• 제목/요약/키워드: Constitutive Relation

검색결과 167건 처리시간 0.019초

A constitutive model for confined concrete in composite structures

  • Shi, Qing X.;Rong, Chong;Zhang, Ting
    • Steel and Composite Structures
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    • 제24권6호
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    • pp.689-695
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    • 2017
  • The constitutive relation is an important factor in analysis of confined concrete in composite structures. In order to propose a constitutive model for nonlinear analysis of confined concrete, lateral restraint mechanism of confined concrete is firstly analyze to study the generalities. As the foundation of the constitutive model, peak stress and peak strain is the first step in research. According to the generalities and the Twin Shear Unified Strength Theory, a novel unified equation for peak stress and peak strain are established. It is well coincident with experimental results. Based on the general constitutive relations and the unified equation for peak stress and peak strain, we propose a unified and convenient constitutive model for confined concrete with fewer material parameters. Two examples involved with steel tube confined concrete and hoop-confined concrete are considered. The proposed constitutive model coincides well with the experimental results. This constitutive model can also be extended for nonlinear analysis to other types of confined concrete.

Applications of an improved estimator of the constitutive relation error to plasticity problems

  • Gallimard, L.;Ladeveze, P.;Pelle, J.P.
    • Structural Engineering and Mechanics
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    • 제14권4호
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    • pp.381-400
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    • 2002
  • This paper presents several applications of an improved estimator of the constitutive relation error (CRE) for plasticity problems. The cumulative aspect of the CRE estimator with respect to time is analyzed and we propose a first analysis of the local effectivity indexes of the CRE estimator in plasticity.

해성점토의 압밀구성관계 (Constitutive Relation of Consolidaion for Marine Clay)

  • 차경섭
    • 한국농공학회지
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    • 제42권3호
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    • pp.89-96
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    • 2000
  • Most soft ground in the southern and western coasts in Korea consists of very compressible alluvial deposits. Four samples in these alluvial deposite were selected to manifest the constitutive relations of consolidation. A series of tests were performed to investigate void ratio -effective stress relationand void ratio-coefficient of permeability relation on soil samples obtained at Haenam. Jindo Mankyung and Janghung permeabilities by CRS thoery were similar to directly measured data but those of indirectly computed by $C\upsilon$ shows difference. Several models about compressibility and permeability were compared with test data.

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Cracking behavior of RC shear walls subject to cyclic loadings

  • Kwak, Hyo-Gyoung;Kim, Do-Yeon
    • Computers and Concrete
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    • 제1권1호
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    • pp.77-98
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    • 2004
  • This paper presents a numerical model for simulating the nonlinear response of reinforced concrete (RC) shear walls subject to cyclic loadings. The material behavior of cracked concrete is described by an orthotropic constitutive relation with tension-stiffening and compression softening effects defining equivalent uniaxial stress-strain relation in the axes of orthotropy. Especially in making analytical predictions for inelastic behaviors of RC walls under reversed cyclic loading, some influencing factors inducing the material nonlinearities have been considered. A simple hysteretic stress-strain relation of concrete, which crosses the tension-compression region, is defined. Modification of the hysteretic stress-strain relation of steel is also introduced to reflect a pinching effect depending on the shear span ratio and to represent an average stress distribution in a cracked RC element, respectively. To assess the applicability of the constitutive model for RC element, analytical results are compared with idealized shear panel and shear wall test results under monotonic and cyclic shear loadings.

압전 벤더의 효과적인 모델링 기법 (An Effective Quasi-static Modeling of the Piezoelectric Benders)

  • 박종규;문원규
    • 대한기계학회논문집A
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    • 제28권2호
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    • pp.133-142
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    • 2004
  • In this article, the constitutive relations of three types of piezoelectric benders, which are a unimorph bender, a bimorph bender and a triple-layer bender, are derived based on the beam theory under the quasi-static equilibrium condition. The relation coefficients are described as the geometry and material properties of the benders. More general constitutive relations involving fixed-free, fixed-roll, and fixed-simply supported boundary conditions under the inconsistent length condition between the piezoelectric layer and the nonpiezoelectric one are discussed. The complicated constitutive relations can be easily calculated and checked by using the symbolic function in ‘Mathematica’. The relation coefficients for the benders are plotted in three dimensional graph using the developed program.

AN INDIFFERENT CONSTITUTIVE LAW IN FINITE ELASTICITY

  • Akinola, Ade
    • Journal of applied mathematics & informatics
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    • 제8권3호
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    • pp.919-934
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    • 2001
  • The concepts of material frame-indifference and material symmetry group with respect to isotropic scalar functions, as represented by energy functions, are discussed. An energy function for a structured heterogeneous (transversal isotropic) medium in large elastic deformations, which is known to satisfy the Ponyting’s effect [1], is highlighted. It is shown that the constitutive relation due to this energt function is material frame-indifferent.

변형구배 결정소성 유한요소해석법을 이용한 니켈기 다결정 합금의 Hall-Petch 관계 모델링 (Modeling the Hall-Petch Relation of Ni-Base Polycrystalline Superalloys Using Strain-Gradient Crystal Plasticity Finite Element Method)

  • 최윤석;조경목;남대근;최일동
    • 한국재료학회지
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    • 제25권2호
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    • pp.81-89
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    • 2015
  • A strain-gradient crystal plasticity constitutive model was developed in order to predict the Hall-Petch behavior of a Ni-base polycrystalline superalloy. The constitutive model involves statistically stored dislocation and geometrically necessary dislocation densities, which were incorporated into the Bailey-Hirsch type flow stress equation with six strength interaction coefficients. A strain-gradient term (called slip-system lattice incompatibility) developed by Acharya was used to calculate the geometrically necessary dislocation density. The description of Kocks-Argon-Ashby type thermally activated strain rate was also used to represent the shear rate of an individual slip system. The constitutive model was implemented in a user material subroutine for crystal plasticity finite element method simulations. The grain size dependence of the flow stress (viz., the Hall-Petch behavior) was predicted for a Ni-base polycrystalline superalloy NIMONIC PE16. Simulation results showed that the present constitutive model fairly reasonably predicts 0.2%-offset yield stresses in a limited range of the grain size.

벌크비정질합금의 미세성형 : 구성모델과 적용 (Microforming of Bulk Metallic Glasses : Constitutive Modelling and Applications)

  • 윤승채;백경호;김형섭
    • 소성∙가공
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    • 제13권2호
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    • pp.168-173
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    • 2004
  • Microforming can be a good application for bulk metallic glasses. It is important to simulate the deformation behaviour of the bulk metallic glasses in a supercooled liquid region for manufacturing micromachine parts. For these purposes, a correct constitutive model which can reproduce viscosity results is essential for good predicting capability. In this paper, we studied deformation behaviour of the bulk metallic glasses using the finite element method in conjunction with the fictive stress constitutive model which can describe non-Newtonian as well as Newtonian behaviour. A combination of kinetic equation which describes the mechanical response of the bulk metallic glasses at a given temperature and evolution equations fur internal variables provide the constitutive equation of the fictive stress model. The internal variables are associated with fictive stress and relation time. The model has a modular structure and can be adjusted to describe a particular type of microforming process. Implementation of the model into the MARC software has shown its versatility and good predictive capability.

준설매립토지반의 압밀침하량 예측 (Prediction of Consolidational Settlement of Dredged and Reclaimed Ground)

  • 유남재;박병수;정길수
    • 산업기술연구
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    • 제21권A호
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    • pp.317-327
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    • 2001
  • For soils with high void ratios, the inverse method of utilizing results obtained from centrifuge model test was used to find the constitutive relation of effective stress - void ratio - permeability whereas conventional oedometer test and constant rate of strain consolidation test were also used to fine its relation at ranges of relatively low void ratio. Results of column test about settlement of interface and pore pressure and distribution with time were compared with numerically estimated values to confirm such a constitutive relation as obtained from the inverse method. Consolidational settlement in dredged and reclaimed ground, where the consolidation was in progress, was predicted by using the numerical technique implemented with the finite strain consolidation theory.

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Comparative study of constitutive relations implemented in RELAP5 and TRACE - Part I: Methodology & wall friction

  • Shin, Sung Gil;Lee, Jeong Ik
    • Nuclear Engineering and Technology
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    • 제54권9호
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    • pp.3526-3539
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    • 2022
  • Nuclear thermal-hydraulic system analysis codes have been developed to simulate nuclear reactor systems, which solve simplified governing equations by replacing source terms with constitutive relations for simulating entire reactor systems with low computational resources. For half a century, many efforts have been made for wider versatility and higher accuracy of system codes, but various factors can affect the code analysis results, and it was difficult to isolate these factors and interpret them individually. In this study, two system codes, RELAP5 and TRACE, which have many users and are highly reliable, are selected to analyze only the effects of constitutive relations. The influence of constitutive relations is analyzed using in-house platforms that replicate constitute relations of RELAP5 and TRACE equally to exclude factors that may affect analysis results, such as governing equation solvers and user effects. Among the various constitutive relations, the analysis is performed on the wall variables expected to have the most influence on the analysis results. Part 1 paper presents the methodology and wall friction model comparison, while Part 2 paper shows wall heat transfer comparison of the two selected codes.