Guide on the Effective Block Approach for the Fatigue Life Assessment of Metallic Structures
DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
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Simpler empirical characterisation of the mechanics of metal fatigue crack growth can offer an alternative to physics-based models, where the latter can be challenged by complex material behaviour of commercial metals when loaded by variable amplitude spectra. Such characterisation is anticipated to be more appropriate for cases where the loading consists of repeating blocks of spectra or other scenarios that result in near steady-state crack growth rates. This report examines the many types of characteristic block approaches available, and recommends a particular type that is considered suitable for fatigue life assessments, herein titled the Effective Block Approach, or EBA. Guidance is given on methods and implementation and several case studies are reviewed where the EBA has been used to assess the life of RAAF airframes. In addition to computational efficiency, significant accuracy gains were achieved when the approach was underpinned by representative coupon tests. This capability is anticipated to give the RAAF more options to better assess and manage the safety, availability and cost of ownership of its air vehicles.
- Inorganic Chemistry