• 제목/요약/키워드: Elastic sheet

검색결과 178건 처리시간 0.021초

유한요소 다결정 모델을 이용한 마그네슘 합금 AZ31B 판재의 압연 집합 조직 예측 (Prediction of Rolling Texture for Mg Alloy AZ31B Sheet using Finite Element Polycrystal Model)

  • 원성연;김영석;나경환
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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    • pp.72-82
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    • 2004
  • The deformation mechanism of hexagonal close-packed materials is quite complicate including slips and twins. A deformation mechanism, which accounts for both slip and twinning, was investigated for polycrystalline hop materials. The model was developed in a finite element polycrystal model formulated with initial strain method where the stiffness matrix in FEM is based on the elastic modulus. We predicted numerically the texture of Mg alloy(AZ31B) sheet by using FEM based on crystal plasticity theory. Also, we introduced the recrystallized texture employed the maximum energy release theory after rolling. From the numerical study, it was clarified that the shrink twin could not be the main mechanism for shortening of c-axis, because the lattice rotation due to twin rejects fur c-axis to become parallel to ND(normal direction of plate). It was showed that the deformation texture with the pyramidal slip gives the ring type pole figure having hole in the center.

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섬유시트 보강 구조체의 거동에 관한 해석적 연구 (Analytical Study of Behavior on Structure Reinforced Fiber Sheet)

  • 서성탁
    • 한국산업융합학회 논문집
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    • 제12권2호
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    • pp.107-112
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    • 2009
  • The effective reinforcement methods of structure is required to improve the durability of existing structures. Recently, the continuous fiber sheets to the concrete structures are widely used in the earthquake-proof reinforcement method. This study examines suitability and effect to concrete structure of fiber by FEM analysis. The result of analysis is as follows; All specimens occurred bending tensile failure at the middle span. Ultimate strength of specimen in the RC and reinforced RC specimen were 53.9 kN, 56.3 kN respectively and it was some low by degree 0.89, 0.82 to compare with calculated result. The deflection of specimen at the middle span occurred in approximately 0.2 mm, and did linear behavior in load 20 kN by seat reinforcement. Stiffness did not decrease by occurrence in the finer crack and reinforcement beam's flexure stiffness was increased until reach in failure. To compare calculated value and analysis value, it almost equal behavior in the elastic reign and can confirm effectiveness of analysis. Crack was distributed uniformly by reinforcement of fiber seat at failure and it do not occurred stiffness decreases.

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5182 Al합금판의 전기저항 점용접부 피로거동에 관한 연구 (A Study on the Fatigue Behavior of Resistance Spot Welded Part of 5182 Aluminum Aloy Sheet)

  • 신현일;박용석;강성수
    • Journal of Welding and Joining
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    • 제16권2호
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    • pp.84-92
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    • 1998
  • On this study, the variations of hardness and microstructure were observed at he spot-welded part of 5182 alminum alloy sheets with thickness of 1.2 mm. The hardness of spot-welded part of aluminum alloy indicated the lowest value at nugget center. Also, the position where fatigue crack exists was investigated by surveying microstructure of the spot-welded sections. Mean load-deformation diagrams were obtained from static tensile test. Fracture was occurred completely within 5 mm after transforming elastic into plastic area. Fatigue test was stopped when the specimens of fatigue test had the final displacement of 0.2mm and measured fatigue bending angle and crack length. This study utilized them, investigated the relations between fatigue bending angle and fatigue crack length and made a estimation of the fatigue fracture life of resistance spot welded part of 5182 aluminum alloy sheet. The relative equation o fatigue crack length and fatigue failure life can be represented by {TEX}$L_{C}${/TEX}=α{TEX}$N_{f}^ {β}${/TEX}.

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육면체 요소 재구성을 통한 개방형 사다리꼴이 성형된 판재의 탄성 거동 균질화에 대한 연구 (Analysis of the Homogenization of the Elastic Behavior for a Sheet with Sheared Protrusions using Hexahedral Mesh Coarsening)

  • 이창환;양동열;박종승;강동우
    • 소성∙가공
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    • 제23권3호
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    • pp.171-177
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    • 2014
  • The current collector for the molten carbonate fuel cell (MCFC) which has sheared protrusions is manufactured by the three-stage forming process that integrates slitting, preforming and final forming. Due to the repetition of sheared protrusions, an effective simulation method is required to predict the mechanical behavior. In the current study, a sheet with sheared protrusions was assumed to be an orthotropic plate, which has the same length, width and height. FEM simulations were conducted to evaluate the homogenized properties of the current collector, which has 4 (longitudinal direction) x 4 (transverse direction) sheared protrusions. The simulation model was constructed using hexahedral mesh coarsening. From the verification examples, it was found that the proposed simulation method was efficient within reasonable accuracy. The calculated homogenized properties can be applied to the design of a stack for molten carbonate fuel cells and the prediction of mechanical behavior for other applications.

Active control of three-phase CNT/resin/fiber piezoelectric polymeric nanocomposite porous sandwich microbeam based on sinusoidal shear deformation theory

  • Navi, B. Rousta;Mohammadimehr, M.;Arani, A. Ghorbanpour
    • Steel and Composite Structures
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    • 제32권6호
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    • pp.753-767
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    • 2019
  • Vibration control in mechanical equipments is an important problem where unwanted vibrations are vanish or at least diminished. In this paper, free vibration active control of the porous sandwich piezoelectric polymeric nanocomposite microbeam with microsensor and microactuater layers are investigated. The aim of this research is to reduce amplitude of vibration in micro beam based on linear quadratic regulator (LQR). Modified couple stress theory (MCST) according to sinusoidal shear deformation theory is presented. The porous sandwich microbeam is rested on elastic foundation. The core and face sheet are made of porous and three-phase carbon nanotubes/resin/fiber nanocomposite materials. The equations of motion are extracted by Hamilton's principle and then Navier's type solution are employed for solving them. The governing equations of motion are written in space state form and linear quadratic regulator (LQR) is used for active control approach. The various parameters are conducted to investigate on the frequency response function (FRF) of the sandwich microbeam for vibration active control. The results indicate that the higher length scale to the thickness, the face sheet thickness to total thickness and the considering microsensor and microactutor significantly affect LQR and uncontrolled FRF. Also, the porosity coefficient increasing, Skempton coefficient and Winkler spring constant shift the frequency response to higher frequencies. The obtained results can be useful for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

발열제어부품소재 적용을 위한 실리콘 복합조성물의 열전도 특성 (Thermal Characteristics of Silicone Composites for the Application to Heat-Controllable Components)

  • 곽호두;오원태
    • 한국전기전자재료학회논문지
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    • 제32권2호
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    • pp.116-121
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    • 2019
  • Hexagonal boron nitride particles (s-hBN) modified with 3-aminopropyl triethoxysilane (APTES) were used for the preparation of silicone composite materials. The microstructure of the composite materials was observed, and the thermal conduction and mechanical characteristics of the composite sheets were studied based on the compositions and microstructures. When a small amount of s-hBN particles was used, the thermal conductivity of the composite improved as a whole, and the tensile strength of the sheet also increased. The thermal conductivity and tensile strength of the composite in which a small amount of carbon fiber was added along with s-hBN were further improved. However, the use of carbon nanotubes with structural characteristics similar to those of carbon fiber resulted in lower thermal conductivity and tensile strength. Elastic silicone composites exhibiting 2.5 W/mK of thermal conductivity and a low hardness are expected to be used as thermally conductive interfacial sheet materials.

Nonlocal dynamic modeling of mass sensors consisting of graphene sheets based on strain gradient theory

  • Mehrez, Sadok;Karati, Saeed Ali;DolatAbadi, Parnia Taheri;Shah, S.N.R.;Azam, Sikander;Khorami, Majid;Assilzadeh, Hamid
    • Advances in nano research
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    • 제9권4호
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    • pp.221-235
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    • 2020
  • The following composition establishes a nonlocal strain gradient plate model that is essentially related to mass sensors laying on Winkler-Pasternak medium for the vibrational analysis from graphene sheets. To achieve a seemingly accurate study of graphene sheets, the posited theorem actually accommodates two parameters of scale in relation to the gradient of the strain as well as non-local results. Model graphene sheets are known to have double variant shear deformation plate theory without factors from shear correction. By using the principle of Hamilton, to acquire the governing equations of a non-local strain gradient graphene layer on an elastic substrate, Galerkin's method is therefore used to explicate the equations that govern various partition conditions. The influence of diverse factors like the magnetic field as well as the elastic foundation on graphene sheet's vibration characteristics, the number of nanoparticles, nonlocal parameter, nanoparticle mass as well as the length scale parameter had been evaluated.

보강된 노후 구조물 파괴거동 예측을 위한 수치해석기법 개발 (Numerical Analysis of Fracture Behavior in Aged RC Structures)

  • 신승교;고태호;김문겸;임윤묵
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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    • pp.1031-1036
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    • 2000
  • In this study, a numerical simulation that can effectively predict the strengthening effect of repaired aged RC structures is developed using the axial deformation link elements. In repaired structures, concrete and interface are modeled as quasi-brittle materials. An elastic-perfectly plastic constitutive relationship is introduced for reinforcing bars. Also, a linear-elastic relationship for repair materials such as FRP or CFS. Structural deterioration in terms of corrosion of steel rebar is considered. The interfacial property between steel and concrete which is reduced by corrosion of steel rebar is obtained by comparing numerical results with experimental results of pull out tests. Obtained values are used in repaired reinforced concrete structures under flexural loading conditions. To investigate strengthening effect of the structures repaired with carbon fiber sheet(CFS), repaired and unrepaired RC structures are analyzed numerically. From analysis, rip-off, debonding and rupture failure mechanisms of interface between substrate and CFS can be determined. Finally, strengthening effect according to the variation of interfacial material properties is investigated, and it is shown that interfacial material properties have influence on the mechanical behavior of repaired structure systems Therefore, the developed numerical method using axial deformation link elements can use for determining the strengthening effects and failure mechanism of repaired aged RC structure.

탄성 변형 영역을 고려한 비정상 평면 변형 이상 공정 이론 (Nonsteady Plane-strain Ideal Forming with Elastic Dead Zone)

  • 이원오;정관수;;강태진
    • 소성∙가공
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    • 제13권6호
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    • pp.540-545
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    • 2004
  • Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, fur bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was performed under the plane-strain condition based on the theory previously developed. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-stram flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, fur a prescribed final part shape, schemes to optimize a preform shape out of a class of initial configurations and also to define the evolution of shapes and boundary tractions were developed. Discussions include the two problematic issues on internal tractions and the non-monotonous straining. For demonstration purposes, numerical calculations were made for a bulk part under forging.

Buckling and vibration of porous sandwich microactuator-microsensor with three-phase carbon nanotubes/fiber/polymer piezoelectric polymeric nanocomposite face sheets

  • Arani, Ali Ghorbanpour;Navi, Borhan Rousta;Mohammadimehr, Mehdi
    • Steel and Composite Structures
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    • 제41권6호
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    • pp.805-820
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    • 2021
  • In this research, the buckling and free vibration of three-phase carbon nanotubes/ fiber/ polymer piezoelectric nanocomposite face sheet sandwich microbeam with microsensor and micro-actuator surrounded in elastic foundation based on modified couple stress theory (MCST) is investigated. Three types of porous materials are considered for sandwich core. Higher order (Reddy) and sinusoidal shear deformation beam theories are employed for the displacement fields. Sinusoidal surface stress effects are extracted for sinusoidal shear deformation beam theory. The equations of motion are derived by Hamilton's principle and then the natural frequency and critical buckling load are obtained by Navier's type solution. The determined results are in good agreement with other literatures. The detailed numerical investigation for various parameters is performed for this microsensor-microactuator. The results reveal that the microsensor-microactuator enhanced by increasing of Skempton coefficient, carbon nanotubes diameter length to thickness ratio, small scale factor, elastic foundation, surface stress constants and reduction in porous coefficient, micro-actuator voltage and CNT weight fraction. The valuable results can be expedient for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.