The thesis reviews the literature concerning the high- and low-strain fatigue
which is pertinent to the nucleation of cracks during cyclic stressing.
The methods of investigating the crack nucleation process are discussed with the
disadvantages of each method stated. The thesis deals mainly with the examination
of the cracks by surface replication and electron microscopy.
A direct carbon replica technique is described which allows the results of
macroscopic as well as microscopic deformation to be followed during both low
and high strain fatigue. The microscopic deformation (slip) produced an overall
macroscopic deformation producing an undulating surface topography with accompanying
grain rotations and displacements. The stereoscopic electron micrographs
prepared from OFHC copper subjected to fatigue at room temperature have
shown that the grain boundaries slip at their common interface at the surface
when subjected to a cyclic shear strain. [Continues.]
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.