A hybrid knowledge based system for cost modelling applied to aircraft gas turbine design

This paper presents a novel technique for representing cost information for a candidate design. The underlying principle involves the use of a knowledge based system for cost modelling that makes the cost implications of design decisions more visible and available to the designer at the concept design stage. The development of a hybrid between hierarchical trees and an object-oriented knowledge representation of cost and manufacturing knowledge is given. The representation of cost and manufacturing information as an abstract product structure and reusable object libraries is shown. The extraction of key geometric information needed from a CAD system is discussed and demonstrated. The tool is intended to provide a clear and easily audited response to incremental changes in component geometry and the product definition. The tool is also capable of modelling stochastic quantities present in cost models and can therefore analyse cost risk. A case study demonstrating the research applied to a Rolls-Royce aircraft gas turbine engine component is presented. This case study also demonstrates how the tool is deployed using web technologies through a client running standard browser software.