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Fracture studies of structural elements have been revolutionized in the last 50 years by the analysis of their sensitivity to flaws or cracklike defects. Within these studies an essential ingredient is reasonable and proper stress analysis especially with regard to flaws with high local elevations of stresses from which fractures progress through various crack propagation mechanisms, including corrosion and fatigue cracking.

Full studies of fracture behavior cover both the stress analysis aspects and the material behavior in terms of resistance to the stresses imposed. However, the purpose here is limited to the development of significant stress analysis details and relevant parameters, and to the compilation of available stress analysis results with cracks present insofar as they may be foreseeably related to actual fracture studies.

The redistribution of stress in a body caused by introducing a crack or notch may be solved by methods of linear-elastic stress analysis. Of course the greatest attention should be paid to the high elevation of stresses at or surrounding the crack-tip, which will usually be accompanied by at least some plasticity and other nonlinear effects. Nevertheless linear-elastic stress analysis properly forms the basis of most current fracture analysis, at least for “small scale yielding” where all substantial nonlinearity is confined within a linear-elastic field surrounding the crack-tip. Consequently, the character and significant parameters of linear-elastic crack-tip fields are examined first.