Page 66 - Handbook of Properties of Textile and Technical Fibres

Testing and characterization of fibers 47

(a) 1

2
(b)

(c)

(d)

(e)

20 μm

Figure 2.17 Scanning electron micrograph observation coupled with mechanical tests:
subcritical crack propagation in UHP PA66 fibers. Crack propagation was observed in an SEM
chamber for small-diameter (w27 mm) PA66 fibers. The strain level was increased from
picture (a) to (b) and another strain level was applied between pictures (b) and (c) causing the
crack to propagate at a constant applied strain. Elapsed time between picture (c) and cata-
strophic failure (picture e) is typically around 60 s (Marcellan, 2003).

and in the perpendicular direction called “longitudinal” and “transverse” directions,
respectively, is crucial. Very few studies have dealt with the mechanical analysis of
the single fibers, mainly because mechanical characterization at the single fiber scale
is difficult, especially when the diameter is as small as 10 mm. Transverse properties
have received even less attention.
The transverse compression test consists of compressing diametrically a circular
disk or right circular cylinder of material between two parallel and rigid plates. Diam-
etral compression tests were first presented in the 1950s. Carniero and Barcellos (1953)
from Brazil and Akazawa (1953) from Japan presented almost simultaneously studies
at a conference of the International Association of Testing and Research Laboratories