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Finite Element Analysis on Formability of Parabolic Shape
정상원,이경원 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.4
For the product with small diameter, long column, and parabolic shape, the forging formability of the high-carbon steel wire rod was investigated in this study. By using the three-dimensional finite element method, the formability of wire was reviewed by forming analysis for the desired parabolic shape of local part. Analysis results due to forging direction, forging velocity, friction coefficient and constraint location were also investigated. On the basis of these results, it is noted that the forging direction has the big influence when the product with long column is forged. As the forging velocity increases,buckling tends to be limited and formability of parabolic shape is improved. By constraining the lower parabolic shape part to suppress plastic strain, the effect depending on friction coefficient is not almost appeared. And good parabolic shape is obtained at the region of the forging velocity of more than 0.5 m/s.
Finite Element Analysis on Formability of Parabolic Shape
Sang-Won Chung(정상원),Kyung-Won Lee(이경원) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.4
For the product with small diameter, long column, and parabolic shape, the forging formability of the high-carbon steel wire rod was investigated in this study. By using the three-dimensional finite element method, the formability of wire was reviewed by forming analysis for the desired parabolic shape of local part. Analysis results due to forging direction, forging velocity, friction coefficient and constraint location were also investigated. On the basis of these results, it is noted that the forging direction has the big influence when the product with long column is forged. As the forging velocity increases, buckling tends to be limited and formability of parabolic shape is improved. By constraining the lower parabolic shape part to suppress plastic strain, the effect depending on friction coefficient is not almost appeared. And good parabolic shape is obtained at the region of the forging velocity of more than 0.5 m/s.
Influence of prestressing on the behavior of uncracked concrete beams with a parabolic bonded tendon
Marco Bonopera,Kuo-Chun Chang,Tzu-Kang Lin,Nerio Tullini 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.1
The influence of prestress force on the fundamental frequency and static deflection shape of uncracked Prestressed Concrete (PC) beams with a parabolic bonded tendon was examined in this paper. Due to the conflicts among existing theories, the analytical solutions for properly considering the dynamic and static behavior of these members is not straightforward. A series of experiments were conducted for a total period of approximately 2.5 months on a PC beam made with high strength concrete, subsequently and closely to the 28 days of age of concrete. Specifically, the simply supported PC member was short term subjected to free transverse vibration and three-point bending tests during its early-age. Subsequently, the experimental data were compared with a model that describes the dynamic behavior of PC girders as a combination of two substructures interconnected, i.e., a compressed Euler–Bernoulli beam and a tensioned parabolic cable. It was established that the fundamental frequency of uncracked PC beams with a parabolic bonded tendon is sensitive to the variation of the initial elastic modulus of concrete in the early-age curing. Furthermore, the small variation in experimental frequency with time makes doubtful its use in inverse problem identifications. Conversely, the relationship between prestress force and static deflection shape is well described by the magnification factor formula of the “compression-softening” theory by assuming the variation of the chord elastic modulus of concrete with time.
박승환,문용태,한대섭,박중서,오명석,안도열 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.3
The light emission properties of InGaN/GaN quantum well (QW) light-emitting diodes with non-square layers with graded, triangular, and parabolic shapes are investigated using multiband effective mass theory. These results are compared with those of conventional InGaN/GaN QW structures. The spontaneous emission peak of non-square QW structures is shown to be improved compared to a conventional QW structure. In particular, the parabolic QW structures shows a slightly larger emission peak than the graded or triangular QW structure. This can be explained by the fact that a smaller In composition in the well is needed to give a transition wavelength of 440 nm.