Often product development processes, in the market-pull cases, start with identifying the needs or problems that the product is expected to satisfy or solve. The initial needs and problems should be formulated into abstract, unambiguous, traceable and validatable design requirements (Brace and Cheutet, 2012). Design requirements coordinate the diverse desires in the end product and provide the basis of synthesizing a solution (Darlington and Culley, 2004). Various studies have been conducted in the engineering design field both descriptively to comprehend the design requirement practice, and prescriptively to improve practice through developing theories and methods etc. (Darlington and Culley, 2002). Several procedures for developing design requirements have been proposed in literatures e.g. (Dieter and Schmidt, 2007; Pahl, et Al., 2007; Ulrich and Eppinger, 2011).
Poorly identified design requirements can lead to inappropriate products (Hall, et al., 2002). Understanding the nature of design requirements and the sources, from where they can or should be generated, is critical to before developing methods and processes to support this process. Requirement Engineering research, originated from the software development field, highlights the traceability of design requirements e.g. (Grove, et al., 2005), which also implies the significance of recognizing design requirement sources. However, a clear view of the sources for eliciting design requirements is still lacking, especially in the engineering design field. Therefore, this paper intends to investigate potential design requirement sources and the contribution and challenges of each source. The research question investigates a way: how do design requirement sources contribute to the final design requirement set?