Function Modeling: A Study of Sequential Model Completion Based on Count and Chaining of Functions

Function models are widely recognized as a useful tool in mechanical engineering conceptual design as a bridge between problem and solution space. Unlike many other engineering design tools that are collaborative allowing many designers to contribute to the design task, function modeling has not been historically presented as a collaborative tool. This paper presents a controlled experimental study that explores the how different initial function models are completed by novice engineers influence the number of functions added to the model. Eighty-eight senior mechanical engineering students were given partial function models to two similarly complex engineering design problems. Each student was asked to complete the function model to best address the problem presented. The number of added functions was compared considering two variables: percent completed of initial seed model (10%, 40%, and 80%), initial chaining of functions (forward, backward, and nucleation). It was found that models for Backward Chaining and Nucleation at 10% initial seed resulted in the greatest addition of functions by the students. Further, Backward Chaining and Nucleation yielded more added functions than Forward Chaining in all seed configurations. Recognizing that there is a difference between Forward Chaining and Backward Chaining or Nucleation, further study is warranted to understand how individuals create function models and which approach yields more useful models to either understand the problem presented or to explore solution options.