• 한국농공학회지
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• 제44권1호
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• pp.116-124
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• 2002

Natural resources fur the construction materials such as good soil, sand, and coarse aggregates have been encountered to be short due to excessive use by human. Even though some soil has been found to be unsuitable for construction materials, soil with reinforcement can naturally be an answer to these alternatives. According to recently published papers on fiber mixed soil, fiber mixed with soil can improve shear strength, compressive strength and post-peak load strength retention. In this study, a series of tests were performed to clarify the characteristics of fiber mixed soil and to give basic data for design and construction and their engineering properties, that is, unconfined compressive strength, splitting tensile strength, shear strength, crack by drying, freeze-thaw, creep and Poisson\`s ratio, were investigated and analyzed. It has been shown that fiber mixed soil is one of good alternatives fur the civil and building construction materials.

• Geomechanics and Engineering
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• 제3권1호
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• pp.29-43
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• 2011

In this paper a semi-analytical approach is proposed to study the lateral behavior of a piled footing under horizontal loading. As accurate computation of stresses is usually needed at the interface separating the footing (pile) and the soil, this important location should be appropriately modeled as zero-thickness joint element. The piled footing is embedded in elastic soil with either homogeneous modulus or modulus proportional to depth (Gibson's soil). As the pile is the principal element in the piled footing system, a limited parametric study is carried out in order to investigate the influence of footing dimensions and the interface conditions on the lateral behavior of the pile. Hence, the pile behavior is examined through its main governing parameters, namely, the lateral displacement profiles, the bending moments, the shear forces and the soil reactions. The numerical results are presented for Poisson's ratio of 0.2 to represent a large variety of sands and Poisson's ratio of 0.5 to represent undrained clays.

• Smart Structures and Systems
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• 제22권3호
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• pp.249-257
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• 2018

This study contributes to evaluate multiphase topology optimization design of plate-like elastic structures with constant thickness and Reissner-Mindlin plate theory. Stiffness and adjoint sensitivity formulations linked to Reissner-Mindlin plate potential energy of bending and shear are derived in terms of multiphase design variables. Multiphase optimization problem is solved through alternative active-phase algorithm with Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples verify efficiency and diversity of the present topology optimization method of Reissner-Mindlin elastic plates depending on multiphase and Poisson's ratio.

• 대한기계학회논문집A
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• 제32권9호
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• pp.713-719
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• 2008

Most of the MEMS parts are made of multi-grain silicon wafer, which is the orthotropic material and its material direction is arbitrary. The reliability of the parts must be guaranteed in order to use for the commercial usage. The need of the structural analysis of its parts emerges an important factor. The material properties of the MEMS parts are calculated by the numerical method in order to reduce a material test. In this study, the effective elastic modulus and its Poisson's ratio are calculated by the boundary element method(BEM) and are compared with the results by the finite element method(FEM).

• Advances in concrete construction
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• 제1권4호
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• pp.305-318
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• 2013

Engineering properties such as compressive strength, splitting tensile strength, modulus of rupture, modulus of elasticity and Poisson's ratio of geopolymer concrete (GPC) and steel fibre reinforced geopolymer concrete (SFRGPC) have been obtained from standard tests and compared. A total of 15 specimens were tested for determining each property. The grade of concrete used was M 40. The percentages of steel fibres considered include 0.25%, 0.5%, 0.75% and 1%. In general, the addition of fibres improved the mechanical properties of both GPC and SFRGPC. However the increase was found to be nominal in the case of compressive strength (8.51%), significant in the case of splitting tensile strength (61.63%), modulus of rupture (24%), modulus of elasticity (64.92%) and Poisson's ratio (50%) at 1% volume fraction of fibres. An attempt was made to obtain the relation between the various engineering properties with the percentage of fibres added.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.197-200
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• 2015

푸아송비(poisson's ratio)는 종방향 변형률에 대한 횡방향 변형률의 비로, 우리 주위 대부분의 재료들은 양의 푸아송비를 지닌다. 그러나 재료가 특정한 격자구조를 이루도록 설계할 경우 구성물질이 양의 푸아송비를 가지더라도 거시적으로는 음의 푸아송비를 구현할 수 있으며, 이러한 극한물성물질(metamaterial)을 오그제틱 물질(auxetic material)이라고 부른다. 이전까지 오그제틱 물질을 구현하기 위한 많은 메커니즘들이 개발되고 역학적, 수치적으로 해석되어 왔다. 이 논문에서는 가장 대표적인 오그제틱 구조인 리엔트런트(re-entrant) 오그제틱 구조를 빔 구조물로 모델링하여 유한요소해석을 수행하고 주요 설계 변수인 리엔트런트 각에 따라서 푸아송비와 유효 탄성계수가 어떻게 변화하는지 확인하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.219-226
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• 2003

The structures have intrinsic uncertainties in analysis/design parameters contrary to the assumptions of perfect constant over the structural domain. The material and geometrical parameters are the exemplary ones. The influences of uncertainties in Young's modulus, which are the representative random design variables, on the structural response have been the center of focus in the realm of stochastic analysis. In this study, a formulation to obtain the response variability due to the randomness in the Poisson's ratio is given. In that the previous researches in the literature deal with the response variability due mainly to the uncertainty in the elastic modulus, with the results of this research, it can be asserted to obtain the response variability taking into consideration of uncertainties in all the material constants becomes possible.

• Journal of Mechanical Science and Technology
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• 제19권12호
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• pp.2224-2230
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• 2005

In this study, the validity of the Eshelby-type model for predicting the effective Young's modulus and in-plane Poisson's ratio of the 2-dimensional perforated plate has been investigated in terms of the porosity size and its arrangement. The predicted results by the Eshelby-type model are compared with those by finite element analysis. Whenever the ratio of the porosity size to the specimen size becomes smaller than 0.07, the effective elastic constants predicted by finite element analysis are convergent regardless of the arrangement of the porosities. Under these conditions, the effective Young's moduli of the perforated plate can be predicted within the accuracy of $5\%$ by the Eshelby-type model, which overestimates and underestimates the effective Poisson's ratios by $10\%\;and\;6\%$ for the plates with periodically and non-periodically arranged porosities, respectively.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.387-388
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• 2006

The influence of porosity (P) on Young's modulus (E) and Poisson's ratio $(\upsilon)$ of sintered steels produced from four types of steel powders was investigated. The values of E and $(\upsilon)$ depend mainly on the value of P, and those were a little affected by alloying elements. The relationships between E, $(\upsilon)$, and P were described as following equations: $E\;=\;E_0{\cdot}(1\;-\;k_E{\cdot}P)^2$ and $\upsilon\;=\;({\upsilon}_0\;-\;\upsilon_{sub}){\cdot}(1\;-\;k_{\upsilon}{\cdot}P)2+\upsilon_{sub}$, where subscript 0 means P = 0, and $k_E,\;k_{\upsilon}$ and ${\upsilon}_{sub}$ are empirical constants. These approximate equations showed good agreement with empirical results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.354-356
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• 2005

Novel structure ultrasonic motors which have cross type stator were designed and fabricated. Driving characteristics of the motors were analyzed and measured by changing the materials of the stator. This ultrasonic motor has stator with hollowed cross bar and the stator rotate the rotor using elliptical displacement of the inside tips. This motion is generated by lateral vibration mode of cross bars. This stator was analyzed by finite element analysis and the ultrasonic motors were made by analyzed results. The larger displacements were obtained, when the Young's modulus was increased and the Poisson's ratio was decreased. The fabricated one has high speed in large Poisson's ratio and Young's modulus. And the torque was increased in high Young's modulus.