• Interaction and multiscale mechanics
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• 제4권2호
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• pp.85-105
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• 2011

The influence of surface elasticity and surface residual stress on the elastic field of an isotropic nanoscale elastic layer of finite thickness bonded to a rigid material base is considered by employing the Gurtin-Murdoch continuum theory of elastic material surfaces. The fundamental solutions corresponding to buried vertical and horizontal line loads are obtained by using Fourier integral transform techniques. Selected numerical results are presented for the cases of a finite elastic layer and a semi-infinite elastic medium to portray the influence of surface elasticity and residual surface stress on the bulk stress field. It is found that the bulk stress field depends significantly on both surface elastic constants and residual surface stress. The consideration of out-of-plane terms of the surface stress yields significantly different solutions compared to previous studies. The solutions presented in this study can be used to examine a variety of practical problems involving nanoscale/soft material systems and to develop boundary integral equations methods for such systems.

• 국제물리치료학회지
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• 제11권2호
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• pp.2077-2089
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• 2020

Background: Chronic ankle instability is a common injury that decreases balance and negatively affects functional movements, such as jumping and landing. Objectives: To analyze the effect of taping types and jump heights on balance with eyes open and closed during jump landings in chronic ankle instability. Design: Within-subject design. Methods: The study involved 22 patients with chronic ankle instability. They performed both double-leg and single-leg drop jump landings using three conditions (elastic taping, non-elastic taping, and barefoot) on three different jump platforms (30, 38, and 46 cm). Balance was measured using the Romberg's test with eyes open and closed. Results: Interaction effect was not statistically significant. Balance with eyes open and closed was significantly improved in both the elastic taping and non-elastic taping conditions compared to the barefoot condition. There was no significant difference according to the jump height. Conclusion: Individuals with chronic ankle instability demonstrated increased balance ability with eyes open and closed when jump landing. Elastic taping and non-elastic taping on the ankle joint can positively affect balance during landing in individuals with chronic ankle instability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.79-84
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• 2004

Strain energy due to the mechanical interaction between self-accommodation groups of martensitic phase transformation is called interaction energy. Evaluation of the interaction energy should be accurate since the energy appears in constitutive models for predicting the mechanical behavior of shape memory alloy. In this paper, the interaction energy is evaluated in terms of theoretical formulation and explicit finite element calculation. A simple example with two habit plane variants was considered. It was shown that the theoretical formulation assuming elastic interaction between the self-accommodation group and matrix gives larger interaction energy than explicit finite element calculation in which transformation softening is accounted for.

• 유변학
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• 제4권2호
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• pp.127-137
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• 1992

묽은 고분자 용액의 유변학적 거동을 elastic dumbbell 모델을 사용하여 연구하면서 hydrodynamic interaction(H.I) 효과를 주로 살펴보았다. 먼저 consistent averaging방법을 사용하면서 Oseen tensor와 Rotne-Prager-Yama-kawa(R-P-Y) tensor를 H. I. tensor로 각 각 사용하여 그차이를 비교하였으며 oseen tensor를 사용하는 경우 tti-nger의 알고리듬과 Ahn과 Lee의 알고리듬을 비교하였다. 또 H.I. tensor를 처리하는 방법으로 consistent averaging 방법과 Gaussian approximation 방법의 차이에 대하여도 살펴보았다. Ahn과 Lee 의 알고리듬이 ttinger의 알고리듬보다 훨씬 빠른 계산시간을 보여주었으며 Gaussian approximation 방법을 사용하는 경우 consistent averaging 방법과 달리 second normal stress coefficient가 음의 값을 보이므로 더 합리적인 방법으로 생각된다.

• 한국정밀공학회지
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• 제10권3호
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• pp.107-116
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• 1993

In the design and operation of robitic arm with flexible links, the equation of motion are required to exactly model the interaction between rigid body motion and elastic motion and to be formulated efficientlyl. In this paper, the flexible link is represented by applying the D-H rigid link representation method to measure the elestic deformation. And the equations of motion of robotic arm, which are configured by the generalized coordinates of elastic and rigid degrees of freedom, are formulated from the principle of virtual power. Dynamic characteristics due to elastic deformation of each link are obtained by using F. E. M to model complex shaped link acurately and by eliminating elastic modes of higher order that do not largely affect motion to reduce the number of elastic degrees of freedom. Also presented is the result of simulation of flexible robotic arms whose joints are controlled by direct or PD control.

• Elastomers and Composites
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• 제38권3호
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• pp.273-280
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• 2003

본 연구에서는 분자량이 다른 순수 천연고무 용융체와 다양한 유형의 카본블랙을 혼합한 배합고무 용융체의 탄성반응을 조사하였다. 또한 카본블랙과 고무 분자와의 상호작용과 이들 탄성반응이 갖는 상관성을 규명키 위해 입자의 크기와 구조가 다른 카본블랙을 대상으로 결합고무를 측정하였다. 카본블랙의 함량이 증가할수록 결합고무는 증가하였고 특히 카본블랙 입자의 크기가 작아 비표면적이 넓고 구조가 발달될수록 증가하였다. 카본블랙을 혼합한 배합고무 용융체의 탄성반응은 순수고무 경우에 비해 크게 향상되었으며 특히 결합고무가 큰 경우에 보다 현저하였다. 순수고무 용융체의 분자량이 증가할수록, 그리고 고무에 혼합된 카본블랙 입자의 크기가 작을수록 응력이완 거동은 지연되었으며 복원거동은 보다 탄성적으로 변하였다. 영구변형 거동에 있어서는 고무 분자량이 감소하고 카본블랙 입자 크기가 증가할수록 그 변형정도가 커졌다.

• 한국정밀공학회지
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• 제19권2호
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• pp.140-150
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• 2002

The planar tracked vehicle model used in this investigation consists of two kinematically decoupled subsystems, i.e., the chassis subsystem and the track subsystem. The chassis subsystem includes the chassis frame, sprocket, idler and rollers, while the track subsystem is represented as a closed kinematic chain consisting of rigid links interconnected by revolute joints. In this study, the recursive kinematic and dynamic formulation of the tracked vehicle is used to find the vertical terce and the distance of an arbitrary track moved in the driving direction along the track. These distances and vertical forces obtained are used to get the deformation and sinkage of a terrain. The FEM(Finite Element Method) is adopted to analyze the interaction between tracked vehicle and terrain. The terrain is represented by a system of elements wish specified constitutive relationships and considered as a piecewise linear elastic, plastic and isotropic material. When the tracked vehicle is moving with different speeds on the terrain, the elastic and plastic deformations and the maximum sinkage for the four different types of isotropic soils are simulated.

• 한국방재학회 논문집
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• 제7권5호
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• pp.99-110
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• 2007

A single slab concrete pavement has been modeled and analyzed by ABAQUS program. The stress and displacement of the JCP slab under traffic load with frictionless contact interaction between slab and base calculated by ABAQUS program have been compared with the results obtained by KENSLABS program. The results of the stresses of the two modeling show similar tendency and the difference of the two modeling is very small however the results of the displacement of the two modeling show some dissimilarity. In order to analyze the effects of material and geometric properties on the responses of slab, some varying parameters were chosen as input for the modeling. The changing parameters include the thickness and elastic modulus of the concrete slab, the thickness and elastic modulus of base and the elastic modulus of the subgrade. The contact interaction between the slab and base layer had been also studied and different friction coefficient 0, 2.5, 6.6, 7.5, 8.9 had been used to simulate the different friction interface condition. The results of the analysis showed that the responses of the concrete slab vary with the material and geometric properties of the pavement structure and the slab-base friction condition.

• Structural Engineering and Mechanics
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• 제75권1호
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• pp.109-122
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• 2020

An asymptotic local plane strain elasticity theory is reformulated for the static analysis of a simply-supported, multiple graphene sheet system (MGSS) in cylindrical bending and resting on an elastic medium. The dimension of the MGSS in the y direction is considered to be much greater than those in the x and z directions, such that all the field variables are considered to be independent of the y coordinate. Eringen's nonlocal constitutive relations are used to account for the small length scale effects in the formulation examining the static behavior of the MGSS. The interaction between the MGSS and its surrounding foundation is modelled as a Winkler foundation with the parameter k_w, and the interaction between adjacent graphene sheets (GSs) is considered using another Winkler model with the parameter c_w. A parametric study with regard to some effects on the static behavior of the MGSS resting on an elastic medium is undertaken, such as the aspect ratio, the number of the GSs, the stiffness of the medium between the adjacent layers and that of the surrounding medium of the MGSS, and the nonlocal parameter.

• Structural Engineering and Mechanics
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• 제28권3호
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• pp.295-316
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• 2008

In the present paper a mechanical model to predict the compressive response of high strength short concrete columns with square cross-section confined by transverse steel is presented. The model allows one to estimate the equivalent confinement pressures exercised by transverse steel during the loading process taking into account of the interaction of the stirrups with the inner core both in the plane of the stirrups and in the space between two successive stirrups. The lateral pressure distributions at hoop levels are obtained by using a simple model of elastic beam on elastic medium simulating the interaction between stirrups and concrete core, including yielding of steel stirrups and damage of concrete core by means of the variation in the elastic modulus and in the Poisson's coefficient. Complete stress-strain curves in compression of confined concrete core are obtained considering the variation of the axial forces in the leg of the stirrup during the loading process. The model was compared with some others presented in the literature and it was validated on the basis of the existing experimental data. Finally, it was shown that the model allows one to include the main parameters governing the confinement problems of high strength concrete members such as: - the strength of plain concrete and its brittleness; - the diameter, the pitch and the yielding stress of the stirrups; - the diameter and the yielding stress of longitudinal bars; - the side of the member, etc.