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Title: Unified numerical analysis of cold and hot metal forming processes
Author: Schonauer, M.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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A decoupled thermo-mechanical model which includes elastic behaviour is cast into a finite element formulation, which is numerically unified for simulation of both cold and hot metal forming processes. Computational attention has been focused on the mechanical aspects, where the elasto-plastic constitutive law is utilized for cold (practically rate-independent) regimes, while metalurgically sound high temperature interpolation function are employed in the computational framework of Perzyna type elasto-viscoplasticity for hot (rate-dependent) processes. Introduction of a logarithmic strain based finite strain model within the context of a geometrically nonlinear assumed strain method characterizes the numerical treatment of incompressibility at large elastic-inelastic deformations. The plastic theory of quasi-static friction with a non-associated slip rule is employed for general interface frictional contact condition. The contact constraints are imposed pointwise at the specimen (slave) boundary nodes. The assumption of rigid tools is made and nonlinear tool (master) segment geometry describing the contact kinematics is introduced. Consistent linearization in all aspects of algorithmic development provides robust and quadratically convergent solutions. After the capabilities of the model in representing physically realistic behaviours are rigorously tested in plane strain localization and axisymmetric necking benchmark tests, several numerical examples are presented, where simulations of both cold and hot metal forming processes including spike forming, industrial forging, flat rolling, tube expansion and thin sheet forming are performed. The robust and consistent numerical treatment of the thermo-mechanical theoretical formulations ensures generality and future upgradability of the model.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available