Simple Static Instability

Simple static instability. Flow excursion (Ledinegg instability) involves a sudden change in the flow rate to a lower value. It occurs when the slope of the channel demand pressure drop-versus-flow rate curve (internal characteristic of the channel) becomes algebraically smaller than the loop supply pressure drop-versus-flow rate curve (external characteristic of the channel). The criterion for this first-order instability is... 

Here two simple cases of instabilities are considered to emphasize the concepts described above. We begin by distinguishing the difference between static and d mamic instability by considering the stability of atmosphere as an example. 

The negative slope in the friction-sliding velocity curve or the difference between static and kinematic coefficients of friction can lead to the so-called stick-slip vibratiOTis (see, e.g., [14, 59]). In most instances, researchers adopted the well-known mass-on-a-conveyor model to study the stick-slip vibrations (see, e.g., [17, 60, 61]). In this section, we will also consider this simple model - as shown in Fig. 4.1 - to investigate the effects of the negative damping instability mechanism. 

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