Modification of a Four-Bar Linkage System for a Higher Optimal Flapping Frequency

The goal of this work is to increase the optimal flapping frequency, at which the flapper produces maximum vertical force, of a previously developed flapper actuated by a lightweight piezocomposite actuator (LIPCA). We tested the dynamic response of the LIPCA and conducted a parametric study of a four-bar linkage system. An appropriate combination of linkage lengths can provide a better moment transmission and enhance the optimal flapping frequency. The newly designed flapper was tested with five different flapping frequencies. The experimental results confirm that the optimal flapping frequency of the modified flapper is about 17 Hz, and the flapping angle is 92 ° . The results show 70% increase in the optimal flapping frequency; however, only 8% decrease in the flapping angle compared with the corresponding values of the previous flapper. The highest vertical force produced by the newly designed flapper is 3.6 g at the optimal flapping frequency.