Composing Simulations by expert rules: modeling plasma sprayed films

A hybrid knowledge-based simulation model of a plasma sprayed film is presented. It represents an example of a multiple part simulation model coordinated by an expert system. Films are formed by spraying plasma drops. With the simulated arrival of each plasma drop at its target area on the film, a knowledge-based program tests a set of conditions which take into account various characteristics of the drop and of the target impact area on the film deposited so far. Based on the conditions, one of multiple simulation scenarios corresponding to different physical situations is activated. Thus, one simulation generates the spray and travel through space to the target area; an 'expert system' chooses which of many simulation scenarios to run as each drop makes contact with the film; and the process continues until the completed film is built up. Statistics are run over the whole film volume to determine quality features which are of interest to engineers such as the percentage of crack-like...