Editorial for special issue on structural integrity and failure

Abstract

This special issue of FFEMS was compiled from 108 papers presented at the International Conference on Structural Integrity and Failure (SIF 2010) held at The University of Auckland, Auckland, New Zealand on 4–7 July 2010, with the exception of the opening paper which was contributed by the first guest editor. Fifteen selected authors were invited to extend their papers for this issue, resulting in a total of ten papers from the following countries: Australia, Canada, China, Hong Kong, New Zealand and South Korea. The selection of papers in this issue highlights fracture mechanics as a discipline describing failure in a diverse range of materials and machine systems. From nanocomposites (Liao & Tjong) to large aircraft components (Jaya, Tiong & Clark), the papers here also represent the significance of multi-scalar approaches, which are increasingly becoming important to solving many of today's intriguing fracture mechanics problems. Brittle or ductile, homogeneous or composite, materials fail almost invariably due to developments at the micro-level, with small defects and discontinuities. The papers by Suh et al. present in fine detail the initiation of such minuscule surface crack formation, its coalescence and growth in stainless steel and Waspaloy. The studies in this issue, such as those on novel methods in micro-indentation to determine KIc of brittle materials (Xie et al.) and computer simulation of the split sleeve hole cold expansion process (Houghton & Campbell), also illustrate the importance of both experimental and modelling techniques to traverse complex realities and concepts in fracture mechanics and material analyses. Validation of current concepts, theories and models is crucial, and in the study by Clegg, Duan & McLeod the authors experimentally investigate the validity of the theory of critical distance (TCD) by analyzing fatigue behaviour of disc-shaped compact tension and notched cylindrical steel specimens. Several of the papers in this issue are concerned with novel aspects of fatigue. For example Merati, Hellier & Zarrabi have obtained, using a unique mixed-mode test rig, Mode II–Mode III fatigue threshold interaction diagrams for two common aluminium aerospace alloys. Representative fatigue fracture surfaces are also presented. Small fatigue cracks can initiate under shear loading at lower applied loads than for Mode I, and then later turn into unexpectedly large Mode I cracks. In addition, the important role of our field of study in the area of forensics is highlighted in the paper by Withy, James & Williams, where careful post-mortem analyses of wear and cracking has led to new insight on the level of safety in present fuel pump design in aircraft. The paper by Jaya, Tiong & Clark further addresses important issues pertaining to current failure of aircraft joints, and offers solutions including one involving the novel application of corrosion-inhibiting compounds. Finally, the paper by Conor et al. provides evidence from a set of investigations that support the need for a systems approach to failure analysis of aircraft structure and propulsion defects, when causal factors are complex. Effective failure avoidance can be achieved in this way. This special issue serves as a testament to the active support for the SIF conference as well as the efforts of the international fracture community to continue a collective and integrated academic approach to achieving excellence in this significant area of engineering and materials science research. We are grateful to all the authors and reviewers for their invaluable contribution and thank you, the reader, for your interest in this issue. We are especially grateful to the journal for the opportunity to put together this special issue.