파워흐름해석을 위한 관통보와 평판이 연성된 구조물의 파워투과반사계수 해석

학위논문(석사)--서울대학교 대학원 :조선해양공학과,2001.Maste

Non-steady State Finite Element Analysis of Nonisothermal Hot Container Extrusion through Conical Dies

The study is concerned with the thermo-viscoplastic finite element analysis of nonisothermal hot container extrusion through conical dies. The problem is treated as a non-steady state incorporating the nonisothermal heat transfer analysis. The analysis of temperature distribution includes heat transfer through the boundary surface including conduction, convection and radiation. The analysis of heat transfer is decoupled with the analysis of deformation and the material interaction is considered through iteration procedure. The effect of important process parameters including die angle and extrusion ratio in the process is investigated. Due to the geometric feature for the container extrusion through conical dies, automatic remeshing is mandatory. Automatic remeshing is achieved by introducing the modular remeshing technique

A Three-Dimensional Finite Element Analysis of Hot Square Die Extrusion Considering the Effect of Die Bearing

The Variation of die bearing is primary way to control the metal flow in hot square die extrusion process. Finite element computations are carried out to assess the influence of die bearing on metal flow and state variables. The finit element method is developed based on ALE description for a rigid-viscoplastic material. Since thermal state computational example, hot square die extrusion with varied die bearing lengths has been analyzed for the profile of a L-section

A Three-Dimensional Rigid-Viscoplastic Finite Element Analysis of a Hot Square Die Extrusion with Flow Guide

In square die extrusion, flow guide and ide land play important roles for controlling the metal flow in die design. In the present work, the flow guide and the die land are considered for the die construction. Based on ALE description , rigid-viscoplastic finite element analysid is carried out to assess the effects of process and die design parameters. The thermal state affects greatly the product quality in hot extrusion. in the present work, the temperature distribution is also analyzed in theframwork of rigid-viscoplastic finite element computation. As a computational example, hot square die extrusion with flow guide and die land has been analyzed for the profile of a H section

An ALE Finite Element Formulation for Rigid-Viscoplastic Materials and Its Application to Axisymmetric Extrusion Through Square Dies

An arbitrary Lagrangian-Eulerian (ALE) finite element method has been developed. The finite element formation is derived and implemented for rigid-viscoplastic materials. The developed computer program is applied to the analysis of axisymmetric square die extrusion, which has many difficulties with updated Lagrangian approach. The results are compared with those from updated Largrangian approach. The results are compared with those from updated Lagrangian finite element program. Updating scheme of time dependent variables and mesh control are also examined

평금형을 이용한 3차원 열간 단면재 압출의 강-점소성 유한요소해석

학위논문(박사) - 한국과학기술원 : 기계공학과, 1996.2, [ vii, 141 p. ]The process of extrusion through square dies is widely used to produce profile sections. In recent years, the demand for complicated shapes has been increased and therefore the control of the process and the prediction of mechanical properties have become more important. Square die extrusion is normally carried out at the elevated temperature. Thus, the involved mechanics is basically non-steady and analysis should be made for the non-steady state throughout the entire process, which is not amenable to analysis due to the complicated metal flow in the non-steady hot extrusion process using a square die. Furthermore, the three-dimensional analysis is required, since the usual practical profiles are mostly asymmetric in the cross-sectional shape. In the present study, two kinds of kinematic description have been used to simulate the hot square die extrusion processes. The updated Lagrangian FEM is applied to analyze hot square die extrusion without die land. To carry out the simulation of hot extrusion of profiles, an automatic remeshing technique with modular concept is proposed. An arbitrary Lagrangian-Eulerian(ALE) FEM has been developed for the analysis of hot square die extrusion. The finite element formulation is derived and implemented. Updating scheme of time dependent variables and mesh control are also examined. In order to validate the FEM programs, experiments were carried out using AISI Al-1100 as the working material at the elevated temperature. The computed FEM results are compared with experimental results. The comparison shows that the computational results are generally in good agreement with the experiments in extrusion load, temperature distribution and deformed shape. In square die extrusion of complicated profiles, land parts and flow guides play important roles in controlling the metal flow properly. The effects of lands and flow guides are investigated through the simulation of the process. As industrial examples, extrusion of a H-section ...한국과학기술원 : 기계공학과