• 제목/요약/키워드: equilibrium displacement model

검색결과 90건 처리시간 0.027초

Axisymmetrical bending of single- and multi-span functionally graded hollow cylinders

  • Bian, Z.G.;Wang, Y.H.
    • Structural Engineering and Mechanics
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    • 제45권3호
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    • pp.355-371
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    • 2013
  • Single- and multi-span orthotropic functionally graded hollow cylinders subjected to axisymmetrical bending are investigated on the basis of a unified shear deformable shell theory, in which the transverse displacement is expressed by means of a general shape function. To approach the through-thickness inhomogeneity of the hollow cylinder, a laminated model is employed. The shape function therefore shall be determined for each fictitious layer. To improve the computational efficiency, we resort to a transfer matrix method. Based on the principle of minimum potential energy, equilibrium equations are established, which are then solved analytically using the transfer matrix method for arbitrary boundary conditions. Numerical comparisons among a third-order shear deformable shell theory, an exact elastic theory and the present theory are provided for a simply supported hollow cylinder, from which the present theory turns out to be superior in stress estimation. Distributions of displacements and stresses in single- and three-span hollow cylinders with different boundary conditions are also illustrated in numerical examples.

항공기 재료 성형시의 손상진전에 관한 연구 (A Study on the Damage Propagation of an Aircraft Material During Forming)

  • 김위대;김진희;김승조
    • 소성∙가공
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    • 제4권2호
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    • pp.131-140
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    • 1995
  • In this paper damage propagation of a material during forming is investigated with the concept of continuum damage mechanics. An isotropic damage model based on the theory of materials of type N is adopted to describe the damage process of a ductile material with large elasto-viscoplastic deformation. The stiffness degradation of the loaded material is chosen as a damage measure. The highly nonlinear equilibrium equations are reduced to the incremental weak form and approximated by the total Lagrangian finite element method. To simulate contact condition, extended interior penalty method with modified coulomb friction law is adopted. The displacement control method along with the modified Riks' continuation technique is used to solve the incremental iterative equations. As numerical examples, upsetting problem and backward extrusion problem are simulated and the results of damage propagation and $J_2$ stress contours with and without friction are presented.

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버블패킹방법을 이용한 2차원 자동격자 생성 및 재구성 알고리듬 개발 (II) -비선형 해석- (Development of Algorithm for Two Dimensional Automatic Mesh Generation and Remeshing Technique Using Bubble Packing Method (II) - Nonlinear Analysis -)

  • 정순완;김승조
    • 대한기계학회논문집A
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    • 제25권12호
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    • pp.1926-1932
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    • 2001
  • In this second part of the paper, the automatic mesh generation and remeshing algorithm using bubble packing method is applied to the nonlinear problem. The remeshing/refinement procedure is necessary in the large deformation process especially because the mesh distortion deteriorates the convergence and accuracy. To perform the nonliear analysis, the transfer of state variables such as displacement and strain is added to the algorithm of Part 1. The equilibrium equation based on total Lagrangian formulation and elasto-viscoplastic model is used. For the numerical experiment, the upsetting process including the contact constraint condition is analyzed by two refinement criteria. And from the result, it is addressed that the present algorithm can generate the refined meshes easily at the largely deformed area with high error.

다축거동을 고려한 FRP 콘크리트 부재의 층상화 하중-기초 유한요소모델 개발 (Development of Force-Based Fiber Frame Finite Element for FRP Concrete Members with Multi-axial Behaviors)

  • 조창근;하기주;박문호
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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    • pp.78-81
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    • 2006
  • In the current study, a force-based fiber frame finite element model of FRP concrete structural members has been developed. For compressive behaviors of confined concrete wrapped by FRP jackets, the multiaxial behavior of concrete has been considered with the equivalent tangent modulus of concrete. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimensional stress states. The force-based finite element formulation is based on the force-interpolation functions within the element without using the displacement shape functions to satisfy the equilibrium in element levels.

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Analysis of RC walls with a mixed formulation frame finite element

  • Saritas, Afsin;Filippou, Filip C.
    • Computers and Concrete
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    • 제12권4호
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    • pp.519-536
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    • 2013
  • This paper presents a mixed formulation frame element with the assumptions of the Timoshenko shear beam theory for displacement field and that accounts for interaction between shear and normal stress at material level. Nonlinear response of the element is obtained by integration of section response, which in turn is obtained by integration of material response. Satisfaction of transverse equilibrium equations at section includes the interaction between concrete and transverse reinforcing steel. A 3d plastic damage model is implemented to describe the hysteretic behavior of concrete. Comparisons with available experimental data on RC structural walls confirm the accuracy of proposed method.

Single variable shear deformation model for bending analysis of thick beams

  • Abdelbari, Salima;Amar, Lemya Hanifi Hachemi;Kaci, Abdelhakim;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • 제67권3호
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    • pp.291-300
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    • 2018
  • In this work, a new trigonometry theory of shear deformation is developed for the static analysis of thick isotropic beams. The number of variables used in this theory is identical to that required in the theory of Euler-Bernoulli, sine function is used in the displacement field in terms of the coordinates of the thickness to represent the effects of shear deformation. The advantage of this theory is that shear stresses can be obtained directly from the relationships constitute, while respecting the boundary conditions at the free surface level of the beam. Therefore, this theory avoids the use of shear correction coefficients. The differential equilibrium equations are obtained using the principle of virtual works. A thick isotropic beam is considered, whose numerical study to show the effectiveness of this theory.

A piecewise linear transverse shear transfer model for bolted side-plated beams

  • Li, Ling-Zhi;Jiang, Chang-Jiu;Su, Ray Kai-Leung;Lo, Sai-Huen
    • Structural Engineering and Mechanics
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    • 제62권4호
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    • pp.443-453
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    • 2017
  • The performance of bolted side-plated (BSP) beams is affected by the degree of transverse partial interaction, which is a result of the interfacial slip caused by transverse shear transfer between the bolted steel plates and the reinforced concrete beams. However, explicit formulae for the transverse shear transfer profile have yet to be derived. In this paper, a simplified piecewise linear shear transfer model was proposed based on force superposition principle and simplification of shear transfer profiles derived from a previous numerical study. The magnitude of shear transfer was determined by force equilibrium and displacement compatibility condition. A set of design formulae for BSP beams under several basic load cases was also derived. Then the model was verified by test results. A worked example was also provided to illustrate the application of the proposed design formulae. This paper sheds some light on the shear force transfer mechanism of anchor bolts in BSP beams, and offers a practical method to evaluate the influence of transverse partial interaction in strengthening design.

Enhancement of thermal buckling strength of laminated sandwich composite panel structure embedded with shape memory alloy fibre

  • Katariya, Pankaj V.;Panda, Subrata K.;Hirwani, Chetan K.;Mehar, Kulmani;Thakare, Omprakash
    • Smart Structures and Systems
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    • 제20권5호
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    • pp.595-605
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    • 2017
  • The present article reported the thermal buckling strength of the sandwich shell panel structure and subsequent improvement of the same by embedding shape memory alloy (SMA) fibre via a general higher-order mathematical model in conjunction with finite element method. The geometrical distortion of the panel structure due to the temperature is included using Green-Lagrange strain-displacement relations. In addition, the material nonlinearity of SMA fibre due to the elevated thermal environment also incorporated in the current analysis through the marching technique. The final form of the equilibrium equation is obtained by minimising the total potential energy functional and solved computationally with the help of an original MATLAB code. The convergence and the accuracy of the developed model are demonstrated by solving similar kind of published numerical examples including the necessary input parameter. After the necessary establishment of the newly developed numerical solution, the model is extended further to examine the effect of the different structural parameters (side-to-thickness ratios, curvature ratios, core-to-face thickness ratios, volume fractions of SMA fibre and end conditions) on the buckling strength of the SMA embedded sandwich composite shell panel including the different geometrical configurations.

탄성지반상에 놓인 철근 콘크리트 축대칭 쉘의 정적 및 동적 해석(IV) -축대칭 쉘의 동적 응답에 대한 철근의 영향을 중심으로- (Static and Dynamic Analysis of Reinforced Concrete Axisymmetric Shell on the Elastic Foundation -Effect of Steel on the Dynamic Response-)

  • 조진구
    • 한국농공학회지
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    • 제39권4호
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    • pp.106-113
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    • 1997
  • Dynamic loading of structures often causes excursions of stresses well into the inelastic range, and the influence of the geometric changes on the dynamic response is also significant in many cases. Therefore, both material and geometric nonlinearity effects should be considered in case that a dynamic load acts on the structure. A structure in a nuclear power plant is a structure of importance which puts emphasis on safety. A nuclear container is a pressure vessel subject to internal pressure and this structure is constructed by a reinforced concrete or a pre-stressed concrete. In this study, the material nonlinearity effect on the dynamic response is formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a total Lagrangian coordinate system, and the equilibrium equation of motion is numerically solved by a central difference scheme. The constitutive relation of concrete is modeled according to a Drucker-Prager yield criterion in compression. The reinforcing bars are modeled by a smeared layer at the location of reinforcements, and the steel layer model under Von Mises yield criteria is adopted to represent an elastic-plastic behavior. To investigate the dynamic response of a nuclear reinforced concrete containment structure, the steel-ratios of 0, 3, 5 and 10 percent, are considered. The results obtained from the analysis of an example were summarized as follows 1. As the steel-ratio increases, the amplitude and the period of the vertical displacements in apex of dome decreased. The Dynamic Magnification Factor(DMF) was some larger than that of the structure without steel. However, the regular trend was not found in the values of DMF. 2. The dynamic response of the vertical displacement and the radial displacement in the dome-wall junction were shown that the period of displacement in initial step decreased with the steel-ratio increases. Especially, the effect of the steel on the dynamic response of radial displacement disapeared almost. The values of DMF were 1.94, 2.5, 2.62 and 2.66, and the values increased with the steel-ratio. 3. The characteristics of the dynamic response of radial displacement in the mid-wall were similar to that of dome-wall junction. The values of DMF were 1.91, 2.11, 2.13 and 2.18, and the values increased with the steel-ratio. 4. The amplitude and the period of the hoop-stresses in the dome, the dome-wall junction, and the mid-wall were shown the decreased trend with the steel-ratio. The values of DMF were some larger than those of the structure without steel. However, the regular trend was not found in the values of DMF.

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열-수리-역학 거동 해석을 위한 경계면 요소의 수식화 (Numerical Formulation of Thermo-Hydro-Mechanical Interface Element)

  • 신호성;윤석
    • 한국지반공학회논문집
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    • 제38권9호
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    • pp.45-52
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    • 2022
  • 암반내 불연속면이나 지반-구조물의 접촉면은 열-수리-역학적으로 연계된 거동 특성을 보이므로, 온전한 지배방정식에 근거한 경계면 요소의 개발이 필요하다. 본 논문은 경계면 요소에 대한 힘평형 방정식, 유체의 연속방정식 그리고 에너지 평형 방정식을 유도하였다. 그리고 경계면 요소에 대한 탄소성 역학 모델의 강성행렬을 제시하였다. 개발된 유한요소는 2차원 조건에서 변위는 6절점, 수압과 온도는 4절점을 사용한다. 단층내 유체 주입에 대한 완전연계된 THM 해석은 단층내의 유효응력 감소와 주위 암반의 온도 수축에 의한 주입압의 복합적인 변화을 모델링 할수 있었다. 하지만, 열적 현상을 무시한 HM해석은 수리-역학적 변수를 과다하게 산정하였다.