The theory necessary to integrate the computerized aspects of the engineering product development process in a manner that is consistent with the way engineers perceive design is developed. The engineering design process is discussed. A survey of each of its phases is presented and their features, requirements, and limitations are assessed. Computer aided engineering data structures are investigated. A single data structure that combines features of three common data base structures is proposed. Computerized analysis methods are evaluated. The boundary element method is shown to be well suited for many engineering design applications. Optimization techniques are reviewed and the potential use of artificial intelligence in engineering product development is discussed. A shape varying method of product representation based on a hierarchical integer data structure, with a constraint management scheme and automatic model enhancement features is developed. It is used to integrate the design, analysis, and optimization processes. A beam spring design is used to verify new theories. The feasibility of generating design geometry from simple shapes is shown. Methods for performing design analysis and optimization using shape descriptions are discussed. It is shown that shape defined geometry is consistent with the way engineers perceive design