• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.3
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• pp.105-109
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• 1999

The purpose of this experiment was to see the effect of local basis weight on the local strain during changing moisture content in handsheets. The averaged strain value of the whole size of paper sheet did not give more valuable information to explain non uniform deformation in the paper sheet. The combination of intact strain measurement system KISA (Linear Image Strain Analysis) and local basis weight measurement method using a scanner made it possible to compare local basis weight with local strain to explain moisture induced paper deformation . Usually higher basis weight local area showed higher moisture induced local strain. However, the hygro-induced strain values were highly affected by the behavior of neighbor local areas. Well distributed local basis weight paper would give more uniform local strains than those of non-uniformed local basis weight paper.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1142-1147
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• 2004

In this study, two damage detection techniques are applied to the railway tunnel liner based on the static deformation data. Models based on uniform reduction of stiffness and smeared crack concept are both employed, and the efficiency and relative advantage are compared with each other. Numerical analyses are performed on the idealized tunnel structure and the effect of white noise, common in most measurement data, is also investigated to better understand the suitability of the proposed models. As a result, model 1 based on uniform stiffness reduction method is shown to be relatively insensitive to the noise, while model 2 with the smeared crack concept is proven to be easily applied to the field situation since the effect of stiffness reduction is rather small. Finally, real deformation data of a rail tunnel in which health monitoring system is in operation are introduced to find the possible damage and it is shown that the prediction shows quite satisfactory result.

• Steel and Composite Structures
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• v.37 no.1
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• pp.27-35
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• 2020

This study examines the wave propagation of the functionally graded polymer composite (FG-PC) nanoplates reinforced with graphene nanoplatelets (GNPs) resting on elastic foundations in the framework of the nonlocal strain gradient theory incorporating both stiffness hardening and softening mechanisms of nanostructures. To this end, the material properties are based on the Halpin-Tsai model, and the expressions for the classical and higher-order stresses and strains are consistently derived employing the second-order shear deformation theory. The equations of motion are then consistently derived using Hamilton's principle of variation. These governing equations are solved with the help of Trial function method. Extensive numerical discussions are conducted for wave propagation of the nanoplates and the influences of different parameters, such as the nonlocal parameter, strain gradient parameter, weight fraction of GNPs, uniform and non-uniform distributions of GNPs, elastic foundation parameters as well as wave number.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1686-1699
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• 1993

In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.3
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• pp.207-216
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• 2003

By using the electrochemical method, the relation between the deformation and the geometrical shape, and the effect of cold work on hydrogen absorption-desorption cycling in palladium were investigated, In order to study this problem, four kinds of the Pd specimens used were plates and bars as cold worked and annealed states. As results, it is found that the deformation of thickness direction in the palladium plates increased whereas other lateral directions decreased. But the palladium bars showed the same deformation ratio in all directions because of uniform distribution of the $\beta$ phase. Grains in the plate specimens were greatly deformed after hydrogenation cycling whereas grains in the bar specimens were pulverized. Also, deterioration of the hydrogen absorption rate of the bar specimen was larger than the plate specimen. And the effect of cold work on hydrogen absorption capacity was relatively small.

• Journal of Korea Game Society
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• v.17 no.1
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• pp.89-98
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• 2017

This paper presents a novel ARAP (as-rigid-as-possible) approach to real-time simulation of physics-based deformation. To cope with one, two and three dimensional deformable bodies in an efficient, robust and uniform manner, we introduce a deformation graph of oriented particles and formulate the corresponding ARAP deformation energy. For stable time integration of the oriented particles, we develop an implicit integration scheme formulated in a variational form. Our method seeks the optimal positions and rotations of the oriented particles by iteratively applying an alternating local/global optimization scheme. The proposed method is easy to implement and computationally efficient to simulate complex deformable models in real time.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.747-753
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• 2000

There has been a number of investigations in recent years reporting the results obtained on the structure and properties of metals deformed to severe plastic deformation (SPD). Being deformed to SPD, ultra-fine grains (UFG) are usually formed, and UFG structure exhibits fundamental differences in original physical properties. One method often used to obtain SPD is equal channel angular pressing (ECAP). In order for this technique to be exploited, it is important to understand the deformation behavior during the ECAP processing and relationship to the configuration of die. The finite element method (FEM) has been used to investigate this issue. It has been found that the plastic deformation is sensitive to the channel angle and material properties and is not uniform across the width of the specimen and the pressing load is relative to deformation during the ECAP processing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.680-688
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• 1989

A numerical method for analyzing non-isothermal plastic deformation of sheet metals has been developed and sheet tensile tests have been analyzed using a two-dimensional finite element formulation. A modified Bishop`s method is used to solve the thermoplasticity problem in decoupled form at each time step. The accuracy of the analysis is confirmed by comparison with experimental data. The uniform elongation is found is drop by 0.1 to 2.7% at moderate strain rates, while total elongation decreases upto 6.0% during tensile testing in air compared to the isothermal case. The effect of deformation heating, becomes more pronounced as necking develops and at higher testing speed.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.100-105
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• 2002

This paper predicts the material properties of spatially reinforced composites (SRC) and analyzes the thermo-elastic behavior of a kick motor nozzle manufactured from that material. To find the appropriate SRC structure for the nozzle throat that satisfies given design conditions, the equivalent material properties of the SRC are predicted using the superposition method for those of rod and matrix. Studied are the elastic behavior, temperature distribution, and thermo-elastic behavior of a kick motor nozzle composed of carbon/carbon SRC as a throat part. The elastic deformation of the nozzle composed of 3D carbon/carbon SRC shows asymmetry in a circumferential direction. However, 4D carbon/carbon SRC nozzle shows uniform deformation in the circumferential direction. Stress concentration in connecting parts of the kick motor nozzle is ultimately high due to the high temperature gradient in each connecting part. The thermo-elastic deformations of both the 3D and the 4D SRC nozzles are uniform in the circumferential direction due to the isotropy of CTE of each SRC. The deformation of the 3D SRC nozzle is a slightly smaller than that of the 4D SRC nozzle in the nozzle throat, which is favorably effective on rocket thrust. The circumferential stress is the most critical component of the kick motor nozzle. The 4D SRC nozzle having 1,1,1,1.7 diameters in each direction has the smallest circumferential stress among several SRC nozzles.

• Steel and Composite Structures
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• v.32 no.6
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• pp.701-715
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• 2019

Using first-order shear deformation theory (FSDT), a semi-analytical solution is employed to analyze creep damage and remaining life assessment of 304L austenitic stainless steel thick (304L ASS) cylindrical pressure vessels with variable thickness subjected to the temperature gradient and internal non-uniform pressure. Damages are obtained in thick cylinder using Robinson's linear life fraction damage rule, and time to rupture and remaining life assessment is determined by Larson-Miller Parameter (LMP). The thermo-elastic creep response of the material is described by Norton's law. The novelty of the present work is that it seeks to investigate creep damage and life assessment of the vessels with variable thickness made of 304L ASS using LMP based on first-order shear deformation theory. A numerical solution using finite element method (FEM) is also presented and good agreement is found. It is shown that temperature gradient and non-uniform pressure have significant influences on the creep damages and remaining life of the vessel.