• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.484-489
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• 2003

In this paper, a single phase driven piezoelectric motor design was presented for linear motion Two metal/ceramic composite actuators, a piezoelectric ring which was bonded to a metal endcap from one side, were used as the active elements of this motor. The motor was composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. Motors with 30 [mm] and 35 [mm] diameter were studied by finite element analysis and experiments. As results, the maximum speed of motor was obtained at resonance frequency. When the applied voltage of the motor increased, the speed was increased. Also, bidirectional motion of the motor was achieved by combining two motors which have different resonance frequency. But the characteristics of bidirectional motion were not equaled, because of the problem of reproduction on the fabrication and the experiment. If present motor is used at the auto-zoom device of a camera, it will have much advantage. Because the direct linear motion can be achieved with a simple structure of motor and no gearbox of total system.

• Composites Research
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• v.12 no.5
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• pp.87-97
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• 1999

A clad material is a different type of the typical composites which are composed of two or more matericals joined at their interface surface. The advantge of cald material is that the combination of different materials can satisfy both the need of good mechanical properties and the other demand of user such as electrical properties instantaneously. This paper is concerned with the direct and indirect extrusion processes of copper-clad aluminum rod. Extrusion of copper-clad aluminum rod was simulated using a commercially available finite element package of DEFORM. The simulations were performed for copperclad aluminum rod to predict the distributions of temperature, effective stress, effective strain rate and mean stress for sheath thicknesses, die exit diameters and die temperatures.

• Steel and Composite Structures
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• v.37 no.5
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• pp.533-549
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• 2020

Recently, Concrete-filled double skin steel tubular (CFDST) columns have proven an exceptional structural resistance in terms of strength, stiffness, and ductility. However, the resistance of these column members can be severely affected by the type of loading in which bending stresses increase in direct proportion with axial load and eccentricity value. This paper presents a non-linear finite element based modeling approach that studies the behavior of slender CFDST columns under biaxial loading. Finite element models were calibrated based on the outcomes of experimental work done by other researchers. Results from simulations of slender CFDST columns under axial loading eccentric in one direction showed good agreement with the experimental response. The calibrated models are expanded to a total of thirty models that studies the behavior of slender CFDST columns under combined compression and biaxial bending. The influences of parameters that are usually found in practice are taken into consideration in this paper, namely, eccentricity-to-diameter (e/D) ratios, slenderness ratios, diameter-to-thickness (D/t) ratios, and steel contribution ratios. Finally, an analytical study based on current code provisions is conducted. It is concluded that South African national standards (2011) provided the most accurate results contrasted with the Eurocode 4 (2004) and American Institute of Steel Construction (2016) that are found to be conservative. Accordingly, correction factors are proposed to the current design guidelines to provide more satisfactory results.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.239-243
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• 2010

This paper deals with the optimum design criteria for the premium efficiency of 250 kW traction induction motor, using response surface methodology (RSM) and finite element method (FEM). The focus of this paper is found firstly a design solution through the comparison of torque according to rotor bar shape, rotor dimensions variations. And secondly a mixed resolution with central composite design (CCD) is introduced and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model. The proposed procedure allows to be optimized the rotor copper bar shape, rotor slot, rotor dimensions starting from an existing motor or a preliminary design.

• Advanced Composite Materials
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• v.17 no.4
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• pp.359-372
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• 2008

The moisture absorption behavior of carbon fiber-reinforced plastic (CFRP) and its effect on dimensional stability were examined. Moisture diffusivity in CFRP was determined by measuring a specimen's weight during the moisture absorption test. Three types of CFRP specimens were prepared: a unidirectionally reinforced laminate, a quasi-isotropic laminate and woven fabric. Each CFRP was processed into two geometries - a thin plate for determination of diffusivity and a rod with a square cross-section for the discussion of two-dimensional diffusion behavior. By solving Fick's law expanded to 3 dimensions, the diffusivities in the three orthogonal directions were obtained and analyzed in terms of the anisotropy of CFRP moisture diffusion. Coefficients of moisture expansion (CMEs) were also obtained from specimen deformation caused by moisture absorption. During moisture absorption, the specimen surfaces showed larger deformation near the edges due to the distribution of moisture contents. This deformation was reasonably predicted by the finite element analysis using experimentally determined diffusivities and CMEs. For unidirectional CFRP, the effect of the fiber alignment on CME was analyzed by micromechanical finite element analysis (FEA) and discussed.

• Smart Structures and Systems
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• v.12 no.5
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• pp.483-499
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• 2013

A new piezoceramic $d_{15}$ shear-induced torsion actuation mechanism representative benchmark is proposed and its experimentations and corresponding 3D finite element (FE) simulations are conducted. For this purpose, a long and thin smart sandwich cantilever beam is dimensioned and built so that it can be used later for either validating analytical Saint Venant-type solutions or for analyzing arm or blade-based smart structures and systems applications. The sandwich beam core is formed by two adjacent rows of 8 oppositely axially polarized d15 shear piezoceramic patches, and its faces are dimensionally identical and made of the same glass fiber reinforced polymer composite material. Quasi-static and static experimentations were made using a point laser sensor and a scanning laser vibrometer, while the 3D FE simulations were conducted using the commercial software $ABAQUS^{(R)}$. The measured transverse deflection by both sensors showed strong nonlinear and hysteretic (static only) variation with the actuation voltage, which cannot be caught by the linear 3D FE simulations.

• Structural Engineering and Mechanics
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• v.61 no.1
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• pp.117-124
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• 2017

Load testing is one of the important tests to determine if the structural elements can be used at the intended locations for which they have been designed. It is nothing but gradually applying the loads and measuring the deflections and other parameters. It is usually carried out to determine the behaviour of the system under service/ultimate loads. It helps to identify the maximum load that the structural element can withstand without much deflection/deformation. It will also help find out which part of the element causes failure first. The load-deflection behaviour of the road bridge girder has been studied by carrying out the load test after simulating the field conditions to the extent possible. The actual vertical displacement of the beam at mid span due to the imposed load was compared with the theoretical deflection of the beam. Further, the recovery of deflection at mid span was also observed on removal of the test load. Finally, the beam was checked for any cracks to assert if the beam was capable of carrying the intended live loads and that it could be used with confidence.

• Journal of Adhesion and Interface
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• v.21 no.1
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• pp.20-26
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• 2020

Single lap-shear joints (SLJ) specimens with and without partial round fillets were fabricated to measure the average shear strength of adhesives. The effects of the length of the adherend on the SLJ specimens were also investigated. An epoxy adhesive was used to bond aluminum alloy. Tensile tests were performed on the adhesive bulk specimens to measure the mechanical properties. The finite element analysis (FEA) method was used to measure the adhesive stress distributions, i.e., the peel and shear stresses, on the bonded part. The experimental results revealed that the specimen consisting short length of adherend and without the partial round fillets exhibited the smallest average shear strength of adhesive among the investigated specimens. FEA revealed that the low average shear strength for the specimen with a short adherend length was caused by high stress concentrations on the adhesive at the edge of the bonded part.

• Journal of Electrochemical Science and Technology
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• v.4 no.1
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• pp.41-45
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• 2013

Platinum is a well known element which shows a significant electrocatalytic activity in many important applications. In glucose sensor, because of the poisoning effect of reaction intermediates and the low surface area, the electrocatalytic activity towards the glucose oxidation is low which cause the low sensitivity. So, we fabricate a nanoporous PtZn alloy electrode by deposition-dissolution method. It provides a high active surface and a large enzyme encapsulating space per unit area when it used for an enzymatic glucose sensor. Glucose oxidase was immobilized on the electrode surface by capping with PEDOT composite and PPDA. The composite and PPDA also can exclude the interference ion such as ascorbic acid and uric acid to improve the selectivity. The surface area was determined by cyclic voltametry method and the surface structure and the element were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX), respectively. The sensitivity is $13.5{\mu}A/mM\;cm^2$. It is a remarkable value with such simply prepared senor has high selectivity.

• International Journal of Ocean System Engineering
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• v.1 no.1
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• pp.9-15
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• 2011

This study examined the relationship between the scarf angle and stress distribution, and estimated the strength recovery via a finite element analysis. The following conclusions were drawn from this study. Resin will fracture due to a tensile load with a high scarf angle, which is similar to the patch repair method. An applied stress can be loaded to a repaired laminate if the scarf angle is $5^{\circ}$. The Von-Mises stress increases with decreasing scarf angle, with the exception of a scarf angle of $30^{\circ}$, where the scarf angle can indicate the rates of shear and normal stresses. Strength recovery can be better if the scarf angle is decreased to a lower angle. However, scarf machining requires more time, a high skill level and considerable expense. Therefore, a scarf angle of $5^{\circ}$ is the most effective for a repair. These results may provide a guide for engineers wishing to formulate a standard for repair. The scarf angle needs to be carefully managed for a more efficient composite repair.