It is defined using three optimization parameters (OPT_PARAM): MODETRACKING = <on/off>, <node_group> MODENUMBERS = <number_modes> MODETRACK_REFERENCE =INITIAL | PREVIOUS Mode tracking is activated using the optimization parameter MODETRACKING= ON. The second item in MODETRACKING defines the node group which is used for the mode tracking. The node group can improve performance when the node group is small. If no node group is defined all nodes in the model will be applied as default. This is reasonable for small to medium sized finite element models. By default the mode tracking applies for 5 modes. This can be changed by the item MODENUMBERS = <number_modes>. This number should not be set too high otherwise the CPU-time might have a significant increase. Using the parameter MODETRACK_REFERENCE for the Modal Assurance Criterion (MAC) allows the user to define the reference modes applied when tracking the modes during the optimization iterations. If the parameter MODETRACK_REFERENCE is set to INITIAL then the reference modes are set to be the modes of the initial optimization iteration throughout the entire optimization history. If the parameter MODETRACK_REFERENCE is set to PREVIOUS then the reference modes are always set to be the modes of the previous optimization iteration. Typically, setting MODETRACK_REFERENCE to INITIAL is the most consistent comparison in the modetracking. However, some initial modes may change significantly or completely disappear during the optimization iterations and thereby, the INITIAL comparison may fail. When INITIAL as setting for MODETRACK_REFERENCE is failing then the only option is to apply PREVIOUS even though the comparison might not be so consistent as INITIAL. | |||||||||||