• Journal of Advanced Marine Engineering and Technology
• /
• 제33권1호
• /
• pp.28-36
• /
• 2009

In this paper, based on the measured data of hull deflection, an approximated hull deflection curve is drawn using reverse analyzed hull deflection data and the estimation method for flexibility analysis of shaft alignment is proposed by use of the approximate hull deflection curve. Generally an offset value of after stern tube bearing is a datum point with an fore stern tube bearing however the shaft alignment has a tendency which is able to get higher flexibility if the shafting system has the deflection value from after stern tube bearing as reference to bottom direction according to results of on this study. By applying this result of study, the shaft alignment for next similar ships will be able to estimate how to follow the hull deflection and how to be influenced by hull deflection at shaft alignment analysis state using the approximated hull deflection curve.

• 한국구조물진단유지관리공학회 논문집
• /
• 제6권3호
• /
• pp.119-128
• /
• 2002

This study discusses the issues related to the accuracy of deflection measurement and unstable energy in the testing of FRC. Some deflection methods may include large extraneous deformations. A faulty load-deflection curve will be obtained if an unstable deflection measuring system is used, and inaccurate toughness evaluation can result from this faulty curve. Some load-deflection curve of FRC may be attributed to unstable region of the load-deflection curve. If the unstable region is not correctly evaluated toughness indices from the curve would inappropriately represent true indices. In this paper, the discussion will focus on the effects of the deflection measuring system both on the measurement of the load-deflection response of FRC and the evaluation of FRC toughness and the effects of the unstable region and the management method of unstable region on toughness evaluation of FRC. It is observed that ASTM toughness indices which is based on measured deflection at first cracking is influenced significantly by extraneous deformation of deflection measurement. Extraneous deformation in deflection measurement, however result in negligible errors in toughness evaluation if JSCE and JCI definitions are used.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권1호
• /
• pp.111-120
• /
• 2000

This study discusses the issues related to the accuracy of deflection measurement in the testing of FRC. Some deflection methods may include large extraneous deformations. such as local crushing at the loading points, elastic and inelastic deformations of the loading fixture, etc. A faulty load-deflection curve will be obtained if an unstable deflection measuring system is used, and incorrect toughness evaluation can be reached on the basis of this faulty curve. In this paper, the discussion will focus on the effects of the deflection measuring system on both the measurement of the load-deflection response of FRC and the evaluation of FRC toughness. It is observed that ASTM toughness indices which is based on measuring deflection at first cracking is influenced significantly by extraneous deformation in deflection measurement. But extraneous deformation in deflection measurement result in negligible errors in toughness evaluation using JSCE and JCI definition. However, in order to evaluate toughness accuracy, it is desirable to use net load-deflection curve eliminated extraneous deformation.

• International Journal of Ocean System Engineering
• /
• 제2권3호
• /
• pp.195-199
• /
• 2012

This paper reports a new analytical method to calculate the planar displacement of structures. The cross-sections were assumed to remain in plane and the deflection curve was evaluated using the curvature values geometrically, despite being solved with differential equations. The deflection curve was parameterized with the arc-length of the curvature values, and was taken as an assembly of chains of circular arcs. Fast and accurate solutions of complex deflections can be obtained easily. This paper includes a comparison of the nonlinear displacements of an elastic tapered cantilever beam with a uniform moment distribution among the proposed analytical method, numerical method of the theory and large deflection FEM solutions.

• Smart Structures and Systems
• /
• 제13권6호
• /
• pp.975-991
• /
• 2014

The objective of this study is to develop a reliable method for locating cracks in a beam using data fusion of fractal dimension features of operating deflection shapes. The Katz's fractal dimension curve of an operating deflection shape is used as a basic feature of damage. Like most available damage features, the Katz's fractal dimension curve has a notable limitation in characterizing damage: it is unresponsive to damage near the nodes of structural deformation responses, e.g., operating deflection shapes. To address this limitation, data fusion of Katz's fractal dimension curves of various operating deflection shapes is used to create a sophisticated fractal damage feature, the 'overall Katz's fractal dimension curve'. This overall Katz's fractal dimension curve has the distinctive capability of overcoming the nodal effect of operating deflection shapes so that it maximizes responsiveness to damage and reliability of damage localization. The method is applied to the detection of damage in numerical and experimental cases of cantilever beams with single/multiple cracks, with high-resolution operating deflection shapes acquired by a scanning laser vibrometer. Results show that the overall Katz's fractal dimension curve can locate single/multiple cracks in beams with significantly improved accuracy and reliability in comparison to the existing method. Data fusion of fractal dimension features of operating deflection shapes provides a viable strategy for identifying damage in beam-type structures, with robustness against node effects.

• 대한기계학회논문집
• /
• 제12권2호
• /
• pp.381-388
• /
• 1988

본 연구에서는 설계조건에 만족하는 정확한 지주높이를 얻기 위하여 엄밀해를 가진 현수곡선이론을 바탕으로 하여 설계변수들과의 관계를 유도 및 수식화 하였다. 이를 최적설계문제로 정의하여 필요한 제한조건을 만족시키는 범위 내에서 지주의 굴적각들을 최소로 줄이는 최적화지법을 도입하여 체계적인 설계방법을 제시 하였다. 해석에 관한 설계예의 모델을 선정하여 굴절각들을 비교.검토하고 실험을 통하여 확인하였다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.125-130
• /
• 2002

The most important material parameters are fracture energy and the stress-crack opening displacement($\sigma$-w) curve to determine the behavior of concrete. Especially, the relationship between the $\sigma$-w curve is strongly important to determine the load-displacement curve of concrete that has a major influence on the fracture behavior of a concrete. In this paper, notched plain concrete beams with different strength level were tested under three-point bending and fracture energy, the load-deflection curve, and the load-crack mouth opening displacement(CMOD) curve were obtained from the experimental data. Also, the fictitious crack model(FCM) was applied to determine the load-deflection curve of notched plain concrete beams using various types of $\sigma$-w curve model proposed by Petersson and we compared experimental results with numerical ones carried out by Finite Element Method(FEM).

• Journal of the Korean Wood Science and Technology
• /
• 제37권1호
• /
• pp.48-55
• /
• 2009

집성재 보의 처짐의 경우 목재의 이방성 및 목재의 재질 특성(옹이, 목리경사 등) 때문에 이론식의 신뢰성 검토가 필요하다. 비파괴 탄성계수와 휨강도 시험을 통한 실측 탄성계수를 처짐곡선 미분방정식에 대입하여 휨 처짐을 산출하였으며 화상처리 방법을 통해 얻어진 실제 처짐과 비교하여 이론식에 의한 변형 예측의 타당성을 검토하였다. 방정식에 적용된 탄성계수는 초음파시험기를 이용한 제재판의 탄성계수와 종진동의 고유진동수를 이용한 제재판의 탄성계수로 구해진 예측 탄성계수($E_{cu}$, $E_{cf}$)와 제작된 집성재의 초음파의 통과속도를 이용한 탄성계수($E_{gu}$)와 종진동의 고유진동수를 이용한 탄성계수($E_{gf}$)를 대입하였다. 화상처리에 의한 실제 처짐과 처짐곡선 미분방정식에 의한 예측치을 비교한 결과, 휨탄성계수에 의한 경우 비례한도 영역 내에서 실측치와 예측치 비가 중앙집중하중에서는 1.12, 4점하중에서는 1.14로 비슷한 값을 나타내었다. 초음파 시험기를 이용한 처짐은 실측치와 예측치 비가 중앙집중하중에서는 0.89와 중앙집중하중에서는 0.95였으며 종진동을 이용한 처짐은 중앙집중하중 1.07과 4점하중은 1.10으로 모두 근사치를 나타냈다. 실험결과 집성재 보도 비파괴 탄성계수를 처짐곡선 미분방정식에 대입하여 구한 예측 처짐과 실제 처짐이 잘 일치하는 것을 확인할 수 있었다.

• Steel and Composite Structures
• /
• 제42권1호
• /
• pp.23-32
• /
• 2022

In this paper, a nonlinear numerical method to solve the large deflection problem is introduced. And the non-dimensional load-deflection behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates is parametrically investigated. The large deflection problem is formulated according to the von Kármán nonlinear theory and the (1,1,0)^* hierarchical model, and it is approximated by 2-D natural element method (NEM). The shear locking phenomenon is suppressed by the selectively reduced integration method. The nonlinear matrix equations are solved by combining the incremental loading scheme and the Newton-Raphson iteration method. The proposed method is validated from the benchmark experiments, where the propose method shows an excellent agreement with the reference methods. The nonlinear behavior of FG-CNTRC plates is evaluated in terms of the non-dimensional load-deflection curve, and it is parametrically investigated with respect to the existence/non-existence and gradient pattern of CNTs, the width-to-thickness and aspect ratios of plates and the type of boundary conditions. The non-dimensional central deflection is significantly reduced when CNTs and added, and it decreases with the volume fraction of CNTs. But, it shows a uniform increase in proportion to the width-to-thickness and aspect ratios. Both the gradient pattern of CNTs and the type of boundary conditions do also show the remarkable effects.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.440-447
• /
• 2005

In this study, strain measurement and its applicability to estimated deflection curve using fiber bragg grating sensors was conducted. For this purpose, reinforced concrete beams were made and sensors were attached both on the surface of the beams and inside steel. Two types of sensors were used to detect strain on the beams and steel : fiber bragg grating sensors, electric resistance strain sensors. So fatigue test is done with measuring strain of specimen. In addition, this experiments estimates the optimum deflection curve that converts strain curve data measured by FBG sensors into deflection.