FEA lets designers take first cut analyses

July 10, 2003
Most engineering programs that plug-in or add features to another program often seem a bit clumsy because they require flipping from one environment to the other.

Loads appear as arrows, while restraints have a T on the arrowhead. Users have the option of hiding these symbols to aid viewing and further work.


The hydraulic reservoir provides a real-world part for testing the functions in CosmosWorks 2003, FEA software that works within SolidWorks.


The slider bar to the left lets users adjust mesh density. After an analysis, users might select a finer mesh, rerun the analyses, and compare results to the previous run.


Contour plots show the von Mises stresses on the deformed reservoir.


In addition to remeshing with finer densities, the Study-Properties window lets users apply the p-adaptive method to check solution accuracy.

This is not the case with CosmosWorks 2003, the FEA program that works inside SolidWorks 2003. Both programs are well organized, user friendly, and tailored to the needs of design engineers who want to perform their own first-cut analyses. And CosmosWorks requires fewer analysis decisions to perform preliminary evaluations. To get a feel for the program, I revisited a real design application - the analysis of a hydraulic filter bowl.

Users can comfortably toggle between CAD and FEA using simple mouse clicks in the FeatureManager tool bar. They can also open a separate window for Online Tutorials. This is handy for those wearing several hats who perform FEA only once in a while. Online tutorials provided immediate pop-up help, and within minutes I recalled how to define FEA models. Software tutorials are well written, teach users the analysis basics, and include several verification problems so users develop confidence in results.

It is simple to select element types and assign material properties. The program includes a library of properties for several materials.

The automesher is simple enough for beginners yet lets experienced users manually fine-tune things. Several new features help users mesh complex parts. Should a part fail to mesh, for example, a diagnostic tool tells why and helps correct it. Users can also activate automatic looping in the Mesh Preferences window to test different element sizes on hard-to-mesh parts.

The FEA developer suggests an initial global element size to begin meshing. I reduced the default element size suggested by the program by 50% to see if the program would encounter any difficulties. It did not. I increased and decreased the mesh size several times. Each time the software completed the task. Users define smaller or finer meshes in key regions using Mesh Control options.

For a comparison, I tried the same tasks on the same geometry but with a previous version of the software and had difficulties meshing. Meshing alone could make upgrading worth the investment.

Users can place loads and boundary conditions (restraints) on faces, edges, and vertex CAD geometry. I defined restraints and pressure loads by selecting all the surfaces needed. It takes a little practice holding down the Control key to add multiple selections to the selection list for models where similar loads are applied on several surfaces. It can be somewhat tedious zooming in and out, rotating and panning to position the CAD model in convenient orientations while selecting surfaces (about 30 in this case).

Processing several analysis cases is simplified with the Run Study option. Users export contour plots in image formats such as JPEG, BMP, VRML for reports, and documentation. The software also generates HTML reports for analyses that can be emailed. Even better, users can publish eDrawings of results. This lets them send 3D results to clients and team members. Recipients can zoom in, zoom out, rotate, pan models that show stress results, and even add comments to the eDrawing and send it back.

The program includes many new display and viewing options that lets engineers study results. It will display hidden parts as ghost images or superimpose deformed shapes on top of undeformed ones. Models can be cut into sections with stress results displayed on one side and transparent images of the remaining part geometry on the other. Users can annotate maximum and minimum result in the result-plot legend and place it almost anywhere.

The software lets users check solution accuracy two ways. One is by increasing element density in regions of high-stress gradients - the h-adaptive process. The p-adaptive approach for static analyses keeps mesh density constant and increases the polynomial order of the element-shape function. Reformulating a successfully run FEA model to a p-adaptive solution is less time consuming than remeshing the geometry. It's a powerful analysis tool but needs substantially more processing time than the h-adaptive process so users might want to save it for a final step.

Users will find Design Scenarios useful for studying the impact of different parameters on designs. Parametric inputs could include cost, availability of materials, stock sizes of plate and sheet, standard components, and variable machining dimensions. Considerable savings in manufacturing cost is available with minimal weight penalty when "off-the-shelf" parts are used. Design Scenarios is useful in providing users with necessary information on these trade-offs.

Most design engineers may not need all the software's features. They probably stay within linear-analysis class of FEA: static, resonant vibration, possibly some bucking, and steady-state heat transfer. But the capabilities are there for more adventurous designers who might want to address nonlinear material models, transient heat transfer, contact-gap analysis, kinematics or motion, and fluids. CosmosWorks also lets users analyze assemblies inside SolidWorks. It simulates various contact conditions between parts, including friction.

Of course, no program is perfect. For example, the File-Save function makes the screen go a little wacky when saving a file, but it quickly returns to normal. For the Material Properties input, mass density has units of lb/in.3 This is a common error. Pounds/inch3 is specific weight. Mass density is measured in (lb/in.3)/(386.4 ips2) = lb-sec2/in.4(W/g = m). Analysts should practice with the values for material density and gravitational acceleration on several test problems to ensure they are using their software correctly. I would also like to see load magnitudes on screen in addition to symbols. I found it time consuming to ensure that each face on the model had the correct pressure. There must be a way to simplify applying several identical loads. I'd also like to see more documentation and tutorials on Design Scenarios.

Furthermore, I noticed that Loads and Restraints applied to the backside of CAD geometry showed through in hidden views. This is a minor annoyance. Users have the option of hiding portions of the input definition to aid viewing. Even though tutorials and verification problems are nicely done, I'd recommend designers generate several of their own warm-up or sample problems with known solutions before they start running real problems.

CosmosWorks 2003 comes from SolidWorks Inc., 12121 Wilshire Blvd., 7th Floor, Los Angeles, CA 90025, (310) 207-2800, www.cosmosm.com

- David Dearth

Mr. Dearth is president of Applied Analysis & Technology, Huntington Beach, Calif. ([email protected]). The company's primary focus is in design, analysis, and environmental testing using CAD and FEA technology. The firm also teams with consultants in design, metallurgy, failure analysis, and other disciplines.
About the Author

Paul Dvorak

Paul Dvorak - Senior Editor
21 years of service. BS Mechanical Engineering, BS Secondary Education, Cleveland State University. Work experience: Highschool mathematics and physics teacher; design engineer, Primary editor for CAD/CAM technology. He isno longer with Machine Design.

Email: [email protected]


Paul Dvorak - Senior Editor
21 years of service. BS Mechanical Engineering, BS Secondary Education, Cleveland State University. Work experience: Highschool mathematics and physics teacher; design engineer, U.S. Air Force. Primary editor for CAD/CAM technology. He isno longer with Machine Design.


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