TABLE OF CONTENTS The applied mechanics framework for study of the behaviour of cracked bodies under load is known as fracture mechanics. The application of fracture mechanics to fatigue crack propagation is well established, and most modern books on metal fatigue include an introduction to the topic. The account below is based on Frost et al. (1974) and Pook (2000a, 2002a). These books include numerous references. The book by Frost et al. was the first on metal fatigue in which a fracture mechanics approach was used throughout. It was reprinted in 1999.
Fracture mechanics does not provide any information about the processes involved in fatigue crack propagation. It does provide the descriptive and analytic framework needed for their characterisation, and for the application of fatigue crack propagation data to practical engineering problems.
Simplifying assumptions have become conventional in much present day fracture mechanics, and these are satisfactory for many purposes. The material is assumed to be a homogeneous isotropic continuum, and its behaviour is assumed to be linearly elastic. Crack surfaces are assumed to be smooth, although on a microscopic scale they are generally very irregular. Modifications are made to basic linear elastic fracture mechanics theory to allow for the actual behaviour of real materials. The basic ideas in linear elastic fracture mechanics are straightforward. The mathematics involved is often formidable, but does lead to the useful and easily applied key concept of stress intensity factor, which describes the elastic stress and displacement fields in the vicinity of...
