TABLE OF CONTENTS The term fatigue design is a misnomer, what is meant is assessment of an existing design against the possibility of fatigue failure. The possibility of failure due to metal fatigue is only one of the factors that have to be considered during the design of an engineering component or structure. Usually, fatigue behaviour is checked only after basic design decisions have been taken. There are many successful structures which have been designed without any specific attention to the possibility of fatigue failure. A fatigue assessment sometimes shows that an initial design has to be modified in order to ensure that the product performs as required for its intended lifetime. Where the possibility of fatigue failure is a major preoccupation, design and fatigue assessments are integrated in an iterative approach.
When a fatigue failure does occur, under product liability legislation, anyone connected with the design, manufacture, supply, servicing, repair or operation of the product might find themselves in the position of being held legally responsible for personal injury and material damage caused by the failure (Anon. 2001a). Modifications carried out without consulting the original designer are a frequent cause of fatigue failure, for example Pook (1998). Many authors, for example Jones (2003), have drawn attention to the importance of analysing fatigue failures so that future designs may be modified to avoid similar failures.
In broad terms, if not in detail, the mechanisms of metal fatigue are not very complex (see Section 3.4), and a century and...
