Analysis of the hole-flanging process of sheet metal

• Main Authors: CHEN, TSUNG-CHIA, 陳聰嘉
• Other Authors: Y.M. Huang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/03912077071589337276

碩士 === 國立台灣工業技術學院 === 機械工程技術研究所 === 85 === A methodology for formulating an elasto-plastic finite- element model,whichbased on an updated Lagrangian formulation , Prandtl-Reuss flow rule and vonMises yield condition , is developed to simulate the hole-flanging process.An extended r- min algorithm is proposed to formulate the boundary conditions ,such as nodal penetration and separation , alteration of sliding direction offriction which vary throughout the entire process of sheet bending , lineariz-ation of strain increment and rotatnal increment and altered elasto-plasticstate of material.A modified Coulomb's friction law is introduced to describethe alternation between the sliding state and the sticking state of frictionthe contact interface . The corresponding stiffness equations and solutionalgorithms are introduced . According to the developed finite element model ,the hole-flanging process is simulated under the axisymmetrical condition. Thesimulation results , such as (1) the whole deformation histroy,(2) the entireloading process histroy , (3) final shape of workpiece after unloading and (4)thickness of the workpiece , are compared with the experimental data . A goodagreement between the simulation results and the experimental data is observed.According to the experimental data , the prediction of the phenomenon ofneccking of the hole- flanging occurs at the inner hole is investigated. The smulation clearly demonstrates the efficiency of the model to simulatehole-flanging processes that are carried out under large deformation and con-tact history . This thesis has provided an improved understanding of the hole-flanging processes for improving the manufacturing processes and thedesign oftools.