Mechanical properties and size scaling of long-eared owl primary feather

Velvety down material distributed over the owl wing surface has been investigated for the silent flight characteristics. In order to promote the technical application of the owl's special soft elongated distal barbules, we presented a study on the morphological and mechanical characterisation of the barbules branched on the long-eared owl primary feather. Tensile experiments of the barbules were conducted on a developed micro-tensile tester, and viscoelastic response of their stress and strain was described by the standard linear solid model. Barbules' geometry sizes and mechanical properties were compared with those of other feather hierarchical branches (rachis, barb, barbicel). Consequently, for the whole long-eared owl primary feather, scaling relationships of both the branching diameters and mechanical properties with respect to the branching lengths were established. The purpose of this investigation was to provide a basis for the material and structure design of bionic noise reduction components used in aviation, aerospace, marine and other fields.