• Proceedings of the KSME Conference
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• 2004.04a
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• pp.410-414
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• 2004

Under longitudinal loading continuous fiber reinforced metal matrix composite(MMC) have interpreted an outstanding performance. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, elastic-plastic behavior of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber placement(square and hexagon) and fiber volume fractions were studied numerically. The interface was treated as three thin layer (with different properties) with a finite thickness between the fiber and the matrix. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• Advances in materials Research
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• v.4 no.2
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• pp.87-96
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• 2015

In this paper, three-dimensional finite element method is used to analyze the J integral for repaired cracks in plates with bonded composite patch and stiffeners. For elastic the effect of cracks, the thickness of the patch ($e_r$) and properties of the patch are presented for calculating the J integral. For elastic-plastic a several calculations have been realized to extract the plasticized elements around the crack tip of repaired and un-repaired crack. The obtained results show that the presence of the composite patch and stiffener reduces considerably the size of the plastic zone ahead of the crack. The effects of crack size and the inter-distance of repaired cracks were analysed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.448-451
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• 2005

It was observed that after unloading or removal of the load from the specimen subjected to bending stress, partial or full elastic spring back occurred and considerable stresses have resulted while plastic deformation was considered. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, it was used as the main tool to analyze elastic and plastic deformations of hi-material metal joint. In the case of elastic deformations, the results were comparable to the theoretical data. Plastic deformations and residual stresses of hi-material metal joint under bending moment were obtained by ABAQUS; where the theory needs to be studied and improved further to verify the results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.480-483
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• 2005

A roll forming process is developed for an automotive part of high strength steel. Forming rolls are designed through the plane strain elastic-plastic finite element analysis to estimate the springback. It is assumed that the process can be approximated as a series of multi-step bending processes. Then the 3D elastic-plastic finite element analysis with the solid element is carried out for the designed roll forming process. The prototype roll forming machine and the forming rolls are made and the experiments are carried out. The results of the analysis and the experiments are compared.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.12-12
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• 2006

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.365-371
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• 2004

Generally, fracture of a material is influenced by plastic zone size developed near the crack tip. Hence, according to the relative size of plastic zone in the material, the mechanics as a tool for analyzing the fracture process are classified into three kinds, that is, Linear Elastic Fracture Mechanics, Elastic Plastic Fracture Mechanics, Large Deformation Fracture Mechanics. Even though the plastic zone size is such an important parameter, the practical measurement techniques are very limited and the one for in-situ measurement is not virtually available. Therefore, elastic-plastic FEA has been performed to estimate the plastic zone size. In this study, it is noticed that side necking at the surface is a consequence of plastic deformation and lateral contraction and the relation between the plastic zone and side necking is investigated. FEA for modified boundary layer models with finite thickness, various mode mixities $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$ and strain hardening exponent n=3, 10 are performed. The results are presented and the implication regarding to application to experiment is discussed.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.731-743
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• 2016

Plastic behaviors, based on the von Mises yield criterion, of circular discs containing a purely elastic, circular inclusion under uniform temperature loading are studied with the finite element analysis. Temperature-dependent mechanical properties are considered for the matrix material only. In addition to analyzing the plane stress and plane strain disc, a 3D thin disc and cylinder are also analyzed to compare the plane problems. We determined the elastic irreversible temperature and global plastic collapse temperature by the finite element calculations for the plane and 3D problem. In addition to the global plastic collapse, for the elastically hard case, the plane stress problem and 3D thin disc may exhibit a local plastic collapse, i.e. significant pile up along the thickness direction, near the inclusion-matrix interface. The pileup cannot be correctly modeled by the plane stress analysis. Furthermore, due to numerical difficulties originated from large deformation, only the lower bound of global plastic collapse temperature of the plane stress problem can be identified. Without considerations of temperature-dependent mechanical properties, the von Mises stress in the matrix would be largely overestimated.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.343-356
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• 2022

As a part of round robin analysis to develop a finite element elastic-plastic seismic analysis procedure for nuclear safety class 1 components, a series of parametric analyses was carried out on the simulated pressurizer surge line system model to investigate sensitivity of the analysis results to finite element analysis variables. The analysis on the surge line system model considered dynamic effect due to the seismic load corresponding to PGA 0.6 g and elastic-plastic material behavior based on the Chaboche combined hardening model. From the parametric analysis results, it was found that strains such as accumulated equivalent plastic strain and equivalent plastic strain are more sensitive to the analysis variables than von Mises effect stress. The parametric analysis results also identified that finite element density and ovalization option in the elbow elements have more significant effect on the analysis results than the other variables.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.195-198
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• 2005

The role of elastic/plastic mismatch on the contact crack initiation is investigated for designing desirable surface-coated asymmetric layered composites. Various layered composites such as $Si_3N_4$ ceramics on $Si_3N_4+BN$ composite, soda-lime glass on various substrates with different elastic modulus for the analysis. Spherical indentation is conducted for producing contact cracks from the surface or interface between the coating and the substrate layer. A finite element analysis of the stress fields in the loaded layer composites enables a direct correlation between the damage patterns and the stress distributions. Implications of these conclusions concerning the design of asymmetric layered composites indicate that the elastic modulus mismatch is one of the important parameter for designing layered composite to prevent the initiation of contact cracks.

• Earthquakes and Structures
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• v.5 no.4
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• pp.461-475
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• 2013

A new experimental system of base-isolated structures is proposed. There are two kinds of dampers usually used in the base-isolated buildings, one is a viscous-type damper and the other is an elastic-plastic hysteretic-type damper. The base-isolated structure with a viscous damper and that with an elastic-plastic hysteretic damper are compared in this paper. The viscous damper is modeled by a mini piston and the elastic-plastic hysteretic damper is modeled by a low yield-point steel. The capacity of both dampers is determined so that the dissipated energies are equivalent at a specified deformation. When the capacity of both dampers is determined according to this criterion, it is shown that the response of the base-isolated structure with the elastic-plastic hysteretic damper is larger than that with the viscous damper. This characteristic is demonstrated through the comparison of the bound of the aspect ratio. It is shown that the bound of aspect ratio for the base-isolated structure with the elastic-plastic hysteretic damper is generally smaller than that with the viscous damper. When the base-isolated structure is subjected to long-duration input, the mechanical property of the elastic-plastic hysteretic damper deteriorates and the response of the base-isolated structure including that damper becomes larger than that with the viscous damper. The effect of this change of material properties on the response of the base-isolated structure is also investigated.