In search of the lighter materials and optimized thin-walled components especially for transportation purposes, knowledge about the characteristic ductile damage mechanisms related to their failure, reliability, lifetime etc. in aluminium sheets is crucially needed in manyfold engineering application. Recent reserach has addressed a complex and empirical relationship between strain to fracture and low stress triaxiality below 1 [1] but physical damage mechanisms still remain unclear. Initial void shapes and their shape changes during deformation may be at the origin of the unexpected material failure. In addition, the stages of void nucleation, void shape change and void coalescence are still poorly understood as they are hardly observed experimentally maintaining relevant stress conditions [2]. To overcome the inherent shortcomings of other 3D technique on flat sample, advanced techniques in situ synchrotron microlaminography and ex situ nanolaminography provide information from a few hundred micrometers resolution down to the nanometer scale, allowing the ductile damage nucleation and growth kinetics in metal sheets to be studied. A ‘smiley’ shear sample geometry [3] of 1 mm thick sheet made from a latest generation of recrystallized Al-Cu-Li alloy 2198 in T8 condition [4] is chosen to study its shear damage mechanisms down to 50 nm (voxel size) resolution for a test stopped before fracture. The damage features, including oriented cluster of micro-void cracks and damage linked to intermetallic particles, are found at highly-deformed shear band region. The detrimental flat cracks are proved to be intergranular via EBSD analysis. Cracks are also found to nucleate with intermetallic particles and grow during shearing, due to the constraint of the stiff particles. Shear bands on micrometer scale and dispersoids on nanometer scale are observed via SEM, and the latter are probably linked to the onset of micro-void nucleation by fractography of the fractured in situ sample. Reference [1] Y. Bao, et al., On fracture locus in the equivalent strain and stress triaxiality space, Int. J. Mech. Sci., 46 (2004), 81-98 [2] T. Petit et al., Effect of hardening on toughness captured by stress-based damage nucleation in 6061 aluminium alloy, Acta. Mater., 180 (2019), 349-365 [3] C. C. Roth, D. Mohr, Determining the strain to fracture for simple shear for a wide range of sheet metals, Int. J. Mech. Sci., 149 (2018) 224 – 240. [4] J. Chen, Ductile tearing of AA2198 aluminium-lithium sheets for aeronautic application, PhD thesis (2011)