Natural frequency (mode)
Short definition
The free-oscillation frequency of a mechanical system; the first 5 modes of the pipe+shaft assembly are stored.
Full definition
A natural frequency is where the system oscillates on its own. For the coupled pipe+shaft assembly VibroTheory solves the generalized eigenvalue problem (K − λM)u = 0 on an FEM Euler–Bernoulli beam model (200 pipe + 240 shaft elements). The first 5 modes are stored (freqs_mech_n); for the reference build: 45.5, 63.6, 168.2, 226.8, 396.3 Hz. Modes inside 10–200 Hz are charted as resonances.
Examples
The 45.5 Hz mode: keep the working frequency away from it.