Two Architectures for Bending-Twisting Flapping Using Macro-Fiber Composites

There has been growing interest in the research fields of morphing-wing and flapping-wing aircraft for improved flight efficiency and maneuverability. Recent efforts have focused on the use of smart materials as actuators in biomimetic morphing and flapping. Macro-Fiber Composites (MFCs) are composed of piezoelectric fibers sandwiched between interdigitated electrodes in addition to Kapton and epoxy laminates. The MFC technology offers effective sensing and actuation with its light weight, high flexibility, durability, high performance, and availability in various sizes. Researchers have studied the use of MFCs in structural health monitoring, vibration control, actuation, and energy harvesting. In the last few years, MFCs have been successfully integrated to morphing-wing aircraft by several others. However, there has been limited work on MFC-based flapping wing by dynamic actuation. The flapping-wing flight is more beneficial than conventional flight at relatively small scales due to its high maneuverability. Biological flapping-wing flyers incorporate different wing motions such as dynamic bending, twisting, and folding to create asymmetry for positive lift and thrust resultants. This paper experimentally characterizes the electroelastic dynamics and power consumption of two MFC-based architectures for bio-inspired flapping. The first configuration employs an asymmetric wide bimorph architecture with 0° and 45° piezoelectric fibers to have an actuation authority in bending and twisting. The second configuration uses a double bimorph arrangement made of two narrow bimorphs with 0° fibers with a chord-wise spacing to create both bending and twisting depending on the relative actuation inputs. Both of the bending-twisting architectures considered herein are tested over a wide range dynamic actuation levels and frequencies to characterize the electroelastic response. In addition to measuring the power consumption levels in dynamic bending and twisting, flexible solar films are investigated as the light-weight multifunctional substructure layers that can create both lift surface and electricity toward the concept of self-powered flapping.