Abstract
The research is focused on the development of an expert system to generate welding procedures for arc welding processes. The system has been developed on an IBM AT microcomputer, using an expert system shell KES (Knowledge Engineering System), a product of Software Architecture &38 Engineering Inc. The system is primarily intended for novice users, hence good `help' facilities and graphical representations are provided in the system. The procedure designer has been developed in a modular structure for ease of software readability, editing, and testing, and to readily facilitate further development. The knowledge base is partitioned into several sections; company's data, material and joint specifications, process selection, joint preparation, and welding parameters. For flexibility of the system, these knowledge base sections are embedded in the various modules which are linked to a main program which controls the flow of information throughout the system. Data and information required in the system are stored in database files and some are embedded in the rules within the knowledge base. The main program and program interfaces are written in the `C' programming language. Knowledge and expertise required for the knowledge base were elicited from various resources; welding experts, published welding data and published welding parameters relationships, for example BS 5135. The welding processes included in the fully developed prototype system are Manual Metal Arc, Gas Metal Arc, Submerged Arc and Gas Tungsten Arc Welding, and the materials covered are Mild Steels and Carbon-Manganese Steels with reference to BS 4360. Knowledge is represented using two of the inference engines provided in KES, either as rules in the Production Rules Subsystem or as descriptions in the Hypothesis & Test Subsystem. Values for the entities or attributes, both provided by the user and inferred with the system, are either backward or forward chains to reach the goal. Welding procedures, as the main output generated by the prototype system, are intended to meet the specification of BS 4870 and BS 4871. The research has shown that the expert system can generate welding procedures for a particular application and can be used as a tool to assist novice engineers, in terms of welding and fabrication experience, as well as welding experts in the design and writing of welding procedures. Empirical tests have proven acceptability of the generated welding procedures. The system is capable of further development for use as a procedure designer within an integrated flexible welding system.