Inventor's Functional Design: Is it Really New?

25 Sep, 2006 By: Kenneth Wong

Competitors weigh in on Autodesk's latest catch phrase

At last month's Autodesk Manufacturing Solutions Media Summit, the company put forward a new mantra: functional design. It's a different modeling paradigm, a departure from how we've always been designing, say Autodesk officials. The concept is to use a simple schematic and a series of input variables to automatically generate 3D geometry. In other words, specify the function of the design, then let the software generate the part's geometry. In its online literature, Autodesk calls the concept "innovative technology found only in Autodesk Inventor."

Following that event in August was a barrage of media and individual response -- much of it taking issue with the claim that the functional design concept is new. Is Inventor's functional design in fact a new species -- or was it a preexisting animal? Some Autodesk competitors say it is practically a prehistoric beast. Rainer Gawlick, vice-president of worldwide marketing for SolidWorks, says, "Asking the CAD system to generate geometry is a notion that's been around for a long time. There's nothing new about that. ... It's a notion many vendors, including SolidWorks, have pursued."

Sandy Joung, PTC's director, product marketing, observes that Autodesk's use of the term might be different than what we've seen in the past. "The original functional design solutions from vendors such as ImpactXoft leveraged a predefined feature tree, which was felt by many designers to be too restrictive and not optimal for iterative design. Autodesk, on the other hand, has a different definition."

Hand Over the Handbook
Some of those who say functional design is not new cite as precedent the concepts put forth in the MechSoft Engineering Handbook, a product that's at least half a decade old. Some also point to features in their own CAD systems as distant cousins of functional design, sharing the same MechSoft DNA but brought up in a better environment, they say.

MechSoft was acquired by Autodesk in February 2004. Formerly a privately held Czech-based company, MechSoft maintained headquarters in Austin, Texas, and in Prague. Its family of products included an extensive library of parts, a calculation-driven parts generator and online engineering reference information. Add-ons for various solids modelers included MechSoft for SolidWorks, MechSoft for Pro/ENGINEER and the Solid Edge Engineering Handbook.

To be fair, Autodesk never hid its intent to crossbreed MechSoft technology with its own. At the time, Autodesk announced it would acquire "certain assets of MechSoft," then "integrate key components ... into future versions of Autodesk Inventor Series." In the official announcement, the key components are listed as:

  • more than 50 calculators and design wizards (for example, bolted joint, shaft generation, gear, cam and spring wizards);

  • a drag-and-drop content library consisting of more than 1.5 million parts representing all prominent international standards; and

  • the aforementioned mechanical engineering handbook.

Something Old, Something New, Something Borrowed
"I think [Autodesk's functional design] is a combination of two concepts," suggests PTC's Joung. "They're combining a standard catalog of parts with basic rules in the Engineering Handbook, which govern functional performance requirements and subsequently drive the geometries to meet those requirements."

Andrew Anagnost, Autodesk's senior director of CAD/CAE products, Manufacturing Solutions Division, says, "The Autodesk vision for functional design extends far beyond the acquisition of MechSoft. The MechSoft acquisition was a tactic to execute on key functional paradigms for machinery components. There are many functional environments inside Inventor -- the FrameGenerator, tube and pipe design, and wire harness design are just a few examples -- that are not related to or the result of the MechSoft acquisition. It is our intent to make functional design the pervasive paradigm in the CAD application."

Functional design, as implemented in Autodesk Inventor.

Different Incarnations of Functional Design
When Autodesk bought MechSoft assets, they took them off the market, explains Dan Staples, director of Solid Edge Business Unit at UGS. "So [MechSoft software] is no longer available to anyone else." However, he says Solid Edge users shouldn't lose any sleep over the demise of Mechsoft's Engineering Handbook. "We quickly replaced [the Solid Edge Engineering Handbook, which debuted in 2000] with an offering called Engineers Reference in V18 ... so there was no loss of continuity."

Solid Edge V18's Engineers Reference replaces MechSoft's Engineering Handbook from earlier versions, according to UGS.

SolidWorks' Gawlick adds, "Autodesk took the MechSoft incarnation of the handbook off the market, but there are many software packages that a user could use to get the handbook calculations in an automated way."

Gawlick says Autodesk's acquisition of MechSoft assets "was not a big deal for us, as MechSoft had a very small following in our customer base, probably because the MechSoft approach does not match the workflow people typically use in product design." He says that calculation-based geometry isn't a priority for SolidWorks users.

He argues that two SolidWorks components -- Smart Parts and Optimization features -- can stand in for functional design and, in his view, represent a more sensible approach to letting the software generate geometry.

"Let's say you want to place a bolt at a certain location," he says. "What SolidWorks does is, once you've decided on the type of bolt you want, automatically creates the geometry, sizes the bolt properly and generates the ancillary items like washers for you. If you want to minimize the amount of materials used on a part, subject to certain performance criteria, you specify that there are five dimensions that can be changed on the part, tell the software the part should be able to carry a certain minimum load, then let the software figure out the best geometry to meet these criteria."

Normally after assembling a pulley, one would look up the proper size bushing, screws, key and keyway to add to the assembly. Using SolidWorks Smart Components, all those components are added to the assembly and the keyway is automatically cut into the shaft at the proper location.

Goodbye MechSoft, Hello Mathsoft
PTC's countermeasure is Mathcad, a Windows-based engineering calculation solution from Mathsoft, which PTC acquired in April 2006. "Think of the Mathcad worksheet as the engineering notebook," says Robin Saitz, PTC's vice-president of solutions marketing. "You use it to capture the critical engineering calculations that drive the geometry, so when you tie these calculations to the Pro/ENGINEER model, you drive the functional requirements of the model."

Saitz also reminds us about behavioral modeling, a feature available with Pro/ENGINEER for almost five years now. Using this approach, she explains, "the geometry transforms itself based on your functional requirements."

In PTC's description, "When you have multiple design objectives to consider, such as how to maintain product strength while reducing material wall thickness, it can be very tedious and time-consuming to manually calculate the optimum values. Even then you can't be sure that you have the optimum design, because it simply takes too much time to calculate all of the various possibilities that might work. Pro/ENGINEER BMX (behavior modeling extension) automates this process for you with design studies."

The Ideal Shaft and the Real-World Compromise
SolidWorks' Gawlick warns that most engineers usually start out with readily available parts or standard parts; they don't design an assembly around ideal parts. "The problem with these engineering calculations," he says, "is that you can end up generating parts that no suppliers provide, hence requiring expensive custom parts."

All the features of the shaft (length, bearing journal locations, size and tolerancing, tapped hole, wrench flats and keyway) are determined by the positions of other components. Hence, the workflow isn't likely to start with an idealized shaft. This, argues SolidWorks' Rainer Gawlick, is the reason there hasn't been much enthusiasm for calculation-driven geometry among the software's customer base.

UGS's Staples remarks, "I do think there's still value in [being able to design the ideal part], even though, after looking at its parameters and geometry, if it'll cost too much to custom-manufacture it, I'll go out and get something close enough that'll fit the bill." And that something is probably an existing part from a supplier's online catalog.

What's in a Name?
"Functional design is something most CAD companies do to some degree, and frankly I don't think anyone will lose or win a lot of sales from it," observes Jeffrey Rowe, editor/publisher of MCAD Café and a contributing editor for Cadalyst.

UGS' Staples sums up his feelings about the issue, possibly putting an end to the semantic quibble -- at least for now: "When a CAD system is designed by those who understand the engineering process, it doesn't matter whether you call it 'functional design' or 'apple.' It'll still serve the engineer."

Additional Resources
On the Edge: Engineering Reference in Solid Edge (Cadalyst tutorial), March 2006.
Inventor In-Depth: Autodesk Inventor Features Functional Design (Cadalyst tutorial), June 2006.

About the Author: Kenneth Wong

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