• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2475-2482
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• 1993

The effects of the hole size(2R) and the specimen width(W) on the fatigue strength and the fatigue life in plain woven glass/epoxy composite plates are experimentally investigated under constant amplitude tensile fatigue loading. It is shown in this study that the notch sensitivity under fatigue loading is lower than that under static loading. It can be explained by the fact that the stress concentration is relaxed by the damage developed at the boundary of circular hole. To predict the fatigue strength at a specific cycle, the modified point stress criterion represented as a function of the geometry of the specimen(2R and W) is applied. It is found that the model used in the prediction of the notched tensile strength predicts the fatigue strength with reasonable accuracy. A model for predicting the fatigue life in the notched specimen, based on the S-$N_f$, curve in the smooth specimen, is suggested.

• KSBB Journal
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• v.11 no.1
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• pp.52-57
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• 1996

Bovine aortic smooth muscle cells cultured on the slide glass were exposed to sheared flow up to 120 hours in flow chamber to see the effect of shear stress on cell growth in wall shear stresses of 0 to 26dyn/$cm^2$. From lactate dehydrogenase concentration measurement of the circulating medium, it was shown that sheared flow in the shear stress range did not remove additional smooth muscle cells from the slide glass compared with cells in stationary condition. According to smooth muscle cell counting per$cm^2$ of the surface, smooth muscle cells grew fastest in the stationary condition. As the wall shear stress increased, the growth of cells became slower. When the wall shear stress increased over 17dyn/$cm^2$, cell growth was not observed throughout the experiment.

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.475-483
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• 2015

PURPOSE. The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS. The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimensional finite element models. Four models were prepared according to different cement types (zinc phosphate, polycarboxylate, glass ionomer, and resin). A load of 700 N was applied vertically on the crowns (8 loading points). Maximum principal stress was determined. RESULTS. Zinc phosphate cement had a greater stress concentration in the cement layer, while polycarboxylate cement had a greater stress concentration on the distal surface of the monolithic zirconia crown and abutment tooth. Resin cement and glass ionomer cement showed similar patterns, but resin cement showed a lower stress distribution on the lingual and mesial surface of the cement layer. CONCLUSION. The test results indicate that the use of different luting agents that have various elastic moduli has an impact on the stress distribution of the monolithic zirconia crowns, cement layers, and abutment tooth. Resin cement is recommended for the luting agent of the monolithic zirconia crowns.

• Structural Engineering and Mechanics
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• v.25 no.4
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• pp.365-382
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• 2007

A pilot study has been conducted to guide the development of a finite element modeling formulation for the analysis of architectural glass curtain walls under in-plane lateral load simulating earthquake effects. This pilot study is one aspect of ongoing efforts to develop a general prediction model for glass cracking and glass fallout for architectural glass storefront and curtain wall systems during seismic loading. For this study, the ANSYS finite element analysis program was used to develop a model and obtain the stress distribution within an architectural glass panel after presumed seismic movements cause glass-to-frame contact. The analysis was limited to static loading of a dry-glazed glass curtain wall panel. A mock-up of the glass curtain wall considered in the analysis with strain gages mounted at select locations on the glass and the aluminum framing was subjected to static loading. A comparison is made between the finite element analysis predicted strain and the experimentally measured strain at each strain gage location.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.625-635
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• 1989

Mixed mode fracture problem is analyzed for the finite orthotropic plate where an inclined crack parallel to the fiber direction is centrally placed. Modified mapping collocation method with both uniform stress and uniform displacement boundary conditions is utilized to calculate stress intensity correction factors for glass/epoxy and graphite/epoxy composites. Computed results are presented for selected combinations of crack length to width ratio L/W and plate aspect ratio H/W with various fiber orientations.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.31-36
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• 2008

Architectural membrane are now used in the roof of large span structures throughout the world with the merits of free shape and lightness. Some membrane have some problems of structural capacity by the wind or snow load conditions, large span structures was shown to the tearing of the membrane. This paper is the experimental test on the stress strain curve of cycling load for the glass fiber membrane. In the result of stress strain relationship curve by the cycling load, glass fiber membrane was reduced the tensile strength, the polyester membrane was shown to occur the increase of displacement without load reduction in each load step.

• Journal of Information Display
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• v.4 no.3
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• pp.12-16
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• 2003

In connection with the ion exchange strengthening on soda-lime-silicate, substrate glass for display use was investigated. In the processing, the temperature was varied during the ion exchange in order to make stress profile and to determine optimum condition. In the present work, we found that the maximum value of strength was 617.8 MPa after an ion exchange process at 470 $^{\circ}C$ for 1h, and then, at 450 $^{\circ}C$ for 24h. Also, the effect of residual stress placed on the near surface was measured by analyzing the number of crack branches and brittleness. This approach allowed us the residual stress profile to be engineered to improve mechanical reliability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.193-200
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• 2007

Micro forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load effect to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG).

• Design & Manufacturing
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• v.16 no.1
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• pp.50-54
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• 2022

Coverglass of electronic equipments is thinner and slimmer, so the glass must have good bending strength. In these days, the polishing edge of glass is used by solid tool like grinding wheel. But solid tool leave micro crack or edge chipping in edge of glass. MR polishing is an optimal method by polishing edge of glass. MR polishing is used MR fluid that is a liquid tool. MR polishing doesn't leave tool path or residual stress, micro crack and edge chipping unlike grinding wheel polishing. In this paper, the results of grinding and MR polishing were compared and analyzed to improve bending strength by minimizing edge chipping of cover glass. It was derived that the depth and size of cracks have a significant influence on the bending strength of the glass edge. The edges of the glass using MR grinding were analyzed to have a better surface and higher bending strength than the glass using abrasive wheel grinding. It was confirmed that MR polishing had an effect on strength improvement by effectively removing cracks in the specimen.

• Transactions of Materials Processing
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• v.11 no.7
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• pp.581-588
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• 2002

Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.