Abstract: The three determinants for a successful product development are higher quality, lower cost and shorter time-to-market. These determinants interact with each other in the whole process of product design and the emphasis on any one of them will induce the cost of others. The needed balance among them is extremely complex, especially in the design process, which is a major part of the product development processes. The primary problems lie in that a design process inherently contains a number of coupling activities, which imply potential iteration of the process. Hence, how to model the design iterations and seek the balance on allocating limited resources to facilitate each of the three determinants for an iterative design process has become one focus of recent research. An analytical model (M-WTM) is presented for modeling design iterations and providing estimates in terms of time, costs, and resources by dint of detailed analysis of the interrelationship among design activities, which is based on the work transformation matrix (WTM). According to the resources, this model will tackle purely sequential iteration, purely parallel iteration or mixed iteration. A complicated example, profiled bar product development design, was employed to illustrate the effectiveness of M-WTM.

Key words: product design iteration, mixed iteration, M-WTM model