Fatigue in ship structures - new light on an eternal issue

摘要

All steel, when overloaded, will fail, and one of the most common failure modes is by fracture. Where the material is subjected to cyclic loading, the fracture is generally associated with reaching a fatigue limit at a stress that is considerably below its ultimate strength. Fatigue failure - or more accurately, fracture resulting from the initiation and propagation of a fatigue crack - can be particularly insidious. Small fatigue cracks can easily start and grow undetected and, like old age, can creep upon one until the ailment becomes suddenly and unpredictably all too real. Fatigue cracks can only initiate from a free surface. Guy Gibbons", RCNC, hopes to throw some new light on a perennial issue. Although written by an expert on naval vessels, the subject is applicable to all hull types. In a second part, in a future issue, the author will examine the subject of fracture.