• Steel and Composite Structures
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• v.14 no.1
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• pp.85-104
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• 2013

The present work deals with the thermomechanical bending response of functionally graded plates resting on Winkler-Pasternak elastic foundations. Theoretical formulations are based on a recently developed refined trigonometric shear deformation theory (RTSDT). The theory accounts for trigonometric distribution of transverse shear stress, and satisfies the free transverse shear stress conditions on the top and bottom surfaces of the plate without using shear correction factor. Unlike the conventional trigonometric shear deformation theory, the present refined trigonometric shear deformation theory contains only four unknowns as against five in case of other shear deformation theories. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The elastic foundation is modelled as two-parameter Pasternak foundation. The results of the shear deformation theories are compared together. Numerical examples cover the effects of the gradient index, plate aspect ratio, side-to-thickness ratio and elastic foundation parameters on the thermomechanical behavior of functionally graded plates. It can be concluded that the proposed theory is accurate and efficient in predicting the thermomechanical bending response of functionally graded plates.

• Advances in materials Research
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• v.5 no.4
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• pp.223-244
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• 2016

In this paper, a higher order shear and normal deformation theory is presented for functionally graded material (FGM) plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a hyperbolic variation of ail displacements across the thickness and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. Equations of motion are derived from Hamilton's principle. Analytical solutions for the bending and free vibration analysis are obtained for simply supported plates. The obtained results are compared with three-dimensional and quasi- three-dimensional solutions and those predicted by other plate theories. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and free vibration responses of functionally graded plates.

• Korean Journal of Computational Design and Engineering
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• v.21 no.3
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• pp.234-241
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• 2016

Conventional bent plate used in mandibular reconstruction surgery needs safety verification since its mechanical properties are changed due to the plastic deformation during the bending process. In this study we investigate stability of the plastically deformed plate and the plate with the same shape without plastic deformation through the finite element analysis(FEA). First we simulate the process of plate bending to fit the defect in patient. Then, the other plate is modelled to represent a customized plate with the same shape of the plastically deformed one, but without any residual stresses from plastic deformation. After binding these plates to the mandible, we conduct the masticatory simulation. Finally, we compare the resulting Von Mises stress of the customized plate and of the bent plate. The bent plate shows much higher stress than the customized one due to the residual stresses form the bending process. The study shows that plastic deformation in the plate may decrease the safety of the reconstruction surgery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1050-1057
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• 1997

The sheet bending with large radius of curvature is analyzed with both theoretical and experimental methods. Sheet bending in elastic limit is accomplished by the plastic deformation of flange. The springback model is developed theoretically and the effects of the factors are evaluated. The prediction accuracy of the model is also evaluated by comparing with the experimental data. Finally, an algorithm to design the sheet-bending die is suggested for usage in industry.

• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.781-790
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• 2015

We apply higher-order beam theory to analyze the deflections and stresses of a cantilevered single leaf flexure in bending. Our equations include shear deformation and the warping effect in bending. The results are compared with Euler-Bernoulli and Timoshenko beam theory, and are verified by finite element analysis (FEA). The results show that the higher-order beam theory is in a good agreement with the FEA results, with errors of less than 10%. These results indicate that the analysis of the deflections and stresses of a single leaf flexure should consider the shear and warping effects in bending to ensure high precision mechanism design.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.450-456
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• 2002

Die desig for manufacturing hooks from steel wires has been depended on empirical procedures based on trial and error method. To design die, at first the curvature and bending angle of hook are computed by using AutoCAD and developed program which is composed of Visual Basic. Then spring back should be considered because the elastic recovery of material is very important in bending process. In this study, bending analysis of elastic-plastic materials is applied to predict curvature of hook and spring back. Therefore, systematic procedure of die design for bending hook is achieved to consider elastic recovery in terms of hook shapes. Experimental results are good agreement with calculated results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.672-676
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• 2012

This paper studies the relation between the deformation of platen caused by clamping force, the bending stress and elongation at the tie-bar in injection molding machine of toggle type. These data are analyzed through analytical molding and numerical approach by tensile tester. The effect of bending stress on the stress concentration of teeth and nut system is also analyzed by 2 dimensional numerical approach. The bending stress of tie-bar caused by platen deformation becomes less than 20% of average tensile stress. And the effect of bending stress on stress concentration at teeth and nut system of tie-bar is found to be small.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.320-323
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• 2008

In this study, a macroscopic approach was carried out to gain insight into the bending mechanism of metallic sandwich plates. Shear force-punch stroke curves for various clearances were analytically derived for mild steel (CSP 1N) sandwich plates with the total thickness of 3 mm and 0.5 mm face sheets. As the clearance increases, shear force of the inner structures and sensitivity of punch stroke decrease. These data are useful to derive a criterion of judgment for core shear failure and de-bonding failure during U-bending.

• Journal of the Korean Wood Science and Technology
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• v.48 no.5
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• pp.608-617
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• 2020

For efficient use and expansion of domestic small- and medium-diameter woods, cross-laminated wood panels composed of tropical hardwoods and domestic temperate woods were fabricated, and the bending creep behavior under long-term loading was investigated. The bending creep curve of the cross-laminated wood panels showed an exponential function graph with a sharp increase at the top right side. The wood panel composed of a teak top layer and larch core and bottom layers recorded the highest initial deformation, and that composed of a merbau top layer and tulip core and bottom layers showed the lowest initial deformation. Creep deformation of the cross-laminated wood panels showed the highest value in that composed of a teak top layer and larch core and bottom layers and showed the lowest value in that composed of a merbau top layer and tulip core and bottom layers. The obtained creep deformation is 3.1-4.3 times that of merbau, however, it is remarkably lower than that of tulip and larch. The highest relative creep was recorded by the wood panel composed of merbau top layer and larch core and bottom layers, whereas that composed of the teak top layer and tulip core and bottom layers showed the lowest relative creep.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.