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Resonant passive energy balancing for a morphing helicopter blade

Zhang, Jiaying; Shaw, Alexander D.; Wang, Chen; Gu, Huaiyuan; Amoozgar, Mohammadreza; Friswell, Michael I.


Jiaying Zhang

Alexander D. Shaw

Chen Wang

Huaiyuan Gu

Michael I. Friswell


The idea of morphing a helicopter blade by using compliant structures promises augmented capabilities in terms of manoeuvrability and fuel efficiency. To achieve morphing, compliant structures work by elastically deforming to achieve the desired response, and therefore actuation must work against the inherent structural stiffness in addition to external loads. Passive Energy Balancing has previously addressed this problem for quasistatic loads, by adding negative stiffness elements in parallel with the structural stiffness, so that stiffness is reduced almost to zero and lighter actuators may be used. This work extends this idea to the case of dynamic actuation, where negative stiffness is optimally used to reduce the natural frequency of a morphing blade, so that it may resonate at the desired actuation frequency. A negative stiffness mechanism in parallel with the structural stiffness can be used to tailor the natural frequency of a morphing blade system. Furthermore, the negative stiffness mechanism introduces nonlinearity that has some benefits in stabilising the resonant response amplitude compared to a linear resonance, and is also shown to be beneficial to achieve a weight efficient mechanism. A spiral pulley negative stiffness mechanism has previously addressed this problem for quasistatic loads and is extended here to achieve linear frequency tailoring and nonlinear frequency tailoring, respectively. The equivalent stiffness of the extended spring used in the rotating system has been investigated. Resonant morphing strategies exploiting dynamic tailoring have been studied showing encouraging preliminary results.


Zhang, J., Shaw, A. D., Wang, C., Gu, H., Amoozgar, M., & Friswell, M. I. (2022). Resonant passive energy balancing for a morphing helicopter blade. Aerospace Science and Technology, 128, Article 107786.

Journal Article Type Article
Acceptance Date Jul 25, 2022
Online Publication Date Aug 4, 2022
Publication Date Sep 1, 2022
Deposit Date Sep 5, 2022
Publicly Available Date Aug 5, 2023
Journal Aerospace Science and Technology
Print ISSN 1270-9638
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 128
Article Number 107786
Keywords Aerospace Engineering
Public URL
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