• Journal of Korean Association for Spatial Structures
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• v.7 no.5
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• pp.83-87
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• 2007

Elastic critical loads of sinusoidally tapered bars with simply supported ends are determined by finite element method. The parameters considered in the analysis are taper parameter (=a) and section property parameter (=m). The analysis result for the special case of porismatic bar (a=0) shows good agreement with the existing value. The changes of the critical load coefficients are expressed by an algebraic equation. The coefficients appearing in the equations are determined by regression technique. The critical loads coefficients estimated by the proposed equations reveal little errors when they are compared with those determined by finite element method.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.44-53
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• 1991

The proper feeding conditions for thin Al-Alloy (AA336, JIS AC8A) castings in permanent mold were investigated to eliminate microshrinkage porosity. 5mm-thick plates (200mm long, 60mm wide) were cast with increasing padding taper from 0 to 5% under different conditions : (1) constant mold temperature of $350^{\circ}C$, (2) continuous production with uniform mold thickness (10mm), (3) continuous production with a negative taper of 2.5% in mold thickness (thickness decreasing in direction to riser). The test casting were machined off to the midplane and the shrinkage porosity was examined visually. The critical padding taper which can just eliminate the shrinkage porosity was determined for each condition, i.e. : (1) 4.5% at the constant mold temperature, (2) 3.5% for continuous production with the uniform mold thickness (3) 1.5% for continuous production with the taper in mold thickness. A computer simulation by a finite difference analysis program was applied to the test casting. The liquid fraction gradient (LFG) and the temperature gradient divided by the square root of the cooling rate (G /SR) were calculated at the end of solidification and compared with the shrinkage porosity area in the castings. For the case of constant mold temperature, LFG is a better parameter to predict shrinkage porosity than G /SR and its critical value is around 11%/cm. But for the case of continuous production, neither LFG nor G /SR could be a reliable parameter. The experimental results about the critical padding taper are of practical interest for designing permanent molds and castings. The computer simulation results stimulate further research to be directed on the prediction of centerline microshrinkage porosity in continuous production.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.521-525
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• 2004

This paper has the object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. vibration analysis that tapered thick plate subjected to In-plane stress is presented in this paper Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis tapered plate which is supported on pasternak foundation. The ratio of In-plane stress to critical load is varied with $0.2\sigma_{cr},\;0.4\sigma_{cr},\;0.6\sigma_{cr}$, and the Winkler parameter is 0, 10, 100, 1000 the shear foundation parameter 0, 10. The taper ratio is applied as 0.0, 0.2, 0.4, 0.6, 0.8 respectively. This paper is analyzed varying thickness by taper ratio with In-plane stress.

• Advances in materials Research
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• v.13 no.1
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• pp.1-18
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• 2024

The present experimental investigation focuses on finding optimal parametric data-set of laser micro-drilling operation with minimum taper and Heat-affected zone during laser micro-drilling of Carbon Nanotube/Epoxy-based composite materials. Experiments have been conducted as per Box-Behnken design (BBD) techniques considering cutting speed, lamp current, pulse frequency and air pressure as input process parameters. Then, the relationship between control parameters and output responses is developed using second-order nonlinear regression models. The analysis of variance test has also been performed to check the adequacy of the developed mathematical model. Using the Response Surface Methodology (RSM) and an Accelerated particle swarm optimization (APSO) technique, optimum process parameters are evaluated and compared. Moreover, confirmation tests are conducted with the optimal parameter settings obtained from RSM and APSO and improvement in performance parameter is noticed in each case. The optimal process parameter setting obtained from predictive RSM based APSO techniques are speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), Air pressure (1 kg/cm²) for Taper and speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), air pressure (3 kg/cm²) for HAZ. From the confirmatory experimental result, it is observed that the APSO metaheuristic algorithm performs efficiently for optimizing the responses during laser micro-drilling process of nanocomposites both in individual and multi-objective optimization.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1033-1041
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• 2008

The purpose of this paper is to investigate natural frequencies of tapered thick plate with concentrated masses subjected to in-plane force on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Finite element analysis of rectangular plate is done by using rectangular finite element with 8-nodes. For analysis, plates is supported on pasternak foundation. The Winkler parameter is varied with 10, 102, the shear foundation parameter is 5. The taper ratio is applied as 0.0, 0.25, 0.5 and the ratio of the concentrated mass to plate mass as 0.25, 0.5 respectively. As results, we can see that when stiffener's sizes or foundation parameter are larger, the natural frequency increases, and when the concentrated mass or taper ratio or in-plane stress is larger, the natural frequency decreases.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.681-688
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• 2006

This paper has the object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. the Winkler parameter is varied with 10, $10^2,\;10^3$ and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0 respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.388-394
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• 2005

This paper has the object of investigating natural frequencies of tapered thick plate on Pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Vibration analysis for tapered thick plate subjected to in-plane stress is presented in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. Analysis conditions of tapered thick plate are as follows each. The ratio of in-plane stress to critical load is varied with $0.2\sigma_{cr}$, $0.4\sigma_{cr}$, $0.6\sigma_{cr}$. The Winkler parameter is 0, 10, 100, 1000, the shear foundation parameter is 0, 10 and the taper ratio is 0.0, 0.2, 0.4, 0.6, 0.8.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.49-57
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• 1986

The vibrations problem of thin orthotropic skew plates of linearly varying thickness is analyzed using the small deflection theory of plates. Using dimensionless oblique coordinates, the deflection surface can be expressed as a polyonmial series satisfying the boundary conditions. For orthotropic plates which is clamped on all the four edges, numerical results for the first two natural frequencies are presented for various combinations of aspect ratio, skew angle and taper parameter. The properties of material used are one directional glass fibre reinforced plastic GFRP. The results obtained may be summarised as follows: 1. In case of the first mode vibration of plates with increase in the skew angle, the natural frequencies of plates decrease. 2. As the aspect ratio decrease, the natural frequencies of plates decrease. 3. For the identical skew angle, natural frequencies of plates increase with the taper parameter of thickness.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.4
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• pp.59-66
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• 2014

This paper deals with vibration of plates with concentrated mass on elastic foundation. The object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Free vibration analysis that tapered thick plate in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. The Winkler parameter is varied with 10, $10^2$, $10^3$ and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0. And the Concentrated Mass is applied as P1, Pc, P2 respectively.

• Steel and Composite Structures
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• v.33 no.1
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• pp.133-142
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• 2019

In the present study, microstructure-dependent static stability analysis of inhomogeneous tapered micro-columns is performed. It is considered that the micro column is made of functionally graded materials and has a variable cross-section. The material and geometrical properties of micro column vary continuously throughout the axial direction. Euler-Bernoulli beam and modified couple stress theories are used to model the nonhomogeneous micro column with variable cross section. Rayleigh-Ritz solution method is implemented to obtain the critical buckling loads for various parameters. A detailed parametric study is performed to examine the influences of taper ratio, material gradation, length scale parameter, and boundary conditions. The validity of the present results is demonstrated by comparing them with some related results available in the literature. It can be emphasized that the size-dependency on the critical buckling loads is more prominent for bigger length scale parameter-to-thickness ratio and changes in the material gradation and taper ratio affect significantly the values of critical buckling loads.