Wool fibre microdamage caused by opening processes. part IV: In-situ sem studies on the compressive microdamage and failure of wool fibres looped around opening elements

The compressive behaviour of wool fibre looped around an opening element was studied under quasi-dynamic conditions by using a compressive stage inside an SEM chamber. Real-time images of the microdamage imposed upon the fibre were monitored and recorded during the compression. This study shows that test fibres experience large compressive deformations in the contact area. Study of the mechanism of fibre failure through in-situ fractography shows that the breakage starts from the outer surface of the bend and propagates into the compressed surface. The present study also reveals that creep can hide some cracks formed on the surface of the contacted fibre. The failure of wool fibre in contact with a sawtooth and with a pin element is compared and discussed. The likely mechanism of compressive failure of contacted wool fibre is also explored.