EC3 Fatigue Damage in Steel Welds.xls

Calculation Reference
Gene Mathers from TWI has written an overview of fatigue.

This ESDEP lecture gives an explanation of the mechanism of fatigue and the influence of welding on that mechanism. It summaries the primary factors affecting fatigue strength and introduces S-N Curves. The classification of fatigue details is presented and important details reviewed. The calculation of stress range is summarised. The principal types of fatigue loading and the bases for their calculation are presented with an introduction to cycle counting and damage calculations for mixed amplitude loading.

The data on fatigue strength given in Eurocode 3 [1] are briefly reviewed in this ESDEP lecture . The strengths of longitudinal and transverse welds are related to the quality of workmanship. The need for inspection and the limitations of non-destructive testing are examined. The implications for economic design, detailing and specification are set out.

The geometric stress concept and the classification method used for the fatigue design of hollow section joints are discussed in more detail and illustrated by design examples in this ESDEP lecture. Guidelines and simplified design graphs are given to give insight into the stress concentration factors to stimulate optimal design.

This ESDEP lecture introduces improvement techniques primarily as remedial measures for welded structures. Initial analyses of the reasons for the poor fatigue performance of welded joints leads to a classification system for improvement methods. The various methods used in practice are then described and evaluated. The methods described are:
    The AWS improved profile
    The use of special electrodes
    Grinding
    Weld toe remelting
    TIG dressing
    Plasma dressing
    Hammer peening
    Shot peening
Guidance on current design rules is summarised; the need for improvement to design standards and guidance is highlighted.

Fatigue Structures
EC3 Steel