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For linear design validation, try visualNastran 4D
by Paris Altidis, Staff Engineer, Borg Warner Automotive, Chicago, IL -- Design News, March 10, 2002
The latest version of visualNastran 4D merges a compendium of tools into one environment, for the engineer with needs in structural and dynamic analysis, and controls. Although it's in a pre-release state, this "almost beta version" is stable enough to display its merits. visualNastran 4D (herein vN4D) is the successor to MSC.visualNastran Desktop 2001, which set the stage for a single interface that allows the engineer to handle all the variables in a dynamic analysis.
The vN4D core product is based on Working Model 3D, so a Working Model user will be right at home. The differences are in how vN4D organizes the information for each part in the assembly, the other parts that are connected to it, and the types of constraints imposed on it. Creating your custom templates for different classes of problems is the best way to take advantage of the many settings for units, material, geometry, surface texture, FEA, and contact. I like the use of tabs to access the various input and output lists, annotation, and animation controls.
Among enhancements, the new "paint the constraint" concept allows users to specify the starting point and drag the end point as if they were drawing a line connecting two points.
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VN4D is geared for first-pass design validation. |
The formula window represents one of the key parts of this version. The window offers a number of ways to assign or extract information from your models. You can use an equation with entities from Working Model such as position, velocity, math, or logic, or prescribed functions like step, ramp, or harmonic. VN4D will calculate the formula and attach it to the selected note, so the annotation can be used to display information on the fly.
Using a subset of NASTRAN, MSC's flagship software package, vN4D's capabilities are for a first-pass design validation. Although it is limited to linear models, its FEA tools allow you to complete structural, steady-state thermal, modal, and buckling types of analyses with a fast, iterative solver.
The procedure is rather simple. Mark any part to be a candidate for FEA, and after specifying some material parameters, mesh the part, solve it, and the results are a few mouse clicks away. As far as meshing capabilities, vN4D applies one element size to the whole part with no localized element size biasing. For better results, use the default settings for a first-pass H-Adaptive run, and then lower the default error level to allow vN4D to perform successive runs for better mesh densities. The FEA runs can be for a single-load application, or linked to motion with dynamic loading, calculating the results for each frame.
However, during the analysis of a simple model whose excessive displacement exceeded the limits of the linear regime, a warning message prompted me to explore MSC's advanced modules. But a design engineer with no extensive FEA experience could miss the severity of this warning—I would have expected a better explanation.
A new feature in this version allows you to use its integrated FE solver to account for correct load application and distribution, which would have been impossible—if not erroneous—by just using equations of motion alone.
The Matlab/Simulink integration into the vN4D is now more robust than its predecessor's. A vN4D application can start from Matlab's Launch Pad, where other documents like online help, demos, and other tools of your choice may be accessed.
And, vN4D is fully integrated with all the major players in the midrange CAD market. This allows it to be loaded from within SolidWorks, SolidEdge, or Autodesk's Inventor or Mechanical Desktop. As a result, vN4D supports ACIS, Parasolid, DWG, DXF, IGES, STEP, and STL.
MSC targets this package for design engineers who need an analytical tool for the early stages of design, without demanding extensive support. But from my standpoint as an analytical engineer, its capabilities exceed these limits in many respects.
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