• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.100-105
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• 2000

In this study the structural design concepts of main parameters of a Cathode Ray Tube(CRT) such as frame spring and shadow mask were proposed to guarantee a failure-proof CRT under mechanical shock. With computer simulation and experiments some information on the structural design concept was obtained as followings: the frame and the shadow mask of the CRT needed designing to increase strength so double-beads shape at the corner of frame was newly designed for it, And the spring which interconnected frame with panel glass was required to deform elastically for the purpose of absorbing the shock energy in the direction of drop. A new type of spring 'twisting spring' was designed to achieve the flexibility in that direction. By using it the deformation energy of a shadow mask could reduced to some degree. To accomplish those simulations commerical codes Pam-Crash and I-DEAS were used and a typical CRT was analyzed as an example to prove the usefulness of this study.

• Journal of KSNVE
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• v.6 no.3
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• pp.287-296
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• 1996

A virtual work form of flexible multibody dynamic formulation with rotary inertia has been derived. For the analysis of large flexible multibody systems, deformation modal coordinates have been employed to represent coupled motion between gross and vibrational motion. For the efficient evaluation of the entries in the mass matrix, a flexible body has been treated as a collection of mass points. The rotary inertia was generated from the consistent mass matrix in a finite element model. Deformation mode shapes were obtained from finite element analysis. Bending and twisting vibration analyses of a cantilever have been carried out to see rotary inertia effects. A space flexible robot simulation has been also carried out to show effectiveness of the proposed formulation. This formulation is effective to the model that consists of beam, plate, or shell element that contains rotational degree of freedom at the nodal point. It is also effective to the flexible body model to which a large lumped rotary inertia is attached.

• Journal of the Korea Computer Graphics Society
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• v.12 no.1
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• pp.21-25
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• 2006

This paper proposes a real-time simulation technique for thin shells undergoing large deformation. Thin shells are almost two-dimensional structures visually well approximated as surfaces, such as leaves, paper sheets, hats, aluminum cans. Unfortunately accurate simulation of these structures requires one of the most complex formulations in continuum mechanics, shell theory [4]. Moreover, there has not yet been any work reported to produce visually convincing animation of them while achieving real-time performance. Motivated by discrete shells [5] and modal warping [3], we formulate dynamics of thin shells using mass-spring models instead of finite element models, and then apply the modal warping technique to cope with large rotational deformation of thin shells. Experiments show that the proposed technique runs in real-time, and that it can simulate large bending and/or twisting deformations with acceptable realism.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.21-27
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• 1998

In the case of existing in free-edge delaminations of composite laminates which are symmetry with respect to mid-plane in laminates also, in the case of asymmetry and anti-symmetry, the generalized quasi-three dimensional displacement field equations developed from quasi-three dimensional displacement field equations can be applied to solve above cases. We introduce three paramenters in this paper, which have not been used in quasi-three dimensional displacement field equations until now. To the laminate subjected to the axial extension strain $\varepsilon$0(C1) in $\chi$-direction, the bending deformation $\chi$$\chi$(C$_2$) around у-direction, the bending deformation w$\chi$(C$_4$) around z-direction and the twisting deformation $\chi$$\chi$y(C$_3$) around $\chi$-direction .The generalized quasi-three dimensional displacement field equations are able to be analyzed efectively.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.9-12
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• 2011

Structural analysis of a tire is done using a commercial software, ANSYS Workbench. The properties of rubber of the tire is represented using a Mooney-Rivlin model. The bead in the tire is made of structural steel. 3D CAD model of the tire is obtained from a commercial CAD-specialized software, CATIA. Using an imported 3D CAD geometric model, a mesh system with fifty thousand nodes is constructed using ANSYS. A time-variant point force is applied to the rim of the tire, and the deformation of the tire is computed. It is found that both bending and twisting of the tire are observed where the point force is applied. The deformation of the tire is asymmetric, which results in the help of ripping the tire using the helper. It is also found that the deformation undergoes linearly with the applied force. When the force is larger than 1500N, then the deformation becomes larger than the half of the thickness of the tire. In the future, a more realistic rubber model will be applied and validated with the measured data.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.703-707
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• 1992

In the field of assembly processes, non-rigid parts such as wires, tubes, gaskets and 0-rings cannot be assembled automatically. And although many researches have been made for rigid part mating, there are not substantial studies in flexible parts assembly field. In this paper, assembly stages of flexible parts are classified and some analysis are made. FEM was used to estimate the relationship between deformation and reactive forces. An assembly algorithm adopting reciprocal twisting motion was proposed and the assembly tool design methodology was discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.48-71
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• 1996

Rectangular frames of thin sheet metals are press formed during their manufacture. The multistage process includes blanking, stamping, bending, and trimming. After stamping the sheet is subjected to warping and twisting due to residual stresses. The twist is not desirable since it affects the subsequent assembly processes. Study has been performed to predict the twist.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.13-27
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• 1996

소성가공이란 원재료를 소성변형(Plastic deformation)을 통해서 고체의 제품을 만드는 가공법이다. 가공중에 물체의 질량과 체적에는 크게 변화가 없다. 소성 가공중 주응력이 어떻게 작용하느냐에 따라서 소성가공을 여러가지로 분류하고 있다. 즉, Metal Forming은 다음과 같이 분류할 수 있다. 1) Compound Forming에는, Rolling, Free forming, Die forming, Stamping, Pressing 2) Tension compression forming에는, Drawing, Deep-drawing, Rimming, Spinning, Bulge forming 3) Tension forming에는 Lengthening, Widning, Deepening 4) Bending에는 Bending with linear tool motion, Bending with rotary tool motion 5) Thrust forming에는 Swaging, Twisting이 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.849-859
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• 2013

This paper proposes a real-time simulation technique for thin rods undergoing large rotational deformation. Rods are thin objects such as ropes and hairs that can be abstracted as one-dimensional structures. Development of a real-time physical model that can produce visually convincing animation of thin rods has been a challenging problem in computer graphics. We adopt continuum mechanics to formulate the governing equation, and develop a modal warping technique for rods to integrate the governing equation in real-time; This is a novel extension of the previous modal warping techniques developed for solids and shells. Experimental results show that the proposed method runs in real-time even for large meshes and it can simulate large bending and/or twisting deformations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1263-1274
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• 1996

In this paper, as elastic-plastic fracture toughness test under mixed mode loading was proposed using a single edge-cracked specimen subjected to bending moment(M), shearing force(F), and twisting moment(T). The J-integral of a crack in the specimen is expressed in the form J=$J_I$+ $J_II$$J_III$, where $J_I$, $J_II$ and $J_III$ are the components of mode I, mode II and mode III deformation, respectively. $J_I$, $J_II$ and $J_III$ can be estimated from M-$\theta$ ($\theta$;crack opening angle), F-U(U; crack shear displacement) and T-$\alpha$ ($\alpha$;crack twisting angle). In order to obtain the the M<-TEX>$\theta$, F-U and T-$\alpha$ diagram inreal time, a new deformaiton gage for mixed mode loading was proposed using the optical position sensing device(PSD). The elastic-plastic fracture toughness test was carried out with an aluminum alloy. The loading apparatus was designed and manufactured for this experiment. For the loading condition of the crack initatio in the mixed mode, the MMT -3(mode I+ mode II+ mode III) has the lowest values out of the all specimens. This implies that MMT-3 is possible of the crackinitation at lower load, if the specimen acts on together with the torque under the same loading condition. An elastic-plastic fracture toughness test using the PSD brings a successful experimentation in measuring the crack deformation(mode I+ mode II+ mode III).