PhD with Airbus in Integrated Computational-Experimental Study of Microstructurally Short Crack Propagation in AA7xxx alloys

This project is a joined initiative between Airbus and The University of Manchester.

New generation 7xxx series (Zn-Mg-Cu) Al alloys are commonly used materials in aircraft structural applications due to their high specific strength and low production costs. However, the alloys can exhibit an increased suscepti bility to environmentally assisted cracking (EAC). The EAC performance of these alloys is thus an area of growing concern for the aerospace industry. In particular, the critical early stages of EAC is currently poorly understood with little published research. This project will thus aim to improve understanding of the initiation of cracks and specifically how microstructurally-short cracks grow, and their transition to a viable long crack which may go on to cause failure. During the short-crack phase, growth is dominated by the specific crack-front geometry and microstructural interactions, such as neighbouring cracks and grain boundaries. However, existing models for short-crack driving forces neglect these details and are thus limited in their predictive capability.

The aim of this project is to refine existing crack growth models, to be more realistic of the early stages of crack growth, by considering the spatially-resolved crack-front geometry and microstructural interactions. Temporally and spatially resolved 3D X-ray computed tomography (CT) data of crack propagation from state-of-the-art in-situ testing will be directly imported into FE simulations to obtain the crack tip stress field and a local description of crack-front driving forces. The objective is to complement existing global crack-propagation models with local microstructural detail. This will provide insight into why some cracks propagate to form long cracks, whilst other cracks arrest whilst they are still small, and why in some cases the growth of arrested cracks restarts.

The project is with Airbus, a leading pan-European international company. The student will spend time with Airbus technical experts to gain an understanding of their commercial operation, and will link with the Airbus Centre of Metallurgical Excellence, a joint initiative between Airbus and The University of Manchester with ~20 researchers, for which Airbus hold an annual student conference to facilitate networking amongst their PhD students spread across Europe. For more information please contact Dr Pratheek Shanthraj ([Email Address Removed]).