Development of an Automatic Design and Optimization System for Industrial Silencers

Current computer-aided design (CAD) software tools focus on rapid production of computer models, which usually takes place after the product design is completed. The product design process, which has more significant influence on product life-cycle costs, is not fully supported. This work documents the development of an automatic design and optimization system for industrial silencers. The developed system greatly reduces the silencer design time from one day to a few minutes. Moreover, the system proves the feasibility of developing an open-architecture CAD system supported by design of experiment (DOE) based optimization methods to integrate product life-cycle considerations into the design. It is expected that the developed system can help the development of similar systems for other products. Through the development of this system, some further research issues are identified.

Today's global market demands quicker, cheaper, and better product designs for manufacturing industries. The computer-aided technologies help to reduce production time and costs. However, most current CAD tools function as a productivity aid to help speed up the modeling and drawing generation process. The product design, which generally influences 70-80% of product life-cycle costs (Boothroyd, Dewhurst, and Knight 1994), has not been directly supported by current CAD tools.

In the framework of concurrent engineering, much research has been done recently in the area of design automation with integrated optimization tools in CAD systems. One contribution proposed by the research team from Brigham Young University (Rohm III et al. 2000) provides a methodology of integrating parametric design with a programmatic toolkit to optimize product design. The methodology was applied to the design of a jet component using an interactive CATIA® environment together with the programmatic program, the CATIAIUA language. The complicated free-form surfaces of the airfoil and impeller of a turbine blade are designed using the CATIA programmatic toolkit. Also, the Brigham Young team tried to develop a common graphical user interface (GUI) to ease the programming and communication between various CAD packages. Line and Steiner (2000) in their research proposed a concept of automatic calculation of product architecture metrics using a solid modeling program, I-deas®, as the modeling tool. A program that uses internal I-deas functions is created to find all of the joined parts. The strength of each joint is calculated for adjusting the parts connectivity and the average joint strength to obtain a satisfactory design. Line and Steiner define the architecture of the product as the scheme in which functions are mapped to physical components. The result is a modular architecture (a one-to-one mapping of function to component) and an integral architecture (a many-to-one mapping of function to component). Then, Line and Steiner's method of architecture calculation is coded and integrated with the CAD tool to perform the calculation of architecture metrics automatically. A similar concept on design automation was developed by Chan and Lewis (2000), which involved integration of manufacturing and cost information into the engineering design process. Their research was proposed to create a design for manufacture (DFM) system called the DFM-C system for small to medium-sized enterprises (SMEs) to seek manufacturing and economic benefits. The DFM-C system was designed to apply to the conceptual phase of the design process, and its structure was based on an expert system called CLIPS (C-Language Integrated Production System).