To foster an effective collaboration during product lifecycle activities, product information must include data on geometry and topology, assembly constraints and associations, design and product processes, the functions and behaviors of the product, and the design intent. A product has many associations among its parts in terms of assembly, function, behavior, tolerance, kinematics, etc. These associations need to be represented in a consistent way, so that they will not conflict with each other. There have been many efforts to connect function and behavior to structure, but there exists no complete, consistent method yet. It is especially critical in the conceptual development of a product, as well as during its evaluation. The work described in this paper should help people make intelligent decisions by allowing them to manage product lifecycle activities from different perspectives (i.e., function, structure, etc.) using the knowledge of how the product information is interconnected, and how artifacts affect each other. In this study, functional and behavioral models have been developed to represent assembly-related product knowledge. These models connect functions, behaviors and structures - Through the parts of artifacts using input/outputs and artifacts' functional associations (i.e. spatial and design relations/requirements) at different abstract levels of product information. A planetary gearbox has been used as a case study to show how the functional/structural model can be implemented.