• 한국자동차공학회논문집
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• 제8권4호
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• pp.149-157
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• 2000

Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.877-882
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• 2005

Dynamic stability of an axially accelerating beam stucture is investigated in this paper. The equations of motion of a fixed-free beam are derived using the hybrid deformation variable method and the assumed mode method. Unstable regions due to periodical acceleration are obtained by using the Floquet's theory. Stability diagrams are presented to illustrate the influence of the dimensionless acceleration, amplitude, and frequency. Also, buckling occurs when the acceleration exceeds a certain value. It is found that relatively targe unstable regions exist around the first bending natural frequency, twice the first bending natural frequency, and twice the second bending natural frequency. The validity of the stability diagram is confirmed by direct numerical integration of the equations of motion.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.890-893
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• 2002

This study is focused to predict the behavior of Al foam with closed-cell structure during the 3 point bending test and the upsetting test according to aspect ratio. We calculated characters of aluminum foams with closed-cell structure and took the simulation. The effects on the aspect ratio of the cell was investigated parametrically. The analysis was carried out on two models, First, the bending test in elasticity of the rectangular beam, and Second, the upsetting test in plasticity of the circular cylinder. In the analysis, the deformation of the beam and the cylinder was influenced by the aspect ratio of the cell. Further, We assumed that the geometry of feared aluminum cell change the stress and strain in the test.

• 소성∙가공
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• 제16권6호
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• pp.432-437
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• 2007

Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control sidewall curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. The analytical model includes the variables of applied tensile force, the yield strength, the elastic modulus, the bending radius, and the sheet thickness, which are the primary factors affecting sidewall curl during sheet stamping operations. For the accuracy of analytical model, six possible deformation patterns are proposed on the basis of material properties and bending geometries.

• 소성∙가공
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• 제16권6호
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• pp.438-442
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• 2007

Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. For the verification of analytical model, sidewall curl is experimentally measured after deformation of a strip using a bending-under-tension test system. The results show a consistent relationship between the theoretically predicted value and the experimentally obtained one, especially in regions of high curl.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.362-365
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• 2006

This paper presents a model for evaluating the contribution by arch action to shear resistance in shear-critical RC beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, The behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled.

• 한국해양공학회지
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• 제16권5호
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• pp.66-72
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• 2002

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. However, effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. Acoustic emission(AE) has been widely used in various fields because of its extreme sensitivity, dynamic detection ability and location of growing defects. In this study, we investigated failure modes of locally wall thinned pipes and AE signals by bending test. From test results, we could be divided four types of failure modes of ovalization, crack initiation after ovalization, local buckling and crack initiation after local buckling. And fracture behaviors such as elastic region, yielding region, plastic deformation region and crack progress region could be evaluated by AE counts, accumulative counts and time-frequency analysis during bending test. The result of the frequency range is expected to be basic data that can inspect plants in real-time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.34-34
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• 2010

This paper describes effect of the bending deformation of high voltage composite bushing with winding tension. The composite bushing can be formed, by adding silicone rubber sheds to a tube of composite materials. The FRP tube is internal insulating part of a composite bushing and is designed to ensure the mechanical characteristics. Generally the properties of FRP tube can be influenced by the winding angle, wall thickness and winding tension. As winding tension is increased glass contents was increased in the range of 70.4~76.6%. In the bending test, winding tension is increased residual deflection was decreased in the range of 14.0~12.2 mm.

• 대한기계학회논문집A
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• 제24권11호
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• pp.2696-2704
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• 2000

This paper presents a new laminated plate theory for the cylindrical bending of laminated plated. The theory assumes that in plane displacements vary exponentially through plate thickness. Analytical solutions are derived for simply supported plates subjected to transverse loading. The accuracy of the present theory is examined for unsymmetric laminates, and the numerical results are compared with three-dimensional elasticity solutions of Pagano. The present theory predicts displacements and stresses for very thick plates very accurately. In particular, transverse shear stresses obtained form constitutive equations are predicted very accurately.

• Steel and Composite Structures
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• 제24권5호
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• pp.537-548
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• 2017

In this paper presents bending characteristic of single wall carbon nanotube reinforced functionally graded composite (SWCNTRC-FG) plates. The finite element implementation of bending analysis of laminated composite plate via well-established higher order shear deformation theory (HSDT). A seven degree of freedom and $C^0$ continuity finite element model using eight noded isoperimetric elements is developed for precise computation of deflection and stresses of SWCNTRC plate subjected to sinusoidal transverse load. The finite element implementation is carried out through a finite element code developed in MATLAB. The results obtained by present approach are compared with the results available in the literatures. The effective material properties of the laminated SWCNTRC plate are used by Mori-Tanaka method. Numerical results have been obtained with different parameters, width-to-thickness ratio (a/h), stress distribution profile along thickness direction, different SWCNTRC-FG plate, boundary condition, through the thickness (z/h) ratio, volume fraction of SWCNT.