Knowledge Based Synthesis System for Injection Molding

An interactive computer-based design system is developed to eliminate the need for costly iterations of protype tooling in injection molding. A knowledge-based synthesis system is constructed to embody the principle of a rational design strategy for injection molding by combining a rule-based expert system with process analysis programs. The thermomechanical properties of a molded part are predicted via a usertransparent cavity filling simulation program. A unique automatic mesh generation program is developed to complete the cavity filling simulation in real time. A boundary-pressure-reflection scheme is established to solve the moving boundary problem of mold filling. A theoretical model for weldline strength is presented to provide a comprehensive knowledge of the bonding process at the weldline interface. Based on the mathematical models for weldline and molecular orientation, the spatial variation of microstructural anisotropies within a molded part is predicted from the result of cavity filling simulation. Heuristic knowledge of injection molding is formalized as production rules of the expert consultation system. The expert system interprets the analytical results from the process simulation, evaluates the design and generates recommendations for optimal design alternatives. A prototype knowledge-based system is built to integrate the two domains of knowledge of injection molding, heuristics and analytics, into a rational design strategy. Thesis Supervisor: Prof. Nam P. Suh Title: Professor of Mechanical Engineering