On Evaluation of Design Concepts : Modelling Approaches for Enhancing the Understanding of Design Solutions

Sammanfattning: This dissertation embraces the issue of evaluating design concepts. Being able to sort out the potential“best solutions” from a set of solutions is a central and important part of the design process. The subjectdiscussed in this dissertation has its origins in the lack of knowledge about design concepts, somethingwhich is characteristic of the initial part of the design process and which frequently causes problems whenit comes to evaluation and selection of solutions. The purpose of this dissertation is to develop aids andmethods that enhance the understanding of design concepts in the early phases of the design process.From deductive reasoning about the fundamental mechanisms of the evaluation activity, the work hasbeen divided into three different areas: process and system modelling, concept optimisation, andidentification of potential failures.The bearing of the work within the area of process and system modelling has a verifying character. Theobjective of the work has been to analyse how established design methodology, which has its commonapplications within traditional engineering industry, may be applied within an area that is characterised bymore multidisciplinary interfaces, like biotechnology. The result of a number of case studies, in whichdifferent types of biotechnical systems where analysed and modelled, shows that the methodology isapplicable even for biotechnical products. During the work the methodology has also been furtherelaborated on in order to better suit the distinguishing characteristics exhibited in the development ofbiotechnical systems.Within the area of concept optimisation, an approach for optimising the concept generation has beenelaborated. By formalising the step in both concept generation and evaluation, it has been possible toapply genetic algorithms in order to optimise the process. The work has resulted in a model thatautomatically creates and sorts out a number of potential solutions from a defined solution space and adefined set of goals.The last area, which deals with identification of potential failures, has resulted in a rather novel way toconsider and model the behaviour of a system. The approach is an elaboration of the modellingtechniques within system theory, and deduces the system’s behaviour from known physical phenomenaand the system’s ability to effectuate them. The way the different behaviours interact with one another, byaffecting the properties of the system, determines the potential for a failure to occur. A “failure”,according to the model, is described as an unintended behaviour which obstructs the system’sfunctionality, i.e. which affects the conditions of a desired behaviour.The dissertation has resulted in three different means for approaching the difficulties associated with theevaluation of design concepts. The means are applicable during different parts of the design process, butthey all address the same issue, viz. to enhance the understanding of the design solutions.