• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.225-228
• /
• 2005

The purpose of this study is to investigate effects of the plastic/elastic deformation energy on wet etching characterization on the surface of material by using the nanoindentation and HF wet etching technique. Indents were made on the surface of Pyrex 7740 glass by the hyperfine indentation process with a Berkovich diamond indenter, and they were etched in $50\;wt\%$ HF solution. After etching process, convex structure was obtained due to the deformation-induced hillock phenomena. In this study, effects of indentation process parameters (normal load, loading rate) on the morphologies of the indented surfaces after isotopic etching were investigated from an angle of deformation energies.

• Applied Microscopy
• /
• v.45 no.2
• /
• pp.52-57
• /
• 2015

Bulk metallic glass (BMG) shows higth strength, high elastic limit, corrosion resistance and good wear resistance and soft magnetic properties and has been considering as a candidate for new structural materials. But they show limited macroscopic plasticity and lack of tensile ductility due to highly localized shear deformation, which should be solved for real structural application. In this paper researches on the enhancement of plasticity of BMG were reviewed briefly. Introducing heterogeneous structure in glass is effective to induce more shear transformation zones (STZs) active for multiple shear band initiation and also to block the propagating shear band. Several methods such as BMG alloy design for high Poisson's ratio, addition of alloying element having positive heat of mixing, pre-straining BMG and variety of BMG composites have been developed for homogenous distribution of locally weak region, where local strain can be initiated. Therefore enhancement of plasticity of BMG is normally accompanied with some penalty of strength loss.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.385-390
• /
• 2003

As growing of industrialization and increasing of population, the quantities of waste glasses are rapidly growing in the earth. It cause some problems such as the waste of natural resources and environmental pollution. In this context, recycling waste glass as a material of concrete has a great advantage environmentally and economically. This study is aimed to investigate the effect of load and deflection on fiber reinforced concrete slab model utilizing waste glass by fine aggregates. The flexural strength of the concrete including waste glass increased considerably, as the inclusion rate of steel fiber were increased. And the first crack load, maximum load and energy absorption capacity increased remarkably as the inclusion rate of steel fiber were increased. Therefore, in this study we confirmed the possibility of application for the usage of waste glass to the steel fiber reinforced concrete.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.21-23
• /
• 1994

By adding La₂O₃ to optical multicomponent glass composition, after making mother glass and core fiber that enable to enlarge the infrared transmittance region, then surveyed the optical properties. Through thermal analysis of the glass abstained by melt-quenching after selecting stable basic composition on devitrification and replace SiO₂ by 4-12wt% La₂O₃. As La₂O₃ increases up to l2wt% transition temperature, refractive index, density, deformation temperature increased, whereas thermal expansion coefficient decreased. As a result of inspectig transmittance in UV/VIS/IR region, visable region indicated the decrease of transmittance by increasing the La₂O₃ and transmittance region was enlarged by increasing the La₂O₃ in IR region. Also, fabricate core fiber at 820℃ and severy the optical loss we could fact that La₂O₃ composition added 12wt% showed the minimum optical loss.

• Transactions of Materials Processing
• /
• v.13 no.6 s.70
• /
• pp.509-514
• /
• 2004

An analysis using FEM simulation was conducted to predict residual stresses and birefringence in simple compressed cylindrical glass as a preliminary part of the optimum design determination of optical lenses. The FEM simulation with the Maxwell viscoelastic constitutive model was used to predict thermal induced residual stresses and birefringence during the compression test considering stress relaxation. Also the linear photoelastic theory was introduced to calculate birefringence from the residual stress state. The error of simulation results between experimental results in the birefringence value at the center of glass specimen is $4.2\%$, and the error in the maximum radius of deformed glass specimen is $1.2\%$. The simulation results were in good agreement with deformation and birefringence distribution in the existing experimental result.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.42-47
• /
• 2004

Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications including impact. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation on a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact loading. These results were compared with those of spherical indentation under quasi-static and impact loading. The interface bonded specimens were adopted to observe the appearances of subsurface damage induced during indentation under different loading conditions.

• Journal of the Korean Society of Safety
• /
• v.23 no.6
• /
• pp.34-37
• /
• 2008

The composite materials are widely used in the many applications of industry as well as aerospace field because of their high specific stiffness and strength which benefits the material and provides potential energy savings. However, composite materials also have a low property about external applied impact. In this paper, impact tests were conducted on different sample types(glass, carbon and kevlar composite) to obtain information such as absorbed energy and composite deformation using an instrumented impact test machine (DYNATUP 8250). 3 type samples were compared to experimental results. The data from impact test provided valuable information between the different type samples by wet lay up. This paper shows results of that kevlar composite has larger absorption energy and deformation than others.

• Design & Manufacturing
• /
• v.17 no.2
• /
• pp.62-69
• /
• 2023

In this study, we conducted a study on the optimization of injection molding conditions to minimize deformation of plastic product. The charging management system housing of the vehicle was selected as the research subject. Melting temperature, cooling temperature, packing time, and packing pressure were selected as the main factors expected to affect the deformation of molded products. Each main factor was divided into 5 levels. Optimization of injection molding conditions to minimize deformation was performed using the Taguchi Method. We performed an analysis of variance (ANOVA) to identify significant factors affecting the deformation of plastic product. In order to select injection molding conditions that minimize deformation of plastic products, injection molding analysis was additionally performed for insignificant factors. We then compared the deformation of the molded part before and after optimization. As a result of comparing the injection analysis results of the basic conditions and the injection analysis results of the optimal conditions, it was confirmed that the amount of deformation after optimization was improved by about 10.9%.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.11 s.176
• /
• pp.165-172
• /
• 2005

In MEMS (Micro-Electro-Mechanical System), packaging induced stress or stress induced structure deformation becomes increasing concerns since it directly affects the performance of the device. In the decoupled vibratory MEMS gyroscope, the main factor that determines the yield rate is the frequency difference between the sensing and driving modes. The gyroscope, packaged using the anodic bonding at the wafer level and EMC (epoxy molding compound) molding, has a deformation of MEMS structure caused by thermal expansion mismatch. This effect results in large distribution in the frequency difference, and thereby a lower yield rate. To improve the yield rate we propose a packaged SiOG (Silicon On Glass) process technology. It uses a silicon wafer and two glass wafers to minimize the wafer warpage. Thus the warpage of the wafer is greatly reduced and the frequency difference is more uniformly distributed. In addition. in order to increase robustness of the structure against deformation caused by EMC molding, a 'crab-leg' type spring is replaced with a semi-folded spring. The results show that the frequency shift is greatly reduced after applying the semi-folded spring. Therefore we can achieve a more robust vibratory MEMS gyroscope with a higher yield rate.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.8
• /
• pp.73-82
• /
• 2010

The GFRP(Glass-Fiber Reinforced Plastic) pipe is designed to behave safely against the external forces and to secure stability of deformation and settlements of pipe, since it is laid under the ground. In this study, the evaluation for the pressure stability was carried out by performing the laboratory experiments to figure out the mechanical properties of Glass-Fiber Reinforced Plastic pipe, take a theoretical approach, and suggest the mechanical properties necessary for the analysis and design of GFRP. Numerical analysis is also conducted to evaluate on the field application through the comparison concerning relations between deformation and differential settlement in the GFRP and hume pipes when all and half sections are under the surcharge load.