Tech Trends: Model, Mesh and Analyze31 Mar, 2005 By: Arnie Williams
Harnessing Analysis Technology for CAD
Think back to the emergence of digital cameras, not so long ago, as the point-and-shoot choice of the everyday photographer. At first, professionals no doubt looked down their noses at these contraptions. All this trend will do, thought many of them, is make it easier for the untrained masses to take bad photographs. But as time has progressed, digital cameras have grown more sophisticated. And not only vacation-bound amateurs are toting digital cameras—professionals have embraced the technology.
An analogy between point-and-shoot photography and desktop design analysis isn't that far-fetched. Once the closely guarded province of highly educated and trained analysis specialists, desktop FEA (finite-element analysis) programs have enabled designers to minimize the probability of failure of their products by performing basic FEA and other analyses early in the design phase.
The math behind the analysis and the sophistication of the technology have advanced to the point where most designers can now take a model, mesh and design approach throughout early stages of product design.
Irreversible TrendWhen software developers began placing basic analysis tools in the hands of designers a decade or so ago, many analysis specialists were mortified. They feared that too many untrained people would use technology meant for experts and end up manufacturing shoddy products. Some of the fear was cultural, no doubt, but there was also a legitimate concern that if designers were able to perform any kind of analysis early in the design phase, they might be tempted to skip the expert analysis that specialists bring to bear during the product-development cycle.
SolidWorks Corp. and the developers of COSMOSWorks (www.cosmosworks.com), its analysis wing, have kept the concerns of analysis experts very much in mind as they've studied the kind of analysis designers need to perform.
This approach to analysis exemplifies where the industry is headed today. The trend throughout the CAD industry, at this point irreversible, is to put enough analysis capability at the disposal of design teams so that basic behavior studies and failure studies can contribute to more efficient design (figure 1).
Figure 1. Stress analysis, as performed using COSMOSWorks on the model of the camera back shown here, is typical of the kind of FEA capability available today to product designers.
There doesn't have to be a war between analysis experts and product designers, notes Suchit Jain, vice-president of analysis software at SolidWorks. The invaluable training and knowledge of experts can be channeled into developing analysis templates that keep a designer from making mistakes. With these templates, much of the math and other highly complex calculations take place behind the scenes, giving the designer only what is needed in the results to make product design more efficient. COSMOSWorks was developed to work within SolidWorks, employing the same interface and behaving in the same way.
A designer can complete basic analysis in SolidWorks without learning a new software program devoted just to analytical elements. During the early product design stages, designers can perform model, mesh and analyze operations for a snapshot of the product's behavior under conditions that analysts typically examine.
From the early days of using FEA within CAD primarily to run failure analysis tests and so minimize the need to build expensive prototypes, COSMOSWorks, like other analysis products, has moved into producing advanced, color-contoured, animated results of part and assembly behavior, rather than just a set of numbers that must be interpreted (figure 2). This is fairly typical of design-level analysis.
Figure 2. Analyzing parts early in product design to detect stress parameters is a common approach to FEA when product designers use applications such as COSMOSWorks.
The advantages of analysis in the early stages of a design are undeniable. Analysis leads to more efficient design, shorter cycle times and lower costs.
"Effective product design requires more than simply creating a geometric shape for a particular function," says Jain. "Designers have to balance a range of design variables and options, from the properties of available materials to size, weight and loading constraints. Quick and easy design analysis results, even if they show only the approximate deflection or stresses instead of the exact results demanded by analysts, can help designers make prudent decisions at the beginning of the design cycle that minimize problems, delays and costs later on."
Jain illustrates a number of trends that we can expect to see in FEA-type programs for product designers. General-purpose stress and behavior analysis tools applicable to a broad range of uses will increasingly target specific physics functionality, such as drop test and bolt simulation.
"Just as customers are demanding customization in everything from automobiles to computers, engineers require analysis capabilities that address a narrow range of problems that are particular to their specific industry," he says. Basic capabilities in these areas of specialization will be addressed early on by designers with products such as COSMOSWorks (figure 3).
Figure 3. Drop test simulation studies the effect of impact on a model when its dropped from various heights.
Making these more sophisticated and more specific early analyses will also get easier, says Jain, through the use of templates and a continual revamping of user interfaces. These capabilities will also lead to the spread of early analysis into areas not traditionally involved with FEA, he predicts—disciplines such as the medical products industry. This field is using nonlinear analysis to simulate the superelasticity of arterial stents, for example, which must expand and contract dramatically to clear arterial blockages.
Designer-Analysis Expert PartnershipsJain emphasizes that the spread of FEA throughout the product design cycle and across diverse industries should not replace engineering judgment. There is still a valid concern, he says, that putting analysis technology in the hands of an untrained engineer who is working on mission-critical designs can be dangerous without appropriate guidance. That's why, notes Jain, many FEA training courses for designers now focus more on applying analysis and the engineering principles behind the technology rather than on how to use a particular software product's interface.
"Analysis packages have reached a level of ease of use at which anyone can use them," says Jain. "But applying FEA productively and effectively requires sound engineering judgment and best engineering practices."
The answer to the designer- engineering analyst stand-off is to transform it into a partnership. Jain notes that the early use of analysis in a product-design cycle can make an analyst's job easier later on. By relying on the best practices of analysts, many of which lie behind the templates developed for the software, the information the expert analysts need to run more sophisticated tests will already be incorporated in the CAD model. This will enable analysts to refine results, notes Jain, rather than spend the time to set up the information from scratch.
The role for the analysis expert in this approach to early product design is to establish best practices and to oversee the use of analysis by product designers. In this way, analysts can help product development organizations reduce cycle times and accelerate time to market.
Analysts also benefit from the embedded analytical data in CAD models as modeling technology grows in its ability to capture more and more sophisticated product data.
Arnie Williams, former editor-in-chief of Cadence magazine, is a freelance author specializing in the CAD industry. E-mail Arnie at firstname.lastname@example.org.