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CAD Now Epitomizes the Slogan: Have it Your Way

Physical prototypes are no longer fashionable for vehicle development. But to eliminate them completely, several trends had to fall into place within CAD, including new and improved application modules, surfacing tools, display techniques and data access.

Sticking at Indy

An interesting thing happened on the way toward "paperless" computer-aided design (CAD). "Virtual" became the rage. And that has ramifications. Virtual mockups are replacing physical prototypes. Virtual communication is replacing time and space, paper and fax. Virtual enterprises are replacing staid, hierarchical supply chains.

Now push has to come to shove. Virtual companies are composed of a fluid, but real, set of vendors. Virtual products are based on real products. Designers must see and modify product designs, and this requires new tools. The emphasis today is on designing complete products, not just detailing piece parts. And the software tools must be ready, available, and easy to use.

If all of this didn't exist, the virtual concept would collapse like a house of cards. But that's not going to happen. Today's CAD technology is responding in all sorts of ways.

Easier Virtual Creations

"More and more companies are making this journey from electronic drawings to 3D design, to 3D solid modeling, and now to digital mockup. Then they'll go to virtual product and process modeling and even introducing knowledgeware into the system," claims Philippe Forestier, executive vice president for the Americas of Dassault Systßmes of America (Burbank, CA), developers of CATIA.

Reverse engineering is one way of converting reality to "virtualness." Coordinate measurement machines (CMMs) do a pretty good job of this by scanning the physical model. However, there have been limitations regarding the generation of nice, accurate surfaces. Using laser technology in place of the touch probe, the CMM can collect hundreds of thousands of points and cover some extremely detailed areas previously unreachable. Unfortunately, laser-based CMMs still come up short in the next few steps: checking surface continuity, mating surfaces together, and comparing individual points or entire swaths of sur-faces to existing or imported CAD data. New CAD software is addressing these deficiencies. Take, for example, the STRIM Professional Solution from Matra Datavision, Inc. (Andover, MA). Its Reverse Engineering and Styling package reconstructs the surface model from a cloud of digitized points. It then provides the tools to smooth out the job, including offset (for thickness), fillet, pockets, bosses, and ribs. The finished model can then be exported to other CAD systems using IGES, SET, or VDA translators included with the package.

Better Solids

Regardless of the object to be produced, design and manufacturing technologies are moving from 2D to 3D. The resulting designs are featuring heavily stylized surfaces. In response, surface modelers are combining drafting capabilities with solids capabilities, reinforced by surfacing and surface machining capabilities. For instance, STRIM also gives designers a free-form styling tool that can tug, tweak, and pull surfaces all over the place to create complex surfaces. At the same time, it meshes the surfaces together, maintaining tangency and "curvature continuity" along the boundaries.

According to Bruce Boes, Matra's corporate vice president of Marketing Strategy, "STRIM is capable of creating surfaces of any number of sides within multiple boundaries, a common occurrence with complex blends and corners. The real trick here has been to ensure that you have nice, smooth blending of curves and that the surfaces flow from one to another or flow across a surface. Tangency guarantees smooth surfaces with excellent finishing and that are easier to machine, thus avoiding manual tooling adjustments. Curvature continuity is essential to aesthetic quality."

But creating fancy surfaces is not enough. New surface analysis tools ensure against gaps and overlaps and help to produce high-quality surface models for machining. For example, CATIA's Global Shape Deformation (GSD) module is a high-end module for skin deformation. Based on curves or surface wrapping based on multiple patches surface definition, GSD lets designers create styling effects and deformations, and define or simulate "physical" effects and springback compensations. The designer can control some context parameters, such as coefficient tolerance and surfaces subdivision.

Likewise, the latest version of I-DEAS Master Series from Structural Dynamics Research Corp. (SDRC; Milford, OH) includes features such as transitional views, selective assembly filtering, extended hybrid modeling, and enhanced finite element modeling. The first couple are focused at providing more effective ways of dealing with very large assemblies, such as the entire automobile, explains Mark Goldstein, vice president of the SDRC-Ford Program Office. Hybrid modeling supports the needs of body designers, such as for automotive surfacing. Extended finite element modeling, Goldstein says, "better addresses the needs of people who focused on body panel analysis as opposed to chunky part analysis."

Easier and Prettier Data Access

The Internet is a great example of "virtualness." The Internet can act as a facilitator to broadly publicize tips, techniques, best practices, and methods throughout the world. Intranets do the same, but at a local, intercompany level. "Within the next six to nine months you're going to see that the front end to our product data management product will be very Webcentric," predicts Goldstein.For a hint of this, SDRC's I-DEAS can invoke web browsers that operate on an intranet. Together, the CAD system and the browser go beyond a generic user interface and actually guide the user through the design of the part, subassembly, or entire vehicle. I-DEAS also includes a Virtual Reality Modeling Language (VRML) translator, which lets users view parts and assemblies in an animated fashion along with the presentation of a tip, technique, or best practice. "VRML really makes the conveyance of the message all that much stronger," says Goldstein.

However, don't let the term "virtual reality" confuse you. Points out John Baker, product manager of Geometric Modeling and Assembly Modeling for EDS Unigraphics (Cyprus, CA), "It's not reality. It's something we will be taking advantage of, but not necessarily in the form presented by the mass media, which follows the video game mentality." Baker sees stereo viewing as becoming popular well before "full immersion virtual reality." Stereo viewing is available and it provides more "visually rich, spatial feedback on the average workstation for the average engineer. Full immersion virtual reality is cumbersome, expensive and requires an awful lot of dedicated hardware, which is expensive and leads to other expenses."

Smarter and Easier CAD

CAD systems built upon object oriented (OO) technology are just now hitting the market. OO is making CAD easier by promoting context-sensitive workflow. Gone are the days of rows and rows of icons and the need to enter and exit the solids or surfaces module. Just pick a geometry in Euclid Designer, for example, and the interface will propose only those tools that can be applied to the design action being pursued. The result: interactions with the system are easier, the learning curve is reduced, models are easier to create.

OO really shines in giving lines, shapes, and other design features "intelligence." Explains Boes, "Euclid Designer creates `intelligent' objects that encapsulate information pertinent to their utilization, such as aesthetic criteria, technological function, material selection, and fabrication process." With it, a surface finish is more than a graphic representation on a drawing sheet. The tolerance of that surface finish will determine production speeds, feeds, and cuts, given certain materials.

Have It Your Way

The goal in CAD has always been to let designers design the way they want to design. The CAD system and associated tools shouldn't stand in the way of designing. This is one area that's no longer virtual, but becoming reality. Consider I-DEAS' extended variational technology (VGX). "VGX combines the best features of the two modeling paradigms currently on the market: direct geometry manipulation and history-based modeling," explains Goldstein. VGX lets designers dynamically capture and seamlessly integrate design, manufacturing, and simulation intent within a single master model. It lets designers work directly on the electronic product as if they were shaping the real part in their hands. And it preserves all the product knowledge, such as the inner relationships at the product's component and assembly levels, as the product evolves. As changes are made to the product downstream, the affected areas react accordingly in a fairly automatic fashion.

All together, the latest features in CAD let you go "full cycle," says Boes. "Do you want to start with a physical model, scan it, create a surface, and then build that into your virtual mockup? Or do you want to start with a virtual model, create a prototype of that, modify it, scan it again, reconstruct the surface, and then feed that into your virtual mockup?"

Likewise, what sort of computer do you want for that virtual mockup? Because personal computer (PC) prices are plummeting, CAD systems running on Microsoft Corp.'s Windows NT operating system is on "virtually" everybody's short list, especially at medium to smaller suppliers that are buying anywhere from 1 to 10 CAD seats, says Keith Charron, regional manager for SDRC's Greater Midwest Team. At the prices we're seeing today for PC microprocessors, multi-threaded, feature-rich, beautifully displayed PC-based CAD development lends itself nicely to Tier-3 usage, departmental usage, and even home usage. Throw in the Internet and the decreasing cost and increasing availability of ISDN, and you will be seeing more and more designers working out of their homes-and the virtual explosion of the virtual enterprise throughout the automotive supply chain.