Meeting Abstract
The flukes of cetaceans deflect during the swimming stroke, creating curvatures in both the span- and chord-wise directions, and it is thought that this “cupping” mechanism increases the thrust and efficiency of the stroke. Artificially reproducing the swimming characteristics of these animals necessitates replicating this curvature, which depends on the stiffness of the fluke. However, no measurements of flexural stiffness across the whole fin have yet been undertaken. The purpose of this research was to create a map of flexural stiffnesses across various flukes, both biological and artificial. To accomplish this, a simple rig was built which deflects the fluke while recording force at multiple points across the fin, and the stiffness characteristics of the fins were determined from this data. The stiffness maps of the biological fins would then inform the design of artificial flukes and allow for comparison for biofidelity. Despite differences in tail structure, the same process can also be applied to other efficient swimmers. For example, in thunniforms the stiffness map would instead measure the passive stiffness at the peduncle.
