• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1968-1799
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the necessity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1001-1020
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• 2016

The study is to investigate the free vibration of antisymmetric angle-ply conical shells having non-uniform sinusoidal thickness variation. The arbitrarily varying thickness is considered in the axial direction of the shell. The vibrational behavior of shear deformable conical shells is analyzed for three different support conditions. The coupled differential equations in terms displacement and rotational functions are obtained. These displacement and rotational functions are invariantly approximated using cubic spline. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. The vibration characteristic of the shells is examined for cone angle, aspect ratio, sinusoidal thickness variation, layer number, stacking sequence, and boundary conditions.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.745-750
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is Predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the neccesity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.59-68
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• 1997

The modelling techniques of a center pillar-to-roof rail joint for low frequency vibration analysis are examined and some fundamental problems are addressed. To develop a simplified beam-spring model of the joint, the present work is focused on 1) practical shell modelling techniques and 2) joint spring stiffness estimation methods a practical model-updating method to match the calculated natural frequencies to the experimentally determine ones is proposed, particularly focusing on spot welding modelling. In joint spring modelling, the results from the model with one joint spring are compared with those from the model with three coupled springs. Finally, some fundamental problems in beam-spring modelling are addressed.

• Structural Engineering and Mechanics
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• v.19 no.1
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• pp.73-96
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• 2005

For the spatially coupled free vibration analysis of shear deformable thin-walled non-symmetric curved beam subjected to initial axial force, an exact dynamic element stiffness matrix of curved beam is evaluated. Firstly equations of motion and force-deformation relations are rigorously derived from the total potential energy for a curved beam element. Next a system of linear algebraic equations are constructed by introducing 14 displacement parameters and transforming the second order simultaneous differential equations into the first order simultaneous differential equations. And then explicit expressions for displacement parameters are numerically evaluated via eigensolutions and the exact $14{\times}14$ dynamic element stiffness matrix is determined using force-deformation relations. To demonstrate the accuracy and the reliability of this study, the spatially coupled natural frequencies of shear deformable thin-walled non-symmetric curved beams subjected to initial axial forces are evaluated and compared with analytical and FE solutions using isoparametric and Hermitian curved beam elements and results by ABAQUS's shell elements.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.1-13
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• 2003

In this study, an effective method to estimate the fundamental frequencies of co-axial cylinders immersed in fluid is proposed. The proposed method makes use of the equivalent mass or density that is derived from the added mass matrix caused by the fluid-structure interaction (FSI) phenomenon. The equivalent mass is defined from the added mass matrix based on a 2-D potential flow theory. The theory on two co-axial cylinders extended to the case of three cylinders. To prove the validity of the proposed method, the eigenvalue analyses upon coaxial cylinders coupled with fluid gaps are peformed using the equivalent mass. The analyses results upon various fluid gap is conditions reveal that the present method could provide accurate frequencies and be suitable for expecting the fundamental frequencies of fluid coupled cylinders in beam mode vibration.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.820-830
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• 1999

The coupled turbulent flow and solidification is considered in a typical slab continuous easting process using commercial program FIDAP. Standard $k-{\varepsilon}$ turbulence model is modified to decay turbulent viscosity in the mushy zone and laminar viscosity is set to a sufficiently large value at the solid region. This coupled turbulent flow and solidification model also contains thermal contact resistance due to the mold powder and air gap between the strand and mold using an effective thermal conductivity. From the computed flow pattern, the trajectory of inclusion particles was calculated. The comparison between the predicted and experimental solidified shell thickness shows a good agreement.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.2
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• pp.127-133
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• 2001

With an objective of evolving quantitatively and qualitatively superior bivoltine breeds/hybrids of silkworm Bombyx mori L. for tropical conditions, breeding work was initiated in Central Sericultural Research and Training Institute, Mysore during 1992 by utilizing two Japanese hybrids namely BNl8$\times$BCS25 and Shunrei$\times$Shogetsu along with Indian evolved breed, KA. The breed CSR12 which is characterized with sex-limited larval marking and white oval cocoons was evolved from the Japanese hybrid BNl8 ${\times}$ BCS25 by crossing with KA, while the breed CSR6 which is characterized with normal marking (marked larvae) and white dumbbell cocoons was extracted from the Japanese commercial hybrid Shunrei${\times}$Shogetsu through continuous inbreeding coupled with selection. After fixation, these breeds along with other newly evolved breeds were subjected to hybrid study under optimum environmental conditions in the laboratory for expression of full potential of the genotypes. These hybrids were evaluated by Multiple Trait Evaluation Index (Mano et al., 1993). The hybrid CSR12${\times}$CSR6 was selected based multiple trait evaluation index value. The hybrid CSR12$\times$CSR6 recorded survival of 96.0%, shell weight of 50.0 cg, shell ratio of 24.3%, raw silk percentage of 19.6, filament length of 1,216 m, boil off loss of 22.4% and renditta of 5.1. On the other hand, the control hybrid (KA ${\times}$ NB4D2) has recorded survival of 90.6%, shell weight of 42.1 cg, shell ratio of 20.4%, raw silk percentage of 15.9, filament length of 999 m, boil off loss of 24.8% and renditta of 6.3. The hybrid CSR12$\times$CSR6 was authorized during 1997 by Central Silk Board, Government of India for commercial exploitation during favourable months based on national level race authorization test.

• Advances in nano research
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• v.15 no.5
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• pp.401-410
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• 2023

Vibration investigation of fluid-filled three layered cylindrical shells is studied here. A cylindrical shell is immersed in a fluid which is a non-viscous one. Shell motion equations are framed first order shell theory due to Love. These equations are partial differential equations which are usually solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the wave propagation approach procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Lagrange energy functional is converted into a set of three partial differential equations. It is also exhibited that the effect of frequencies is investigated by varying the different layers with constituent material. The coupled frequencies changes with these layers according to the material formation of fluid-filled FG-CSs. Throughout the computation, it is observed that the frequency behavior for the boundary conditions follow as; clamped-clamped (C-C), simply supported-simply supported (SS-SS) frequency curves are higher than that of clamped-simply (C-S) curves. Expressions for modal displacement functions, the three unknown functions are supposed in such way that the axial, circumferential and time variables are separated by the product method. Computer software MATLAB codes are used to solve the frequency equation for extracting vibrations of fluid-filled.

• Advances in nano research
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• v.10 no.3
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• pp.295-312
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• 2021

A new ionic liquid functionalized magnetic silica nanoparticle was synthesized and characterized and tested as an adsorbent. The adsorbent was used for magnetic solid phase extraction on ICP-MS method. Simultaneous determination of precious metal Au has been addressed. The method is simple and fast and has been applied to standard water and surface water analysis. A new method for separation/analysis of trace precious metal Au by Magnetron Solid Phase Extraction (MSPE) combined with ICP-MS. The element to be tested is rapidly adsorbed on CoFe2O4@SiO2@[BMIM]PF6 composite nano-adsorbent and eluted with thiourea. The method has a preconcentration factor of 9.5-fold. This method has been successfully applied to the determination of gold in actual water samples. Hydrophobic Ionic Liquids (ILs) 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6) coated CoFe2O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (CoFe2O4@SiO2@ILs) and establish a new method of MSPE coupled with inductively coupled plasma mass spectrometry for separation/analysis of trace gold. The results showed that trace gold was adsorbed rapidly by CoFe2O4@SiO2@[BMIM]PF6 and eluanted by thiourea. Under the optimal conditions, preconcentration factor of the proposed method was 9.5-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.01~1000.00 ng·mL-1, 0.001 ng·mL-1, 0.9990 and 3.4% (n = 11, c = 4.5 ng·mL-1). The CoFe2O4@SiO2 nanoparticles could be used repeatedly for 8 times. This proposed method has been successfully applied to the determination of trace gold in water samples.