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Process Control of Microstructure in Manufacturing.
Final rept. 14 Sep 90-31 Dec 93,
WRIGHT STATE UNIV DAYTON OH
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This report presents a systematic methodology for the design of optimal process parameters for forging processes. The procedure for construction of a state space model utilizing nonlinear rigid-viscoplastic finite element formulation is developed. A coupled state space model is built to represent the deformation and thermal behavior of the material, with nodal velocities and nodal temperatures as the state variables, and die velocity as input to the system. The output variables of the state space system are the effective strain rate and critical nodal temperature. The linear quadratic regulator LQR theory with finite time control is used in designing the ram velocity and initial die temperature. Model reduction schemes are adopted in generating reduced order analytical models from the full size state space representation. The methodology developed is demonstrated on axisymmetric and plane strain forging cases. The performance of the procedure is evaluated using measures such as temperature and strain rate variation within the billet, load requirement, and total process time.
APPROVED FOR PUBLIC RELEASE