Paper 19: Stress Analysis in the Design of Flawed Structures

Sophisticated structures with severe operating conditions may provide a potentially serious safety hazard if failure were to occur. The conventional margins of safety of the nominally perfect structure may be inadequate as a basis for discussing the real strength because flaws will probably exist in the materials from fabrication, or by development during service from fatigue or corrosion. The role of linear elastic and yielding fracture mechanics for assessing the strength of flawed structures is reviewed for static, impact fatigue, and environmental conditions. It is concluded that for those problems that warrant such treatment, the basic knowledge exists whereby the initiation, and particularly the propagation, of cracks on the macroscale can be studied near quantitatively during the design process.