• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.160-169
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• 1998

The purpose of this study for the prediction of fatigue crack propagation behavior, Stress Intensity Factor(F) of round bar with 3-Dimensional half circular, semi-elliptical icro surface crack under rotary bending stress for the variable aspect, size, rotation angle was analyzed by Boundary Element Method (BEM). It is predicted that behavior of crack growth is half circular or circular crack (b/a.geq.1) and propagate to b/a.leq.0.85.

• Computers and Concrete
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• v.20 no.2
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• pp.229-246
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• 2017

The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.438-442
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• 2007

Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. For the verification of analytical model, sidewall curl is experimentally measured after deformation of a strip using a bending-under-tension test system. The results show a consistent relationship between the theoretically predicted value and the experimentally obtained one, especially in regions of high curl.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2696-2704
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• 2000

This paper presents a new laminated plate theory for the cylindrical bending of laminated plated. The theory assumes that in plane displacements vary exponentially through plate thickness. Analytical solutions are derived for simply supported plates subjected to transverse loading. The accuracy of the present theory is examined for unsymmetric laminates, and the numerical results are compared with three-dimensional elasticity solutions of Pagano. The present theory predicts displacements and stresses for very thick plates very accurately. In particular, transverse shear stresses obtained form constitutive equations are predicted very accurately.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.88-93
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• 2004

In general, a fundamental structural design consideration for an automobile is the overall dynamic behavior in bending and torsion. Dynamic behavior of the automobile are mainly influenced by the structural stiffness of B.I.W.(body-in-white) and the physical property of trim components. In this paper, the modeling techniques for various trim components of middle-sized bus are presented, and the dynamic effects of the trim components on the vibration characteristics of the bus are investigated. The $1^{st}$ torsional frequency is decreased by attaching windshield and backlite to the B.I.W., but the $1^{st}$ vertical bending frequency and the $1^{st}$ lateral bending frequency are increased. The natural frequencies of the bus are decreased by attaching doors and windows. And also, the natural frequencies of the bus are large decreased by attaching seats, instrument panel etc. The study shows that the dynamic characteristics of the bus can be effectively predicted in the initial design stage.

• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.81-86
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• 1996

This study was performed to evaluate the reduction in bending properties of radiata pine sapwood associated with incipient brown-rot decay. Decayed bending specimens by Tyromyces palustris and Gloeophyllum trabeum for varoious periods were tested destructively. Brown-rot decay by T. palustris and G. trabeum caused serious reduction in bending properties at very early stages of decay, with about 30 percent decrease in bending strength observed for only 1~2 percent weight loss. In general, the reduction in bending properties caused by T. palustris was somewhat greater than that by G. trabeum. Work to maximum load was reduced most severely and rapidly from the onset of decay, while modulus of elasticity showed a much more moderate rate of reduction. Modulus of rupture was affected by decay to a greater extent than was modulus of elasticity. Since a relatively strong correlation between weight loss and bending strength was observed, the residual strength of decayed wood can be predicted by weight loss due to decay. The results of this study indicate that very early stages of brown-rot decay reduce the bending strength significantly. Thus, it is recommended that all load-bearing members in wooden structures, especially those that are periodically wetted, should be inspected regularly to prevent a sudden failure even though there are no definite signs of decay.

• Steel and Composite Structures
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• v.22 no.2
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• pp.257-276
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• 2016

In this paper, a new simple higher-order shear deformation theory for bending and free vibration analysis of functionally graded (FG) plates is developed. The significant feature of this formulation is that, in addition to including a sinusoidal variation of transverse shear strains through the thickness of the plate, it deals with only three unknowns as the classical plate theory (CPT), instead of five as in the well-known first shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT). A shear correction factor is, therefore, not required. 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 accuracy of the present solutions is verified by comparing the obtained results with those predicted by classical theory, first-order shear deformation theory, and higher-order shear deformation theory. Verification studies show that the proposed theory is not only accurate and simple in solving the bending and free vibration behaviours of FG plates, but also comparable with the other higher-order shear deformation theories which contain more number of unknowns.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.421-427
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• 2015

In this paper, a description is given of finite element method (FEM) simulations of the elastic bending modulus of multi-layered graphene sheets that were carried out to investigate the mechanical behavior of graphene sheets with different gap thicknesses through molecular mechanics theory. The interaction forces between layers with various gap thicknesses were considered based on the van der Waals interaction. A finite element (FE) model of a multi-layered rectangular graphene sheet was proposed with beam elements representing bonded interactions and spring elements representing non-bonded interactions between layers and between diagonally adjacent atoms. As a result, the average elastic bending modulus was predicted to be 1.13 TPa in the armchair direction and 1.18 TPa in the zigzag direction. The simulation results from this work are comparable to both experimental tests and numerical studies from the literature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.653-661
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• 2006

Metallic sandwich plates with various inner cores have important new features with not only ultra-light material characteristics and load bearing function but also multifunctional characteristics. Because of production possibility on the large scale and a good geometric precision, sandwich plates with inner dimpled shell structure from a single material have advantages as compared with other solid sandwich plates. Inner dimpled shell structures can be fabricated with press or roll forming process, and then bonded with two face sheets by multi-point resistance welding or adhesive bonding. Elasto-plastic bending behavior of sandwich plates have been predicted analytically and measured. The measurements have shown that elastic perfectly plastic approximation can be conveniently employed with less than 10% error in elastic stiffness, collapse load, and energy absorption. The dominant collapse modes are face buckling and bonding failure after yielding. Sandwich plates with inner dimpled shell structure can absorb more energy than other types of sandwich plates during the bending behavior.

• Steel and Composite Structures
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• v.8 no.2
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• pp.145-158
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• 2008

In slender sections there is a substantial post-buckling strength provided after the formation of local buckling waves. These waves happened due to normal stresses or shear stresses or both. In this study, a numerical investigation of the behavior of slender I-section beams in combined pure bending and shear has been described. The studied cases were assumed to be prevented from lateral torsional buckling. To achieve this aim, a finite element model that simulates the geometric and material nonlinear nature of the problem has been developed. Moreover, the initial geometric imperfections were included in the model. Different flange and web width-thickness ratios as well as web panel aspect ratios have been considered to draw complete set of interaction diagrams. Results reflect the interaction behavior between flange and web in resisting the combined action of moments and shear. In addition, the web panel aspect ratio will not significantly affect the combined ultimate shear-bending strength as well as the post local buckling strength gained by the section. Results are compared with that predicted by both the Eurocode 3 and the American Iron and Steel specifications, AISI-2001. Finally, an empirical interaction equation has been proposed.