Question:
Is it possible to display natural frequencies separately for each direction?
Answer:
Spatial models in which multiple directions are selected in the RF‑/DYNAM Pro - Natural Vibrations add-on module do not output mode shapes separately for the individual directions. It may happen that one mode shape of the vibrations is dominant in one direction (thus, the mass is only excited in one direction, such as in the X-direction only). However, it may also happen that one mode shape has vibrations in several directions at the same time (that is, the mass is excited in two or more directions, for example in the X- and Y-directions at the same time). Therefore, the mode shapes are not dependent on the global coordinate system, but on the stiffnesses of the structure in the individual directions.
You can check the direction in which the dominant vibration of a mode shape acts by displaying the "Effective Modal Mass Factors" table and checking whether the mass was excited in the individual directions. In Image 01, you can see from the effective modal masses that the first mode shape acts exclusively in the Y-direction, the second in the X-direction, and the third one is a torsional vibration.
It is possible to define several natural vibration cases and to activate the masses only in one direction. Thus, the mode shapes for each direction are obtained separately in each case.