Meeting Abstract
Bio-logging tags that enable behavioral studies of marine mammals are often secured using suction cups to minimize impact to the animals. However, suction cup performance is dependent on the dynamics of the attachment surface. Marine mammal skin is made up of tissue layers that possess viscoelastic properties and exhibit a nonlinear stress-strain relationship during loading, but in-vivo measurements of the tissue at the attachment sites are lacking. Further, the highly integrated tissue layers that make up the skin are not distributed uniformly, resulting in a variable viscoelastic composite. The goal of this research is to characterize the response of the composite tissue under vacuum loading. In our preliminary work, a static suction cup (SSCup), a half-dome device equipped with a linear variable differential transformer, was used to measure the peak skin displacements under three types of loading (static step vacuum loading, repetitive loading, and creep/relaxation) at three different sites (Site 1: anterior to the blowhole; Site 2: above the pectoral fin; Site 3: below the dorsal fin) on six bottlenose dolphins. The results indicate Site 3 is stiffer than Sites 1 or 2 and shows little hysteresis, while Sites 1 and 2 have comparable force vs displacement curves. While promising this system only measures the maximum deformation of the skin. To enable full field deformation and strain measurements, this study presents a portable 3D-printed device that uses digital image correlation to make full field deformation and strain measurements of skin. These results will lead to a better understanding of the tissue and facilitate improved suction cup design.
