• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1267-1281
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• 2015

Carbon steel plate girders have been used on a large scale in the building industry. Nowadays, Lean Duplex Stainless Steel (LDSS) plate girders are gaining popularity as they possess greater strength and are more impervious to corrosion than those that are constructed from carbon steel. Regardless of their popularity, there is very limited information with regards to their shear behavior. In this paper, the non-linear finite element analysis was employed to investigate the shear behavior of LDSS plate girders. Parameters considered were the web thickness, the flange width, and the girders aspect ratio. The analysis revealed that although the shear behavior of the LDSS girders was no different from that of carbon steel plate girders, it had obviously been affected by the non-linearity of the material. Furthermore, the selected parameters were found to pronounce effect on the shear capacity of the LDSS girders. That is, the shear capacity increased considerably with web thickness, and increased slightly with flange width. However, it was reduced as the aspect ratio increased. Comparisons between the finite element analysis failure loads and those predicted by the current European Code of Practice revealed that the latter underestimated the shear strength of the LDSS plate girders.

• Steel and Composite Structures
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• 제43권1호
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• pp.117-127
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• 2022

This study investigates the wave propagation in porous functionally graded (FG) sandwich plates subjected to hygrothermal environments. A new simple three-unknown first-ordershear deformation theory (FSDT) incorporating an integral term is utilized in this paper. Only three unknowns are used to formulate the governing differential equation by applying the Hamilton principle. The FG layer of the sandwich plate is modeled using the power-law function with evenly distributed porosities to represent the defects of the manufacturing process. The plate is subjected to nonlinear hygrothermal changes across the thickness. The effects of the power-law exponent, core to thickness ratios, porosity volume, and the relations between volume fraction and wave properties of porous FG plate under the hygrothermal environment are investigated. The results showed that the waves' phase velocities increase linearly with the waves number in the FGM plate. The porosity of the FG materials plate has a noticeable impact on the phase velocity when considering the high ratios of the core layer. It has a negligible effect on small core layers. Finally, it is observed that changing temperatures and moistures do not influence the relationship between the power law and the phase velocity.

• Journal of Welding and Joining
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• 제30권4호
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• pp.4-9
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• 2012

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.55-59
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• 2021

Generating electromagnetic waves with Orbital Angular Momentum (OAM) properties is a fast-growing research subject in both radio and optics. This paper describes the generation of OAM carrying waves using a circular array of rectangular planar monopole antennas. The proposed design combines simplicity, compactness, and most importantly very wideband of operating frequencies (about 20-160 GHz, bandwidth ratio about 1:8) which makes it suitable for future applications.

• 공학논문집
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• 제4권1호
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• pp.69-85
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• 2002

병유리 파유리는 생산하고자 하는 제품과 같은 조성을 가지고 있어 아무리 투입해도 문제가 발생하지 않지만 수급에 문제가 발생하고 있어 예전에는 사용하지 않고 폐기하던 판상 파유리를 사용하고 있다. 그러나 현재 판상 파유리를 사용하면서 판상 파유리의 이질성 때문에 실투, Stone과 같은 많은 문제가 발생하고 있다. 이것의 원인은 $Al_2O_3$의 감소라 생각하고 장석을 통하여 $Al_2O_3$ 함량을 늘리고 판상 파유리의 사용량을 늘려 보고자 하였다. 자원의 재활용(파유리 재활용 증대)과 천연 원료의 사용량 감소에 따라 경제 적으로 많은 이익을 얻을 수 있고 자연 환경의 보전 즉 환경 문제에도 도움을 줄 것이다. 판상 파유리의 비율이 증가함에 따라 $Al_2O_3$의 함량이 감소하는 모습을 볼 수 있었다. 부족한 $Al_2O_3$의 양을 보완하기 위해 장석의 투입량을 증가시켜 $Al_2O_3$의 함량을 보완했다. EDS DATA를 분석해 보면 Si, O의 Pick 만이 존재하는 것을 확인 할 수 있어 나타난 결함이 $SiO_2$계임을 알 수 있었고, SEM 사진을 분석해 보면 $120^{\circ}$의 세 방향으로 열팽창 계수 차에 의해 모습을 볼 수 있어 이것이 Crystobalite 또는 Tridymite라는 것을 알 수 있었다. 편광 현미경에 의한 관찰 결과를 보면 Quartz, tridymite 그리고 Crystobalite Stons과 비슷한 모습을 볼 수가 있었다. 그리고 상평형도에 삼성분에 의한 삼중점을 찾아본 분석해보면 삼중점들이 Tridymite 상의 위치에 있는 것을 볼 수 있어 Tridymite라고 결론을 지을 수 있었다. 따라서 $Al_2O_3$의 한계 임계율은 7.5%인 것을 알 수 있었다.

• 한국표면공학회지
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• 제47권4호
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• pp.186-191
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• 2014

Double layer films which consisted of aluminum(Al) and magnesium(Mg) have been prepared by e-beam deposition. The structure, alloy phase, and corrosion resistance of the prepared films were investigated before and after heat treatment. The first (bottom) layer fixed with Al, and the thickness ratio between Al and Mg layers has been changed from 1 : 1 to 5 : 1, respectively. Total thickness of Al-Mg film was fixed at $3{\mu}m$. The cold-rolled steel sheet was used as a substrate. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 2, 3 and 10 min. Surface morphology of as-deposited Al-Mg film having Mg top layer showed plate-like structure. The morphology was not changed even after heat treatment. However, cross-sectional morphology of Al-Mg films was drastically changed after heat treatment, especially for the samples heat treated for 10 min. The morphology of as-deposited films showed columnar structure, while featureless structure of the films appeared after heat treatment. The x-ray diffraction data for as-deposited Al-Mg films showed only pure Al and Mg peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ appeared after heat treatment of the films. It is believed that the formation of Al-Mg alloy phase affected the structure change of Al-Mg film. It was found that the corrosion resistance of Al-Mg film was increased after heat treatment.

• 한국주조공학회지
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• 제29권1호
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• pp.45-51
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• 2009

Conventionally, Al-Sn bearing manufacturing involves casting the Al-Sn alloy and roll-bonding to a steel backing strip. This article will describe the microstructural control of Al-Sn metal bearing alloy following heat treatment. When the pure aluminum rod dipped in the melt of tin maintained below the melting point of aluminum, the melting of aluminum was accelerated with penetration of tin along the grain boundary of aluminum. The length of plate-shaped eutectic tin was decreased with heat treatment time. With even longer heat treatment time over 1 hour the length of eutectic tin didn't decrease any more, while resulting in coarsening of aluminum matrix. Exuded liquid of eutectic tin was formed at the surface of Al-Sn alloy after heat treatment even at below eutectic temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.784-789
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• 2001

In order to investigate the fracture behaviors(penetration modes) and the resistance to penetration during ballistic impact of cold-rolled Al 5052 H34 alloy laminates, anodized Al 5052 H34 alloy laminates, and Al 5052 H34 alloy after cold-rolling, ballistic testing was conducted. In general, superior armor material is brittle materials which have a high hardness. Ballistic resistance of these materials was measured by protection ballistic limit(V50), a statical velocity with 50% probability for incomplete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are observed respectfully, resulting from V50 test and Projectile Through Plate(PTP) test at velocities greater than V50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V50 tests with 0$^{\circ}$obliquity at room temperature were also conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface Hardness, resistance to penetration, and penetration modes of Al 5052 H34 alloy laminates compared to those of cold-rolled Al 5052 H34 alloy laminates and anodized Al 5052 H34 alloy laminates anodized Al 5052 H34 alloy after cold-rolling.

• Journal of Welding and Joining
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• 제34권4호
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• pp.34-39
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• 2016

Recently, aluminum alloy has used various industry, such as automobile, shipbuilding and aircraft because of characteristics of low density and high corrosion resistance. Al 6061-T6 is heat treatment materials so it has high strength and mostly used for assembly by mechanical fastening such as a bolting and riveting. In GMA (Gas Metal Arc) welding of alloy, some defects which are hot cracking, porosity, low-mechanical properties and large heat affected zone is generated, because of high heat conductivity. It reduces mechanical properties. In this study, the major factor effected on properties are analyzed after welding in Al 6061-T6 in GMAW, then optimize heat treatment conditions. Plate of Al 6061-T6 with a thickness of 12 mm is welded in V groove and applied welding method is butt joint. Mechanical properties and microstructure are analyzed according to heat treatment condition. Tensile strength, microstructure and Hardness are evaluated. Result of research appears that Al 6061-T6 applied heat treatment show outstanding mechanical properties.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.159-166
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• 2011

Si-rich-layer-coated U-7 wt%Mo plates were prepared in order to evaluate the diffusion barrier performance of the Si-rich layer in U-Mo vs. Al interdiffusion. Pure Si powder was used for coating the U-Mo plates by annealing at $900^{\circ}C$ for 1 h under vacuum of approximately 1 Pa. Si-rich layers containing more than 60 at% of Si were formed on U-7 wt%Mo plates. Diffusion couple tests were conducted in a muffle furnace at $560-600^{\circ}C$ under vacuum using Si-rich-layer-coated U-Mo plates and pure Al plates. Diffusion couple tests using uncoated U-Mo plates and Al-(0, 2 or 5 wt%)Si plates were also conducted for comparison. Si-rich-layer coatings were more effective in suppressing the interaction during diffusion couple tests between coated U-Mo plate and Al, when compared with U-Mo vs. Al-Si diffusion couples, since only small amounts of Al in the coating could be found after the diffusion couple tests. Si-rich-layer-coated U-7wt%Mo particles were also prepared using the same technique for U-7 wt%Mo plates to observe the microsturctures of the coated particles.