Research project: Micromechanistic analysis of damage evolution in aerospace and automotive materials - Dormant - Dormant

In this Airbus sponsored project the micromechanisms of fatigue crack propagation in model and conventional airframe alloys are being investigated via in situ experiments at the European Synchrotron Radiation Facility (ESRF).  This analysis allows the investigation of the effects of crack closure and stress state on fatigue crack propagation during constant amplitude and post-overload growth in high strength Al-alloys.  The results have informed the development and are being used as part of a wider experimental programme to validate a multi-mechanism based analytical model of crack growth.

The micromechanisms of fatigue crack growth have also been assessed in Al-Si casting alloys.  These alloys contain many alloying additions and therefore exhibit a multiphase microstructure.  As such the evolution of damage during the lifetime of a fatigue crack is a complex process that is dependent on the mechanical properties, morphology, size and interconnected nature of the constituent phases.  High resolution X-ray tomography has been used as part of a large experimental programme to gain an in-depth understanding o the influence of the microstructure in all stages of fatigue life.

Recent work has also been performed at ESRF to gain a greater understanding of the micromechanisms of failure in composite materials during tensile deformation.  Using X-ray CT it was possible to capture the development of the complex damage evolution in these materials, for example the inter and intra lamina failure and individual fibre breakage.  These results will inform the development of a cohesive zone model, which may then be used to predict the damage tolerance of composite materials in a computationally efficient manner.