SRAC Cosmos/Works

A few weeks ago we had the opportunity to spend several hours at SRAC, the developers of the COSMOS series of FEA (finite element analysis) software. We were particularly interested in SRAC's design optimization, a modestly priced add on ($1995) to COSMOS/Works. Over the years we have watched interest in FEA based design optimization and the related software solutions ebb and flow. One reason for this is that optimization, say for minimum mass, involves a tight integration between the CAD system and the FEA system. Another is that until recently, solvers simply took too long to solve even small problems. Often 8 to 10 iterations are needed to develop a trend. If each iteration takes 30 minutes, the process could hardly be called interactive. What has changed only recently is the introduction of fast solvers as well as vast improvements in desktop processor speeds. Surely, 1 GHz processors can help with some of the optimization drudgery. Another improvement is fostered because of the tight integration of FEA software into desktop CAD systems that allow such software to easily interchange the data required to access solid modeling parameters. In fact this is exactly what we observed at SRAC, using COSMOS/Works and SolidWorks.

To optimize (actually improve is a better term) a design manually, the user analyzes the results, tries a series of changes to the design model and reruns the problem to determine whether the results have improved. When the results are returned from the FEA solver, decisions need to be made about the solution. Is it within limits? Is the solution a minimum? What solid modeling parameters can be changed, and in what sequence to produce the best answer?

Using COSMOS/Works we were able to organize our problem easily using the built in guidance of the COSMOS menu structure. First we set an objective, such a minimum mass. Then we chose the design variables which we wanted the optimization process to alter. The system supports up to 25 variable, but usually about 5 or so are the practical limit to understand the impact of the changes. Next the range of variation of each of these design variables is entered and constraint values for the desired FEA values such as stress, deflection, etc. Then initiate the process, and in prior implementations we would advise to sit back, have a cup of coffee and wait. But, in the example of a clutch plate (the image link is in the next paragraph), with a 48,000 degree of freedom model and 3 design variables, we had the answer in less than 5 minutes!

For those of you interested in viewing a sample sequence of events you can go to this link where you can view the annotated images. Visit SRAC for more data on optimization and a paper discussing AccuStress, a new transitional mesher that automatically adds transition patches to insure accuracy. Today SRAC's optimization runs only with Solid Works, but SRAC expects to introduce similar functionality for Solid Edge and Inventor before year end 2000. COSMOS/Works costs $5995.

In our opinion, there is little or no reason why every design engineer should not be running optimization on their designs. The tools are in place today, are fast, easy to use, and require no special FEA expertise. Consider design optimization the engineer's spell checker.

http://www.cosmosm.com