ALGOR Professional Static/LM V15 Makes Linear Static Stress FEA Easy to Use and Faster

By Garland E. Borowski, P.E.
President
Borowski Engineering & Analytical Services, Inc.
Mobile, AL

What's new in linear static stress analysis (LSSA)? Some might say, "Nothing," because LSSA is such proven, mature technology. Indeed, LSSA is the most common type of finite element analysis (FEA), used for simulating product design tests to study stress, strain, displacement and shear and axial forces that result from static loading. However, as LSSA has become more widely used by design engineers and even non-engineers, such as medical doctors and architects, it has become increasingly important that the user interface be easy to learn and use.

Of the FEA products available for LSSA, I use ALGOR software. ALGOR's Professional Static/LM core package is their dedicated LSSA solution, which includes FEMPRO, a complete finite element modeling, results evaluation and presentation interface. The recently released ALGOR V15 has several new features that provide significant improvements to both the user interface and analysis capabilities, which makes LSSA even easier to use and faster than ever.

CAD-like sketching tools enable you to quickly define FEA models directly within the ALGOR FEMPRO single-user interface.

Automatic, unstructured meshing of this 2-D assembly is accessed from a right-click menu option.

Material properties can be selected from an extensive built-in library or exchanged with third-party libraries through XML.

ALGOR V15 enables you to specify allowable stress values and then display factor of safety contours for linear static stress analysis. This contour shows a color-coded graphical display of where stresses in the model are below and above the specified allowables.

Strain energy density contours let you determine where additional material may be needed.

ALGOR’s report wizard automatically generates an organized, professional report about your analysis in standard HyperText Markup Language (HTML).

Sketching and Meshing in FEMPRO

For example, V15 added new capabilities for Superdraw sketching and meshing directly within the FEMPRO single-user interface, which makes it even easier to perform first-pass or proof-of-concept analyses.

With the new sketching tools, I'm able to quickly and easily draw my model geometry in a modern, CAD-like manner. The tools are intuitively laid out in pull-down menus, icon toolbars, selection-based pop-up menus and a tree view. You can draw points, lines, rectangles, arcs, circles and splines and then modify these objects with commands including copy, divide, fillet, intersect, rotate, mirror, move, parallel, trim/extend and delete. The user interface guides you along the way with a lot of visual feedback, such as text instructions, cursor changes, and mouse-over and selection highlights. Operations such as rotating, moving and scaling sketch entities are performed by pointing and clicking in a visual, interactive process. There is also an unlimited undo and redo capability, which allows you to easily correct any modeling mistakes.

With V15, an automatic, unstructured mesh can be easily created from sketches through a right-click menu option, resulting in a FEA model that is ready for analysis. When you generate a mesh, the sketch is also preserved and a dialog button enables you to toggle between previewing the mesh and going back to modify the sketch. The mesh is then automatically updated based on changes made to the sketch. If needed, contact between parts, user-specified division values and mesh refinement points are all easily set up through graphical, interactive point-and-click operations.

ALGOR V15's integrated Superdraw sketching and meshing tools provide increased speed in moving from concept to analyzed model. Although I still frequently build my models in CAD, V15 now allows me to consider the use of only one package for both modeling and analysis. Plus, I can easily modify CAD models or finite element meshes in FEMPRO by simply adding lines to include truss, beam, spring, rigid or gap elements for mixed element type models, such as a beam-plate model.

The addition of the sketching tools within a CAD-like environment also makes the training of young engineers much easier than with many other FEA packages because such users are already familiar with this type of interface.

Setting Up and Performing Analyses

Specifying the data needed for analysis is easy with FEMPRO, which features docking toolbars, multiple view windows, a tree view of model parts and associated data, Windows-native data input screens with real-time data checking for reasonable input and right-click functionality for applying, modifying and deleting loads, constraints and FEA properties. Defaults within the analysis inputs have been well considered during the development of the software, but to change those defaults is easily accomplished. Plus, V15 includes additional materials in the built-in library and the capability to exchange material data with third-party material libraries through Extensible Markup Language (XML).

Professional Static/LM's analysis capabilities include static stress analysis with linear material models; weight, center of gravity and mass moment of inertia analysis; linear contact; and consideration of thermal stress and voltage-induced effects. Additionally, V15 added a new parallel iterative solver that provides even faster LSSA solution times on computers with parallel processors.

The software also comes with an Accuracy Verification Examples CD, which contains more than 150 of the test problems that are used to verify the software. Additionally, I have compared ALGOR against ANSYS and COSMOS and found that, with controlled inputs and identical models, the results are well within expected deviations (generally <3%) and can be correlated to hand calculations within a reasonable tolerance (often <1% deviation for simple models).

Evaluating and Presenting Results

A built-in graphics environment provides extensive results evaluation and presentation capabilities within FEMPRO and features transparent display options, multiple-window displays, fast dynamic viewing controls and customization options including user-defined color palettes and annotations. All analysis results can be displayed graphically as contours; output in a variety of graphic file formats (BMP, JPG, TIF, PNG, PCX and TGA); animated with AVI creation and display tools; and presented in text or HTML reports.

Additionally, V15 added new results evaluation and presentation capabilities including realistic visualization of beam and plate elements, which is particularly useful when presenting results to non-engineers through images and animations included with reports. Being able to see the actual beam shape makes graphical presentations much more meaningful and more easily understood.

Also new are factor of safety and strain energy density contours for LSSA. I have done a great deal of design work and the ability to determine your factor of safety is extremely useful in the iterative processing that comes from optimizing a design.

Strain energy density contours are very useful for a composite structural designer. Since the purpose of using composites is generally weight-driven, the ability to see the areas of high strain energy allows the designer to place additional structure (weight) in the areas where it is most needed.

ALGOR’s report wizard is unmatched by any other FEA package that I have seen. The reporting capability provides a professional look without significant effort. It is possible to extract an excellent report straight from the software in a format that is readily presentable to a supervisor or client. With the press of a button and a few customizations, you have a completed report. I enjoy the ease with which additional graphics and comments can be included. At a minimum, the generated report is worth putting in the appendix of your own write-up.

Finally, the supporting documentation is always improving and up-to-date and the technical support staff at ALGOR is always friendly and capable when needed.

ALGOR V16, available later this Fall, will continue this trend by providing the complete Superdraw suite of modeling tools within FEMPRO, including options for creating 2- and 3-D structured meshes as well as additional analysis features for fluid flow, motion and contact analysis.

The improvements to the user interface and analysis capabilities in ALGOR Professional Static/LM V15 make LSSA easy to use and faster for a wide group of users. By using LSSA and first-pass or proof-of-concept analyses, you can improve designs early in the design cycle, reduce the number of prototypes needed, speed up time to market and make better, safer products at a lower cost.

Borowski Engineering & Analytical Services, Inc. is a consulting firm that performs structural, thermal and fluid analyses as well as originates advanced material designs for commercial or military programs. Garland E. Borowski, P.E., the firm's president, earned a Master's degree in Mechanical Engineering at the University of South Alabama. He has used ALGOR FEA since 1996. He has worked on projects in the military shipbuilding industry and in support of various metallurgical evaluations for litigation as well as a wide variety of structural applications during 13 years of professional experience.