What the Designer Should Know About Fracture Mechanics Fundamentals

This design oriented paper provides an introduction to the fracture mechanics parameters controlling below-yield-strength fractures and subcritical crack growth, due to either fatigue loading or environmental attack. Emphasis has been placed on those basic fracture control concepts, which can aid the designer in material selection, to prevent the above mentioned occurrences. The major concepts that have been outlined within the paper are: the elastic crack tip stress field and its magnitude as measured by the stress intensity factor, the relationship between the stress intensity factor and the material's fracture toughness, the small scale yield model and the plastic zone correction, the relationship between the range in the stress intensity factor and the rate of fatigue crack growth, and a quantitative measure of a material's resistance to environmental attack under static loading.