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FEMtools 3.4 Release Information

FEMtools 3.4 is a major revision of the FEMtools software suite that introduces new functionality for meshing, model updating and structural optimization in addition to numerous improvements and extensions to existing tools. Some of the highlights of this version are the following:

On the Windows OS, FEMtools 3.4 adds support for Windows 7 but is also still available for Linux, AIX, HP-UX and SUNOS.

This version now supports add-on tools that can be separately installed and uninstalled from the new Add-ons menu.

To accommodate the growing number of commands, the main toolbar now contains a list ox from which a desktop configuration can be selected. This listbox loads menus, toolbars, popup menus and adapts the explorer to the selected configuration. The following configurations are supported: Dynamics, Pretest Analysis, Correlation, Model Updating and Optimization. All commands that belong to the same configuration are now conveniently located in the Tools menu using less submenus. As a result, navigation to all commands in a same configuration like e.g. correlation analysis has become easier and faster. In addition, a new Add-ons menu is included to accommodate special purpose tools that extend the functionality of FEMtools.

There are two new User’s Guides that come with FEMtools 3.4, that respectively document the mesh generation and function library and the rigid body properties extraction add-on tool. The FEMtools Optimization User’s Guide has been significantly expanded to include the new Design of Experiments and Response Surface Modelling tools.

A function library is added to generate surface meshes and volume meshes. Unstructured surface meshes can be generated for generic surface patches that are defined using simple geometry description (vertex, curve, surface). Volume meshes are obtained from 2D meshes with operations like extrusion and revolving. This new FEMtools API function library complements the already available lattice-based mesh deformation ('morphing') and provides the functionality to mesh very complex geometries. It can be used for applications like parametric meshing for shape optimization, meshing design spaces for topology optimization or to implement mesh coarsening and refinement tools.

New tools to verify the quality of imported or generated finite element meshes are now included. Quality metrics like aspect ratio, convexity, taper, warp angle and others can be computed on the fly and visualized with color-coded mesh graphics. Results can be further post-processed by computing histograms or sorting mesh quality values. Additional mesh quality metrics can be implemented using the FEMtools Script programming language.

The data interfaces with ANSYS, NASTRAN, ABAQUS, and I-DEAS have been extended and updated to support the latest versions of these programs.

This new add-on tool is used to obtain the mass (M), center of gravity (CoG) and mass moments of inertia (MoI) from the low-frequency portion of measured accelerances (FRFs). These properties can be used as targets for finite element model updating, or to reduce components to lumped masses for model reduction in structural dynamics simulations or motion analysis.

Experimentally obtained vibration shapes (Operational Deflection Shapes or ODS) can now be used to update stiffness, mass and damping parameters. To simulate the ODS, the dynamic excitation forces must be known. These forces can be measured, for example as forcing displacements, velocities or accelerations and are applied to the finite element model. From the differences between simulated and experimentally-obtained ODS, adjustments of stiffness, mass and damping can be obtained. An important application of ODS-based model updating is monitoring of vibrating machinery for damage and structural health.

By using efficient data management and powerful algorithms for sensitivities and model updating, FEMtools can handle very large numbers of updating parameters. Element-by-element updating of parameters like thickness or elastic modulus may result in a large number of updated properties that can vary from element to element. This is a standard technique for explorative model updating to obtain information on local changes that may be required. Results must be interpreted in terms of changes that may be required to geometric refinement or mesh density. Such updated models, however, are usually not suitable for further analysis due to the large number of property cards in the finite element model. A new postprocessing tool is now available to regroup elements based on their properties to obtain a smaller and practical number of different properties.

Design of Experiments (DOE) and Response Surface Modeling (RSM) was already available in FEMtools 3.3 for applications in model updating. In FEMtools 3.4 these methods have now also been integrated in FEMtools Optimization and can be used with generic optimization parameters, objective functions and constraint equations. Design of experiment (DOE) techniques aim at sampling the design space in an efficient way with a minimum number of sampling points, as the evaluation of each sampling point requires an additional run of the FE-model. FEMtools provides the following designs: factorial designs, central composite designs, Latin hypercube designs, D-optimal designs, and user-defined designs. Response Surface Modeling (RSM) is used to build an approximate model from the DOE runs to predict the response of the system in function of the design parameters. This approximate model can then be used to optimize the response of the considered system instead of the finite element model of which it was derived.

There are 92 new commands to be used in command scripts. Programmers will benefit from 7 new FEMtools Script functions and 56 new FEMtools API functions.

For the complete list of changes, see the FEMtools 3.4 Release Notes.

Minimum System Requirements

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

• Windows XP, Vista, 7 (32-bit)
• Window XP Pro, Vista , 7 64-bit
• HP - UX 11.00+
• Solaris 2.8+
• IBM AIX 5.1+
• Linux 32-bit
• Linux 64-bit