As recently as five or six years ago, getting accurate results from most finite element analysis (FEA programs required the skills of specially educated dedicated analysts who created their own models from CAD designs. Many mid- to small-sized companies couldn't afford separate analysis departments, and even the huge aerospace, automotive, and major industrial companies that had been the mainstay of traditional analysis began to shrink their analysis departments as cost competition took its toll. While companies needing complex analyses such as nonlinear, dynamic response, advanced computational fluid dynamics (CFD), and electromagnetics still need the services of dedicated analysts-whether on staff or acting as consultants-more and more day-to-day FEA (linear static, dynamic, and thermal) lands on the desk of the general engineer.
Today's desktop FEA programs analyze models taken directly from CAD, in CAD-like interfaces, using CAD modeling kernels, often bi-directionally associated with individual CAD programs. Vendors design these analysis programs to be used by design engineers as well as specialist analysts, automating some of the specialized functions, and making them as easy to use as the CAD packages with which they work.
Controversy continues within the FEA industry about whether designers have sufficient knowledge to be trusted with analysis tools because, if for no other reason, the old rule of thumb applies to FEA as much as to any other software-"garbage in, garbage out." But in a field where well-meaning errors can cause product failure, desktop FEA developers make sure to automate critical functions and prevent inaccurate results.
The popularity of desktop FEA continues to grow. The major players in the arena keep adding new, sophisticated tools and safeguards to their software. Companies embrace design analysis because designers can run analyses at every stage of the design process, and catch possible problems very early in the design cycle-reducing the need for multiple prototypes and helping them get product to market faster.
Two major trends can be seen in modern desktop FEA: scalability and integration with motion simulation. Algor, Pro/-MECHANICA and visualNastran incorporate motion analysis within their FEA packages. ANSYS'DesignSpace and Structural Research & Analysis Corp.'s (SRAC) Cosmos/DesignSpace and Cosmos/Works offer back-and-forth sharing of dynamics information with separate motion simulation programs. DesignSpace and visualNastran communicate with full scale ANSYS and Nastran. SRAC's designer packages have always linked to full Cosmos/M and the company is beginning to move advanced capabilities into its CAD-linked packages. Pro/MECHANICA now lets users access high-end solvers from other companies.
Additionally, engineers can access and learn about some of these analysis programs over the Internet.
What to look for in new desktop FEA releases
Algor: Michael Bussler, president of Algor, says, "Basic FEA technology is years away from its fullest implementation. It's all leading toward virtual reality simulation." He also says, "More and more design errors are being eliminated along the way, thanks to analysis-all resulting in better, safer, less-expensive designs." Bussler says that this year's changes to Algor's software will come in many small steps driven by customer requests, and the company has added new capabilities in recent months:
A new actuator element provides a means to describe complex motion over time. The actuator element was developed in response to an engineer's requirements for dynamically analyzing an amusement park ride. The elements allow users to specify contraction and extension values over time to drive motion between connected parts.
Along with a faster mesher, Algor also introduced a midplane meshing feature that the company says "automatically heals gaps inherent in midplane extraction." The new feature converts thin, solid parts, such as car body panels, into plate/shell elements using the midpoint of the surface elements.
Algor offers training over the Web, using weekly webcasts to educate engineers.
ANSYS: Lee Stotler, business unit manager for DesignSpace, says that upcoming features "will reflect an increase of automation and built-in intelligence." He says, "DesignSpace tries not to put traditional FEA into a Windows interface, because customers tell us that people who need traditional FEA need more than they can find in Windows."
New capabilities will focus on parameters and improved assembly analysis. DesignSpace automatically sets up assembly analyses, and Stotler says that two more types of assembly contact will soon be added-"one that allows sliding, and one that does not. DesignSpace will be able to tell what kind of contact an assembly has-as, for instance, in a gear wheel where the teeth touch." In general, surface-to-surface contact will be more automated, to allow some nonlinear analysis.
In addition, he says, " We're striving to get closer and closer to our CAD partners and look at the CAD parameters. In time we'll be able to update the CAD model directly from changes to the analysis model. The next step will be the ability to pick dimensions and change them in the analysis model, and then monitor them and relate them to maximum stress and deflection-even if just on a spreadsheet. This all relates to design studies and better what-if scenarios."
DesignSpace will also have an advanced controls panel to let customers decide which capabilities they will make available to users-so that only those design engineers who have been trained in the various analysis functions can use them.
Ansys, too, makes use of the Web, introducing a recent version of its software over the Internet and organizing webcasts.
MSC.Software: MSC.Software recently released MSC.visualNastran (formerly Working Model 4D) Desktop version 6.2. The new release illustrates the division's "grand vision," as stated by Vice President and General Manager David Baszucki, to be "a big paradigm shift in FEA away from heavy-duty engineering users, and more toward building a manufacturable 3D model and testing to see where it might fail."
MSC.visualNastran 6.2 offers an iterative solver to provide up to four or five times faster solve times than previous versions, along with a 25% speed improvement in its mesher. The new release also has improvements in annotation, custom vector objects, and faster navigation of FEA results. The program displays FEA results directly on the motion simulation model, giving users a dynamic view of changing results at different stages of motion.
An Internet version, called e.visualNastran, is available on MSC's engineering-e.com ASP website. That version works in the user's browser window, and provides the same capabilities as visualNastran Desktop.
Built-in scalability allows users to move up to full Nastran in neutral MSC .dat file format.
PTC: Pro/MECHANICA Release 2000i 2 offers two modes of operation: an integrated mode (working as before within Pro/E), and a new FEM mode. The FEM mode, says Ken Short, director of simulation products marketing, provides scalability. "Customers who design and analyze with Pro/-MECHANICA want to re-use design intelligence and analysis data for system-level analysis using in-house solvers or solvers from developers other than PTC," he says.
The FEM mode uses traditional FEA capabilities, formerly found in PTC's Pro/MESH, and makes the simulation mo-del created by Pro/MECHANICA in the Pro/E environment exportable to advanced solvers in MSC/Nastran, ANSYS, and COSMOS/M. Short says that this will allow companies to use analysis software they already have in-house and get more out of the analyses they run on Pro/-MECHANICA.
He says that the Pro/MECHANICA model "can be condensed to a stiffening matrix that represents model behavior exactly, and then incorporated as a super-element into another model" for export.
The new release also offers baseline fatigue analysis, more flexibility in defining constraints and loads, streamlined material definition and orientation data, along with several additional technical improvements. Historically, Pro/MECHANICA's biggest drawback was slow solution speed. The new release handles structural and thermal analyses 10 to 100% faster than in the past, with disk storage space use reduced between 10 and 20%.
SRAC: SRAC has always allowed users of its design analysis programs the option of accessing the advanced capabilities of COSMOS/M by providing additional configurations of its CAD-oriented software to do so. By the end of this year, the company will add beam and shell elements, nonlinear contact and nonlinear materials (those not requiring complex input), modal analysis, and time history to its COSMOS/DesignStar and Cosmos/Edge packages. SRAC also plans to add random vibration capabilities, either this year or next year. Cosmos/DesignStar works with virtually all commercial CAD programs.
Vasu Chavakula, SRAC's vice president of engineering, sees the typical present and future user of the software as "a designer/analyst." He likens the analyst to a car mechanic "who knows how the car works and can create a finite element model and analyze it accurately." The designer, says Chavakula, "is like the driver. He doesn't have to know exactly how it works to drive it. Our programs all use the original CAD model and can select the right elements."
In addition to Cosmos/DesignStar, the company offers Cosmos/Works, an integrated program for SolidWorks. Suchit Jain, engineering product manager for Cosmos/Works says that version 6.0, due for release in late July, "has greatly enhanced gap contact, within a new interface. We're also adding a new interface to shell any face of a solid or surface-taking advantage of the new surfacing capability in SolidWorks." The program will also feature adaptive p-method (polynomial) convergence data, which Jain says "will be shown graphically."