• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.333-346
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• 2018

This study presents a mathematical modeling approach for developing models based on non-ideal conditions related to the membrane structure including porous supporting layer and deformation under pressure. Comparison of the findings with experimental data reveal the importance of considering the resistance in porous supporting layer though the effect of concentration polarization in the permeate stream could be neglected. Investigations on deformation of fibers under pressure ascertain that at larger fiber inner radius to outer radius ratios, increasing driving force may lead to an initial increase in permeability. After that, the effects of deformation dominates and thus permeability may be decreased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.617-626
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• 2021

During supersonic flight of vehicles, the thermal behavior of structures under high-temperature environment is important for thermal-structural design. In this study, full-field thermal deformation and stress concentration of the notched structure was performed using global-local multi-digital image correlation (multi-DIC) systems. This techniques were developed and implemented by multi-DIC systems consists of 2D DIC system and 3D DIC system. The specimen was heated in a heating chamber to achieve the thermal expansion behavior. Then the images of structure's deformation and stress concentration at various temperature were recorded and analyzed by multi-DIC system. Afterward, full-field thermal deformation of the notched structure was determined with DIC technique and stress concentration at the notched structure was calculated by further processing. Finite element analysis of the notched structure is performed in ABAQUS^TM and the results of the experiments show good agreement with those obtained from simulation. The results achieved in this study show the efficiency of the muilti-DIC method in thermal deformation as well as stress concentration of notched structure.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.207-211
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• 2015

In this paper, 2 kinds of models about bike frame are simulated with static structural analysis. A bike frame with diamond type is compared with another model that Down tube is eliminated from original diamond frame. About both types of models, Property of a material and conditions of restriction & load are the same. This study shows reinforcement effects of a partial frame by adding down tube and impacts generated by applying a load at the frame such as weak points & high stress parts as well as expected deformation. The structural result of this study indicates that the equivalent stress or total deformation decreases by 57.1% or 36.4%, respectively. Also stress concentration sites are leg connecting parts, front/rear wheels fixed region and Max deformation is generated from Seat tube. In conclusion, A Down tube is highly efficient as reinforcement than frame without non down tube. Furthermore, The safety rises in case of reducing top tube thickness and increasing a reinforcement at leg connecting parts or concentration regions.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.133-138
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• 2005

The deformation of sheet metal due to the residual stress during blanking or piercing process, is numerically simulated by means of a commercial finite element code. Two dimensional plain strain problem is solved and then its result is applied to the deformation analysis of the lead frame. The plain strain element is applied to the 2D problem to observe the Von Mises equivalent stress concentration at the both shearing edges. As the punch penetrates into the sheet material, the stress concentration generated on both edges is getting increased to be the shearing surface. The limits of the punching depth applied to the simulation is 16% and 24% of the sheet thickness for the plain strain element and the hexahedral element, respectively. The hexahedral element and the limit of punching depth were applied to the deformation analysis of the lead frame for the blanking process. The FEM results for the lead deformation were very good agreement with the experimental ones. This paper shows that the coarse mesh has enabled to analyze the lead deformation generated due to the blanking mechanism. This simple approach to save the calculation time will be very effective to the design of the blanking tools in industries.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1616-1622
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• 2001

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.

• Geotechnical Engineering
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• v.13 no.2
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• pp.17-28
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• 1997

In this study sodium chloride solution is employed for chemicals, and several cylindrical triaxial tests are performed on the sand-bentonite mixtures saturated with sodium chloride solution. Deformation(elastic modulus, E) and strength(cohesion, c', and angle of friction, f') parameters are obtained from the triaxial tests as functions of confining pressure and sodium chloride solution concentrations. The results here indicate an increase in the value of effective cohesion with increase in the concentration of NaCl solution, which can be explained by using the Gouy-Chapman model. The value of the effective angle of shearing resistance does not show significant change with the increase in concentration of NaCl solution. The Young's modulus also increases with the increase in concentration of NaCl solution.

• Proceeding of KASS Symposium
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• 2005.05a
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• pp.89-98
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• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. Therefore membrane structures arc unstable structures initially. These soft structures need to be introduced initial stresses first because of its initial unstable state, and it happens large deformation phenomenon. To find the structural shape after large deformation caused by initial stiffness introduced, we need the shape analysis considering geometric nonlinearity in structural design procedure. In this study, we investigate into the stress concentration at crack of membrane structures. Therefore, using the nonlinear analysis program that NASS (Nonlinear Analysis for Spatial Structures) perform nonlinear analysis, and stress distribution for creak length investigate for using linear elastic fracture mechanics.

• Transactions of Materials Processing
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• v.15 no.5 s.86
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• pp.382-386
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• 2006

Preform design is an effective means of achieving the homogeneous deformation of workpiece materials and decreased load in metal forming. However, this approach has not been applied to equal channel angula. pressing (ECAP). In this paper, plastic deformation behavior of workpieces having four different preform shapes during ECAP was investigated using finite element analyses. The results indicated that a preform design of the workpiece head has a beneficial effect on homogeneous deformation, reducing the maximum pressing load at the initial stage and eliminating folding defects at strain concentration points.

• Journal of the Korean Home Economics Association
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• v.23 no.1
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• pp.33-47
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• 1985

The rheological properties of acorn starch gel were investigated in region of small and large deformation. The properties were compared with those of potato and wheat starch gel. On the physical characteristics and the effect of tannin contents of acorn starch were examined. RESULTS : 1. X-ray diffractogram of acorn starch showed C-type and its granules swelled gradully with heating. 2. Hardness, brittleness and both small and large deformation of the acorn starch gel were remarkably large, also the concentration dependence of the acorn starch gel could be recognized in small deformation and hardness. 3. The Young's modulus of Hookean body in small deformation and the rupture stress in large deformation differed obviously from the parameters of rheological properties in various gels. 4. It was found that the selling power, viscosity and rhelogical properties were affected obviously by the tannin.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.540-545
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• 2005

The transformer tank is pressurized by atmosphere at the time of vacuum oiling and, plastic deformation occurs at the section of stress concentration on transformer tank at this time. It is important to predict where the sections of stress are in order to prevent deformation and to add reinforcement. This paper presents prediction results where the sections of stress are occurred and whether plastic deformation occur or not, using structure analysis program(ANSYS-design program).