Rules for the assessment of interacting surface cracks under mode I load

A review of the current widely used methods for the assessment of adjacent and coplanar surface cracks under LEFM conditions shows them to be neither realistic nor always safe, having little scientific basis. Since such cracks can interact they cannot necessarily be assumed to be independent, so improved methods of accounting for the interaction are required and are provided by this work. In a companion paper a continuous method of estimating the interaction factors for two coplanar surface cracks was developed and proven. This enables realistic predictions of crack interaction and growth and is used as a basis for comparison of simpler assessment methods, the crack interaction estimation being somewhat cumbersome for general use. The assessment methods developed are thus shown to be safe. Furthermore they are realistic and straightforward to use. Cracks under tension, bending, and combined tension and bending load are considered.