An Early Modeling and Simulation Approach for Fast Evaluation of Early Design Concepts

Being able to quickly model and simulate very early design solutions in the design process is an important practical issue for engineering designers. Early design is characterized by the small amount of quantitative data available at the beginning of the development process. The task is becoming cumbersome for engineers when in addition they do not possess extensive knowledge of the domain of interest. In this context, traditional modeling and simulation methods are disqualified for supporting the early engineering design choices because they require too much details and precise quantitative information. The approach considered in this article to supply the deficiency of traditional modeling methods is combining three domains of physics and mathematics: qualitative physics, dimensional analysis and graph-based representation. The present article develops the general framework which is emerging from this combination. The authors develop the framework to the fast modeling and simulation of an air bearing. The structure of the article is the following, first the basis of the modeling and simulation method are briefly presented. In a second step the entire approach is developed on the case of an air bearing concept with the goal of making the presentation as pedagogical as possible. A causal ordering heuristic is used and combined with the topology of the concept to test. This is gradually leading to a causal graph which is transformed into a flow graph that can be simulated in system dynamics simulation tools. A new and easy approach to discover the laws governing the system dynamic model is also explained. Finally the model is simulated and analyzed. As a result, the method presented in this article offers several advantages: 1- it can be supported by a dedicated computer aided approach, 2- it brings simulation capabilities at very early design stage level where it is seldom present.