• Smart Structures and Systems
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• 제19권4호
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• pp.431-439
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• 2017

This investigation is aimed to develop a model of experimental-computation determination of a support moment of a cantilever beam loaded with concentrated force at its end including the optimal choice of coordinates of deflection data points and parameters of transformation of deflection data in case of insufficient accuracy of the assignment of initial parameters (support settlement, angle of rotation of the bearing section) and cantilever beam length. The influence of distribution and characteristics of sensors on the cantilever beam on the accuracy of determining the support moment which improves in the course of transition from the uniform distribution of sensors to optimal non-uniform distribution is shown. On the basis of the theory of inverse problems the method of transformation reduction at numerical differentiation of deflection functions has been studied. For engineering evaluation formulae of uncertainty estimate to determine a support moment of a cantilever beam at predetermined uncertainty of measurements using sensors have been obtained.

• Steel and Composite Structures
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• 제26권5호
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• pp.607-620
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• 2018

Vibration analysis of deep curved FG nano-beam has been carried out based on modified couple stress theory. Material properties of curved Timoshenko beam are assumed to be functionally graded in radial direction. Governing equations of motion and related boundary conditions have been obtained via Hamilton's principle. In a parametric study, influence of length scale parameter, aspect ratio, gradient index, opening angle, mode number and interactive influences of these parameters on natural frequency of the beam, have been investigated. It was found that, considering geometrical deepness term leads to an increase in sensitivity of natural frequency about variation of aforementioned parameters.

• Computers and Concrete
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• 제6권3호
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• pp.235-252
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• 2009

Due to the reduction of bond strength resulting from the high corrosion level of reinforcing bars, influence of this reduction on flexural capacity of reinforced concrete (RC) beam should be considered. An extreme case is considered, where bond strength is complete lost and/or the tensile steel are exposed due to heavy corrosion over a fraction of the beam length. A compatibility condition of deformations of the RC beam with partially unbonded length is proposed. Flexural capacity of this kind of RC beam is predicted by combining the proposed compatibility condition of deformations with equilibrium condition of forces. Comparison between the model's predictions with the experimental results published in the literature shows the practicability of the proposed model. Finally, influence of some parameters on the flexural capacity of RC beam with partially unbonded length is discussed. It is concluded that the flexural capacity of the beam may not be influenced by the completely loss of bond of the whole beam span as long as the tensile steel can yield; whether or not the reduction of the flexural capacity of the beam resulting from the loss of bond over certain length may occur depends on the detailed parameters of the given beam.

• 한국정밀공학회지
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• 제20권2호
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• pp.76-84
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• 2003

Stereolithography is the technique using a laser beam to cure a liquid resin, a photopolymer, with three dimensional computer-aided design (CAD) data. The build parameters of stereolithography such as beam size, scan velocity. hatch spacing, layer thickness and etc. are determined by the accuracy of prototype, the build time and the cured properties of the resin. In particular, beam size is important processing parameter fur the other parameters. Therefore, this study observed the cured property to beam size. For this purpose, according to hatch spacing and beam size, the cure width and depth were measured on single cured line. Also, the cure width and depth were measured at single cured layer As a result of experiments. cure depth which varied from 0.23mm to 0.34mm was directly proportioned to beam radius. on the other hand, cure width which varied from 0.42mm to 1.07mm was inversely proportioned to beam radius. Surface roughness varied from 1.12 to 2.23 m for the ratio of hatch spacing to beam radius.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.863-869
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• 2007

An improved method based on a normal frequency response function (FRF) is proposed to identify structural parameters such as mass, stiffness and damping matrices directly from the FRFs of a linear mechanical system. The method for estimating structural parameters directly from the measured FRFs of a structure is presented. This paper demonstrates that the characteristic matrices are extracted more accurately by using a weighted equation and eliminating the matrix inverse operation. The method is verified for a four degree-of-freedom lumped parameter system and an eight degree-of-freedom finite element beam. Experimental verification is also performed for a free-free steel beam whose size and physical properties are the same as those of the finite element beam. The results show that the structural parameters, especially the damping matrix, can be estimated more accurately by the proposed method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.582-588
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• 1998

The experimental study for the interior beam-column joint for high strength conccrete using Belite cement is presented. Test parameters are compressive strength, flexual strength ratio and joint shear stresslevel. The results from cyclic loading tests show different behaviors from the various parameters. Also, The different behaviors on beam-column joint can be achived by the different concrete strength.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.71-76
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• 2004

This paper describes the antenna analysis of the multi-beam for communicationsatellite. The design core parameters of the antenna system are optimal antennadiameter, feed horn type and hom size, F/D, and the coordinate of offset horns. Thepaper deals with the method to determine design core parameters of optimal antennadiameter, feed horn type and horn size. F/D, and the coordinate of offset horns, andthe performances of design result.

• Structural Engineering and Mechanics
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• 제62권1호
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• pp.79-84
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• 2017

Utilizing composite members in structures has been considered by many researchers in the past few decades. Using FRP can be very effective owing to its excessively high-tensile strength, which compensate concrete weak performance in tension. In this research, the studied composite beam includes a GFRP semi-confined trapezoidal section covered by GFRP and concrete layers. To assess the bearing capacity, a finite-element model of a composite beam subjected to displacement control loading has been developed and the results were validated using experimental results found throughout the literature. Several parameters affecting the bending performance and behavior of the semi-confined beam have been investigated in this study. Some of these parameters included the thickness of GFRP trapezoidal section members, concrete layer thickness, GFRP layer thickness and the confinement degree of the beam. The results revealed that the beam confinement had the highest effect on the bearing capacity due to prevention of separation of concrete from GFRP which causes the failure of the beam. From the results obtained, an optimal model of primary beam section has been introduced, which provides a higher bearing capacity with the same volume of materials used in the original beam section.

• 한국정밀공학회지
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• 제30권5호
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• pp.537-543
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• 2013

In this paper, a novel radial beam coupling model was proposed and the design parameters were studied for the efficient transmission of torque. To develop a high performance radial beam coupling, an analytical way to predict the performance in design phase is required. One of the best ways to estimate the performance of the coupling without manufacturing is to evaluate the stress and torsional stiffness by building a finite element model with a special attention to the radial beam cutting part. For the best results of FEA, the material properties were obtained through testing. To verify the reliability of finite element model, the results of FEA were compared with the experiments. The main design parameters of radial beam cutting width, radial beam cutting depth, and radial beam cutting direction were considered for the performance of radial beam coupling.

• Advances in aircraft and spacecraft science
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• 제4권5호
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• pp.585-611
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• 2017

This article covenants with the post buckling witticism of carbon nanotube reinforced composite (CNTRC) beam supported with an elastic foundation in thermal atmospheres with arbitrary assumed random system properties. The arbitrary assumed random system properties are be modeled as uncorrelated Gaussian random input variables. Unvaryingly distributed (UD) and functionally graded (FG) distributions of the carbon nanotube are deliberated. The material belongings of CNTRC beam are presumed to be graded in the beam depth way and appraised through a micromechanical exemplary. The basic equations of a CNTRC beam are imitative constructed on a higher order shear deformation beam (HSDT) theory with von-Karman type nonlinearity. The beam is supported by two parameters Pasternak elastic foundation with Winkler cubic nonlinearity. The thermal dominance is involved in the material properties of CNTRC beam is foreseen to be temperature dependent (TD). The first and second order perturbation method (SOPT) and Monte Carlo sampling (MCS) by way of CO nonlinear finite element method (FEM) through direct iterative way are offered to observe the mean, coefficient of variation (COV) and probability distribution function (PDF) of critical post buckling load. Archetypal outcomes are presented for the volume fraction of CNTRC, slenderness ratios, boundary conditions, underpinning parameters, amplitude ratios, temperature reliant and sovereign random material properties with arbitrary system properties. The present defined tactic is corroborated with the results available in the literature and by employing MCS.