• Coupled systems mechanics
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• v.9 no.3
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• pp.237-264
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• 2020

This article investigates the static behaviour of functionally graded (FG) plates sometimes declared as advanced composite plates by using a simple and accurate quasi-3D and 2D hyperbolic higher-order shear deformation theories. The properties of functionally graded materials (FGMs) are assumed to vary continuously through the thickness direction according to exponential law distribution (E-FGM). The kinematics of the present theories is modeled with an undetermined integral component and satisfies the free transverse shear stress conditions on the top and bottom surfaces of the plate; therefore, it does not require the shear correction factor. The fundamental governing differential equations and boundary conditions of exponentially graded plates are derived by employing the static version of principle of virtual work. Analytical solutions for bending of EG plates subjected to sinusoidal distributed load are obtained for simply supported boundary conditions using Navier'is solution procedure developed in the double Fourier trigonometric series. The results for the displacements and stresses of geometrically different EG plates are presented and compared with 3D exact solution and with other quasi-3D and 2D higher-order shear deformation theories to verify the accuracy of the present theory.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.322-329
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• 2016

Reconstruction of the maxillectomy with an obturator is to restore masticatory, swallowing, phonetic and esthetic problems. Stress created by lateral forces is minimized by the proper selection of an occlusal scheme, elimination of premature occlusal contacts, and wide distribution of supporting area. It should be considered that properly designed retainers reduce the stresses transmitted to the abutment while the obturator is in function. The following clinical report presents palatal obturator treatment with implant assisted removable partial denture (IARPD) design that restores normal function and esthetics in patients who experienced maxillectomy and dental implant failure.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.68-76
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• 1997

The welding-induced initial imperfections such as residual stresses and initial strains in plated structures of ships and offshore structures can be effectively evaluated by the thermal elasto-plastic analysis method proposed in this paper. In the analysis of heat conduction of plate structures, both the analytical method and the numerical method are used. For the thermal elasto-plastic analysis of plates, the finite element analysis is performed, based on the initial strain method. In the plastic domain during incremental process, the 2nd order terms of stress increments and yield stress increments were considered, so that time increment could be controlled for more stable solution. To measure temperature distribution and angular distortion of plates during welding, bead-on-plate experiment are perform with various heat input and plate thickness. Measured data show good agreement with the calculated results.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.93-98
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• 2001

CFT column has excellent structural properties due to the composite action between concrete and steel tube. The bond behavior between the constituent elements has to be found for analyzing the behavior of CFT column. A new model is necessary because most of existing models for bond stress-slip relationship of the deformed bar cannot be applied to the CFT column. Therefore, the objective of this research is to develop a new model related to the bond behavior of CFT column considering the relation between bond stress and vertical stress, and the distribution of lateral stress under the confinement created by steel casing. From equilibrium condition, the formula for relationship between bond stress and vertical stress is derived, and the relationship for the lateral stresses of the CFT column section is obtained by an Airy stress function. The experiments are performed for five CFT column specimens axially loading on concrete alone. The relation between bond strength and lateral stress is investigated from the regression analysis using the measured strains. Finally a new bond strength model is proposed, which is able to predict the relationship for the stress of each direction of CFT column loading on concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.165-170
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• 2015

Pipe-rack structures supporting high temperature and pressure are of great importance to ensure the safety of the operation of the plants. If some damage occurred in the pipe-rack structure, the facilities not only bring damage to the commercial property, but also result in economic losses. Specially, since pipe-rack structures are exposed to various environmental conditions, it is essential to evaluate the thermal behavior of the structure caused by environmental conditions for the appropriate design and maintenance of the pipe-rack structure. Thus, based on a selected, typical pipe-rack structure, a thermal-stress coupled analysis was conducted to evaluate the temperature distributions and thermal stresses of the structure. For this, this study accounted for the operating condition of the pipe and the effect of environmental conditions, Yeosu in South Korea and Saudi Arabia in the Middle East. The results of the study showed the need for accounting for a variance in the environmental factors to evaluate the thermal behavior of the pipe-rack structure along with the working condition of pipe.

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.185-196
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• 2006

Statement of problem: The researches on the influence of design variables on the stress distribution in cortical and trabecular bones and on optimal design for implant system were limited. Purpose: The purpose of this study is to identify the sensitivities of design parameters and to suggest the optimal parameters for designing the onebody type implant system. Material and methods: Stresses arising in the implant system were obtained by finite element analysis using a three dimensional model. An onebody type implant system[Oneplant (Warrantec. Co. Ltd., Korea)] was considered in this study. Vortical load(150 N) was applied on the top of the abutment along the axial direction. The initial design variables set for sensitivity analysis were radius of fixture, numbers of micro thread, numbers of power thread, height of micro thread, future length, tapered angle of future, inclined angle of thread, width of micro thread and width of power thread. The statistical technique of Design of Experiments(DOE) was applied tn the simulation model to deduce effective design parameters on stress distributions in bones. The deduced design parameters were incorporated into a fully automated design tool which is coupled with the finite element analysis and numerical optimization to determine the optimal design parameters. Results: 1. The result of sensitivity analysis showed six design variables - radius of future, tapered angle of fixture, inclined angle of thread, numbers of power thread, numbers of micro thread and height of micro thread - were more influential than the others. 2. The optimal values of design variables can be deduced by coupling finite element analysis (FEA) and design optimization tool(DOT).

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.34-41
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• 2014

The goal of this study is to investigate some crack behaviors which affect the crack propagation angle at the planar solid oxide fuel cell with cracks under the fabricating and operating temperature and analyze the stresses by 3 steps processing on the solid oxide fuel cell. Currently, there are lots of researches of the performance improvement for fuel cells, and also for the more powerful efficiency. However, the planar solid oxide fuel cell has demerits which the electrode materials have much brittle properties and the thermal condition during the operating process. It brings some problems which have lower reliability owing to the deformation and cracks from the thermal expansion differences between the electrolyte, cathode and anode electrodes. Especially the crack in the corner of the electrodes gives rise to the fracture and deterioration of the fuel cells. Thus it is important to evaluate the behavior of the cracks in the solid oxide fuel cell for the performance and safety operation. From the results, we showed the stress distributions from the cathode to the anode and the effects of the edge crack in the electrolyte and the slant crack in the anode. Futhermore the crack propagation angle was expected according to the crack length and slant angle and the variation of the stress intensity factors for the each fracture mode was shown.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.37-42
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• 2005

Most of the welding steel plate structures have complicated mechanical problems such as rolling directional characteristics and residual stresses caused by manufacturing process. For the enhancement of reliability and safety in those structures, therefore, a systematic investigation is required. SS400 steel plate used for common structures was selected and welded by FCAW butt-welding process for this study, and then it was studied experimently about characteristics of fatigue crack propagations with respect to rolling direction and welding residual stress of welded steel plates. When the angles between rolling direction and tensile loading direction in base material are increased, their ultimate strength not show a significant difference, but yielding strength are increased and elongations are decreased uniformly. It is also shown that fatigue crack growth rate can be increased from those results. When the angles between welding bead direction and loading direction in welded material are increase, fatigue crack growth rate of them are decreased and influenced uniformly according to the conditions of residual stress distribution. In these results, it is shown that the welded steel plate structures are needed to harmonize distributed welding residual stress, rolling direction and loading direction fur the improvement of safety and endurance in manufacture of their structures.

• Computers and Concrete
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• v.25 no.4
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• pp.311-325
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• 2020

In this research work, the hygrothermal and mechanical buckling responses of simply supported FG sandwich plate seated on Winkler-Pasternak elastic foundation are investigated using a novel shear deformation theory. The current model take into consideration the shear deformation effects and ensures the zero shear stresses on the free surfaces of the FG-sandwich plate without requiring the correction factors "Ks". The material properties of the faces sheets of the FG-sandwich plate are assumed varies as power law function "P-FGM" and the core is isotropic (purely ceramic). From the virtual work principle, the stability equations are deduced and resolved via Navier model. The hygrothermal effects are considered varies as a nonlinear, linear and uniform distribution across the thickness of the FG-sandwich plate. To check and confirm the accuracy of the current model, a several comparison has been made with other models found in the literature. The effects the temperature, moisture concentration, parameters of elastic foundation, side-to-thickness ratio, aspect ratio and the inhomogeneity parameter on the critical buckling of FG sandwich plates are also investigated.