By Peter Bartholomew
Editor’s Note: The topics addressed in this article are treated in greater detail in the recent NAFEMS publication, “The State of Current Practice in Engineering Design Optimization.” Those with a desire to increase their involvement are encouraged to become members of the newly formed NAFEMS Working Group on Optimization.
This should be the decade where design optimization finally emerges from the province of university research and specialist groups within the aeronautics and automotive industries to take its place in the mainstream of engineering product design. Industrial-strength commercial software is now available in the marketplace, and is becoming increasingly accessible to designers as the trend to incorporate engineering analysis into CAD products gathers momentum.
As a concept, design optimization is as old as that of stress analysis. In 1687, Galileo published work on the optimum strength design of a variable depth cantilever.
By the time of the Second World War, optimization played a key role in establishing the principles used for the design of compression structures in aircraft.
The state of the art was to change totally during the 1960s, with the increasingly widespread availability of the digital computer. The structural design optimization problem could be formulated as a combination of numerical optimization methods that were being developed under the name of Mathematical Programming to support the Operations Research community and the emerging finite-element method.
By 1980, Christian Petiau was able to report a decade of optimization applications at Dassault built around the use of Elfini.
With such strong foundations, it is interesting that the area has had to wait so long to take its place as a major driver for innovation in product design, with the potential to impact both time and quality and, ultimately, the financial viability of companies.
As an organization, NAFEMS makes every effort to remain in touch with the needs of its 1,000 or so corporate members worldwide, and in one EU collaborative project, 110 European organizations operating within eight industry sectors provided prioritized requirements for engineering analysis. At that time (2005), optimization ranked 41st in importance out of the 74 topics identified; with validation and verification ranking highest, along with the development of high fidelity methods for the capture of increasingly complex structural behavior.
However, a different balance of priority was to emerge two years later from the AutoSim project. Integration had become a major driver, and both process automation and multidisciplinary design optimization were seen as key elements for the delivery of new products. The goal of the project was to achieve an 18-month product development cycle with upfront simulation, driving design from analysis.
This shift from simulation as a product validation tool to part of upfront design provides fresh impetus to product optimization. It requires a paradigm shift involving changed processes, new tools and, even more critically, new mental behaviors and the acquisition of new skill sets for engineers.
Whereas analysis takes a pre-existing product or concept and predicts performance, optimization reverses the process. Given a set of performance metrics defined by requirements, it establishes the best form for the design and determines optimal values for the defining parameters. To work well, it is essential that the analysis itself is accurate and that the geometric features of the model are sufficiently flexible in their definition.
Both the closer working of designers and analysts within a team and the democratization of simulation, allowing approved simulation processes to be made available to designers within CAD systems and integrated within process automation systems, are factors that are making it possible to apply design optimization techniques at the point in the process where substantial design freedom still exists.
Peter Bartholomew chairs the NAFEMS CAD/CAE Integration Working Group, and has been active within NAFEMS since its inception. Send e-mail about this article to DE-Editors@deskeng.com.