• Transactions of Materials Processing
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• v.20 no.2
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• pp.132-139
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• 2011

Three dimensional simulations were performed for the deformation of a slab in a roller hearth type slab reheating furnace. The main objective of this study was to examine the deformation pattern of the slab due to the shadow effect, i.e., the temperature difference between the upper and lower slab surfaces, in particular, the variations of displacement and effective stress in the vertical direction. A commercially available FE code, ANSYS Workbench $12.1^{TM}$, was used in a fully coupled thermo-elasticity analysis. Several cases with different slab surface temperatures were selected for the simulations. For the sake of simplicity, the temperature environment inside the furnace was assumed to be homogeneous for the upper and lower faces of the slab. Two cases of with different slab width were selected as model geometry. The deformation patterns were computed and explained in terms of periodicity and symmetry. The results indicated that the shadow effect leads to a significant displacement in the vertical direction and, thereby, is one of the main reasons for the separation of the slab and its supports. These simulations also predicted that the deformation is more severe along the transverse direction than along the longitudinal direction.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.37-44
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• 2007

Mechanical and thermomechanical properties of the bulk metallic glass (BMG) are so unique that the deformation behavior is largely dependent on the temperature and the strain rate. Impacting behavior of NiTiZrSiSn bulk metallic glass powder during kinetic spraying was investigated in this study. Considering the impact behavior of the BMG, the kinetic spraying system was modified and attached the powder preheating system to make the transition from the inhomogeneous deformation to the homogeneous deformation of impacting BMG particle easy BMG splat formation is considered from the viewpoint of the adiabatic shear instability. It is suggested that the impact behavior of bulk metallic glass particle is determined by the competition between fracture and deformation. The bonding of the impacting NiTiZrSiSn bulk amorphous particle was primarily caused by the temperature-dependent deformation and fracture (local liquid formation) behavior.

• Steel and Composite Structures
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• v.44 no.5
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• pp.721-740
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• 2022

In this paper, an accurate kinematic model has been developed to study the mechanical response of functionally graded (FG) sandwich beams, mainly covering the bending, buckling and free vibration problems. The studied structure with homogeneous hardcore and softcore is considered to be simply supported in the edges. The present model uses a new refined shear deformation beam theory (RSDBT) in which the displacement field is improved over the other existing high-order shear deformation beam theories (HSDBTs). The present model provides good accuracy and considers a nonlinear transverse shear deformation shape function, since it is constructed with only two unknown variables as the Euler-Bernoulli beam theory but complies with the shear stress-free boundary conditions on the upper and lower surfaces of the beam without employing shear correction factors. The sandwich beams are composed of two FG skins and a homogeneous core wherein the material properties of the skins are assumed to vary gradually and continuously in the thickness direction according to the power-law distribution of volume fraction of the constituents. The governing equations are drawn by implementing Hamilton's principle and solved by means of the Navier's technique. Numerical computations in the non-dimensional terms of transverse displacement, stresses, critical buckling load and natural frequencies obtained by using the proposed model are compared with those predicted by other beam theories to confirm the performance of the proposed theory and to verify the accuracy of the kinematic model.

• Wind and Structures
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• v.22 no.3
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• pp.291-305
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• 2016

In this paper, a refined shear deformation plate theory which eliminates the use of a shear correction factor was presented for FG sandwich plates composed of FG face sheets and an isotropic homogeneous core. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the plate. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present refined shear deformation plate theory, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern buckling behavior of FG sandwiches plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, Boundary condition, and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.342-347
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• 2004

The deformation behavior of a $Zr_{55}Al_{10}Ni_5Cu_{30}$ bulk metallic glass under tensile loading at different range of strain rates and temperatures between 680 K and 740 K were investigated. The variation in the deformation behavior of $Zr_{55}Al_{10}Ni_5Cu_{30}$ bulk metallic glass which resulted from the crystallization induced during testing was reported. The$Zr_{55}Al_{10}Ni_5Cu_{30}$ bulk metallic glass has showed either homogeneous or inhomogeneous deformation depending on test condition. It exhibited a maximum elongation of about 560 % at the condition of $407^{\circ}C{\times}\;10^{-4}/s$. The flow behavior exhibited three different types and the flow stress became lower at higher temperatures and lower strain rates. The increase of the time elapsed during heating resulted in the partial crystallization of bulk metallic glass phase and eventually strain hardening and brittle fracture.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.31-36
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• 2004

Defective components of interest include not only homogeneous components, but also components with weldments where tensile properties vary across the weldment. Noting that the region near the weldment is the most vulnerable place for crack initiation and subsequent growth, defect assessment methods for homogeneous structure. Moreover, weldment width and crack location also affects the deformation and fracture behavior of the welded joints. These weld characteristics can evaluate using plastic limit load. So in this paper, evaluate plastic limit load both full circumference part-throughwall cracked pipes and circumference through-wall cracked pipes considering weld characteristics. And using evaluate results, proposed J-integral and crack opening displacement(COD) estimate method based on reference stress method.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.411-427
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• 2015

Based on linear elastic theory of quasicrystals, various equations and solutions for quasicrystal beams are deduced systematically and directly from plane problem of two-dimensional quasicrystals. Without employing ad hoc stress or deformation assumptions, the refined theory of beams is explicitly established from the general solution of quasicrystals and the Lur'e symbolic method. In the case of homogeneous boundary conditions, the exact equations and exact solutions for beams are derived, which consist of the fourth-order part and transcendental part. In the case of non-homogeneous boundary conditions, the exact governing differential equations and solutions under normal loadings only and shear loadings only are derived directly from the refined beam theory, respectively. In two illustrative examples of quasicrystal beams, it is shown that the exact or accurate analytical solutions can be obtained in use of the refined theory.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.544-551
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• 2005

This paper investigates the effectiveness of the MR damper-based control systems for seismic protection of base isolated building sturcutres employing some semiactive control algorithms, such as the modified clipped-optimal control, the maximum energy dissipation, and the modulated homogeneous friction, by examining the Phase I smart base isolated benchmark building problem. The results of the numerical simulations showed that most of the control systems considered herein could be beneficial in reducing seismic responses, especially base displacement or isolator deformation, of base isolated building structures. It is also verified that another version of the modified clipped-optimal control algorithm proposed in this study and the modulated homogeneous friction algorithm are more effective than other semiactive control algorithms.

• Progress in Superconductivity
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• v.3 no.2
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• pp.193-197
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• 2002

There are many problems in wire fabrication of long length Bi-2223 superconductor by using conventional extrusion method. They are mainly due to high surface resistance and inhomogeneous distribution of inner stress. Hydrostatic extrusion process will not only decrease the extrusion pressure but also enhance homogeneous deformation of material by reducing friction force between billet and container Hydrostatic extrusion method is considered to be useful fur fabrication of the homogeneous wire with high density. In this paper, hydrostatic extrusion process is introduced to fabricate Bi-2223 superconducting tape, and also discussed are the interface homogeneity and microstructural aspects of extruded BSCCO/Ag billet.

• Steel and Composite Structures
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• v.38 no.2
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• pp.213-221
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• 2021

The objective of this paper is to study the deformation in a homogeneous isotropic thermoelastic solid using modified couple stress theory subjected to ramp-type thermal source with two temperature. The advantage of this theory is the involvement of only one material length scale parameter which can determine the size effects. Laplace and Fourier transform technique is applied to obtain the solutions of the governing equations. The components of displacement, conductive temperature, stress components and couple stress are obtained in the transformed domain. A numerical inversion technique has been used to obtain the solutions in the physical domain. The effect of two temperature is depicted graphically on the resulted quantities. Numerical results show that the proposed model can capture the size effects of microstructures.