Given the initial functional specifications for a product, a designer must create the description of a physical device that meets those requirements. The final design must simultaneously meet cost and quality requirements, as well as meet the constraints imposed by activities such as manufacturing, assembly, and maintenance. Mechanical designs are often composed of highly integrated, tightly coupled components where the interactions are essential to the behavior and economic execution of the design. Therefore, concurrent rather than sequential consideration of requirements, such as structural, thermal, and manufacturing constraints, will result in superior designs