Wen Li, Weaver James C, Lauder George V
The Museum of Comparative Zoology, 26 Oxford Street, Harvard University, Cambridge, MA 02138, USA School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China
Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA.
J Exp Biol. 2014 May 15;217(Pt 10):1656-66. doi: 10.1242/jeb.097097.
Although the functional properties of shark skin have been of considerable interest to both biologists and engineers because of the complex hydrodynamic effects of surface roughness, no study to date has successfully fabricated a flexible biomimetic shark skin that allows detailed study of hydrodynamic function. We present the first study of the design, fabrication and hydrodynamic testing of a synthetic, flexible, shark skin membrane. A three-dimensional (3D) model of shark skin denticles was constructed using micro-CT imaging of the skin of the shortfin mako (Isurus oxyrinchus). Using 3D printing, thousands of rigid synthetic shark denticles were placed on flexible membranes in a controlled, linear-arrayed pattern. This flexible 3D printed shark skin model was then tested in water using a robotic flapping device that allowed us to either hold the models in a stationary position or move them dynamically at their self-propelled swimming speed. Compared with a smooth control model without denticles, the 3D printed shark skin showed increased swimming speed with reduced energy consumption under certain motion programs. For example, at a heave frequency of 1.5 Hz and an amplitude of ± 1 cm, swimming speed increased by 6.6% and the energy cost-of-transport was reduced by 5.9%. In addition, a leading-edge vortex with greater vorticity than the smooth control was generated by the 3D printed shark skin, which may explain the increased swimming speeds. The ability to fabricate synthetic biomimetic shark skin opens up a wide array of possible manipulations of surface roughness parameters, and the ability to examine the hydrodynamic consequences of diverse skin denticle shapes present in different shark species.
尽管由于表面粗糙度产生的复杂流体动力学效应，鲨鱼皮的功能特性一直备受生物学家和工程师的关注，但迄今为止，尚无研究成功制造出一种能够详细研究流体动力学功能的柔性仿生鲨鱼皮。我们首次对合成的、柔性的鲨鱼皮膜进行了设计、制造和流体动力学测试研究。利用鼠鲨（尖吻鲭鲨）皮肤的显微CT成像构建了鲨鱼皮小齿的三维（3D）模型。通过3D打印，将数千个刚性合成鲨鱼小齿以可控的线性阵列模式放置在柔性膜上。然后，使用机器人扑翼装置在水中对这个柔性3D打印鲨鱼皮模型进行测试，该装置使我们能够将模型保持在固定位置，或以其自推进游泳速度动态移动它们。与没有小齿的光滑对照模型相比，在某些运动程序下，3D打印鲨鱼皮的游泳速度提高，能耗降低。例如，在垂荡频率为1.5Hz、振幅为±1cm时，游泳速度提高了6.6%，能量运输成本降低了5.9%。此外，3D打印鲨鱼皮产生了一个比光滑对照具有更大涡度的前缘涡，这可能解释了游泳速度的提高。制造合成仿生鲨鱼皮的能力开启了对表面粗糙度参数进行多种可能操作的大门，以及研究不同鲨鱼物种中存在的各种皮肤小齿形状的流体动力学后果的能力。
