• Title/Summary/Keyword: Apparent elasticity method

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Characterization of the mixed soil with waste and application to geotechnical field (폐기물을 포함한 혼합토의 특성 및 지반공학분야에의 응용)

  • 이기호
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.11a
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    • pp.72-84
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    • 2001
  • In order to utilize mass of oyster shells for a partial substitute material for reclamation, we investigate the shear characteristics of dredged sluge mixed with oyster shells. the apparent modulus of elasticity of the this mixture are obtained from the triaxial compression tests and is utilized to characterize the apparent modulus of elastic of the oyster shells by carrying out some numerical analysis based upon the homogenization theory. We got the conclusion by a series of experiment, 1) It is verified that modulus of elasticity of dredged clay is improved by mixing with oyster shells. 2) The homogenization method for deducing apparent modulus of elasticity of oyster shells, which can consider micro-structure of mixed soil, is introduced. The elastic modulus is affected from the skeleton structure of oyster shell. The effect of 49kPa is bigger than that of 98kPa.

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Mechanical Properties of Apple and Pear (사과 및 배의 기계적 특성)

  • 김만수;정현모;박종민;이영희
    • Journal of Biosystems Engineering
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    • v.24 no.3
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    • pp.243-252
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    • 1999
  • The damage caused in the processes and distributions after harvesting the fruits and vegetables is attributed to the mechanical factors such as compressive and impact forces. Compression tests of biological materials provide an objective method for determining the apparent modulus of elasticity and mechanical properties which are significant in quality evaluation and control, and them maximum allowable compressive forces for minimizing mechanical damage. This study was performed to determine the mechanical properties of apple and pear, and to investigate effect of specimen shapes on the mechanical properties of them. A computer program was developed for measuring the mechanical properties and analyzing the data obtained from the measurement. Compression tests on the sample were performed with then replications at each treatment and at 25 mm/min loading rate. Mechanical properties of the apple was generally shown the higher value than those of the pear, and it was though that data obtained form the cylindrical specimen removed from the sample was more reliable than from the specimen cut in half.

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Vibration and mode shape analysis of sandwich panel with MWCNTs FG-reinforcement core

  • Tahouneh, Vahid
    • Steel and Composite Structures
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    • v.25 no.3
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    • pp.347-360
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    • 2017
  • The goal of this study is to fill this apparent gap in the area about vibration analysis of multiwalled carbon nanotubes (MWCNTs) curved panels by providing 3-D vibration analysis results for functionally graded multiwalled carbon nanotubes (FG-MWCNTs) sandwich structure with power-law distribution of nanotube. The effective material properties of the FG-MWCNT structures are estimated using a modified Halpin-Tsai equation. Modified Halpin-Tsai equation was used to evaluate the Young's modulus of MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the MWCNTs wt% range considered. Also, the mass density and Poisson's ratio of the MWCNT/phenolic composite are considered based on the rule of mixtures. Parametric studies are carried out to highlight the influence of MWCNT volume fraction in the thickness, different types of CNT distribution, boundary conditions and geometrical parameters on vibrational behavior of FG-MWCNT thick curved panels. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary conditions including Free, Simply supported and Clamped at the curved edges. For an overall comprehension on 3-D vibration analysis of sandwich panel, some mode shape contour plots are reported in this research work.

Design and Development of a Broadband Ultrasonic Transducer Operating over the Frequency Range of 40 to 75 kHz (40-75 kHz의 주파수 범위에서 동작하는 광대역 초음파 변환기의 설계 및 개발)

  • Lee, Dae-Jae;Kwak, Min Son;Kang, Hee-Young
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.47 no.3
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    • pp.292-301
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    • 2014
  • The objective of this study was to design and develop a broadband ultrasonic transducer that has both wide bandwidth and high sensitivity to measure broadband echoes related to identifying fish species. A broadband ultrasonic transducer providing a nearly flat transmitting response band of 40.2-75.5 kHz with a -12 dB bandwidth of 35.3 kHz was achieved by integrating 12 tonpilz transducer elements operating at different resonance frequencies. The average transmitting voltage response, receiving sensitivity, and figure of merit values in this frequency band were 168.4 dB (re $1{\mu}Pa/V$ at 1 m), -196.8 dB (re $1V/{\mu}Pa$), and -28.4 dB, respectively. The results suggest that bandwidth and sensitivity can be widened and improved by adjusting the array pattern and the structure of tonpilz transducer elements.

Experimental Study of Ductility and Strength Enhancement for RC Columns Retrofitted with Several Types of Aramid Reinforcements (아라미드계 섬유 보강을 통한 RC기둥의 연성과 강도 증진에 대한 실험 연구)

  • Lee, Gayoon;Lee, Dong-Young;Park, Minsoo;Lee, Kihak
    • Journal of the Earthquake Engineering Society of Korea
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    • v.27 no.4
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    • pp.171-180
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    • 2023
  • This study proposed a seismic reinforcement of RC columns with non-seismic details, a fiber reinforcement method of aramid sheets and MLCP (high elasticity aromatic polyester fiber material) with different characteristics, and 4 full-size column specimens and conducted experiments. The results show that a non-seismic specimen (RC-Orig) rapidly lost its load-bearing capacity after reaching the maximum load, and shear failure occurred. The RC column reinforced with three types of aramid did not show an apparent increase in strength compared to the unreinforced specimen but showed a ductile behavior supporting the load while receiving a lateral displacement at least 1.57 to 1.95 times higher than the unreinforced specimen. The fracture mode of the specimen, according to the application of lateral load, also changed from shear to ductile fracture through aramid-based reinforcement. In addition, when examining the energy dissipation ability of the reinforced specimens, a ductile behavior dissipating seismic energy performed 4 times greater and more stably than the existing specimens.