Westland Helicopters Limited

Alan E Staple

Bruce A MacDonald

Andrew L Jordan

Daniel M Wells

A force-generating actuator connected at or across points of a structure capable of relative motion at an exciting frequency is operated to input a predetermined load into the structure and the response of the structure is measured for analysis. In one form of the invention the actuator is one of a plurality of actuators of an active vibration control system which is isolated and operated independently in a shake test mode. Advantageously, especially in a helicopter application, the remaining actuators can continue to be operated to reduce background vibration.

Method and apparatus for in-flight shake testing of an aircraft fuselage

This invention monitors data produced by a vibration reducing system relating to the vibration of a structure, compares the data against a predetermined value and provides a warning if the predetermined value is exceeded to provide an integrated vibration reducing and structural health monitoring system.

Integrated vibration reducing and health monitoring system for a

An active vibration control system for reducing vibration of a structure includes a first control loop comprising sensors for sensing forces in a primary vibratory load path and providing signals to a control unit incorporating time domain control logic for providing first actuator demand signals, a second control loop comprising sensors for sensing secondary vibration forces and providing signals to a control unit incorporating frequency domain control logic for providing second actuator demand signals, and a summing device for summing the first and second actuator demand signals and providing resultant signals for operating a plurality of actuators for inputting controlled vibration response forces into the structure to reduce vibration.

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Stoke-sub-Hamdon, United Kingdom

Alan E Staple