Design and experimental verification of a semi-active pitch link for helicopter vibration attenuation

Abstract

Piezoelectric materials have been widely applied to vibration reduction systems in several fields of engineering. Recently, different configurations of piezoelectric switch circuits for vibration reduction (i.e., semi-passive and semi-active controllers) have been presented in the literature of vibration control and some of them may be directly compared to mechanical systems used to reduce vibration in helicopters. One of these mechanical systems is the active pitch link, which has been successfully designed and tested by Canadian researchers. Such system uses the combination of springs to provide stiffness variation to the pitch link, yielding to attenuation of relevant frequencies and, therefore, enhancing the comfort of helicopter passengers. Although a remarkable control performance has been achieved with the active pitch link in experimental tests, some drawbacks (i.e. external voltage requirement and mechanical failures) are pointed out by the authors. In this sense, the objective of this project is to develop (design and test) a self-powered semi-active pitch link using piezoelectric materials and performing a non-linear treatment of the electric output provided by such materials. A series of investigations will be performed, including bench top vibration tests and Whirl Tower experimental tests, which will be held at Carleton University, in Canada. The new configuration proposed here refers to a solid-state electromechanical system that could address the issues of the mechanical active pitch link and present a good vibration attenuation performance. (AU)