Elements Of The Applied Theory Of Elastic Vibration | Ya. Panovko

We may distinguish at least the following live sufficiently inde­pendent categories of vibratory processes differing in their nature:

free vibrations, i.e., vibrations which are performed by a mecha­nical system having no energy supply from outside if the system is disturbed from its position of equilibrium and then released,

critical states of rotating shafts and rotors which consist in a sudden increase in the deflections of their axes at definite speeds of rotation (or in definite ranges of speeds),

forced vibrations which result when the mechanical system is acted on by fluctuating external forces (driving forces),

parametric vibrations caused by periodic variations of the para­ meters of a system (for example, its stiffness),

self-excited vibrations, i.e., vibratory processes which are main­tained by constant sources of energy of a non-vibratory nature.

Each of these categories of vibratory processes is discussed in the appropriate chapter.