Shear mechanical properties measurements at the surface scale: Enhanced performances of the micro-shear compression specimen

An intensive study combining experimental tests and numerical simulations was carried out to improve the understanding of the micro-shear test using the Micro-shear Compression Specimen (MCS). The results demonstrated good data reliability in the elastic regime up to the yield stress. However, the study also revealed that friction between the flat punch and the MCS significantly affects the plastic regime, and must therefore be accounted for to accurately extract shear mechanical properties. To overcome this limitation, two alternative methods were developed. The first one consists in compressing a new type of micro-shear compression specimen, featuring two perpendicular gauges forming a cross geometry (X-MCS). The second consists of applying multicycle loading to the conventional MCS. Both approaches successfully eliminated friction dependence in the plastic regime, in contrast to the classical method. Finally, the X-MCS geometry was applied to very high strain rate testing on fused silica. Thanks to the small gauge height of the X-MCS, it was possible to measure shear mechanical properties at a strain rate of 10 4 s -1 , which was not achieved using conventional micropillar compression with our micromechanical setup. These methods provide a new pathway for extracting shear mechanical properties, which are critical in the field of tribology, where surfaces are subjected to intense shear deformation.