• Title/Summary/Keyword: Non-axisymmetric Shape

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Numerical Analysis of Non-Axisymmetric Supercavitating Flow Around a Three-Dimensional Cavitator with an Angle of Attack (받음각을 갖는 3차원 캐비테이터에서 발생하는 비축대칭 초공동 유동해석)

  • Dae-Gyu Hwang;Byoung-Kwon Ahn
    • Journal of the Society of Naval Architects of Korea
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    • v.60 no.4
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    • pp.240-247
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    • 2023
  • In this study, morphological and hydrodynamic characteristics of the non-axisymmetric supercavity generated behind a disk-shaped cavitator were examined. By extending the previous study on axisymmetric supercavitating flow based on a boundary element method, hydrodynamic forces acting under the angle of attack condition of 0 to 30 ° and shape characteristics of the supercavity were analyzed. The results revealed that increasing the angle of attack by 30 ° reduced the length and width of the cavity by about 15% and the volume by about 40 %. An empirical formula that can quantitatively estimate the geometrical characteristics and change of the cavity was derived. It is expected that this method can be used to evaluate the shape information and force characteristics of the supercavity for the control of the vehicle in a very short time compared to the viscous analysis in the initial design stage of the supercavity underwater vehicle.

Study on the Influence of Die Corner Radius for Deep Drawing of Elliptical Product of Automobile (자동차용 타원형 디프 드로잉 제품의 다이 반경에 관한 연구)

  • 허영민;박동환;강성수
    • Transactions of Materials Processing
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    • v.11 no.8
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    • pp.668-675
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    • 2002
  • The circles deform into various shape during deformation, the major and minor axes of which indicate the direction of the major and minor principal strains. Likewise, the measured dimensions are used to determine the major and minor principal strain magnitudes. This circular grid technique of measuring strains can be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, of incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

Bearing capacity at the pile tip embedded in rock depending on the shape factor and the flow

  • Ana S. Alencar;Ruben A. Galindo;Miguel A. Millan
    • Computers and Concrete
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    • v.31 no.5
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    • pp.443-455
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    • 2023
  • This is a research analyses on the bearing capacity at a pile tip embedded in rock. The aim is to propose a shape coefficient for an analytical solution and to investigate the influence of the plastic flow law on the problem. For this purpose, the finite difference method is used to analyze the bearing capacity of various types and states of rock masses, assuming the Hoek & Brown failure criterion, by considering both plane strain and an axisymmetric model. Different geometrical configurations were adopted for this analysis. First, the axisymmetric numerical results were compared with those obtained from the plane strain analytical solution. Then the pile shape influence on the bearing capacity was studied. A shape factor is now proposed. Furthermore, an evaluation was done on the influence of the plastic flow law on the pile tip bearing capacity. Associative flow and non-associative flow with null dilatancy were considered, resulting in a proposed correlation. A total of 324 cases were simulated, performing a sensitivity analysis on the results and using the graphic output of vertical displacement and maximum principal stress to understand how the failure mechanism occurs in the numerical model.

An Expert System for the Process Planning of the Elliptical Deep Drawing Transfer Die(II) (타원형 디프 드로잉 트랜스퍼 금형의 공정설계 전문가 시스템(II))

  • 배원락;박동환;박상봉;강성수
    • Korean Journal of Computational Design and Engineering
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    • v.7 no.1
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    • pp.9-17
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    • 2002
  • The study is insufficient on process planning of the elliptical deep drawing product. Thus, in this present study, the expert system for elliptical deep drawing products was constructed by using process sequence design. The expert system was developed to be based on the general concept of each entity. The system was developed in this work consists of sixth modules. The first one is a shape recognition module to recognize non-axisymmetric products and to generate Entity_list. The second one is three dimensional (3-D) modeling module to calculate the surface area for non-axisymmetric products. The third one is a blank design module to create suggested blanks of three shapes with the identical surface area. The fourth one is shape design module based on the production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by inter- viewing field engineers, plastic theory and experiments. The fifth and sixth ones are a graphic module to visualize results of the expert system and a post module to rise user's convenience, respectively. According to constructed the expert system for process sequence design, it was possible to reduce the lead time.

An analysis of bolted opening structure and development of analysis expert system using ANSYS (원자력 주기기용 볼트 개폐구조물의 해석과 ANSYS를 이용한 전용 해석 프로그램의 개발)

  • Jeon, Seong-Mun;Seo, Ui-Gwon;Sim, Hyeon-Bo;Kim, Tae-Hwan;Lee, Bu-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.4
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    • pp.731-742
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    • 1998
  • Bolted opening structures is widely applied for class 1 machinery of nuclear plant with strict design requirement. As the shape of the bolted opening structure is non-axisymmetric due to the existence of stud bolts although it is almost axi-symmetric, 3D analysis is required to satisfy such kind of design requirements. Because as much as possible trial computations are need to get an optimal design condition in the limited period of basic design, an easy and fast analysis tool is useful in the design stage. In the paper, a transformation technique of non-axisymmetric problem into quasi-axisymmetric has been proposed based on the general purpose commercial code ANSYS. Both the pre-processor which incorporates the technique and prepares data and post-processor which prepares arranged results from the huge output of commercial code have been developed to help the design engineers.

A Stud on Punch and Die Shape Radii of Non-Axisymmetric Deep Drawing Product (비축대층 디프 드로잉 제품의 펀치 및 다이 형상반경에 관한 연구)

  • 배원락
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.92-95
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    • 2000
  • In order to obtain the optimal products in deep drawing process elliptical deep drawing tests were carried out with several shape radii of the punch and die. As parameters on testing shape radii of the punch and die were selected, In addition the conventional shape radii have been determined by trial=and-error using industrial experience and post processing test and only approximate shape radii of the punch and die have been presented. The optimal shape radii of the punch and die in elliptical deep drawing process with biaxisymmetric blank shape are proposed. In this study we suggest the appropriate conditions to be applicable to the catual manufacturing processes through the experiment and finite element method.

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Analysis of Sheet Metal Forming for Non-Axisymmetric Deep Drawing Products (비축대칭 디프 드로잉 제품의 박판 성형 해석)

  • 박동환;배원락;강성수
    • Transactions of Materials Processing
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    • v.10 no.3
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    • pp.185-192
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    • 2001
  • In order to obtain the optimal products in deep drawing process, elliptical deep drawing tests were carried out with several shape radii of the punch and die. As parameters on testing, shape radii of the punch and die were selected. In addition, the conventional shape radii have been determined by trial-and-error using industrial experience and post processing test, and only approximate shape radii of the punch and die have been presented. The optimal shape radii of the punch and die in elliptical deep drawing process with biaxisymmetric blank shape are proposed. In this study, we suggest the appropriate conditions to be applicable to the actual manufacturing processes through the experiment and finite element method.

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UBET Analysis of Combined Forging of Non-Axisymmetric Shapes With Inclined Protrusion (경사진 돌출부가 있는 비축대칭 복합단조의 상계요소해석)

  • 윤정호;양동열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.1-12
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    • 1990
  • The study is concerned with the analysis of combined forging of non-axisymmetric shapes with inclined protrusions by UBET technique. Work hardening is considered for the given range of strain rate during the forging process. A complex shape with inclined cavities is analyzed by subdividing the workpiece into finite UBET elements for which simple velocity fields are applicable. An experimental set-up was designed and manufactured for the experiment, and experiments are carried out with lead billets. The devised set-up can be used for closed-die forging of complex shapes with protrusions in which the dies can be separated automatically for easy removal of the forged products. Based on the derived kinematically admissible velocity fields for corresponding UBET elements, general computer programs have been developed. Since the energy dissipation rate for each elemental region is provided by subprograms (Subroutine or Function), the developed program can be applied to the forging problems of various shapes. The present study has shown that the method developed can be effectively applied to forging of non-axisymmetric shapes with complicated protrusions.

Effects of imperfection shapes on buckling of conical shells under compression

  • Shakouri, Meisam;Spagnoli, Andrea;Kouchakzadeh, M.A.
    • Structural Engineering and Mechanics
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    • v.60 no.3
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    • pp.365-386
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    • 2016
  • This paper describes a systematic numerical investigation into the nonlinear elastic behavior of conical shells, with various types of initial imperfections, subject to a uniformly distributed axial compression. Three different patterns of imperfections, including first axisymmetric linear bifurcation mode, first non-axisymmetric linear bifurcation mode, and weld depression are studied using geometrically nonlinear finite element analysis. Effects of each imperfection shape and tapering angle on imperfection sensitivity curves are investigated and the lower bound curve is determined. Finally, an empirical lower bound relation is proposed for hand calculation in the buckling design of conical shells.

Heat and Material Transport Analysis on the Head of Vehicle along the Flight Trajectory (비행궤적에 따른 비행체 앞부분의 열 및 물질전달해석)

  • 서정일;송동주
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.4
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    • pp.88-96
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    • 2002
  • The CSCM Upwind method and Material Transport Analysis(MTA) have been used to predict the thermal response and shape changes for charring/non-charring material which can be used as thermal protection material(TPM) on blunt-body nose tip. We performed intensive flight trajectory simulations to compare 1-D MTA results with those of 2-D/Axisymmetric MTA by using MTAs and Navier-Stokes code. Theheat-transfer rate and pressure distribution were predicted at selected altitudes and wall temperature along the flight trajectory and the shape changes of blunt-body nose tip were predicted subsequently by using current procedure.