On the application of the theory of critical distances to the structural integrity assessment of stress risers

Purpose
– The purpose of this paper is to present and validate a methodology for the structural integrity assessment of components containing a variety of stress risers and subjected to static conditions.

Design/methodology/approach
– The methodology is based on the use of the apparent fracture toughness prediction provided by the theory of critical distances (in this case, the line method), together with a well‐known, widely‐used engineering tool in structural integrity assessments: failure assessment diagrams. In order to validate the proposed methodology, an experimental programme has been conducted, testing 38 specimens made of aluminium alloy Al7075‐T651, each of them containing a certain stress riser. The comparison between the experimental results and the corresponding predictions provided by the proposed assessment methodology has also allowed the situations for which the theory of critical distances provides accurate predictions to be defined.

Findings
– The results show that the methodology provides accurate results as long as the Neuber number, defined as the notch radius divided by the critical distance (L), is sufficiently low. In order to extend the validity to situations where the Neuber number is higher, it is necessary to calibrate L by using notched specimens with similar radii to those found in the defects being analysed.

Originality/value
– The present study is part of Virginia Madrazo’s doctoral thesis, an original research work.