One of the most common industrial cold forging processes is cold heading of steel wire or rod to produce screws, bolts, nuts and rivets. The process is limited by a complicated interplay of many factors. The cold work (pre-drawing) is one of them. Although several investigations into the effects of pre-drawing on the formability of metals during cold heading processes have been conducted, so far no attention has been given to the numerical simulations of this phenomenon. The current work aims at examining effects of pre-drawing on formability during cold heading through numerical simulations. / Physical tests in the literature investigating the effects of pre-drawing on the formability of three metals are simulated using ABAQUS 6.4, with three successive FE models: the drawing model, the cutting model and the upsetting model. A new combined linear kinematic/nonlinear isotropic hardening constitutive model is proposed and derived to account for the Bauschinger effect existing in reverse plastic deformation. The new model is implemented into ABAQUS/Explicit v6.4 by a user subroutine VUMAT, which is verified by one-element numerical tests under tension, compression and reverse loading conditions. In addition, for the purpose of comparison, the Johnson-Cook isotropic hardening model is also applied for the materials. The Cockroft and Latham criterion is employed to predict surface fracture. / Although considerable discrepancies between the experimental and simulation results are observed, the proposed combined hardening model is more accurate in predicting material behavior in the reverse loading than the Johnson-Cook isotropic hardening model. In addition, the simulation results show that the proposed combined hardening material model has the potential to correctly predict the material behavior in the reverse loading process.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.98993 |
| Date | January 2005 |
| Creators | Ma, Lianzhong, 1968- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mechanical Engineering.) |
| Rights | © Lianzhong Ma, 2005 |
| Relation | alephsysno: 002338131, proquestno: AAIMR24990, Theses scanned by UMI/ProQuest. |
Page generated in 0.0089 seconds