Determination of appropriate product design criteria depends on the requirement specifications as well as their interrelations with other life cycle process information. Although the representation of the design requirements for creating a desirable product/part is a necessity, most of the time it has been carried out by the designer based on his/her own experiences. Such requirement handling processes need deep understanding of the product design, materials, manufacturing, working environments, finance and regulations, and are normally cost ineffective and error prone. Furthermore, very little attentions have been paid to the development of a structured requirement modeling for future intelligent applications. After a systematic study on the categorization of product design related information and requirements, this paper proposes an ontological framework for representing information and knowledge about the engineering product requirements. To demonstrate the use of the proposed requirement model and its role in the requirement management process, a case study related to an automotive brake rotor has been discussed in detail.