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FEA ’s Flow to the Future PUBLIC ACCESS

Once The Province of a Subset of Specialists, Finite Element Analysis is Reaching an Ever-Greater Population of Engineers.

[+] Author Notes

Associate Editor.

Mechanical Engineering 122(07), 70-72 (Jul 01, 2000) (3 pages) doi:10.1115/1.2000-JUL-5

Abstract

This article demonstrates the increasing use of finite element analysis (FEA) by engineers. FEA technology from ANSYS lets engineers simulate the airflow over and under an airplane wing. FEA is the use of a complex system of points—called nodes—that form a grid, or mesh, across a model. The engineer assigns nodes at a density throughout the material, depending on the anticipated stress levels of a certain area. Several developers have been working to couple FEA and computer-aided design (CAD) packages tightly, so they share a common database and a single user interface. DuPont used ANSYS simulation software to solve a noise-vibration-harshness problem in the Porsche Boxter exhaust manifold. Professional analysts also are skilled at interpreting results. Plastics analysis has been within financial reach for large companies, but many medium-size and small companies can’t afford to purchase the software needed to analyse CAD solid models of plastic parts. It is stressed that the codes that power FEA software should allow companies to tailor the software to their own processes.

Article

From its inception in the 1940s until about a decade ago, finite element analysis had been performed exclusively by specialized analysts who held Ph.D.’s in the subject and had devoted their careers to the discipline. But the FEA field has seen great change over the past 10 years, with a jump in the number of computer technologies available to all levels and types of engineers, according to Bruce Jenkins, vice president of Daratech, a Cambridge, Mass., marketing and research firm.

FEA is the use of a complex system of points—called nodes—that form a grid, or mesh, across a model. The engineer assigns nodes at a particular density throughout the material, depending on the anticipated stress levels of a certain area. The mesh contains the material and structural properties that define how the part will react to certain load conditions. In essence, finite element analysis is a numerical method used to solve a variety of engineering problems that involve stress analysis, heat transfer, electromagnetism, and fluid flow. If the analysis finds fault with a model, it is sent back for remodeling to correct those faults before a prototype is produced.

In the early 1970s, FEA was run only on mainframe computers owned mainly by the aeronautics, defense, and nuclear industries, Jenkins said. With the rapid decline in the cost of computers and the concomitant increase in computing power, today’s personal computers can now produce accurate FEA results. Many engineering technology vendors are currently marketing simplified analysis, which walks users through a series of steps that allow them to define the analysis they want to run and then interpret the analysis results, he added.

“That’s what the new development is,” Jenkins said. “A reliable aid that guides users through the correct inputs, and then a correct interpretation of the outputs. And you can do design and analysis in the same environment.”

FEA technology from ANSYS lets engineers simulate the airflow over and under an airplane wing.

Grahic Jump LocationFEA technology from ANSYS lets engineers simulate the airflow over and under an airplane wing.

The software is constructed to keep engineers from making a faulty or inaccurate reading of the analysis results, he added.

“It says, here’s what you should do to the design to remove the high stress,” Jenkins said. “Or, here’s how you should move your materials around so you can move from not enough strength to sufficient strength.”

These analysis programs are packaged with, or can be used in combination with, computer-aided design software. This allows what Jenkins termed “ordinary rank-and-file designers” to analyze as they design, and to change and update models to reach a workable design much earlier in the process. It also cuts the cost of having FEA performed by analysts after the product has already been modeled and the associated costs of then moving a model back to the designer for redesign to correct the flaws. With the new programs, the designer can analyze the model and correct faults, then send it to have a prototype made.

Several developers have been working to couple FEA and CAD packages tightly, so they share a common database and a single user interface.

For example, Algor, a Pittsburgh-based engineering technology developer, has been doing that since 1985, said Bob Williams, Algor’s development manager. With the common database, engineers no longer have to translate CAD programs to international graphics exchange specification (IGES) or standard for the exchange of product model data (STEP) files so they can be read by the analysis software.

“This is important because in the past, the FEA people would have to build the whole model again before they could analyze it, since it wasn’t interfaced with the CAD system,” Wilhams said.

The integration is intended to speed up the design cycle. “It allows engineers to loop right through the iterative process, designing and analyzing as they go,”

Williams said. “Typically, they can do this at the same computer whereas before, the design would go through three or four departments in the same company.”

Mark Howards, who owns 3dShapes, a Walpole, Mass., consulting firm that performs FEA, said he has determined that FEA software vendors now offer technologies that are easier to use than the past merging of FEA and CAD software.

DuPont used ANSYS simulation software to solve a noise-vibration-harshness problem in the Porsche Boxter exhaust manifold.

Grahic Jump LocationDuPont used ANSYS simulation software to solve a noise-vibration-harshness problem in the Porsche Boxter exhaust manifold.

“Before, the way a lot of the tools worked, you might have a solid model or a two-dimensional model or a wireframe model, but you’d still have to go in there and manually build a mesh,” he said. “There was an awful lot left up to the user. Now, what’s happening is if you have a solid model, you can automatically generate a mesh. It makes it easier to go from the model to the point where you’re running the analysis, though those tools are still somewhat limited.”

Although the tools exist that allow engineers to design, analyze, and then redesign products at the same desktop computer, ensuring that the software is used correctly is another matter, say some in the field.

“Easy-to-use, comprehensive packages such as ANSYS, a general-purpose, finite element computer program, have become common tools in the hands of design engineers. Unfortunately, many engineers who lack the proper training or understanding of the underlying concepts have been using these tools,” Saeed Moaveni wrote in the introduction to the 1999 book, Finite Element Analysis: Theory and Application With ANSYS, published by Prentice Hall. ANSYS, based in Canonsburg, Pa., provides FEA and other computer-aided engineering technologies.

Moaveni’s book is intended to offer insights into the theoretical aspects of FEA to help design engineers better understand the theory behind the practice.

Brian Reynolds has seen changes firsthand in the way FEA is carried out and delivered. Reynolds is a senior mechanical engineer at American Consulting Services in Chester, S.D., a consulting firm that provides FEA for companies in the agricultural, heavy equipment, defense, and other industries.

“How has it changed? It’s been amazing,” Reynolds said. “It seems like a lot of the personal computers we buy here now are not as powerful as our mainframes were.”

Even so, finite element analysis is performed today on desktops as efficiently as it once was on older mainframes. Reynolds has also noticed that nearly every product made today undergoes analysis before it’s produced. In the past, engineers made prototypes of small or easily designed products, bypassing the analysis stage, he added.

Large companies, such as those in the defense and agricultural industries, used consulting services on a consistent basis, while smaller companies turned to consultants like Reynolds for larger projects, or when engineers couldn’t determine how to redesign a product to fix a structural problem.

“I think it was too expensive in the past,” Reynolds said. “In the old days, we’d just analyze things that were failing. Now I think they’re analyzing every new product.”

Reynolds has also seen more vendors that provide desktop FEA and specialized analysis capabilities entering the marketplace in the past five years, joining his principal software sources, ANSYS and MSC. To keep up, his consulting firm must spend money and time continually updating software, checking out new programs, and training on new software, he said.

Still, the recent availability of these FEA tools to the rank-and-file designer doesn’t threaten the professionals who carry out advanced analysis and often serve as consultants to large companies, said Howards of 3dShapes.

“If everybody has access to FEA tools, on the surface of it, that should really be bad for business because it makes it easier for people to do analysis,” Howards said. “But what you find is, you still have to know what you’re doing. We do analysis for a lot of big companies that have the tools but don’t do it themselves, because we do analysis over and over again, day in and day out. We know what to look for.”

Professional analysts also are skilled at interpreting results. “Even if you’re doing things right, you might not be able to look at the results and make them meaningful. You can’t compare it to analyses you’ve done in the past and know what’s what,” Howards added.

Reynolds agreed. “Normally, not a lot of companies have advanced FEA programs in-house,” he said. “That’s why people call us, because it saves some of the expense of having to maintain in-house software.”

As with other engineering technologies, some FEA software providers are seeking to make their software available online. That is, vendors host software on their own servers and, for a fee, offer engineers access to programs via the Internet. This eliminates the need for engineers to pay for the software any longer than they need it. And they don’t have to download it to their own computers.

For instance, in May, Moldflow of Lexington, Mass., a maker of plastics analysis software, put up a Web site that provides access to iMPA, an electronic version of the company’s plastics flow analysis program. The program is hosted on Moldflow’s server, which users tap into via the Internet.

Plastics analysis has been within financial reach for large companies, but many medium-size and small companies can’t afford to purchase the software needed to analyze CAD solid models of plastic parts, said Ken Welch, Moldflow’s vice president of marketing.

And last February, MSC Software, which is in Costa Mesa, Calif., introduced e.visualNas-tran, an Internet-based version of the company’s FEA program, which lets users perform integrated dynamic motion and FEA simulations on design assemblies. Users go to the company’s Web site, where they subscribe to the software.

Also making use of the Internet, Howards’ consulting company, 3dShapes, offers a secure Web site, where engineers can go to see a working analysis they’ve asked 3dShapes to perform. This allows Howards’ customers to see their analysis in an interactive manner and gain a quick understanding of results. They also receive a written report on those results, he added.

“In the past, so much of the way consulting has been done is to run the analysis and then create a paper report on the results,” Howards said. “It seems kind of foolish, when you have the ability to allow people to see things live.”

Everyone involved in the project that 3dShapes has analyzed—from the engineering company to suppliers and vendors also involved in the design—can visit the Web site independently without waiting for individual written reports, he added.

Immediate access to results cuts the time spent waiting for the printed version. But Howards has found that customers still want a printed report.

“They want something they can hold in their hands,” he said. “It’s almost like the paper has value.”

As for the future of FEA, Reynolds of American Consulting said he expects the pace of change to continue unabated for at least the near future.

“We’ll get more powerful software for analyses and that will be coupled with faster computer speeds,” he said.

FEA is the use of a mesh placed across a model, such as this one of a stool. The mesh defines how the stool will react to load conditions.

For his part, Jim Cashman, the ANSYS president, predicts that the future of FEA hinges on what he termed problem simplification rather than technology simplification. In some future cases, the analysis will simply happen automatically as the model is tweaked. That is, a computer user won’t trigger the analysis. Instead, a change in the design, the design material, or the supplier will automatically signify the need to run a new analysis, Cashman wrote in a recent letter printed for distribution.

He also predicted that a broader range of people involved in the design process—from original conception right through to the manufacturing floor—will have access to the analyses of a particular part and will also have the ability to run FEA on the part.

“The almost hackneyed term ‘ease-of-use’ will take on new dimensions,” Cashman predicted in the letter. “At the most rudimentary levels, FEA technology has developed a commendable level of automation and simplification.”

But he believes the simplification is achieved at the expense of technical sophistication. Each FEA user faces difficult problems he or she needs to solve, regardless of skill level, and the technology must address each person’s needs, he added. Cashman expects the design of FEA software in the future will be such that vendors can offer software tailored to specific uses, and it will allow companies to integrate any in-house simulation tools they may have developed or purchased.

In other words, the codes that power FEA software should allow companies to tailor the software to their own processes, Cashman said.

He also expects product data management tools that track the part creation process and the documents related to that process to be integrated with FEA software. This is because so many more people will have access to the FEA software and to past simulations, making it more necessary than ever to track those items.

Algor’s Williams neatly summarized the path of FEA. In the future, FEA will be easy to do, he said.

“In the past, there was, and there still is, this idea that FEA is difficult, that you have to know all these archaic commands, and that’s just not true anymore,” Williams said. “In the future, users won’t really expect it to be any more difficult than they expect Microsoft Word to be today.

He also expects that future FEA programs will be integrated with a much wider variety of software programs than today’s.

For Reynolds, the increased computing power means more and more FEA programs to buy, to learn, and to use. But with FEA becoming a common part of the design cycle that is now seldom bypassed, he can expect job security as well.

Copyright © 2000 by ASME
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