Dual optimization of contact-aided compliant mechanisms for passive dynamic shape change

Joseph P. Calogero, Mary I. Frecker, Zohaib Hasnain, James E. Hubbard

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A dual optimization method for optimizing contact-aided compliant mechanism design parameters and their spatial distribution in a dynamic ornithopter wing structure for increased pitch agility is presented. This methodology separates the task into two separate optimization problems where, first, a computationally efficient rigid-body dynamics model is used to determine the optimal stiffness and spatial distribution of the compliant mechanisms and, second, a detailed compliant mechanism design is developed and optimized that achieves the desired nonlinear stiffness. A rigid-body mechanics model of the wing structure is used to find the location and stiffness of a contact-aided compliant mechanism that will induce the forward sweep passively by coupling lift loads to forward sweep. The forward-swept compliant mechanism is then developed and optimized to achieve the desirable coupling. The free-flight pitch agility of an ornithopter is shown to increase via sweeping the wings forward during downstroke. A free-flight experiment is performed, and the novel contact-aided compliant mechanism is shown to induce the desired forward sweep during downstroke.

Original languageEnglish (US)
Pages (from-to)3745-3756
Number of pages12
JournalAIAA journal
Issue number9
StatePublished - 2018

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering


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