• 대한조선학회지
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• 제16권3호
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• pp.35-47
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• 1979

Wave resistance of a parabolic thin ship, with its boundary layer and wake taken into account, was calculated up to second order. In addition to the double-model source distribution on the centerplane, image sources of the wave potential were calculated to keep the body introduced boundary condition undisturbed. Boundary layer and wake effects on the wave-making resistance were included by generating an irrotational flow which matches that exterior to the boundary layer and wake. For this purpose, the boundary layer and wake were calculated. The wave resistance refined with second-order corrections are found to be very important for wave resistance calculations even at moderate Froude numbers($Fr=0.2{\sim}0.3$). Wave-potential corrections are dominate around the bow. On the other hand, Viscosity plays and important role at the stern with its boundary layer and wake development.

• 대한조선학회지
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• 제16권3호
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• pp.25-33
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• 1979

The relation between the welding conditions and welding distortions were studied with the weld parameters, current, welding speed and plate thickness, and the form of the distortions were derived theoretically. To derive these formulas, the temperature distribution on the plane normal to the direction of the weld line was assumed to be parabolic. Both the theoretical studies for the transverse shrinkage and angular distoction were compared with the experiments. The experiments were performed on the fundamental cases of a bead welds on rectangular mild steel plates. It was found that the distoction formulas were in good agreement with the results of the experiments. The formulas for the calculation of the distortion were established for the case of bead on plate weld using rectangular mild steel plate and the KS E4313, $4mm\phi$ welding rod.

• 대한조선학회지
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• 제17권2호
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• pp.21-32
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• 1980

The welding distortions, transverse shrinkage and angular change, on the butt welded joint made by the process of shielded metal arc welding, were studied on the basic study of bead on plate weld. On the study of bead on plate weld, the temperature distribution on the plane normal to the direction of the weld line was assumed to be parabolic. The form of the distortion formulas of welded joint for transverse shrinkage and angular change were derived theoretically. Also, the experiments were performed about three cases, for changing type, sizes of welding electrodes and types of grooves, welding on mild steel plate, to compare theoretical study and experiments. It was found that the theoretical study was in good agreement with the result of experiment. Also, the optimal welding conditions for reducing weld distortions were suggested.

• Wind and Structures
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• 제21권3호
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• pp.273-287
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• 2015

In this paper, a free vibration analysis of functionally graded beam made of porous material is presented. The material properties are supposed to vary along the thickness direction of the beam according to the rule of mixture, which is modified to approximate the material properties with the porosity phases. For this purpose, a new displacement field based on refined shear deformation theory is implemented. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Based on the present refined shear deformation beam theory, the equations of motion are derived from Hamilton's principle. The rule of mixture is modified to describe and approximate material properties of the FG beams with porosity phases. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. Illustrative examples are given also to show the effects of varying gradients, porosity volume fraction, aspect ratios, and thickness to length ratios on the free vibration of the FG beams.

• Computers and Concrete
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• 제15권3호
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• pp.337-355
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• 2015

In this scientific work, an improved analytical solution for adhesive stresses in a concrete beam bonded with the FRP plate is developed by including the effect of the adherend shear deformations. The analysis is based on the deformation compatibility approach where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The shear stress distribution is supposed to be parabolic across the depth of the adherends in computing the adhesive shear stress and Timoshenko's beam theory is employed in predicting adhesive normal stress to consider the shear deformation. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of adhesive stress distributions.

• Geomechanics and Engineering
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• 제9권3호
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• pp.361-372
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• 2015

In this paper, a refined exponential shear deformation theory for free vibration analysis of functionally graded beam with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. For this purpose, a new displacement field based on refined shear deformation theory is implemented. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Based on the present refined shear deformation beam theory, the equations of motion are derived from Hamilton's principle. The rule of mixture is modified to describe and approximate material properties of the FG beams with porosity phases. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. Illustrative examples are given also to show the effects of varying gradients, porosity volume fraction, aspect ratios, and thickness to length ratios on the free vibration of the FG beams.

• 대한기계학회논문집
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• 제18권1호
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• pp.65-76
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• 1994

A higher-oder laminated plate theory including the effect of transverse shear deformation is developed to calculate the gross response and the detailed stress distribution. The theory satisfies the continuity condition of transverse shear stress, and accounts for parabolic variation of the transverse shear stresses through the thickness of each layer. Exact closed-ply laminates are obtained and the results are compared with three-dimensional elasticity solutions and a simple higher-order theory solutions. The results of the present work exhibit acceptable accuracy when compared to the three-dimensional elasticity solutions.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제24권3호
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• pp.293-303
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• 2020

The present work aims to analyzed the transient thermoelastic stress analysis of a thin circular plate with uniform internal heat generation. Initially, the plate is characterized by a parabolic temperature distribution along the z-direction given by T = T₀(r, z) and perfectly insulated at the ends z = 0 and z = h. For times t > 0, the surface r = a is subjected to convection heat transfer with convection coefficient h_c and fluid temperature T_∞. The integral transform method used to obtain the analytical solution for temperature, displacement, and thermal stresses. The associated thermoelastic field is analyzed by making use of the temperature and thermoelastic displacement potential function. Numerical results are carried out with the help of computational software PTC Mathcad Prime-3.1 and shown in figures.

• Structural Engineering and Mechanics
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• 제73권1호
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• pp.97-108
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• 2020

This study presents a 4 node, 11 DOF/node plate element based on higher order shear deformation theory for lamina composite plates. The theory accounts for parabolic distribution of the transverse shear strain through the thickness of the plate. Differential field equations of composite plates are obtained from energy methods using virtual work principle. Differential field equations of composite plates are obtained from energy methods using virtual work principle. These equations were transformed into the operator form and then transformed into functions with geometric and dynamic boundary conditions with the help of the Gâteaux differential method, after determining that they provide the potential condition. Boundary conditions were determined by performing variational operations. By using the mixed finite element method, plate element named HOPLT44 was developed. After coding in FORTRAN computer program, finite element matrices were transformed into system matrices and various analyzes were performed. The current results are verified with those results obtained in the previous work and the new results are presented in tables and graphs.

• Structural Engineering and Mechanics
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• 제3권1호
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• pp.49-60
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• 1995

In the present study, a finite strip method for the vibration and stability analyses of anisotropic laminated composite plates is developed according to the higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method based on the first-order shear deformation theory, the present method gives improved results for very thick plates while using approximately the same number of degrees of freedom. It also eliminates the need for shear correction factors in calculating the transverse shear stiffness. A number of numerical examples are presented to show the effect of aspect ratio, length-to-thickness ratio, number of plies, fibre orientation and stacking sequence on the natural frequencies and critical buckling loads of simply supported rectangular cross-ply and arbitrary angle-ply composite laminates.