In this section, we will consider the development of an active dynamic vibration absorber. It may be noted that

• Passive Neutralizer eliminates primary response only at a particular frequency.
• Use of active element - for example, a hydraulic actuator would increase the advantage of tuned mass damping for a broad frequency range.

Figure 19.1: Active dynamic vibration absorber

Let us consider the new model as shown in Fig 19.1. Here, denotes the primary mass and the primary stiffness. The damping of the primary system is neglected. The system is subjected to a harmonic excitation .

The primary system is attached to a secondary system of fixed mass and stiffness and respectively. However, there is an additional spring element with variable stiffness '' representative of a hydraulic actuator.