"Staring Down the Divide," Feature Article, August 2003

FEATURE FOCUS: Working Together—MEs and EEs

staring down the divide

Electrical and mechanical engineers work together on products like cell phones. Too bad their software programs don't.

by Jean Thilmany,
Associate Editor

Like cellular telephones and computers, all products made up of a combination of printed circuit boards and shaped materials like plastics require a rather tight degree of cooperation among mechanical engineers, electrical engineers, and finite element analysts. But today's computer-aided design and finite element analysis technology isn't advanced enough to let them work as skillfully together as they might.

Engineers and analysts still need to translate their designs into a neutral file format in order to pass files between their different software systems and much can be lost in translation. But a number of engineering software developers are refining products to break down some of those barriers.

When technology can integrate electrical and mechanical design with analysis, time to market for products like computers and cell phones, with up-to-the-minute marketability needs, can be slashed considerably, according to Hoss Foadian. He's a manager of business development and engineering services at Abaqus West Inc., a developer of FEA technology in Fremont, Calif.

"Right now, the problem arises from the different goals of different engineering disciplines," Foadian said. "Because of the differences, the process of taking a specification from the marketing people and creating an actual device and taking it to customers in the marketplace is normally longer than desired. People want to bring these disciplines closer and closer to each other to reduce time to market."

In today's consumer electronics marketplace, time to market is a crucial buzzword, said Gian Paolo Bassi, chief technology officer at ImpactXoft, a maker of CAD technology in San Jose, Calif. His company, like many CAD marketers, is taking steps to address the technology disconnect between electrical and mechanical engineers.

In the 1960s, electronics became the big thing in consumer products, Bassi said. Suddenly, everyone wanted a modular plastic stereo or a transistor radio. Mechanical and electrical engineers worked together on increasingly sophisticated products meant to please fickle consumers. The introduction of high-technology products like computers and cell phones ramped up product turnaround times even more. Ultra-modern high-tech items are redesigned and re-engineered frequently and include new features to lure buyers into trading up.

"For instance, take a cell phone," Bassi said. "There's a big rush to sexier shapes and to put more and more new models on the market. But that's not because the fundamentals are changing dramatically. Cell phones have new color displays and have cameras on board now. You need to have 50 different models. If you target business professionals, you don't want to give them a sexy shape and a pink cell phone."

According to Bassi, the weakest link in the development chain is the design of the actual product. He called it the pain and difficulty of consumer product design. Bassi said the pain stems from mechanical CAD programs that can't easily integrate electrical components into a mechanical design.

FROM PART TO WHOLE

Foadian outlined his impression of the usual method that electrical and mechanical engineers follow when designing electrical products. First, a company's marketing department specifies a new product design—say, for a cell phone—that it thinks will be a hit with consumers. Because of the nature of the product, the specifications encompass both the electrical and mechanical engineers' realms.

Electrical engineers draw a schematic design—usually a simple line drawing that shows how different chip sets or printed circuit boards need to be connected via traces in order to power separate components. This early schematic is basically a layout of the electrical components and how they can be tied together.

"They want to make sure you can have a display that can show the incoming calls, show time, and maybe include a clock on it if that's what you need," Foadian said. "They leave everything at this point for the next group of engineers. They don't care about the envelope."

Two CAD views of a cell phone assembly created with software from ImpactXoft. In the bottom view, the electrical engineer has opted for a larger display screen than in the original at top. The mechanical engineer must adjust the size and the fastening method of the display cover and the frame.

The electrical engineer determines how many circuit boards will be necessary: One might operate the cell phone screen, another the clock, and so on.

The electrical engineers then hand off their schematic to the next group of engineers, also electrical. These are the circuit board designers. They use electrical CAD software to design the needed circuit boards. Then the project is handed off to the mechanical engineering department.

"They have the tough job of putting all the boards into this neat handheld device," Foadian said. "On a cell phone there typically might be 10 boards. On a PC, there might be a lot more."

Mechanical designers use their own mechanical CAD programs to design the cell phone around the boards. This, according to Foadian, is where the translation problems between the electrical and mechanical engineers start.

TIME SPENT TRANSLATING

Because mechanical CAD and electrical CAD programs don't speak the same computer language, the electrical design information needs to be translated into a standard file format—often the intermediate data format, or IDF—to be read by the mechanical engineers' CAD systems. When many files are passed back and forth, a slowdown naturally occurs. Also, just as in translation between languages, mechanical engineering requests or design intention may be literally lost in translation.

Just choosing a standard file format can be a hassle unto itself, according to Gregory Smith, an associate technical fellow with Boeing Space and Communications Group of Seattle.

The past few years have seen an increase in the number of standards for the interchange of electrical and mechanical data between CAD systems and between CAD and analysis systems. At the same time, the scope of these standards has expanded dramatically, Smith said. While a few of the standards focus specifically on a unique purpose, others attempt to provide data to support the entire electronics lifecycle.

Recent standards activity includes: the acceptance of STEP AP210 as an international standard, the creation of GenCAM out of the GenCAD format, the extension of EDIF with PCB capabilities, and the extension of IDF with extensive changes to content, format, and representation. You can see where the headaches come from.

Each of the standards offers strengths and weaknesses. And each standard requires the user to enter specific information before he or she can translate the design files.

ANALYSTS IN THE PICTURE

Once the mechanical engineer successfully designs a product that includes the necessary circuit boards, is sexy enough to please the marketing department, and meets design specifications, the CAD files proceed to finite element analysis. But once more the designs must be translated, this time into the analysts' computer language, by turning the CAD information into neutral file formats called standard initial graphics exchange specification, IGES, or standard for the exchange of product model data files, STEP.

"So it's a three-step program here," Foadian said. "Electrical CAD to mechanical CAD to FEA. And whenever you go from one big package like electrical CAD to mechanical CAD, with translating these files, it becomes a waste of time and causes errors. Different programs have different priorities and they ignore the rest, which might be needed by the next program."

Mechanical CAD software applications, for example, need to ensure that part geometries look pleasing to the eye and fit together to make an enticing envelope for the cell phone parts. But the finite element analyst who eventually receives those files in order to test the virtual phone for properties like stress and other physical behaviors doesn't care how it looks.

"The FEA guy might have to spend a lot of time repairing CAD geometries lost in translation to make them exact," Foadian said.

Software that analyzes multiple physical phenomena like fluid flow and electrostatics helps mechanical and electrical engineers collaborate with greater ease.

His company, which markets a technology called Abaqus CAE, is joining a trend among FEA developers to make their products easier to use, so mechanical designers can do more analysis themselves as they design. This ability eliminates the need to translate many features into a neutral file format.

"As finite element analysts, we use our own jargon and language, which is foreign to even a mechanical designer who's closely related to us," Foadian said. "But he deals with design, not analysis issues."

Another step would be for FEA technology to eliminate the need to translate CAD files into a neutral file format before sending them to analysts, Foadian said. This year, Abaqus will release what Foadian called a plug-in between Catia version 5, a CAD program, and Abaqus CAE. The plug-in will eliminate the translation step. Users of the Catia software, from Dassault Systemes of Paris, can pass CAD information directly into the FEA software. Foadian's company would like to expand that capability to all other major CAD packages.

In the future it may provide a link directly between electrical CAD and the FEA software. In that scenario, mechanical engineers or analysts could analyze circuit boards for vibration, shock, drop-impact, and other conditions to make sure they meet specifications. If one doesn't, the board would be passed back to the electrical engineer for redesign. Those that do could be brought into the mechanical CAD system for product design.

Though Abaqus now has no technology on the market to provide direct links between its software and electrical CAD or mechanical CAD, it does create those links at customer request. The company can write customized scripting and graphical user interfaces to offer linking capability between systems.

"More and more customers come to us and they want to work between electrical CAD and mechanical CAD and Abaqus without translation," Foadian said. "We can do it now, but it's not a prepared package for us yet. We do it through customization."

Another maker of FEA technology, Algor of Pittsburgh, makes software that can analyze multiple physical phenomena, including motion, mechanical stress, heat transfer, fluid flow, and electrostatics in one package. The coupling of these effects lets mechanical engineers, electrical engineers, and scientists collaborate on cross-disciplinary projects using the same software, said Bob Williams, product manager at the company. Each user sees one interface, regardless of the phenomena he or she is studying.

Electrical and mechanical engineers commonly use the software to work together on projects like the design of fan-cooled computer central processing units, printed circuit boards, piezoelectric components, and microelectromechanical systems such as optical switches, Williams said.

ANOTHER REDESIGN

Not surprisingly, the disconnect between electrical and mechanical engineers who design together often happens when designs are passed between electrical CAD and mechanical CAD programs. Bassi, the chief technology officer at ImpactXoft, claims that many popular CAD programs aren't structured to help a mechanical engineer who is pulled by electrical designers on one side and FEA analysts on the other. Mechanical engineers, Bassi said, have to design a method for fitting the circuit board into the component, allowing for whether the board is fitted to the component with screws or bolts, or by some other method.

Bassi said that his company's CAD technology makes use of a technique called functional or rules-based modeling, which allows objects like circuit boards to fit into the component in a standard way, regardless of how they are anchored, using already specified techniques that the mechanical engineer has programmed into the system. This saves time and keeps the engineer from getting caught up in designing simple geometries like the circuit board anchoring method again and again, he said.

Also, mechanical engineers can specify that certain standard components meet certain needs—a rib will always extend across the inside of a molded part, for example—which means they don't have to design ribs of different lengths separately. Ribs automatically change to suit redesign.

Other CAD makers partner with technology providers that make the translation process easier.

The product IDF Data Adapter, for example, lets designers pass circuit board information from circuit board design software to OneSpace design software from CoCreate of Fort Collins, Colo., without manual translation. The software uses IDF and automatically imports the solid model of the circuit board into OneSpace software.

Until engineers don't have to rely on these plug-ins to translate files—or worry about translating them manually—the disconnect among mechanical engineers, electrical engineers, and analysts goes on.

Sure, a number of programs make translation easier. But the need for it still exists. Perhaps one day that won't be the case.