• Coupled systems mechanics
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• v.3 no.1
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• pp.111-145
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• 2014

In this paper we present a new model for computing the nonlinear response of reinforced concrete frame systems subjected to extreme thermomechanical loads. The first main feature of the model is its ability to account for both bending and shear failure of the reinforced concrete composites within frame-like model. The second prominent feature concerns the model capability to represent the total degradation of the material properties due to high temperature and the thermal deformations. Several numerical simulations are given to confirm these capabilities and illustrate a very satisfying model performance.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.4
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• pp.173-181
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• 2018

Recently composite materials have dominated most engineering fields, owing to their better performance, increased durability and flexibility to be customized and designed for a specific required property. This has given them unprecedented superiority over conventional materials. With the help of the ever increasing computational capabilities of computers, researchers have been trying to develop accurate material models for the complex and integrated properties of these composites. This has led to advances in virtual testing of composite materials as a supplement or a possible replacement of laboratory experiments to predict the properties and responses of composite materials and structures. This paper presents a review on the complex multi-scale modelling framework of the virtual testing machines, which involve computational mechanics at various length-scales starting with nano-mechanics and ending in structure level computational mechanics, with a homogenization technique used to link the different length scales. In addition, the paper presents the features of some of the biggest integrated virtual testing machines developed for study of concrete, including a multiscale modeling scheme for the simulation of the constitutive properties of nanocomposites. Finally, the current challenges and future development potentials for virtual test machines are discussed.

• Computers and Concrete
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• v.22 no.2
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• pp.227-237
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• 2018

Today, the modeling of concrete as a material within finite element simulations is predominantly done through nonlinear material models of concrete. In current sophisticated computational systems, there are a number of complex concrete material models which are based on theory of plasticity, damage mechanics, linear or nonlinear fracture mechanics or combinations of those theories. These models often include very complex constitutive relations which are suitable for the modeling of practically any continuum mechanics tasks. However, the usability of these models is very often limited by their parameters, whose values must be defined for the proper realization of appropriate constitutive relations. Determination of the material parameter values is very complicated in most material models. This is mainly due to the non-physical nature of most parameters, and also the large number of them that are frequently involved. In such cases, the designer cannot make practical use of the models without having to employ the complex inverse parameter identification process. In continuum mechanics, however, there are also constitutive relations that require the definition of a relatively small number of parameters which are predominantly of a physical nature and which describe the behavior of concrete very well within a particular task. This paper presents an example of such constitutive relations which have the potential for implementation and application in finite element systems. Specifically, constitutive relations for modeling the plane stress state of concrete are presented and subsequently tested and evaluated in this paper. The relations are based on the incremental theory of elastic strain-hardening plasticity in which a non-associated flow rule is used. The calculation result for the case of concrete under uniaxial compression is compared with the experimental data for the purpose of the validation of the constitutive relations used.

• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.709-717
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• 2005

Integral equations occur naturally in many fields of mechanics and mathematical physics. We consider the Fredholm integral equation of the first kind.In this paper we are interested in integral equation of convolution type. We give approximate solution by Meyer wavelets

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.41.2-41.2
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.42.2-42.2
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.72.1-72.1
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.72.2-72.2
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.75.1-75.1
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• 2008

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.29-32
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• 2003

It is shown that using the unified coordiantes of Hui et al.[1 - 4], one can now compute fluid flow without prior grid generation. This represents a great saving of computing time.