• Title/Summary/Keyword: Longitudinal Strain

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Analysis of Linear-type Ultrasonic Motor Using A Finite Element Method (유한요소해석 프로그램에 의한 리니어 초음파 모터의 변위량 해석)

  • 이동준;임태빈;강성택;김영욱;임기조
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.33-36
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    • 1998
  • This paper is a study on a linear ultrasonic motor with a first longitudinal$(L_1)$ and fourth bending $(B_4)$ double-mode rectangular plate. The stator vibrator is composed of an elastic material plate and of a piezo-ceramic element having a motion by electrical excitation. Each strain vector differs by $90^{\circ}$ generate travelling wave with the elliptical displacement motion of a point on the surface. To magnify displacement of longitudinal direction in elliptical displacement motion, the motor has a mechanism of the.displacement enlargement. In this paper, the vibration shape of the stator is simulated using the finite element method. A detailed model considered of the piezoelectric effect and of the exact geometry of the stator is used to calculate the displacement. The position of displacement mechanism is decided by the maximum displacement.

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Buckling Analysis of Roll Forming Process using Finite element method (유한요소법을 이용한 롤포밍 공정에서의 버클링 해석)

  • Kim, Young-In;Kim, Jong-Hun;Jeoung, Young-Chul;Kim, Nak-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.9
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    • pp.1451-1456
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    • 2003
  • In code roll forming processes, the sheet metal strip is gradually and successively bent into a desired profile. Occurrence of buckling is one of the major defects. Buckling may occur due to longitudinal stress and it is difficult to predict buckling behavior. In this study an analytical method for buckling behavior during roll forming is proposed. All numerical simulations are performed by finite element analysis. The behavior of buckling can be predicted with the simulation modeling of the finite element method.

Study on push-out test and bond stress-slip relationship of circular concrete filled steel tube

  • Yin, Xiaowei;Lu, Xilin
    • Steel and Composite Structures
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    • v.10 no.4
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    • pp.317-329
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    • 2010
  • According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

Strength and Ductility of High-Strength Reinforced Concrete Columns under Uniaxial Loads (중심 축력을 받는 고강도 철근 콘크리트 기둥의 내력 및 연성에 관한 연구)

  • 이강건;이재연;김성수;이리형
    • Proceedings of the Korea Concrete Institute Conference
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    • 1990.10a
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    • pp.57-62
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    • 1990
  • This paper is to study the effect of rectilinear confinement in high-strength concrete subjected to a monotonically increasing compressive axial loads. To investigate behavior of columns rectilinearly confined with lateral ties and longitudinal rebars, twelve specimens including two plain concrete specimens were tested. The main variables in this study are volumetric ratio of lateral ties, cistribution of lateral ties, yield strength of logitudinal steel, ratio of area of longitudinal steel to the area of cross section. The test results were not only compared with an empirical model for the stress-strain curve of rectilinearly confined high-strength concrete but also the existing model. The empirical model used calculating column capacity shows better agreement with the test results tham the existing model.

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Wave propagation in double nano-beams in thermal environments using the Reddy's high-order shear deformation theory

  • Fei Wu;Gui-Lin She
    • Advances in nano research
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    • v.14 no.6
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    • pp.495-506
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    • 2023
  • We study the bending wave, shear wave and longitudinal wave characteristics in the double nanobeams in this paper for the first time, in the process of research, based on the Reddy's higher-order shear deformation theory and considering shear layer stiffness, linear stiffness, inter-laminar stiffness, the pore volume fraction, temperature variation, functionally graded index influence on wave propagation, based on the nonlocal strain gradient theory and Hamilton variational principle, the wave equation of the double-nanometer beams are derived. Since there are three different motion states for the double nanobeams, which includes the cases of "in phase", "out of phase" and "one nanobeam fixed", the propagation characteristics of shear-, bending-, and longitudinal- waves in these three cases are discussed respectively, and some valuable conclusions are obtained.

Moment-Curvature behavior of steel and GFRP reinforced beam using AE and DIC Techniques

  • Sharma, Gaurav;Sharma, Shruti;Sharma, Sandeep K.
    • Structural Engineering and Mechanics
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    • v.84 no.2
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    • pp.253-268
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    • 2022
  • Using non-destructive Acoustic Emission (AE) and optical Digital Image Correlation (DIC) methods, the moment-curvature behavior of steel and GFRP bars reinforced concrete beams under flexure was explored in this study. In the tension zone, laboratory studies were carried out on steel-RC and GFRP-RC beams with varying percentages of longitudinal reinforcement ratios of 0.33 %, 0.52%, and 1.11%. The distinct mechanism of cracking initiation and fracture progression of failure in steel-RC and GFRP-RC beams were effectively correlated and picked up using AE waveform characteristics of the number of AE hits and their amplitudes, AE energy as well as average frequency and duration. AE XY event plots and longitudinal strain profiles using DIC gives an online and real-time visual display of progressive AE activity and strains respectively to efficaciously depict the crack evolution and their advancement in steel-RC and GFRP-RC beams. They display a close matching with the micro and macro-cracks visually observed in the actual beams at various stages of loading.

The Characteristics of Chromiun Nitride Thin-Film Strain Gauges (크롬질화박막형 스트레인 게이지의 특성)

  • Seo, Jeong-Hwan;Kim, Il-Myung;Lee, Chae-Bong;Kim, Sun-Cheol;Chung, Gwiy-Sang
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1989-1991
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    • 1999
  • This paper presents characteristics of CrN thin-film strain gauges, which were deposited on glass by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-$(5{\sim}25%)N_2$). The physical and electrical characteristics of these films investigated with the thickness range $3500{\AA}$ of CrN thin films, annealing temperature $(100{\sim}300^{\circ}C)$ and annealing $(24{\sim}72hr)$. The optimized condition of CrN thin-film strain gauges were thickness range of $3500{\AA}$ and annealing condition($300^{\circ}C$, 48 hr) in Ar-10 %$N_2$ deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauge is obtained a high resistivity, ${\rho}=1147.65{\mu}{\Omega}cm$, a low temperature coefficient of resistance, TCR=$-186ppm/^{\circ}C$ and a high temporal stability with a good longitudinal, 11.17. And change in resistance after annealing for the CrN thin-films were quitely linear and stable.

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Fabrication and Characteristics of Tantalum Nitride Thin-Film Strain Gauges (질화탄탈 박막형 스트레인 게이지의 제작과 특성)

  • Chung, Gwiy-Sang;Woo, Hyung-Soon;Kim, Sun-Chul;Hong, Dae-Sun
    • Journal of Sensor Science and Technology
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    • v.13 no.4
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    • pp.303-308
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    • 2004
  • This paper descibes on the characteristics of Ta-N(tantalum nitride) ceramic thin-film strain gauges which were deposited on Si substrates by DC reactive magnetron sputtering in an argon-nitrogen atmosphere (Ar-$(4{\sim}16%)N_{2}$) for high-temperature applications. These films were annealed in $2{\times}10^{-6}$ Torr vacuum furnace at the range of $500{\sim}1000^{\circ}C$. Optimum deposition atmosphere and annealing temperature were determined at $900^{\circ}C$ for 1 hr. in 8% $N_{2}$ gas flow ratio. Under optimum formation conditions, the Ta-N thin-film for strain gauges was obtained a high-resistivity of $768.93{\mu}{\Omega}{\cdot}cm$, a low temperature coefficient of resistance (TCR) of -84 ppm/$^{\circ}C$ and a good longitudinal gauge factor (GF) of 4.12.

Development of a High Temperature and Exactitude Pressure Sensors for Superior Environmental Characteristics (내환경성이 우수한 고온.고정밀용 압력센서의 개발)

  • 서정환;백명숙;임창섭
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2002.05a
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    • pp.13-22
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    • 2002
  • This paper presents characteristics of CrOx thin-film Strain gauge pressure sensors, which were deposited on SUS630 diaphragm by DC reactive magnetron sputtering in an argon-Oxide atmosphere(Ar-(10%)$O_2$). The optimized condition of CrOx thin-film strain gauges were thicknessrange of 2500$\AA$ and annealing condition ($350^{\circ}C$, 3 hr) in Ar-10 %$O_2$deposition atmosphere. Under optimum conditions, the CrOx thin-films for strain gauge is obtained a high resistivity, $\rho$=156.7$\mu$$\Omega$cm, a low temperature coefficiect of resistance, TCR=-86 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 15. The output sensitivity of pressure sensor obtained is 2.46㎷/V and the maximum non-linearity is 0.3%FS and hysteresis is less than 0.2%FS. The output characteristics of pressure transmitter obtained is 4~20㎃ and total accuracy is less than $\pm$0.5%FS. In those conclusions, CrOx thin film pressure sensors is quite satisfactory for many applications in industrial electronics.

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Fatigue Life Estimation of Welding Details by Using a Notch Strain Approach (노치변형률법을 적용한 용접구조상세의 피로수명평가)

  • Han, Jeong-Woo;Han, Seung-Ho;Shin, Byung-Chun;Kim, Jae-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.977-985
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    • 2004
  • An evaluation of fatigue life of welded components is complicated due to various geometrically complex welding details and stress raisers in vicinity of weld beads, ego under cuts, overlaps and blow holes. These factors have a considerable influence on the fatigue strength of welded joints, as well as the welding residual stress which is relaxed depending on the distribution of local stress at the front of the stress raisers. To reasonably evaluate fatigue life, the effect of geometries and welding residual stress should be taken into account. The several methods based on the notch strain approach have been proposed in order to accomplish this. These methods, however, result in differences between analytical and experimental results due to discrepancies in estimated amount of relaxed welding residual stress present. In this paper, an approach that involves the use of a modified notch strain approach considering geometrical effects and a residual stress relaxation model based on experimental results was proposed. The fatigue life for five types of representative welding details, ego cruciform, cover plate, longitudinal stiffener, gusset and side attachment joint, are evaluated using this method.