In this paper a new design approach for predicting fatigue life-the st
ress field intensity approach-is presented from the point of view of m
acromechanics on the basis of the mechanism of fatigue damage of metal
s. In this new approach the stress field intensity over the local regi
on of damage, instead of the stress peak value as in the local stress-
strain approach, was taken as the parameter with which to measure the
fatigue strength of structures. Many fatigue phenomena, which the nomi
nal stress approach and the local stress-strain approach could not exp
lain, can be explained reasonably in this new approach.