FVA-Workbench 11.0
Note
This document is a work in progress. The contents may be modified or amended.
FVA-Workbench 11.0
With this new calculation module, Rotating Rainflow matrices can be considered and used to create pseudo-stress time curves for evaluating gear load capacity. In contrast to using standard load cases, this method also makes it possible to consider cycles resulting from shifting operations and the resulting stresses in the damage accumulation.
(1) Under the "Calculations" tab, the Rotating Rainflow calculation can be activated as an additional calculation to the flexible load spectrum calculation.
(2) A transition matrix with transition frequencies between the individual load cases in the Rotating Rainflow matrix must be entered for the calculation.
(3) The transition matrix can also be displayed in the Quick Results View for quick visual inspection. This is especially helpful for large matrices.
(4) The Rotating Rainflow calculation is performed as part of the system calculation. The results are saved in a model snapshot which only contains the results of the load spectrum calculation. A report template is available for evaluating the results.
Output report for the Rotating Rainflow calculation
Skiving is a high-performance continuous generating process for internal and external gear teeth. The kinematics are based on crossed helical gears. The tool and workpiece are tilted by a cross axial angle and rolled together. To do so, the manufacturing processes for cylindrical gear profile generation have been expanded to include the new "skiving cutter" tool type. Flank and root standard load capacities as well as a 3D contact analysis can be calculated based on gear geometries generated by skiving.
(1) The target profile of a skived gear is determined by specifying the tip and root circles as well as the root radius.
(2) The actual profile is a result of the manufacturing kinematics of the skiving process. Manufacturing deviations are differences between the target and actual profiles. These differences can be considered in the local load distribution calculation.
(3) The data used to determine the actual profile is defined in the new "skiving cutter" tool type.
(1) The envelope cuts of the manufacturing process as well as the resulting contour are displayed. The deviations on the involute and in the tooth root area are shown for both the left and right flanks.
(2) Representation of the skiving cutter profile resulting from the user specifications.
A universal contact friction model was implemented in the FVA-Workbench as part of the FVA 998 series of research projects in collaboration with the RPTU Chair of Machine Elements, Gears and Tribology. This provides FVA-Workbench users access to a high-quality, physical, locally resolved contact friction model which can be used to make more precise statements about rolling bearing load-dependent power loss calculations. It also enables deeper insights into contact conditions and possible damage mechanisms.
This new module can be used for mesh-dependent rolling analysis of gear systems with multiple meshes, such as planetary gears. The load and deformation behavior is calculated sequentially for different rolling positions with consideration of the mesh-dependent tooth stiffnesses, more accurately reflecting real operating conditions. Key results include the load distribution in planetary gears, the transmission error of individual stages, and the total transmission error from input to output. The extended analysis enables targeted identification of excitation influences for more precise evaluation of vibration and deformation behavior in the development process.
Transmission error and spectrum from input to output.
(1) Transmission error of the planet-ring gear engagement with cross-influences from the overall system.
(2) Transmission error of the planet-ring gear engagement without cross influences.
Bugfixes
If the face load factor KHβK_{H\beta}KHβ for the LRS load capacity calculation was specified by the user, an error message that the value is not available was incorrectly shown. This has been fixed.
The following geometry parameters are now also calculated for the bevel gear geometry design according to ISO 23509 and the load capacity calculation according to ISO 10300 (2023):
Inner and outer tip cone and root cone diameters
Inner and outer helix angle
The wizard for importing bevel gear measurement data has been revised.
Planetary gear plain bearing calculations
The new COMBROS PG calculation module is focused on planetary gear plain bearings, especially for wind turbine applications. The calculation model includes a stationary pin with the oil supply on the inner side and the rotating planetary gear on the outer side. COMBROS PG is based on an efficient thermo-elasto-hydrodynamic calculation approach that has been theoretically and experimentally validated by the TU Clausthal Institute of Tribology and Energy Conversion Machinery. The COMBROS PG-FEM calculation variant uses corresponding FE structures to consider the elastic deformation of planet pins and planetary gears.
Plain bearing coordinate system
The coordinate system for plain bearings has been standardized. Parameterization is now independent of the direction of rotation. Diagrams are also now displayed in the FVA-Workbench coordinate system so that the results can be transferred directly to the model.
Output diagrams now use the FVA-Workbench coordinate system.
Additional changes
The plain bearing tables according to FVA 961 have been expanded. Tilting pad bearings with profiling >= 1.25 are now supported.
Imperial units in report tables
Metric and imperial units can now be selected for displaying the values of results in report tables.
Output can now be toggled between metric and imperial units in the report settings.
Metric and imperial units can be defined for each attribute in the "units and decimal places" dialog box.
Additional changes
Values and tables that do not differ between two model snapshots can be hidden in comparison reports. This is now also possible for diagrams with no differences.
The x-axis mirroring in diagrams over the common facewidth feature introduced in FVA-Workbench 10.1 can now be turned on or off in the reporting settings.
The log level for calculation messages output in the report can now be configured. This makes it possible, for example, to only show errors and warnings, but not information messages.
The gearbox layout in the 2D Modeler is now saved during an FVA-Workbench session. As long as no significant changes are made to the components, the layout is maintained when the 2D Modeler is reopened.
The configured grid size, snap mode, and rotation angle are now permanently saved.
The position of multiple shafts can now be moved simultaneously.
Multiple shafts can be selected and moved using CTRL + click or via a selection rectangle.
In the 2D Modeler, schematics can used as background images for tracing the shaft geometry. These images can be cropped to a defined area. This makes it possible to use a schematic of the entire gearbox and individually crop it for each shaft in the 2D Modeler
Previously, background images could only be displayed while modifying the shaft contour. They can now also be displayed in the standard component view.
Background images can be individually shown or hidden for each shaft using the checkboxes of the Model Tree in the 2D Modeler.
The center of a shaft section is now also considered as a snap point in the "snap to edges" snap mode.
(1) "Snap to edges" snap mode
(2) "Snap to grid" snap node
Free cutting plane
The free cutting plane has been revised and can now be used directly via the toolbar in the 3D Model.
(1) Activates the free cutting plane and allows it to be moved and rotated.
(2) Locks the free cutting plane in its current settings and allows you to continue working in the model as normal.
3D Model right-click menu
The 3D Model right-click menu has been revised and simplified. The following changes have been made:
For cutting planes, it is now possible to select the stage whose angle should be used for the cutting plane.
Cross-sections through individual components now function the same way as cutting planes.
The options for displaying FE coupling nodes have been moved to a submenu. FE reduction nodes can now also be displayed.
The assembly part library options have been moved to a submenu.
With the new exportDiagram() feature, reporting diagrams can now be exported as image files via scripting.
Here, the exportDiagram() feature was used to export the pressure distribution, flank modification, load distribution across the facewidth, and transmission error diagrams after each step of a variational calculation. The individual images were then combined into a GIF animation using the ezgif tool.
The number of planetary gears in a planetary stage can now be set via scripting using the setNumberOfPlanets() feature.
The getAttr() feature has been extended so that attributes of instance components, which are actually only defined for the associated parent component, can now also be queried. In the FVA-Workbench, only values that apply to the individual instance are stored on instance components. The new logic of the feature first checks whether the desired attribute is present on the instance component. If this is not the case, the associated parent component is automatically queried. Example: It was previously not possible to read the number of teeth of a planetary gear directly from a concrete instance of a planet (e.g.; Planet @ 120°), but only from the parent component. This is now possible.
The readFileAsString() feature has been extended with a parameter to specify the encoding of the file to be read.
The runCalcMethod() feature has been extended so that when the "createResultpath" option is activated, the calculation kernel files are also written to the specified directory in the event of an error or termination. This makes it easier to investigate failed or terminated calculations.