The use of parametric CAD models in engineering, analysis, and optimization has greatly enhanced the effectiveness and efficiency of the product development process. Parametric models provide an attractive avenue for expansive design exploration. There still exists, however, a great challenge for products requiring design input from multiple disciplines. The collaboration of engineering disciplines can be hampered by many factors including: competing design objectives, communication of design changes, the use of different design and analysis software, and different geometry definitions. These obstacles become compounded when developing products at the assembly level. The use of solid parametric assembly models is not readily employed for products developed by groups from differing engineering disciplines. This is due to the huge cooperative effort required to create, analyze, and iterate on the geometry of the assembly model. The objective of this thesis is to present a method for separate disciplines to be able to analyze multiple parameterizations of the same CAD assembly to help develop a master parametric assembly, and to define the design space to be explored during analysis and optimization. This is done through a custom application developed using the Application Programming Interface of Siemens' NX CAD software. The custom application allows the user to monitor the affects of manipulating the driving parameters of an assembly by observing user specified geometry, features, or parametric expressions. The application also allows switching from one set of parametric design rules controlling the assembly to another in a matter of seconds. Manipulating and observing key geometry from different parameterizations allows engineering teams to discover the impact of each discipline's driving equations and geometry on another discipline. This will have a profound impact on multidisciplinary design teams in developing a robust parametric assembly, while still taking consideration of the requirements of each discipline. The collaborative efforts in the development of parametric assembly models used by multidisciplinary design teams are vastly improved through the method and application developed herein. This research will also show both the enhancements that could be made to existing CAD software, as well as the benefits of custom design tool development within the CAD environment.



College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering



Date Submitted


Document Type





CAD, API programming, interdisciplinary design, MDO, parametric modeling, design space, assembly design