• Journal of Korean Association for Spatial Structures
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• v.24 no.1
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• pp.37-45
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• 2024

Steel plate shear walls (SPSWs) have been recognized as an effective seismic-force resisting systems due to their excellent strength and stiffness characteristics. The infill steel plate in a SPSW is constrained by a boundary frame consisting of vertical and horizontal structural members. The main purpose of this study was to investigate deformation modes and hysteretic characteristics of steel plate shear walls (SPSWs) to consider the effects of their aspect ratios and width-to-thicness ratios. The finite element model (FEM) was establish in order to simulate cyclic responses of SPSWs which have the two-side clamped boundary condition and made of conventional steel grade. The stress distribution obtained from the FEA results demonstrated that the principal stresses on steel plate with large thickness-to-width ratio were more uniformly distributed along its horizontal cross section due to the formation of multiple struts.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.363-367
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• 2009

Recently, the manufacturing of micro-cavity by means of laser surface texturing (LST) technique and low friction study by the LST have been in great progress. Most of current works have been dealing with the effect of cavity on friction and wear. The main objective of the present study was to investigate numerically two-dimensional lubrication characteristics of micro-dimple shapes fabricated on solid surfaces, and this study utilized the commercial CFD code (Fluent V.6.3). For the evaluation, preliminary simulation was conducted and numerical predictions were compared with the analytic solution obtained from the Reynolds's equation. Mainly, the present study investigated the influence of dimple depth, pattern shapes, and film thickness on lubrication characteristics related to the reduction of friction. It is found that the existence of micro-dimpled surface makes it possible to substantially reduce the friction forces exerted on the surfaces. In particular, substantial decrease in shear stresses was observed as the lubricant film thickness decreases. For instance, in the case of the film thickness of 0.01 mm, the estimated shear stress decreases up to about 40%. It indicates that the film thickness would be important factor in designing the micro-dimpled surfaces. Furthermore, it was observed that such a optimum dimple depth would be present because the dimple depth larger than the optimum value did no longer affect the reduction in shear stresses.

• Advances in nano research
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• v.4 no.4
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• pp.251-264
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• 2016

In this paper, a simple and refined nonlocal hyperbolic higher-order beam theory is proposed for bending and vibration response of nanoscale beams. The present formulation incorporates the nonlocal scale parameter which can capture the small scale effect, and it considers both shear deformation and thickness stretching effects by a hyperbolic variation of all displacements across the thickness without employing shear correction factor. The highlight of this formulation is that, in addition to modeling the displacement field with only two unknowns, the thickness stretching effect (${\varepsilon}_z{\neq}0$) is also included in the present model. By utilizing the Hamilton's principle and the nonlocal differential constitutive relations of Eringen, the equations of motion of the nanoscale beam are reformulated. Verification studies demonstrate that the developed theory is not only more accurate than the refined nonlocal beam theory, but also comparable with the higher-order shear deformation theories which contain more number of unknowns. The theoretical formulation proposed herein may serve as a reference for nonlocal theories as applied to the static and dynamic responses of complex-nanobeam-system such as complex carbon nanotube system.

• Structural Engineering and Mechanics
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• v.62 no.4
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• pp.401-415
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• 2017

A new higher shear deformation theory (HSDT) is presented for the thermal buckling behavior of functionally graded (FG) sandwich plates. It uses only four unknowns, which is even less than the first shear deformation theory (FSDT) and the conventional HSDTs. The theory considers a hyperbolic variation of transverse shear stress, respects the traction free boundary conditions and contrary to the conventional HSDTs, the present one presents a new displacement field which includes undetermined integral terms. Material characteristics and thermal expansion coefficient of the sandwich plate faces are considered to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are supposed as uniform, linear and non-linear temperature rises within the thickness direction. An energy based variational principle is used to derive the governing equations as an eigenvalue problem. The validation of the present work is carried out with the available results in the literature. Numerical results are presented to demonstrate the influences of variations of volume fraction index, length-thickness ratio, loading type and functionally graded layers thickness on nondimensional thermal buckling loads.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.361-368
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• 2020

The authors developed a new type of steel slit shear wall (SSSW) having the function of structural condition assessment through visually inspecting the out-of-plane deformation of the designed tapered links subjected to lateral deformation. To facilitate its practical application, this paper studies how to design dimensions of the tapered links. Two parameters, the width-to-thickness ratio of the tapered links and steel yield stress, were studied. The performance of structural condition assessment was affected by both parameters with the width-to-thickness ratio being the controlling one. Through both numerical and experimental study, the designed width-to-thickness ratio of tapered links for different levels of structural condition assessment was established considering the effect of different steel grades used. In practice, the dimensions of tapered links can be determined following the design equation provided. Finally, a design procedure for the proposed SSSW system is provided.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.156-158
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• 2003

Sheets of aluminum alloy 1050 were asymmetrically cold rolled in a rolling mill with different roll speeds. In order to promote the shear deformation during asymmetrical rolling, cold rolling without lubrication was performed. The variation of the shear strain state during asymmetrical rolling was tackled by means of FEM calculations. Asymmetrical rolling gave rise to the development of pronounced residual shear strain gradients throughout the thickness layers.

• 한국해양학회지
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• v.15 no.1
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• pp.1-7
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• 1980

The results of measurements of shear current induced in water by wind in wind wave tunnel are presented briefly. The shear current distributions are found to fit reasonably well an exponentiall form. This form was used to estimate surface velocity and boundary layer thickness used in stability analysis. An analysis of hydrodynamic stability of the shear current was carried out, using a broken line as an approximate profile, to see the stability as a possible mechanism of wind wave generation. Comparison between experimental results and theoretical ones shows that there exists a large discrepancy particularly in phase velocity and hydrodynamic instability of the shear current seems not to be the basic mechanism of wind wave generation.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.421-427
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• 2000

The present study has focused on the development of shear textures during groove pressing in an aluminum alloy sheet. The shear components 23 and 13 developed during the groove pressing process. The process consisting of two steps of grooving and flattening each effectively gave rise to a high shear deformation In the sheet without reduction in thickness. The main texture component obtained from the process was the rotated Bs-orientation. The evolution of shear components during the groove pressing caused an increase in R-value of aluminum sheet comparing to a normally processed rolled sheet.

• Smart Structures and Systems
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• v.22 no.1
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• pp.121-132
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• 2018

This research investigates the free vibration analysis of advanced composite plates such as functionally graded plates (FGPs) resting on a two-parameter elastic foundations using a hybrid quasi-3D (trigonometric as well as polynomial) higher-order shear deformation theory (HSDT). This present theory, which does not require shear correction factor, accounts for shear deformation and thickness stretching effects by a sinusoidal and parabolic variation of all displacements across the thickness. Governing equations of motion for FGM plates are derived from Hamilton's principle. The closed form solutions are obtained by using Navier technique, and natural frequencies are found, for simply supported plates, by solving the results of eigenvalue problems. The accuracy of the present method is verified by comparing the obtained results with First-order shear deformation theory, and other predicted by quasi-3D higher-order shear deformation theories. It can be concluded that the proposed theory is efficient and simple in predicting the natural frequencies of functionally graded plates on elastic foundations.

• Structural Engineering and Mechanics
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• v.28 no.5
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• pp.603-633
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• 2008

A four-node plate finite element for the analysis of laminated composites which is developed using strain gradient notation is presented. The element is based on a first-order shear deformation theory and on the equivalent lamina assumption. Strains and stresses can be calculated at different points through the thickness of the plate. They are averaged values due to the equivalent lamina assumption. A shear correction factor is used as the transverse shear strain is taken to be constant over the plate thickness while its actual variation is parabolic. Strain gradient notation, which is physically interpretable, allows for the detailed a-priori analysis of the finite element model. The polynomial expansions are inspected and spurious terms responsible for modeling errors are identified in the shear strains polynomial expansions. The element is corrected by simply removing the spurious terms from the shear strains expansions. The element is implemented into a FORTRAN finite element code in two versions; namely, with and without spurious terms. Results are compared to show the effects of the spurious terms on the solutions. It is also shown that a refined mesh composed of corrected elements provides solutions which approximate very well the analytical solutions, validating the procedure.