Roller-screw inerter: a novel strut-mounted device for vibration isolation

Abstract

The struts that connect the main rotor and gearbox assembly to the fuselage carry the weight of airframe and payload during flight, and guarantee smooth operation to the drive system. While performing the functions they are designed for, these struts transmit the vibratory loads originating from the main rotor periodic aerodynamic loading to the airframe with essentially negligible alleviation. One technique to cure this problem is to implement strut-mounted vibration alleviation devices, to improve ride comfort by isolating the airframe from the main rotor excitation. This work presents a novel strutmounted vibration attenuation device and demonstrates the concept through experiments and numerical analysis. The design is based on a roller screw inerter, which is mounted in parallel to the strut, sharing its attachment points. The inerter transforms the relative displacement between the two ends of the strut into a corresponding rotation of a body about an axis parallel to that of the strut. As a result, the inerter applies to its two terminals a counter-force proportional to their relative acceleration. In the ideal, frictionless case, a global isolation of the fuselage can be achieved.