• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.243-247
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• 2009

Primary charging roller is rotated with contacting surface of OPC drum and take charge OPC drum. Owing to this reason, primary charging roller is made by elasticity substance with electric conduction. Properties of charging and image is changed by class of coating, method of coating and environment. This study developed coating material and coating method to make print image of good quality.

• Computers and Concrete
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• v.19 no.1
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• pp.33-39
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• 2017

In this study, two types of aggregate were used for making self-compacting concrete. Standard cubic specimens were exposed to different temperatures. Seventy-two standard cylindrical specimens ($150{\times}300mm$) and Seventy-two cubic specimens (150 mm) were tested. Compressive strengths of the manufactured specimens at $23^{\circ}C$ were about 33 MPa to 40 MPa. The variable parameters among the self-compacting concrete specimens were of sand stone type. The specimens were exposed to 23, 100, 200, 400, 600, and $800^{\circ}C$ and their mechanical specifications were controlled. The heated specimens were subjected to the unconfined compression test with a quasi-static loading rate. The corresponding stress-strain curves and modulus of elasticity were compared. The results showed that, at higher temperatures, Scoria aggregate showed less sensitivity than ordinary aggregate. The concrete made with Scoria aggregate exhibited less strain. The heated self-compacting concrete had similar slopes before and after the peak. In fact, increasing heat produced gradual symmetrical stress-strain diagram span.

• Advances in materials Research
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• v.8 no.4
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• pp.259-274
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• 2019

Flexoelectric effect has a major role on mechanical responses of piezoelectric materials when their dimensions become submicron. Applying differential quadrature (DQ) method, the present article studies dynamic characteristics of a small scale beam made of piezoelectric material considering flexoelectric effect. In order to capture scale-dependency of such piezoelectric beams, nonlocal elasticity theory is utilized and also surface effects are included for better structural modeling. Governing equations have been derived by utilizing Hamilton's rule with the assumption that the scale-dependent beam is subjected to thermal environment leading to uniform temperature variation across the thickness. Obtained results based on DQ method are in good agreement with previous data on pizo-flexoelectric beams. Finally, it would be indicated that dynamic response characteristics and vibration frequencies of the nano-size beam depends on the existence of flexoelectric influence and the magnitude of scale factors.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.471-479
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• 2020

This paper aims to study the effect of the elastic nonlocality on the transient waves in a two-dimensional thermoelastic medium influenced by thermal loading due to the laser pulse. The bounding plane surface is heated by a non-Gaussian laser beam. The problem is discussed under the Eringen's nonlocal elasticity model and the Green-Naghdi (G-N) theory with and without energy dissipation. The normal mode analysis method is used to get the exact expressions for the physical quantities which illustrated graphically by comparison and discussion. The effects of nonlocality and different values of time on the displacement, the stresses, and the temperature were made numerically. All the computed results obtained have been depicted graphically and explained.

• Interaction and multiscale mechanics
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• v.4 no.3
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• pp.207-217
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• 2011

International efforts have focused recently on the development of tungsten surfaces that can intercept energetic ionized and neutral atoms, and heat fluxes in the divertor region of magnetic fusion confinement devices. The combination of transient heating and local swelling due to implanted helium and hydrogen atoms has been experimentally shown to lead to severe surface and sub-surface damage. We present here a computational model to determine the relationship between the thermo-mechanical loading conditions, and the onset of damage and failure of tungsten surfaces. The model is based on thermo-elasticity, coupled with a grain boundary damage mode that includes contact cohesive elements for grain boundary sliding and fracture. This mechanics model is also coupled with a transient heat conduction model for temperature distributions following rapid thermal pulses. Results of the computational model are compared to experiments on tungsten bombarded with energetic helium and deuterium particle fluxes.

• Structural Engineering and Mechanics
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• v.24 no.1
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• pp.19-29
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• 2006

The evolution process of an initially homogeneous bone structure under axial and transverse loads is investigated in this paper. The external loads include axial and external lateral pressure, electric, magnetic and thermal loads. The theoretical predictions of evolution processes are made based on the adaptive elasticity formulation and coupled thermo-magneto-electro-elastic theory. The adaptive elastic body, which is a model for living bone diaphysis, is assumed to be homogeneous in its anisotropic properties and its density. The principal result of this paper is determination of the evolution process of the initially homogeneous body to a transversely inhomogeneous body under the influence of the inhomogeneous stress state.

• Fire Science and Engineering
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• v.12 no.4
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• pp.31-40
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• 1998

Very often, whether accidentally or intentionally set fire, according as building are elevated, varied or complicated day by day. It is of primary importance that we have a treatment of fire damaged structure. In general, strength and elasticity modulus of heated concrete are reduced. Product background of cement, sand and coarse aggregate differ from country to country, so that thermal behaviour of concrete make a difference in high temperature. To cope with demand, this paper is a study on relation to microstructure and strength reduction. In consequence of experiments, concrete exposed to high temperature are estimating the reduction of mechanical properties in comparison with microstructure characteristics which are abtained from the SEM/EDX, XRD and DSC-TG analysis of heated specimens under various temperature.

• Coupled systems mechanics
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• v.7 no.1
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• pp.5-25
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• 2018

A fully-coupled thermodynamic-based transient finite element formulation is proposed in this article for electric, magnetic, thermal and mechanic fields interactions limited to the linear case. The governing equations are obtained from conservation principles for both electric and magnetic flux, momentum and energy. A full-interaction among different fields is defined through Helmholtz free-energy potential, which provides that the constitutive equations for corresponding dual variables can be derived consistently. Although the behavior of the material is linear, the coupled interactions with the other fields are not considered limited to the linear case. The implementation is carried out in a research version of the research computer code FEAP by using 8-node isoparametric 3D solid elements. A range of numerical examples are run with the proposed element, from the relatively simple cases of piezoelectric, piezomagnetic, thermoelastic to more complicated combined coupled cases such as piezo-pyro-electric, or piezo-electro-magnetic. In this paper, some of those interactions are illustrated and discussed for a simple geometry.

• Smart Structures and Systems
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• v.26 no.1
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• pp.77-87
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• 2020

By employing a quasi-3D plate formulation, the present research studies static stability of magneto-electro-thermo-elastic functional grading (METE-FG) nano-sized plates. Accordingly, influences of shear deformations as well as thickness stretching have been incorporated. The gradation of piezo-magnetic and elastic properties of the nano-sized plate have been described based on power-law functions. The size-dependent formulation for the nano-sized plate is provided in the context of nonlocal elasticity theory. The governing equations are established with the usage of Hamilton's rule and then analytically solved for diverse magnetic-electric intensities. Obtained findings demonstrate that buckling behavior of considered nanoplate relies on the variation of material exponent, electro-magnetic field, nonlocal coefficient and boundary conditions.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.1
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• pp.41-47
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• 2010

The carbon fiber reinforced plastics, one of unidirectional fiber-reinforced composite materials, are widely used in various field including space and aviation industries, sports and leisure industries and general structural members and parts as have high strength in comparison with the weight, elasticity coefficient, high fatigue strength and lower thermal transformation. This paper present analytical behavior of CFRP pipe reinforced rib under the external force. From the results, the maximum compressive stress occurs at the upper flange of CFRP pipe and tensile stress occurs middle flange of the CFRP pipe. The stress of rib CFRP pipe by increasing effective cross-sectional area was reduced by approximately 35%.