FEMtools™ 3.1 & 3.1.1 Release Notes

The FEMtools 3.1 release includes numerous improvements and continues to add new functionality. The new release confirms the technological leadership in the FE model validation and updating field and extends the application reach of FEMtools into the optimization field.

Some of the highlights of FEMtools 3.1 are

• Easy definition of superelements and integrated Craig-Bampton reduction
  Superelements can now be easily defined using the FEMtools user interface from element sets. The Craig-Bampton reduction method has been integrated to obtain reliable reduced component matrices for structural dynamics synthesis applications. Reduced superelement matrices can be exported as Nastran DMIG. Alternatively, a Nastran driver can be used for doing the reduction outside FEMtools.
  
  
• Superelement-based model updating
  Components that are reduced in FEMtools (e.g. using Craig-Bampton) or imported Nastran DMIG can be used in model updating runs. Only the residual parts of a model, i.e. the parts that are not reduced and connect the superelements, are updated. This approach allows to significantly cut analysis time and reduces database size requirements.
  
  
• Generic finite difference gradients
  New drivers for FE solvers and automation routines are included to compute the finite difference gradients for any structural response and parameter combination. FEMtools now offers a complete range of methods for sensitivity analysis from fast approximate modal methods over internal differential methods up to exact finite difference perturbation methods. Depending on the number and type of parameters, and the required precision, the most suitable method can be chosen for the given application.
  
  
• Mesh morphing
  New functions for mesh morphing enable users to quickly modify existing Finite Element (FE) models instead of regenerating new models through the lengthy and error-prone process of meshing from CAD. Morphing of FE meshes is done by modifying the position of some control points and works extremely fast, even for large models. By defining the position of the control points as the variables in a design optimization routine, the shape and size of designs can be optimized faster and more efficiently than using parametric CAD models.

Dynamic Design Solutions is releasing FEMtools 3.1.1, a maintenance release that provides several improvements and corrections. Some highlights in this version are changes to data translators, and new settings for superelements analysis, sensitivity analysis and model updating:

• Upgraded versions of the NASTRAN, ABAQUS and I-DEAS 12 file translators are included.  A new version of the Universal File for modal test data interface program is provided, supporting local coordinate systems and definition of surface elements.

• For superelement analysis, new settings are provided to extend the frequency range covered by a component compared to the frequency range of interest for the assembled structure.

• Sensitivity analysis and model updating can now make use of an improved approximation of proportionality for the shell thickness parameter. Using this improvement, the differential sensitivities are much closer to the ‘exact’ finite differences for elements that show important membrane and membrane-bending coupling while at the same time realizing significant analysis time savings compared to costly finite difference sensitivity analysis. This is most visible in analysis with many updating or optimization parameters

Minimum System Requirements

The following are the minimum OS levels required to run FEMtools 3.1:

• Windows 2000 and XP
• HP - UX 10.20+ 
• Solaris 2.8+ 
• SGI IRIX 6.5+
• IBM AIX 4.3+ 
• Red Hat Linux 7.3+

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Last modified: December 20, 2006