Int J Interact Des Manuf (2009) 3:13–23 DOI 10.1007/s12008-009-0057-9 ORIGINAL PAPER Analysis and evaluation of product design through design aspects using digraph and matrix approach V. Paramasivam · V. Senthil Received: 17 November 2008 / Accepted: 15 January 2009 / Published online: 6 February 2009 © Springer-Verlag 2009 Abstract Product design evaluation is essential for all manufacturing industries to explore the soundness and effec- tiveness of the product design. This paper presents a math- ematical model for evaluating and analyzing the product design alternatives using graph theory and matrix approach. In this paper, various contributing factors are identified and their relative importance has been considered. A digraph model is constructed to represent the abstract information of the product design which takes into account of all the factors and is much useful for visual analysis. The digraph model is converted into matrix form, which is used for computer processing. An index is obtained from the product design evaluation function, derived from the matrix for all prod- uct design alternatives and it shows the effectiveness of the product design. Indices are calculated for all product design alternatives and they are ranked in ascending order and the product design corresponding to the first rank is selected as best one. The proposed methodology is quite versatile from the point of view that it integrates all factors of the prod- uct design. An example has been included to illustrate the methodology proposed in this paper. Keywords Product design · Digraph and matrix approach · Product design evaluation index V. Paramasivam (B ) Department of Mechanical Engineering, PSNA College of Engineering and Technology, Dindigul-5, India e-mail: pudidha@yahoo.com V. Senthil Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, India e-mail: vsenthil_cit@yahoo.com.sg 1 Introduction A successful product design fulfils the consumer’s needs. It is very important for the designers to recognize these needs go beyond the utilitarian and functional to include the inspi- rational, emotional and cultural. Also new product develop- ment is indeed very important for manufacturers. However, developing newer products is a risky and uncertain process. In order to reduce the risks and uncertainties, companies need to evaluate their new product initiatives carefully and make accurate decisions. This demonstrates the increasing impor- tance of the role of design both for economic competitiveness and for improvement of the quality of life and work. One of the major directions during the design process is that the products should manifest end users point of view, from ini- tial concept to their distribution to the market place. Thus the product design evaluation is must at all phases of the product development process from concept phase to detailed design phase. Design evaluation is time consuming and laborious, since many factors have to be considered in relation to the development and design which vary in character and com- plexity. Design evaluation cannot be made without structured decision making tools (aids) since the decision alternatives are too many and simultaneous criteria impact on the decision are too vast to consider at once by human decision makers. Maddulapalli and Azarm [1] addressed both kinds of var- iability, i.e., variability in the preferences of the decision maker and variability in the attribute levels of the design alternatives. They presented a method for product design selection with variability in preferences for an implicit value function and later extended it to account for variability in attribute levels of design alternatives. Besharati et al. [2] pre- sented an integrated design and marketing approach to facili- tate the generation of an optimal robust set of product design alternatives to carry forward to the prototyping stage. Their 123