Fatigue '87. Papers presented at the International Conference on Fatigue and Fatigue Threshold (3rd) Held in Charlottesville, Virginia on June 28-July 3, 1987. Volume 1

摘要

Fracture by the progressive growth of incipient flaws under cyclically varying loads, i.e., by fatigue, must now be considered as the principal cause of in-service failures of engineering structures and components, whether associated with mechanical sliding and friction (fretting fatigue), rolling contact, aggressive environments (corrosion fatigue), rolling contact, aggressive environments (corrosion fatigue), or elevated temperatures (creep-fatigue). Of particular importance are the early stages of fatigue damage, involving the initial extension of microcracks and their subsequent growth at very low velocities, as these processes tend to dominate overall lifetime. This has been reflected by trends in fatigue research over the past five years, which have focused largely on so-called 'small cracks,' of dimensions comparable with the scale of microstructure or local plasticity, and on crack growth in the near-threshold regime, i.e., at stress intensities approaching the fatigue threshold below which cracks are presumed dormant. In addition, associated mechanistic studies have highlighted the critical role of crack tip shielding in fatigue, which arises predominantly from crack closure and deflection, and this has proved to be important in modeling aspects of environmentally-assisted cracking and behavior under variable amplitude loads, and in rationalizing the classical stress/strain-life and defect-tolerant design approaches. The series of international conferences 'Fatigue '87' covered a wide range of diverse views of the fundamental and applied aspects of fatigue. This included questions of cyclic deformation, crack initiation and propagation, small cracks, crack closure, variable amplitude effects, and environmentally-influenced behavior.