The mechanical properties of primary feathers

Abstract

The mechanical properties of biological materials often surpass their manmade counterparts. However because of their complexity many of these materials are yet to be fully understood and as a result, their solutions to engineering problems cannot benefit the design of man-made analogues. Lucas and Stettenheim (1972) stated that feathers are probably the most complex derivatives of the integument to be found in a vertebrate animal and recent work suggests that the longest, stiffest, strongest, and most deserving of mechanical investigation are the flight feathers. These feathers attach to the manus and allow birds to fly. A small amount of research into the broader aspects of their mechanics is already present in the literature, but some of the finer details, such as the shaft’s laminar micro-structure, have only been superficially explored. This thesis develops a method based on ultra-high resolution CT scanning to measure the orientation and thickness of layers in the shaft of the first primary feather from three swans. Results show the first quantifiable and repeatable measure of thickness and orientation at different locations in the feather shaft. These results are supported by other techniques and longstanding definitions of the calamus:rachis delimitation are inappropriate. Raman spectroscopy is used to show that secondary protein structures vary within, and between layers, and a discussion is presented from a mechanical perspective. Tensile tests are then completed on smaller pieces of feather from different places on the shaft and analysed using Classical Laminate Theory. Results from all three experiments are then discussed together and suggestions are made to future workers who might further the methods developed as part of this work and contribute to an exciting new area of science, in which many international groups are now working.

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