FEMtools 3.4 Release Information

FEMtools 3.4 is a major release 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:

Mesh Generation Function Library

A function library is added to generate surface and volume meshes from a definition of the geometry (vertex, curve, surface). Unstructured surface meshes can be generated for generic surface patches and 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.

Mesh Quality

Functions 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.

Rigid Body Properties Extraction (RBPE) From FRF Measurements

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.

ODS-based Model Updating

Experimentally obtained vibration shapes (Operational Deflection Shapes or ODS) can now be used to update stiffness, mass and damping parameters if information is available on the dynamic excitation forces. These forces can be measured themselves, 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, conclusions can be drawn on required adjustments of stiffness, mass and damping. This new functionality is completely integrated within FEMtools Model Updating and can complement other updating types like using mode shapes or FRFs as reference responses. An important application of ODS-based model updating is monitoring of vibrating machinery for damage and structural health.

Postprocessing of Local Model Updating Results

By using efficient data management and powerful algorithms for sensitivities and model updating, FEMtools can handle very large numbers of updating parameters. Model updating using local element 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 strategy 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 not suitable for further analysis due to the large number of property cards in the finite element model. New postprocessing tools are now available to regroup elements based on their properties into a lower and practical number.

Structural Optimization using DOE/RSM

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 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 of a problem in an efficient way. The main goal of DOE is to obtain the required information 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 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.

Windows 7

FEMtools 3.4 supports the newest Microsoft Windows 7 operating systems in native 32-bit and 64-bit versions.

Minimum System Requirements

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

• Windows 2000 and XP, Windows Vista 
• Window XP Pro 64-bit and Windows Vista 64-bit
• HP - UX 11.00+
• Solaris 2.8+
• IBM AIX 5.1+
• Linux 32-bit
• Linux 64-bit

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Last modified: January 26, 2010