Evaluation activity in the conceptual phase of the engineering design process
Chapter 4 describes the synthesis and development of a Conceptual Design Evaluation Method (CDEM) that is an amalgam of a number of methods and approaches taken principally from the probability, reliability, and quality domains. Decomposition of design is employed to enable evaluation at design characteristic level with the total design evaluation being achieved via recomposition by means of Conceptual Design Factor Ratings (CDFR) and Conceptual Design Solution Ratings (CDSR). This methodology is next tested, within a controlled design environment, in order that its validity can be assessed. The experimental approach used is described in Chapter 5. The results of this experiment, which uses students along with technical and academic staff from the Department of Mechanical Engineering at the University of Glasgow as subjects, indicate that the developed Conceptual Design Evaluation Methodology does exhibit validity within the limits of the experimental environment. It is shown that the CDEM can match expert selection of preferred concept options thus offering the potential of enhancing novice capability and of providing advisory support to experienced designers. The experiment also exposes the problem of objectivity in design evaluation however it is also shown that the CDEM approach acts to mitigate against this tendency by effectively reminding the designer of the benefits of a range of conceptual options. In parallel, the experiment also exposes the limits of human objective evaluation in terms of the complexity of criteria addressed as well as the number of conceptual options considered. Once again CDEM is shown to enable evaluative objectivity to be maintained with increasing complexity. It is also suggested that the CDEM approach is appropriate for a concurrent engineering environment since it displays a capacity to enhance traceability of design decision making. Finally, conclusions are provided regarding the specific outcomes of the described research along with implications for the wider issues of coherent design research strategy and professional engineering design practice.