• Structural Engineering and Mechanics
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• 제57권6호
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• pp.1143-1156
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• 2016

This paper presents a comparative study of finite element method (FEM) and analytical method for the plane problem of a layered composite containing an internal perpendicular crack in literature. The layered composite consists of two elastic layers having different elastic constants and heights. External load is applied to the upper elastic layer by means o a rigid punch and the lower elastic layer rests on two simple supports. Numerical simulations are realized by the world wide code ANYS software. Two dimensional analysis of the problem is carried out and the results are verified by comparison with solutions reported in literature. Main goal of the numerical simulation is to investigate the normal stress ${\sigma}_x$(0, y), stress intensity factors at the crack factor and the crack opening displacements.

• Computers and Concrete
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• 제7권6호
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• pp.497-510
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• 2010

For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.

• Coupled systems mechanics
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• 제2권3호
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• pp.271-288
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• 2013

In the present study an elastic-plastic strain analysis is carried out for fibrous composites by using numerical modeling. Application of homogeneous transversely-isotropic model was chosen based on problem solution of a square plate with a circular hole under uniaxial tension. The results obtained in this study correspond to the solution of fiber model trial problem, as well as to analytical solution. Further, numerical algorithm and software has been developed, based on simplified theory of small elastic strains for transversely-isotropic bodies, and FEM. The influence of holes and cracks on stress state of complicated configuration transversely-isotropic bodies has been studied. Strain curves and plasticity zones that are formed in vicinity of the concentrators has been provided. Numerical values of effective mechanical parameters calculated for unidirectional composites at different ratios of fiber volume content and matrix. Content volume proportions of fibers and matrix defined for fibrous composite material that enables to behave as elastic-plastic body or as a brittle material. The influences of the fibrous structure on stress concentration in vicinity of holes on boron/aluminum D16, used as an example.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.55-56
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• 2015

This study is corroborated as a fundamental resource to develop structural lightweight paste containing silica fume as a part of cement. Paste using foaming agent is generated much foam and decreased density of paste. This study is measured at 0.8% of foaming agent dosage but over 0.8% of foaming agent dosage raise density of paste because of interconnection with foam. Also, FEM analysis using SEM image is confirmed correspondence of between Elastic modulus of experiment and FEM analysis.

• Computers and Concrete
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• 제22권6호
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• pp.501-514
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• 2018

The paper presents the thermo-mechanically induced non-linear response of multiwall carbon nanotube reinforced laminated composite beam (MWCNTRCB) supported by elastic foundation using higher order shear deformation theory and von-Karman non-linear kinematics. The elastic properties of MWCNT reinforced composites are evaluated using Halpin-Tsai model by considering MWCNT reinforced polymer matrix as new matrix by dispersing in it and then reinforced with E-glass fiber in an orthotropic manner. The laminated beam is supported by Pasternak elastic foundation with Winkler cubic nonlinearity. A generalized static analysis is formulated using finite element method (FEM) through principle of minimum potential energy approach.

• Computers and Concrete
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• 제26권2호
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• pp.107-114
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• 2020

In this study, a two dimensional model of receding contact problem has been analyzed using finite element method (FEM) based software ANSYS and ABAQUS. For this aim finite element modeling of elastic layer and two homogeneous, isotropic and symmetrical elastic quarter planes pressed by means of a rigid circular punch has been presented. Mass forces and friction are neglected in the solution. Since the problem is examined for the plane state, the thickness along the z-axis direction is taken as a unit. In order to check the accuracy of the present models, the obtained results are compared with the available results of the open literature as well as the results of two software are compared using Root Mean Square Error (RMSE) and good agreements are found. Numerical analyses are performed considering different values of the external load, rigid circular radius, quarter planes span length and material properties. The contact lengths and contact stresses of these values are examined, and their results are presented. Consequently, it is concluded that the considered non-dimensional quantities have noteworthy influence on the contact lengths and contact stress distributions, additionally if FEM analysis is used correctly, it can be an efficient alternative method to the analytical solutions that need time.

• 대한기계학회논문집A
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• 제20권8호
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• pp.2458-2467
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• 1996

The rigid-plastic finite element analysis was performed for analysis of ofhot forging and cold sizing of a bevel gear. Two dimensional analysis was carried out to investigate the defect occurrence on vertical symmetric planes during hot forging and three dimensional analysis was to understand the filling behavior on horizontal planes during cold sizing. The involute curve of a tooth was approximated by a circle for convenience in the present analysis. In order to estimate the elastic deformation of the gear and dies during cold sizing, linear elastic finite element analysis was performed. Results of the analysis can be used to predict grain flows and strength distributions in the forged gear, and to design dies and an appropriate preform for the cold sizing.

• 대한기계학회논문집A
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• 제33권2호
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• pp.145-152
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• 2009

SGBEM(Symmetric Galerkin Boundary Element Method)-FEM alternating method has been proposed by Nikishkov, Park and Atluri. In the proposed method, arbitrarily shaped three-dimensional crack problems can be solved by alternating between the crack solution in an infinite body and the finite element solution without a crack. In the previous study, the SGBEM-FEM alternating method was extended further in order to solve elastic-plastic crack problems and to obtain elastic-plastic stress fields. For the elastic-plastic analysis the algorithm developed by Nikishkov et al. is used after modification. In the algorithm, the initial stress method is used to obtain elastic-plastic stress and strain fields. In this paper, elastic-plastic J integrals for three-dimensional cracks are obtained using the method. For that purpose, accurate values of displacement gradients and stresses are necessary on an integration path. In order to improve the accuracy of stress near crack surfaces, coordinate transformation and partitioning of integration domain are used. The coordinate transformation produces a transformation Jacobian, which cancels the singularity of the integrand. Using the developed program, simple three-dimensional crack problems are solved and elastic and elastic-plastic J integrals are obtained. The obtained J integrals are compared with the values obtained using a handbook solution. It is noted that J integrals obtained from the alternating method are close to the values from the handbook.

• Steel and Composite Structures
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• 제25권6호
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• pp.671-684
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• 2017

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

• 비파괴검사학회지
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• 제36권1호
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• pp.9-17
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• 2016

The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method.