• Steel and Composite Structures
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• 제21권1호
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• pp.217-247
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• 2016

Five extended cylindrical reticulated shells are proposed by changing distribution rule of diagonal rods based on three fundamental types. Modeling programs for fundamental types and extended types of cylindrical reticulated shell are compiled by using the ANSYS Parametric Design Language (APDL). On this basis, conditional formulas are derived when the grid shape of cylindrical reticulated shells is equilateral triangle. Internal force analysis of cylindrical reticulated shells is carried out. The variation and distribution regularities of maximum displacement and stress are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of cylindrical reticulated shells and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization for three fundamental types and five extended types is calculated with the span of 30 m~80 m and rise-span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise-span ratio are analyzed with contrast to the results of shape optimization. The optimal combination of main design parameters for five extended cylindrical reticulated shells is investigated. The total steel consumption affected by distribution rule of diagonal rods is discussed. The results show that: (1) Parametric modeling method is simple, efficient and practical, which can quickly generate different types of cylindrical reticulated shells. (2) The mechanical properties of five extended cylindrical reticulated shells are better than their fundamental types. (3) The total steel consumption of cylindrical reticulated shells is optimized to be the least when rise-span ratio is 1/6. (4) The extended type of three-way grid cylindrical reticulated shell should be preferentially adopted in practical engineering. (5) The grid shape of reticulated shells should be designed to equilateral triangle as much as possible because of its reasonable stress and the lowest total steel consumption.

• 동력기계공학회지
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• 제13권5호
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• pp.46-51
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• 2009

Recently, the shock resistance and dynamic characteristics of hard disk drives have become more important due to their highly increased storage density and miniaturization. In this study, we have developed an ANSYS/Mechanical/LS-DYNA based HDD vibration/shock simulation tool for design engineers. This simulation tool using ANSYS APDL can produce a parametric finite element modeling of HDD automatically and has GUI-based applications using the script program language Tcl/Tk. In the present tool, we adopt the reliable methodology of vibration/shock simulation, which is experimentally verified. It is expected that this simulation tool can make the repetitive computational efforts for the shock-proof design of HDD drastically reduced.

• 한국CDE학회논문집
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• 제3권3호
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• pp.145-153
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• 1998

An approach has been developed to generate parametric models with Boolean operations. The approach combines Boolean operations and graph manipulation on the constraints imposed on primitives. A Boolean operation is first performed on two primitives and new geometric elements such as vertices and edges are computed. Then to generate the constraint graph of the polygon the each constraints graph of two primitives are merged by adding the new geometric elements with its corresponding constraints. In the merging process, some of the geometric elements belonging to the primitives may be eliminated based on its contribution to the polygon. A computer implementation in a 2D space is described to illustrate the approach with examples.

• Wind and Structures
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• 제34권3호
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• Computers and Concrete
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• 제19권3호
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• pp.263-273
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• 2017

In this paper, a finite element model (FEM) in ATENA-3D software was constructed to investigate the behavior of circular ultra high performance concrete (UHPC) filled steel tube stub columns (UHPC-FSTCs) under concentric loading on concrete core. The "CC3DNonLinCementitious2User" material type for concrete in ATENA-3D software with some modifications of material laws, was adopted to model for UHPC core with consideration the confinement effect. The experimental results obtained from Schneider (2006) were then employed to verify the accuracy of FEM. Extensive parametric analysis was also conducted to examine the influence of concrete compressive strength, steel tube thickness and steel yield strength on the compressive behavior of short circular UHPC-FSTCs. It can be observed that the columns with thicker steel tube show better strength and ductility, the sudden drop of load after initial peak load can be prevented. Based on the regression analysis of the results from parametric study, simplified formulae for predicting ultimate loads and strains were proposed and verified by comparing with previous analytical models, design codes and experimental results.

• 한국CDE학회논문집
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• 제4권3호
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• pp.173-179
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• 1999

In reverse engineering, when a shape containing multi-patched surfaces is digitized, the boundaries of these surfaces should be detected. The objective of this paper is to introduce a computationally efficient segmentation technique for extracting edges, ad partitioning the 3D measuring point data based on the location of the boundaries. The procedure begins with the identification of the edge points. An automatic edge-based approach is developed on the basis of local geometry. A parametric quadric surface approximation method is used to estimate the local surface curvature properties. the least-square approximation scheme minimizes the sum of the squares of the actual euclidean distance between the neighborhood data points and the parametric quadric surface. The surface curvatures and the principal directions are computed from the locally approximated surfaces. Edge points are identified as the curvature extremes, and zero-crossing, which are found from the estimated surface curvatures. After edge points are identified, edge-neighborhood chain-coding algorithm is used for forming boundary curves. The original point set is then broke down into subsets, which meet along the boundaries, by scan line algorithm. All point data are applied to each boundary loops to partition the points to different regions. Experimental results are presented to verify the developed method.

• 한국유체기계학회 논문집
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• 제15권5호
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• pp.37-41
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• 2012

High-efficiency and low-noise axial flow fan is developed by combining the FanDAS, a computerized axial fan design/performance analysis system, and CFD software(CFX). Based on fan design requirements, FanDAS conducts 3-D blade geometry design, quasi-3D flow/ performance analyses and noise evaluation by using through-flow analysis method and noise models for discrete frequency and broadband noise sources. Through the parametric studies of fan design variables using FandDAS, preliminary and baseline design is achieved for high efficiency and low noise fan, and then can be coupled with a CFD technique such as the CFX code for constructing final and optimized fan design. The FanDAS-CFX coupled system and its design procedure are applied to actual fan development practice. The FanDAS provides an optimized 3-D fan blade geometry, and its predictions on the performance and the noise level of designed fan are well agreed with actual test results.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권3호
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• pp.124-132
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• 2000

In this paper, presented are an active surface-micromachined silicon accelerometer, force rebalance loop using parametric robust control method, and experimental results with a real micromachined accelerometer. And finally, a robust controller of the form of PID compensator was designed to construct force rebalance loop. Through the frequency response analysis, it is shown that the loop guarantees appropriate stability and robustness. Experiments with a real accelerometer demonstrated that the proposed loop effectively controls the position of the accelerometer's proof mass. It also demonstrated that the resolution of the fabricated accelerometer is better than 1mg. Compared with a commercial accelerometer the proposed force rebalance silicon accelerometer showed better performances.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.612-615
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• 2002

The main advantages of Disk type Single-Phase Switched Reluctance Motor (DSPSRM) is the simple construction, rugged structure, low manufacturing cost and simple driving circuit. It is especially possible to make the short axial length of DSPSRM. Therefore, it is suitable to setup this motor in a narrow space. This paper presents the shape design to maximize the average torque of DSPSRM that is achieved by 3D Finite Element Method (3D FEM) considering the nonlinear of magnetic material. The characteristics of two different rotor shapes are compared. The design parameters, such as the rotor and stator pole arc, are selected to the parametric study. The effect of pole arc ratios on the torque performance is investigated. From these results, the optimal pole arc to produce the maximum torque is determined.

• 한국CDE학회논문집
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• 제3권2호
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• pp.127-134
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• 1998

This paper presents d new algorithm to compute the offlet curve of a given planar parametric curve. We reduce the problem of computing an offset curve to that of intersecting a surface to a paraboloid. Given an input curve C(t)=(x(t), y(t))∈R², the corresponding surface D/sub c(t)/ is constructed symbolically as the envelope surface of a one-parameter family of tangent planes of the paraboloid Q:z=x²+y²along a lifted curve C(t)=(x(t), y(t), x(t)²+y(t)²∈Q. Given an offset distance d∈R, the offset curve C/sub d/(t) is obtained by the projection of the intersection curve of D/sub c(t)/ and a paraboloid Q:z=x²+y²-d² into the xy-plane.