Active isolation of noise transmission through a helicopter gearbox support strut using multiple magnetostrictive actuators

摘要

Successful noise control often depends on effective isolation of a vibrating machine from its support structure. If it is not checked at source, vibrational energy tends to propagate through a structure causing unwanted sound radiation at some remote location. In the case of a helicopter, such as the Westland/Augusta EH 101, the main rotor drive and gearbox assembly are linked to the passenger-carrying cabin by four cylindrical steel load-bearing struts (Figure 1) which are the major transmission path for structural vibration. The main function of these gearbox support struts is to hold the craft together: they are essential for structural integrity. Unfortunately they offer little vibration isolation.