Computer modeling of complex metal forming processes using the upper bound elemental technique (UBET) and modified upper bound elemental technique (MUBET)

Metal forming is one of the most important manufacturing techniques that has been used to produce a variety of metal products for centuries. This dissertation addressed the development and use of mathematical models for the analysis and design of profile ring rolling, complex forging processes, and forging pre-form design using backward simulation.; The objective of this research work is to develop a mathematical model for profile axial-radial ring rolling and closed-pass ring rolling and to establish an effective design tool to determine optimum forging strategy for a given final geometry, which implies maximum material utilization and reduction of die design tryouts and manufacturing costs by using appropriate pre-form, achieving required microstructure, identifying critical process variables and parameters in order to improve the consistency of the process, and reducing material waste and energy consumption.; The developed model for simulating the process of axial-radial profile ring rolling and closed-pass profile ring rolling is based on the Upper Bound Elemental Technique (UBET). Also, the models developed for forging pre-form design as well as forging process are based on modified UBET, in which the kinematical admissible velocities fields are derived based on volume mapping approach and evaluated by minimizing the total energy rate of UBET.; The developed models have been successfully tested and implemented using verities of test cases. These models have several advantages, such as computation efficiency, while maintaining a reasonable degree of accuracy as well as capabilities to predict the various process variables.; The research work developed can be applied directly or with simple modifications to other forming processes. The developed models have several advantages, such as prediction of process variables with acceptable accuracy and with quick calculation time. These models can be used as analysis and design tools.