Multi-Scale Modelling of the Fatigue and Fracture of Aerospace Alloys

The drive for greater fuel efficiency is making the production of lightweight structures with adequate strength and endurance a primary concern for the aerospace industry. A damage-tolerant approach is being developed to predict the fatigue life and optimise the design of thinner parts. Cracks are allowed in parts of an aircraft but must be frequently monitored to assess the tolerance of the structure and the need for repair or replacement.

While the propagation of relatively long cracks is well understood, the formation of short cracks and their early microstructure-dependent propagation requires more advanced research in order to develop effective life prediction models. This project will aim to model fatigue crack propagation from the nucleation phase (stage I), the transition towards a microstructure-independent crack (stage II) and final failure (stage III) for aerospace alloys.

A multi-scale approach will be developed combining crystal-plasticity finite element modelling to simulate the deformation of microstructures, novel crack propagation simulation techniques and scale-transition algorithms. The model will be informed and validated using full-field strain measurement techniques such as Digital Image Correlation, grain orientation measurements using Electron-Back Scattered Diffraction and new experimental procedures. Fatigue testing will be carried out using the University of Sheffield’s state-of-the-art facilities.