Funded PhD Thesis : Development of X-ray phase-contrast imaging method for the analysis of lightning-struck aeronautical materials

Replacing aluminum by carbon fiber composites (CFRP) in the aeronautic industry is a research effort towards sustainable aviation. But compared to aluminium, CFRP have lower thermal and electrical conductivities and a sheet-like structure, meaning that there is a larger risk of thermo-mechanical damage if lightning strikes occur. A better understanding of the physical phenomena leading to this type of damage would enable aircraft manufacturers to make a reliable assessment of the type of lightning protection they need to put in place to further optimize aircraft weight and materials management.

In situ investigation of materials requires the use of X-rays. However, images of CFRP, which are light materials, have low contrast if the imaging method is based solely on X-rays absorption (absorption contrast imaging or radiography). ONERA and CEA are therefore developing innovative imaging methods that also exploit X-rays deflection (phase contrast imaging or XPCI). The related imaging bench has recently provided tangible results to characterize the core damage of CFRP stricken on the ONERA lightning test bench (post-mortem analysis). These results have aroused strong industrial interest and led to the award of an ANR research grant.

In this thesis, you will use the XPCI numerical simulation tools of CEA and material damage tools of ONERA to develop XPCI imaging of CFRP impacted by lightning. The modelled images will be compared with experimental images to help in the interpretation and analysis of damage. Developments will be guided by the long-term objective of dynamically imaging CFRP damage during lightning strikes on ONERA's lightning test bench.