite element analysis (FEA). Methods: Three-dimensional models of the mandible with implant abutments were created using Siemens NX software (NX10.0.0.24, Siemens). FEA was conducted using Abaqus to simulate occlusal loads and assess stress distribution and deformation. Material properties such as Young's modulus and Poisson's ratio were assigned to each component based on literature and experimental data. Results: The FEA results revealed distinct stress distribution patterns among the materials. Titanium alloy abutments exhibited the highest stress resistance and the most uniform stress distribution, making them highly suitable for long-term stability. Zirconia abutments showed strong mechanical properties with higher stress concentration, indicating potential vulnerability to fracture despite their aesthetic advantages. PEEK abutments demonstrated the least stress resistance and higher deformation compared to other abutment materials, but offered superior shock absorption, though they posed a higher risk of mechanical failure under high load conditions. Conclusion: The study emphasizes the importance of selecting appropriate materials for dental implants. Titanium offers durability and uniform stress distribution, making it highly suitable for long-term stability. Zirconia provides aesthetic benefits but has a higher risk of fracture compared to titanium. PEEK excels in shock absorption but has a higher risk of mechanical failure compared to both titanium and zirconia. These insights can guide improved implant designs and material choices for various clinical needs.

• Wind and Structures
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• v.13 no.5
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• pp.413-431
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• 2010

The focus of this article is on the assessment of vertical wind vector components and their aerodynamic impact on lattice framework, specifically two distinct sections of a guyed transmission tower. Thunderstorm winds, notably very localized events such as convective downdrafts (including downbursts) and tornadoes, result in a different load on a tower's structural system in terms of magnitude and spatial distribution when compared to horizontal synoptic winds. Findings of previous model-scale experiments are outlined and their results considered for the development of a testing rig that allows for rotation about multiple body axes through a series of wind tunnel tests. Experimental results for the wind loads on two unique experimental models are presented and the difference in behaviour discussed. For a model cross arm with a solidity ratio of approximately 30%, the drag load was increased by 14% when at a pitch angle of $20^{\circ}$. Although the effects of rotation about the vertical body axis, or the traditional 'angle of attack', are recognized by design codes as being significant, provisions for vertical winds are absent from each set of wind loading specifications examined. The inclusion of a factor to relate winds with a vertical component to the horizontal speed is evaluated as a vertical wind factor applicable to load calculations. Member complexity and asymmetric geometry often complicate the use of lattice wind loading provisions, which is a challenge that extends to future studies and codification. Nevertheless, the present work is intended to establish a basis for such studies.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.724-732
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• 2002

Although the demands for diesel engine is increased, our world is faced with very serious problems related to the air pollution due to the exhaust emissions of the diesel engine. In this study, the potential possibility of oxygenated fuel such as Methyl tertiary butyl ether (MTBE) was investigated for the sake of exhausted smoke reduction from diesel engine. MTBE has been used as a fuel additive blended into unleaded gasoline to improve octane number, but the study of application for diesel engine was incomplete. Because MTBE includes oxygen content approximately 18%, it is a kind of oxygenated fuel that the smoke emission of MTBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at high load and speed in diesel engine. But, the NOx emission of MTBE blended fuel is increased compared with commercial diesel fuel. And. it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from $C_1$to $C_{6}$ in exhaust gas using gas chromatography to seek the reason for remarkable reduction of smoke emission. The results of this study show three conclusions. 1. The smoke omission of the MTBE blended fuel is lower than that of the diesel fuel at all experimental region in direct injection diesel engine. 2. Individual hydrocarbons(C$_1$~ $C_{6}$) as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with diesel fuel. 3. Smoke emission from diesel engines was strongly depended on oxygen content in fuel regardless of operating condition.