Simulations are wonderful "after-the-fact" tools. Consider two graphic animations of some prominence: the CIA-produced computer simulation of the last minutes of TWA Flight 800 and the computer simulation of the last hours of R.M.S. Titanic featured in James Cameron's film. Both provided keen insight into the death throes of great machines. Neither managed to do the passengers and crew any good.
Universities and manufacturers are developing a new generation of analysis techniques that enable designers to study realistic computer models in lifelike, dynamic settings using commercially available software. Moreover, the software will be familiar to most CAD users. These simulation-based design (SBD) technologies promise unprecedented flexibility and realism. Ideally, SBD will highlight problems early enough on in the product development process, where they may be addressed more cost-effectively.
Up and running . In recent years, engineers have achieved a measure of success with virtual prototyping. Many leading manufacturers, among them Boeing, Chrysler, and General Dynamics' Electric Boat, have saved millions of dollars on fighter planes, automobiles, and submarines by replacing physical prototypes with computer mock-ups. Solid-modeling CAD systems have provided the enabling technology in this area. In practice, these successful programs enable engineers to fly-through static, if complex, models examining assembly, interference, and accessibility issues.
In SBD, the virtual mock-up is merely a starting point. Virtual prototypes may contain many different subsystems and components, all of which interact with each other. These definitions come courtesy of the Defense Advanced Research Projects Agency (DARPA), which is sponsoring a multi-phase effort to define the essential characteristics of SBD and see them implemented in defense-related contracts and private enterprise.
In its formative years, DARPA's SBD program centered on developing technologies and procedures for improving the nation's shipbuilding capabilities. Two contractor teams won bids to conduct feasibility demonstrations: General Dynamics, Electric Boat Division teamed with Deneb Robotics, Intergraph, Loral Federal Systems, Parametric Technology Corp., Silicon Graphics Inc., the University of Iowa, and the University of North Carolina; and Lockheed Missiles and Space Company (now Lockheed Martin) teamed with Newport News Shipbuilding, Science Applications International Corporation, and Fakespace. The Phase I demonstrations refined procedures for creating and refining CAD assembly models and related product data.
Phase II began in fiscal year 1995. During this phase, critical technologies will be developed and integrated in a prototype system, as broadly defined during Phase I. DARPA selected a team headed by Lockheed Martin to develop a prototype SBD system. While no specific product will be designed or developed, a generic surface warship was chosen as a demonstration project. To date, Lockheed Martin has produced design simulations of deck gun firing arcs using the dVISE simulation package from Division Inc.
DARPA specifies a number of potential SBD payoffs:
- Design times may be reduced in half.
- Advanced technologies can be investigated "on-the-fly."
- Physical prototypes can be eliminated.
- Initial design quality can be im-proved, resulting in significant life-cycle cost reductions.
- Communication can be enhanced using virtual reality technologies, giving a sense of experiencing the design.
- Manufacturing and operations can be assessed prior to construction.
According to Paul