Feather shafts have been found to be made of a multi-layered fibrous composite material, much like carbon fibre.
Feather shafts have been found to be made of a multi-layered fibrous composite material, much like carbon fibre.

Feather shafts (rachises) have evolved to be some of the lightest, strongest and most fatigue resistant natural structures. However, relatively little work has been done on their morphology, especially from a mechanical perspective and never at the nanoscale. 

 
Ths scientists used nano-indentation, a materials testing technique, on the feathers. It revealed that the number, proportion and relative orientation of rachis layers is not fixed, as previously thought, and varies according to flight style.
 
“We started looking at the shape of the rachis and how it changes along the length of it to accommodate different stresses,” said the university’s Christian Laurent, who is lead author of the study.  “Then we realised that we had no idea how elastic it was, so we indented some sample feathers. 

Aeronautical findings

“Previously, the only mechanical work on feathers was done in the 1970s but under the assumption that the material properties of feathers are the same when tested in different directions, known as isotropic – our work has now invalidated this.” 
 
The researchers tested the material properties of feathers from three birds of different species with markedly different flight styles; the Mute Swan (Cygnus olor), the Bald Eagle (Haliaeetus leucocephalus) and the partridge (Perdix perdix). 
 
“In terms of engineering, we hope to apply our future findings in materials science to yacht masts and propeller blades, and to apply the aeronautical findings to build better micro air vehicles in a collaboration engineers at the University,” said Laurent.