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MSC/NASTRAN for Windows, Version 4
By Hunter Davidson, Northrop Grumman Oceanic Systems -- Design News, September 20, 1999
Since the inception of MSC/NASTRAN for Windows, MSC has been a leader in providing easy-to-learn and use access to the NASTRAN solver. Version 4 continues this trend, offering significantly enhanced modeling tools, fast and flexible meshing, and full access to Windows resources.
Enterprise Software's FEMAP provides pre- and post-processing, and automatically launches analysis for virtually all commonly used solver functions. Through care in integration and documentation, the combination of the two company's resources is invisible to the user, yet MSC wisely retains FEMAP's multi-solver capability, with notable additions of direct communications with MARC and LS-DYNA3D. This allows multi-solver users to perform all work with a common interface if desired.
With Version 4, solid modeling is a fully developed capability, not just a translation tool. Models can be created from scratch using either Parasolid or ACIS geometry engines in the preprocessor. This approach assures accurate, native model input from the many CAD systems using these standards. STEP and IGES import provide access to models from virtually all remaining CAD software.
Solid models can be created from scratch, or imported models can be refined with the extensive solids construction and editing tools. Frequently, I found it convenient to build basic models in CAD, then analyze them, finally refining and re-analyzing the models in the preprocessor. Parasolid models can be exported, as well. Combined with effective load, constraint, and attribute application at the geometry level, I find that I now use solid models for a majority of my work for thick section parts.
Version 4 adds a useful tool for thin section parts which originate as CAD solid models. Before the rise in popularity of solid modeling, such FEA models were normally imported as 2D geometry, or built from scratch with the preprocessor, then meshed with 2D elements. Solid meshing of thin solids can produce a very large element count, with little benefit, or even loss in accuracy compared to 2D modeling. Version 4 provides a wide range of tools for reducing thin-walled solids to midsurfaces, which are then easily meshed with 2D elements. This process is performed with a high level of automation, dramatically reducing the time required to obtain FEA models. Each midsurface is assigned a unique property, with a useful default process, allowing wide control over local details.
Version 4 offers a wide range of meshing enhancements. Tet meshing is very fast, frequently eliminating performance concerns and accuracy compromises associated with automatic meshing of medium- and large-sized models. With such models, there is less need to consider time-consuming local mesh modification, or bottom-up construction. Combined with the relaxation of earlier memory access limitations, and flexible solid model import capability, even large models can be approached with a nearly turnkey import, mesh, and analyze technique.
The new, semi-automatic hex meshing isn't for all models; although I found it to be fully automatic for many practical parts. Basically, the hex mesher can automatically mesh solids created as extruded or revolved profiles; however, the single-part automatic feature extends this definition to include any part which accommodates regular development between two identically mapped end meshes.
Hex meshing of much more complex parts is practical if the part can be sliced into pieces which meet the automatic meshing requirement. Editing tools make this slicing process simple, and the mesher automatically matches meshes at inter-segment boundaries. This approach combines the user's ability to visualize complex geometry, and the mesher's ability to rapidly and predictably mesh simple shapes, to provide an effective solution to a very complex problem. Now, I rarely revert to my old processes to generate hex-meshed models.
Improved command access combined with the high performance of even low priced OpenGL video boards makes dynamic model viewing very effective. I was very pleased with performance using a board that cost less than $200.
SPEC BOX
MSC/NASTRAN for Windows, Version 4
Recommendations: a Pentium processor, 32 Mbytes or higher of RAM, 150 Mbytes of program disk space, and 500+ Mbytes of disk space for temporary storage. OpenGL support is excellent.
List Price: $4,000 and higher depending on configuration and seats
The MacNeal-Schwendler Corp., 815 Colorado Blvd., Los Angeles, CA 90041; Tel: (213) 258-9111. Product Code 4866A similar product: ANSYS, ANSYS Inc., Southpointe, 275 Technology Dr., Canonsburg, PA 15317; Tel: (800) 937-3321; www.ansys.com Product Code 4867
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