Newsletter Artikel

New Features in FEMFAT 5.2

These new features are worthy of special mention:

Residue-free rainflow counting and default method

The residue-free rainflow counting implemented in MAX as of FEMFAT 5.1 ensures that the damage due to periodic loading is proportional to the number of repetitions.

As of V 5.2, this method is now the default setting. However, this can result in changes in the analysis results.

The default setting for the combination method for the influence factors has been changed in V 5.1 so that it is consistent with the “Guide for an operational strength analysis” by Gudehus/Zenner, 3rd edition, 1995. This can result in differences in the analysis results for material classes GJV, GJS, GT, GS and for sintered steel.

Figure 1:  Mirroring of all open hystereses

Analysis of the delamination based on volume elements

In a LAMINATES analysis, it is now possible to assess failure due to delamination based on Abaqus volume elements with COMPOSITE sections. When this is done, not only the stress components in the laminate plane are considered, but also the stress components perpendicular to the laminate plane. In order to assess the additional components, corresponding static and cyclical material parameters must be specified. Further information can be found in the MAX user manual.

Figure 2:  Example for delamination

Scratch file format without 2GB limit in TransMAX

Now only a single scratch file using the hdf5 format is created for the stress data of the base material. The default setting for the name of the file is the project name with the file extension “*.fss”. However, the user is also able to select the name as desired. For WELD and SPOT, the files that have been used up until now continue to be created, however in the medium term, all scratch files will go into the ffs file.

This means that the 2GB size limitation no longer applies for the base material.

Parallel tokens for an increasing number of processors

In order to compensate for the decreasing speed-up with a greater number of CPUs, the number of parallel tokens now no longer increases proportionately, but degressively. For example, the number of parallel tokens required for a typical ChannelMAX analysis in the vehicle sector (WELD, SPOT) goes down.

Figure 3:  Comparison between old / 5.2 prallel token system


Volume-based weld assessment using the SOLID WELD method

With this method, the weld roots and toes are analyzed based on a relatively coarse volume mesh (approx. 3 elements greater than the metal thickness in the area of the weld seam) with no rounding radiuses by means of a critical distance method.

Stresses in the proximity of the surface of weld roots and weld seams are taken and assessed using master S/N curves derived from the FAT project.

The special advantages of the method are the accurate representation of the stiffness, the flexibility in the integration of the welds (esp. end) and in the modeling (connection of sheet material and cast components, no mid-plane generation for shell models).

Figure 4:  Example for coarse solid weld modelling