Rheo-nichtlineare Schwingung

Description: Parameter-excited Oscillation occurs if parameters of the oscillation system (parameters of inertia, Damping values or spring constants) are subject to time-dependent and mostly periodic changes. One example is the time-dependent change in the length of a simple pendulum. The excitation process is heteronomous (external), with a time-dependent influence on the oscillator, but it has no impact on the system as long as this is in a state of Equilibrium. This distinguishes parameter-excited oscillation from Forced oscillation. The equilibrium can be unstable, which means even a slight disturbance can cause parameter-excited oscillations. Parameter-excited oscillations are also called rheo-linear or rheo-non-linear oscillations. This refers to the form of the differential equations describing them. Parameter-excited oscillations occur, for example, in rotating systems. When a Shaft rotates, the vertical shaft stiffness changes periodically. In the case of turbines, the unwinding of blades also results in a time-variant change in the stiffness matrix.