A study on fracture of components With short cracks using threshold Methods

Abstract

The concept of defect tolerant design is perhaps the major newlinejustification for the use of fracture mechanics This concept accepts the newlinepossibility that an element remains useful when it has been subject to damage newlineupon fabrication transportation or even after several years in service Such newlinedamage is often manifested by cracking Of particular importance when newlineadopting a defect tolerant design approach are the concepts of safety and newlinedurability newlineBoth safety and durability requirements can be satisfied by newlineconsidering initial damage in the component and assuring that such damage newlinedoes not grow and reach specific limits in the prescribed time intervals newlineDefect tolerant approaches to fatigue design are commonly newlineemployed in which the Stress Intensity Factor SIF is calculated and limits newlineare imposed on the values using conventional Linear Elastic Fracture newlineMechanics LEFM methodologies But these conventional approaches were newlinereported to be unconservative when the crack size is very small and of the newlineorder of 100 m or less Pearson 1975 Dowling 1976 The challenges newlineinvolved in obtaining reliable results on stress intensity factors SIF for newlinegeometries with short cracks have been discussed in detail by many newlineresearchers newline newline