Optionally natural frequencies and harmonic response can be calculated using the software. The setting Calculate natural frequencies has to be activated for this.
First the nonlinear static equilibrium is calculated. Then the natural frequencies and the harmonic response are calculated using the linear equations of motion with the tangent stiffness matrices from the static equilibrium. Therefore the results are only valid for small amplitudes around the static solution.
The natural frequencies are calculated using the given rotation speed. The critical frequencies are the intersections between shaft speed and natural frequency at this shaft speed. The critical frequencies are shown in a special report or they can be found in the Campbell diagram.
In the menu Calculations an additional calculation of frequency response is available. To use this, one or more dynamic forces have to be placed on a shaft and the calculation of natural frequencies needs to be active. It allows to define one dynamic force and to vary its frequency over a given range. Results for displacement, velocities and forces are available for documentation points or supports.
